Functional Anatomy of the Cervical Spine: Difference between revisions

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<div class="editorbox"> '''Original Editor '''- [[User:Robin Tacchetti|Robin Tacchetti]] based on the course by [https://members.physio-pedia.com/course_tutor/daphne-xuan/ Daphne Xuan]<br>
'''Top Contributors''' - {{Special:Contributors/{{FULLPAGENAME}}}}</div>


== Introduction ==
== Introduction ==
The cervical spine supports and promotes movement of the head and neck. <ref>Frost BA, Camarero-Espinosa S, Foster EJ. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6356370/ Materials for the spine: anatomy, problems, and solutions]. Materials. 2019 Jan;12(2):253</ref> <ref name=":0">Kaiser JT, Lugo-Pico JG. [[Anatomy, Head and Neck, Cervical Vertebrae]]. 2019.</ref>The cervical spine is subjected to extrinsic factors such as repetitive movements, whole body vibrations and static load.<ref>Petersen JA, Brauer C, Thygesen LC, Flachs EM, Lund CB, Thomsen JF. [https://bmjopen.bmj.com/content/12/2/e053999 Prospective, population-based study of occupational movements and postures of the neck as risk factors for cervical disc herniation]. BMJ open. 2022 Feb 1;12(2):e053999.</ref>  
The cervical spine supports the weight of the head and enables head and neck movement.<ref>Frost BA, Camarero-Espinosa S, Foster EJ. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6356370/ Materials for the spine: anatomy, problems, and solutions]. Materials. 2019 Jan;12(2):253</ref> <ref name=":0">Kaiser JT, Reddy V, Lugo-Pico JG. Anatomy, Head and Neck: Cervical Vertebrae. [Updated 2022 Oct 6]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539734/</ref> Intervertebral discs maintain the spaces between the vertebrae. These discs act like shock absorbers throughout the spinal column to cushion the bones as the body moves. Ligaments hold the vertebrae in place, and tendons attach the muscles to the spinal column. The cervical spine is subjected to a range of extrinsic factors such as repetitive movements, whole-body vibrations and static load.<ref>Petersen JA, Brauer C, Thygesen LC, Flachs EM, Lund CB, Thomsen JF. [https://bmjopen.bmj.com/content/12/2/e053999 Prospective, population-based study of occupational movements and postures of the neck as risk factors for cervical disc herniation]. BMJ open. 2022 Feb 1;12(2):e053999.</ref>[[File:C-spine-picture.jpg|thumb|250x250px|Cervical spine]]
 
== Key Terms ==
== Key Terms ==
[[Cardinal Planes and Axes of Movement|Axes]]: lines around which an object rotates. The rotation axis is a line that passes through the centre of mass. There are three axes of rotation: ''sagittal'' passing from posterior to anterior, ''frontal'' passing from left to right, and ''vertical'' passing from inferior to superior. The rotation axes of the foot joints are perpendicular to the cardinal planes. Therefore, motion at these joints results in rotations within three planes. Example: supination involves inversion, internal rotation, and plantarflexion.
[[Cardinal Planes and Axes of Movement|Axes]]: lines around which an object rotates. The rotation axis is a line that passes through the centre of mass. There are three axes of rotation: ''sagittal'' passing from posterior to anterior, ''frontal'' passing from left to right, and ''vertical'' passing from inferior to superior. The rotation axes of the foot joints are perpendicular to the cardinal planes. Therefore, motion at these joints results in rotations within three planes. Example: supination involves inversion, internal rotation, and plantarflexion.


[[Bursitis|Bursae]]: reduce friction between the moving parts of the body joints. A bursa is a fluid-filled sac. There are four types of bursae: adventitious, subcutaneous, [[/www.physio-pedia.com/Synovial Fluid Analysis|synovial]], and sub-muscular.
[[Bursitis|Bursae]]: reduce friction between the moving parts of the body joints. A bursa is a fluid-filled sac. There are four types of bursae: adventitious, subcutaneous, [[Synovial Fluid Analysis|synovial]], and sub-muscular.


[[Capsular and Non-Capsular Patterns|Capsule]]: one of the characteristics of the synovial joints. It is a fibrous connective tissue which forms a band that seals the joint space, provides passive and active stability and may even form articular surfaces for the joint. The capsular pattern is "the proportional motion restriction in range of motion during passive exercises due to tightness of the joint capsule."
[[Capsular and Non-Capsular Patterns|Capsule]]: one of the characteristics of the synovial joints. It is a fibrous connective tissue which forms a band that seals the joint space, provides passive and active stability and may even form articular surfaces for the joint. The capsular pattern is "the proportional motion restriction in range of motion during passive exercises due to tightness of the joint capsule."


Closed pack position: the position with the most congruency of the joint surfaces. In this position, joint stability increases. For example, the closed pack position for the interphalangeal joints is a full extension.
Closed pack position: the position with the most congruency of the joint surfaces. In this position, joint stability increases. For example, the closed pack position for the interphalangeal joints is full extension.


Degrees of freedom: the direction of joint movement or rotation; there is a maximum of six degrees of freedom, including three translations and three rotations.
Degrees of freedom: the direction of joint movement or rotation; there is a maximum of six degrees of freedom, including three translations and three rotations.
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== Cervical Spine Structure ==
== Cervical Spine Structure ==


=== '''Cervical vertebrae''' ===
=== Cervical Vertebrae===
There are seven lumbar vertebrae, which are known as C1-C7.   Considering the small weight-bearing load of the cervical spine, large vertebral bodies are not required. In this section of the spine, vertebral size is not as important as flexibility and range of motion. Increased movement correlates to a heightened injury potential of the spinal cord and its associated neurovascular structures.<ref name=":0" />
There are seven cervical vertebrae, which are known as C1-C7. Their role is to support the head and neck and to promote head movement. The cervical spine is only exposed to small weight-bearing loads. Therefore, the cervical vertebral bodies do not need to be large and "an increased range of motion takes priority over vertebral size and rigidity".<ref name=":0" /> However, because of this increased range of motion at the cervical spine, there is a heightened injury risk for the spinal cord and the associated neurovascular structures.<ref name=":0" />
 
The cervical vertebral bodies (C3-C6) have unique characteristics:<ref name=":0" /><ref name=":1">Teach me anatomy The cervical Spine Available from:https://teachmeanatomy.info/neck/bones/cervical-spine/</ref>


* Vertebral body
* vertebral bodies are smaller compared to the rest of the spine
** Triangular vertebral foramen
* vertebral foramen is triangular
** Bifid spinous process – spinous process splits into two distally
* spinous process is bifid (i..e. it splits into two distally)
** Transverse foramina – holes in the transverse processes.
* there are openings in the transverse processes which allow passage for the vertebral artery, vein, and sympathetic nerves
*** space for vertebral artery, vein and sympathetic nerves<ref name=":1">Teach me anatomy The cervical Spine Available from:https://teachmeanatomy.info/neck/bones/cervical-spine/</ref>
<nowiki>**</nowiki> The C7 vertebrae has a singular and larger spinous process which is similar to those in the thoracic vertebrae.<ref name=":0" />


==== Atlas and Axis ====
The Atlas (C1), Axis (C2) and C7 have further distinguishing features:
The [[atlas]] and [[axis]] vary in their features from other cervical vertebrae.<ref name=":1" />


''he [[Atlanto-axial joint|atlanto-axial joints]] are formed by the articulation between the atlas and the axis:''
<div class="row">
<div class="col-md-8 ">[[Atlas]] (C1)<br>
* has no vertebral body or spinous process
* instead, it has lateral masses for articulation with the occiput of the head and the second cervical vertebra (the Axis)
</div>
<div class="col-md-4">[[File:Cervical vertebra 1 close-up bottom (1).png|thumb|200x200px|Atlas - C1]]<br>
</div>
</div>


* ''Lateral atlanto-axial joints (x2) – formed by the articulation between the inferior facets of the lateral masses of C1 and the superior facets of C2. These are plane type synovial joints.''
<div class="row">
<div class="col-md-8 ">[[Axis]] (C2)<br>
* has a bony projection from the anterior portion called the dens, or the odontoid process, which articulates with the atlas
* it is the primary weight-bearing bone of upper cervical region
</div>
<div class="col-md-4">[[File:Cervical vertebra 2 close-up bottom.png|thumb|200x200px|Axis - C2]]<br>
</div>
</div>


* ''Medial atlanto-axial joint – formed by the articulation of the dens of C2 with the articular facet of C1. This is a pivot type synovial joint.''
<div class="row">
<div class="col-md-8 ">C7<br>
* singular spinous process
* larger spinous process
* spinous process is not bifid
</div>
<div class="col-md-4">[[File:Cervical vertebrabifud.jpg|thumb|C3-C6]]<br>
</div>
</div>
<nowiki>**</nowiki>In supine, it may be difficult to palpate the spinous process of C3-C6 in individuals with normal cervical lordosis.


''The [[Atlanto-occipital joint|atlanto-occipital joints]] consist of an articulation between the spine and the cranium. They occur between then superior facets of the lateral masses of the atlas and the occipital condyles at the base of the cranium. These are condyloid type synovial joints, and permit flexion at the head i.e. nodding.   NEED REFERENCE''
=== Intervertebral Discs (IVD) ===
The intervertebral discs make up 25% of the height of the entire spine. However, in the cervical region, they make up 40% of the height. This increased height relative to vertebral body height provides a mobility advantage.<ref name=":2">Learn muscles . Cervical spine joints. Available from: https://learnmuscles.com/blog/2017/08/01/cervical-spinal-joints/ (last accessed 29.1.2020)</ref>


==== Atlas- need reference ====
The nucleus pulposus of the cervical discs is gelatinous in children and young people. However, it dries out by the age of 30 years and becomes a firm, fibrocartilaginous plate.<ref>Peng B, Bogduk N. [https://academic.oup.com/painmedicine/article/20/3/446/5232305?login=false Cervical discs as a source of neck pain. An analysis of the evidence.] Pain Medicine. 2019 Mar 1;20(3):446-55.</ref>[[File:Cervical Vertebra Unlabeled.jpg|thumb|Intervertebral disc]]
The atlas is the first cervical vertebra and articulates with the occiput of the head and the axis (C2). It has no spinous process or  vertebral body.  
The following are characteristics of the cervical spine intervertebral discs:


* lateral masses connected by arches
* thicker anteriorly than posteriorly
** anterior
* concave superior surface
*** articulates with dens of axis
* convex inferior surface
*** secured by transverse ligament of atlas
* movement limited by the uncinate process
** posterior
* anteroposterior translation does occur
*** groove for C1 spinal nerve and [[vertebral artery]]
* facets
** superior articular facet
*** articulates with occipital condyles
** inferior articular facet
*** articulates with C2


==== Axis- need reference ====
<nowiki>**</nowiki> Due to the location of the uncinate process, posterolateral disc herniations are less frequent.
=== Cervical Lordosis ===
Typically, the cervical spine has a lordotic curvature. A lordotic posture can resist large compressive loads. It also helps to decrease stress on vertebral end plates. Compressive loads are distributed differently in the cervical spine than in the thoracic and lumbar spine. In the cervical spine, the anterior column absorbs 36% of the load, and the posterior facet (zygapophyseal) joints absorb 64%.<ref>Guo GM, Li J, Diao QX, Zhu TH, Song ZX, Guo YY, Gao YZ. [https://josr-online.biomedcentral.com/articles/10.1186/s13018-018-0854-6 Cervical lordosis in asymptomatic individuals: a meta-analysis. J]ournal of orthopaedic surgery and research. 2018 Dec;13(1):1-7.</ref>
== Kinematics and Joints of the Cervical Spine ==
[[File:Cervical spine exercises.png|thumb|Range of Motion in Cervical Spine]]
The cervical spine is the most mobile part of the vertebral column. 


* C2 has an odontoid process (dens)
'''Flexion''' range of motion is usually around 40 degrees, and extension is around 50 degrees. The largest contributors to flexion/extension are:   
** extends superiorly from the anterior portion of the vertebra
** articulates with the anterior arch of the atlas creating atlanto-axial joint
*** facilitates rotation of the head independently from torso


== Intervertebral Disc (IVD) ==
* C4/C5 and C5/C6 in sitting
In general, intervertebral discs involve 25% of the height of the entire spine.  In the cervical region, the discs compromise 40% of the height.  This increased height compared to vertebral body height gives the advantage of greater range of motion potential. <ref name=":2">Learn muscles . Cervical spine joints. Available from: https://learnmuscles.com/blog/2017/08/01/cervical-spinal-joints/ (last accessed 29.1.2020)</ref>Disks are thicker anteriorly than posteriorly to enable the lordotic curvature of the cervical spine. The nucleus pulposus of cervical discs dries out by the age of 30 to a firm, fibrocartilaginous plate.<ref>Peng B, Bogduk N. [https://academic.oup.com/painmedicine/article/20/3/446/5232305?login=false Cervical discs as a source of neck pain. An analysis of the evidence.] Pain Medicine. 2019 Mar 1;20(3):446-55.</ref>
* C6/C7 in supine
* Coronal plane
** concave superior surface 
** convex inferior surface to conform to adjacent vertebral bodies
** movement limited by uncinate process
** anteroposterior translation does occur
<nowiki>**</nowiki> Due to location of uncinate process, posterolateral disk herniations are less frequent


* Cartilaginous endplate
C7/T1 contributes the least to flexion/extension.  
** composed of hyaline cartilage
** located adjacent to the subchondral bone.
** serves as a barrier to nucleus pulposus pressure on the vertebral body
*** limiting protrusion.


* ''The ALL and the posterior longitudinal ligament (PLL) are confluent with the outer fibers of the annulus<ref>Musculoskeletal Cervical spine Available from:https://musculoskeletalkey.com/cervical-spine-anatomy/ </ref>''
'''Lateral flexion''' range of motion is normally close to 30 degrees. C3/C4 and C6/C7 allow for the most movement in this plane of motion.


''<br />''
Cervical '''rotation''' range of motion is usually close to 70 degrees. Flexibility in this plane is mainly achieved through the C1/C2 segment.<ref>Lindenmann S, Tsagkaris C, Farshad M, Widmer J. [https://link.springer.com/article/10.1007/s10439-022-03088-8 Kinematics of the Cervical Spine Under Healthy and Degenerative Conditions: A Systematic Review]. Annals of Biomedical Engineering. 2022 Dec 10:1-29.</ref>
{| class="wikitable"
{| class="wikitable"
|+
|+'''Joints of the Cervical Spine'''<ref name=":2" /><ref>RSNA Joints of Luschka Available from: https://pubs.rsna.org/doi/10.1148/66.2.181 (last accessed 28.1.2020)</ref>
!Joints
!Joint
!Disc Joint
!Location/Articulations
!Facet Joint or Zygapophyseal joints
!Function
!Uncovertebral
!Orientation/Composition
|-
|'''Intervertebral Disc Joint'''
|
* <small>Between the vertebral bodies</small>
|
*<small>Bear weight</small>
* <small>Facilitate motion</small>
* <small>Absorb shock</small>
|
|-
|<small>'''Facet (Zygapophyseal) Joints'''</small>
|
* <small>Formed by articulations between the superior and inferior articular processes of adjacent vertebrae</small>
|
*<small>Guide motion at the segmental level</small>
* <small>Determine the direction of motion</small>
|
* <small>Upper cervical spine =  horizontal</small>
* <small>Lower cervical spine = more vertical</small>
|-
|-
|location/articulations
|<small>'''Uncovertebral Joint'''</small>
|between vertebral bodies
|
|formed by articulations of superior and inferior articular processes from adjacent vertebrae
*<small>Between the five lower cervical vertebral bodies</small>
* <small>Anteromedially to the nerve root</small>
* <small>Posteromedially to the vertebral artery</small>
|
* <small>Control movement</small>
* <small>Limit lateral flexion</small>
|
|
* between 5 lower cervical vertebral bodies
* anteromedially to nerve root
* posteromedially to vertebral artery
|-
|-
|functions
|<small>'''Atlanto-Axial Joint'''</small>
|
* <small>Between the atlas and axis</small>
* <small>Two lateral: interior facets of the lateral masses of C1 and superior facets of C2</small>
* <small>One medial: between the dens of C2 and the articular facet of C1</small>
|
|
# bear weight
* <small>Cervical rotation (60% of cervical rotation occurs at this joint)</small>
# facilitate motion
# absorb shock
|
|
# guide motion at the segmental level
* <small>Lateral: plane-type synovial joint</small>
# determine direction of motion
* <small>Medial: pivot-type synovial joint</small>
|small synovial articulationsto form anterior wall of foramen
|-
|-
|Orientation
|<small>'''Atlanto-Occipital Joint'''</small>
|
|
* <small>Between the spine and cranium</small>
* <small>Between the superior facets of the lateral masses of the atlas and the occipital condyles</small>
|
|
# upper c-spine- horizontal
* <small>Flexion and extension of the head on the neck</small>
# lower-more vertical
* <small>Lateral flexion</small>
|
|
* <small>Condyloid-type synovial joint</small>
|}
|}
<ref name=":2" /><ref>RSNA Joints of Luschka Available from: https://pubs.rsna.org/doi/10.1148/66.2.181 (last accessed 28.1.2020)</ref>
=== ''Lumbar Lordosis'' ===
''Lordosis = the natural curve for the lumbar spine. This curve defines lumbar spine alignment in the saggital plane. However, the pelvis is "the cornerstone of spinal sagittal alignment". The curve of the sacrum determines the lumbar curve.''
''The sagittal alignment of the lumbar spine offers two main benefits during locomotion:''
* ''Allows the body's centre of mass to be positioned above the hip, knee, and ankle joints''
* ''Minimises the muscular force used for postural control''
''Assessment of lumbar spine alignment must include an analysis of the alignment of the lower limbs. For instance, measuring the degree of knee flexion and pelvic shift might help clinicians identify compensatory mechanisms resulting from the sagittal plane malalignment.''


== ''Bones, Articulations and Kinematics of the Lumbar Spine'' ==
== Spinal Ligaments ==
=== ''Bones and Articulations'' ===
Ligaments present throughout the entire vertebral column:
''The lumbar spine has two types of joints located between each lumbar vertebra:''


# ''intervertebral disc joint''
# Anterior longitudinal ligament: anterior surface of the vertebral bodies; limits extension of the spine
# ''zygapophyseal joint or facet joint''
# Posterior longitudinal ligament: posterior surface of the vertebral bodies; limits flexion of the spine
# Ligamentum flavum: connects the laminae of each vertebrae; series of short ligaments
# Intertransverse ligament: a series of short ligaments that connect the laminae of each vertebrae; preserves upright posture and prevents hyperflexion of the spine<ref name=":3" />


{| class="wikitable"
{| class="wikitable"
|+
|+'''Ligaments Unique to the Cervical Spine'''
!'''''Bones'''''
!'''<small>Ligament</small>'''
!'''''Articulations'''''
!'''<small>Origin</small>'''
!'''''Characteristics'''''
!'''<small>Insertion</small>'''
!'''''Key palpation points'''''
!'''<small>Role/Function</small>'''
|-
|<small>'''Nuchal ligament'''</small>
|<small>Occiput</small>
|<small>Tips of the spinous process from C1-C7</small>
|<small>Limits hyperflexion</small>
|-
|<small>'''Transverse ligament'''</small>
|
|<small>Attaches to lateral masses of atlas</small>
|<small>Anchors dens in place</small>
|-
|<small>'''Apical ligament'''</small>
|<small>Dens of the axis</small>
|<small>Foramen magnum</small>
|Connects the dens of the axis to the foramen magnum
<small>Stabilises the skull on the spine</small>
|-
|-
|''Vertebral body''
|<small>'''Alar ligament'''</small>
|''Intervertebral disc joint''
|<small>Dens of the axis</small>
|''This joint is formed between the inferior surface of one vertebral body and the superior surface of the vertebral body that lies below (for example, the inferior surface of L1 and the superior surface of L2). An intervertebral disc separates the vertebral bodies.''
|<small>Occiput</small>
|''To find each segment of the lumbar spine, position the patient prone. The location of the spinous processes will determine the location of each segment. You can palpate the spinous processes in the centre of the patient's back.''
|Connects the dens of the axis to the occiput
''Start with finding T12 by palpating the patient's lowest rib and following your finger along the border of the rib towards the centre of the spine. The T12 spinous process is in line with the 12th rib (which inserts into T12 spinal segment). Below T12, you can palpate L1 and continue along the spinous process of L2, L3, and L4. If you start your palpation from the distal end of the lumbar spine, you must consider the following: the spinous process of L4 "is usually determined by the position of the highest point on both sides of PSIS", but the accuracy of palpation is only 36%.''
<small>Limits atlanto-axial rotation</small>
|-
|-
|''Articular processes''
|<small>'''Cruciform or cruciate ligament'''</small>
|''Zygapophyseal joint (Facet joint)''
|''Formed between the articular processes of each lumbar vertebra.''
''Located on the left and right sides of the spine.''


''They link one vertical segment to the other. For example, the facet joint between L3 and L4 will connect L3 to L4.''
<small>1. Superior longitudinal band</small>


''The superior articular surface is vertical and concave, and the inferior is vertically convex.''
<small>2. Inferior longitudinal band</small>


''Their primary role includes the stabilisation of the spinal motion segment. They also contribute to axial compressive load transmission.''
<small>3. Transverse band</small>
|''The facet joint CANNOT be directly palpated due to overlying soft tissue. When you move your fingers two to three centimetres in the lateral direction from the spinous process, you will be on the muscles overlying the '''facet joint.'''''
|
# <small>Superior: transverse band</small>
# <small>Inferior: transverse band</small>
# <small>Transverse: dens of the axis</small>
|
# <small>Superior: foramen magnum</small>
# <small>Inferior: second vertebral body</small>
# <small>Transverse: between the lateral masses of the atlas</small>
|<small>Holds dens in place</small>
|}
|}
<nowiki>**</nowiki> ligaments in spinal column


=== ''Kinematics'' ===
== Muscles of the Cervical Spine ==
''The lumbar spine is considered a three-joint complex or an articular triad. The zygapophyseal (facet) joints and intervertebral disc joint are part of a "spinal motion segment". The various parts of the spinal motion segment work together to allow spinal motion and to protect the spine from excessive movements.''
The muscles of the cervical spine can be divided by location or by function.[[File:Prevertebral neck muscles.png|thumb|271x271px|Anterior vertebral muscles]]


''The spinal motion segment has the following characteristics:''
=== Anterior (Prevertebral) Vertebral Muscles ===
* [[Rectus Capitis Anterior|Rectus capitis anterior]]
* [[Rectus Capitis Lateralis|Rectus capitis lateralis]]
* [[Longus Capitis|Longus capitis]]
* [[Longus Colli|Longus colli]]/ Longus cervicis (3 portions: superior oblique, inferior oblique, vertical)
These muscles are also known as the deep cervical (neck) flexors.


* ''The intervertebral disc joint transmits mostly vertical compressive loads''
=== Lateral Vertebral Muscles ===
* ''The facet joints guide and stabilise the motion segment''
[[Scalene|Scalenes]]
* ''In an erect standing position and erect sitting posture, spine load is also transmitted through the facet joints''


{| class="wikitable"
* [[Anterior Scalene|anterior]]
|+
* [[Middle Scalene|middle]]
!''Joint''
* [[Posterior Scalene|posterior]]
!''Type of joint''
* [[Scalenus Minimus|minimus]] (not always present)
!''Plane of movement''
!''Motion''
!''Kinematics''
!''Closed pack position''
!''Open pack position''
|-
|[[Intervertebral disc|''Intervertebral disc joint'']]
|''Cartilaginous joint, symphysis''
|''A single joint: structurally fused but allows very limited, multidirectional movements''
''All lumbar intervertebral disc joints and zygapophyseal joints combined together: Saggital Frontal Transverse''
|''Single joint: Translating, tilting, rocking and compressing movements.''
''All lumbar intervertebral disc joints and zygapophyseal joints combined together:''


''Flexion/extension''
[[File:Neck triangles.png|thumb|Lateral view of cervical muscles]]


''Lateral flexion''
=== Posterior Vertebral Muscles ===
These can be further divided into intrinsic and extrinsic muscles.


''Rotation''
==== Extrinsic muscles ====
|''All lumbar intervertebral disc joints and zygapophyseal joints combined together:''
''Flexion 60 degrees''


''Extension 25 degrees''
* [[Trapezius]]
* [[Levator Scapulae|Levator scapulae]]


''Lateral flexion 20-30 degrees''
==== Intrinsic muscles ====
[[File:Cervical Spine Muscles.jpg|thumb|500x500px|Posterior muscles of the cervical spine]]
* Superficial muscles :
** [[Splenius Capitis|splenius capitis]]
** [[Splenius Cervicis|splenius cervicis]]
* Deep muscles:
** suboccipital group
*** [[Rectus Capitis Posterior Major|rectus capitis posterior major]]
*** [[Rectus Capitis Posterior Minor|rectus capitis posterior minor]]
*** [[Obliquus Capitis Inferior|obliquus capitis inferior]]
*** [[Obliquus Capitis Superior|obliquus capitis superior]]
** transversospinalis muscles
*** [[Semispinalis Capitis|semispinalis capitis]]
*** [[Semispinalis Cervicis|semispinalis cervicis]]
*** rotatores cervicis
*** multifidus (these are also known as deep neck extensors)
** interspinales and intertransversarii


''Rotation 1-5 degrees''
=== Movement ===
|''Full extension''
{| class="wikitable"
|''Halfway between flexion and extension''
|+
!<small>'''Motion'''</small>
!<small>'''Flexion'''</small>
!<small>'''Extension'''</small>
!<small>'''Lateral Flexion'''</small>
!<small>'''Rotation'''</small>
|-
|-
|''Zygapophyseal joint (facet joint)''
|<small>'''Muscles'''</small>
|''[[Synovial Joints|Synovial]] plane joint''
|
|''Facilitate a multiplanar and multidirectional movement of the spine.''
* [[Longus Colli|<small>Longus colli</small>]]
''Enable lumbar spine extension, lateral flexion, and rotation in the saggital, transverse and frontal planes.''
* <small>[[Sternocleidomastoid]]</small>
|''Flexion/extension''
* [[Scalene|<small>Scalene anterior</small>]]
''Lateral flexion''
* [[Longus Capitis|<small>Longus capitis</small>]]
* <small>[[Rectus Capitis Anterior|Rectus capitis anterior]] (head only)</small>
|
* [[Iliocostal Cervicis|<small>Iliocostal cervicis</small>]]
* [[Splenius Cervicis|<small>Splenius cervicis</small>]]
* [[Splenius Capitis|<small>Splenius capitis</small>]]
* <small>[[Trapezius]]</small>
* [[Erector Spinae|<small>Erector spinae</small>]]
* <small>[[Rectus Capitis Posterior|Rectus capitis posterior,]] [[Rectus Capitis Posterior Major|major]] and [[Rectus Capitis Posterior Minor|minor]] (head only)</small>
* <small>Sternocleidomastoid</small>
* <small>Longissimus capitis</small>
* <small>Spinalis capitis</small>
|
* <small>Scalene anterior, medius and posterior</small>
* <small>Sternocleidomastoid</small>
* <small>Splenius capitis</small>
* <small>Trapezius</small>
* <small>Erector spinae</small>
* <small>[[Rectus Capitis Lateralis|Rectus capitis lateralis]] (head only)</small>
* <small>Spinalis capitis</small>
|
* [[Semispinalis Cervicis|<small>Semispinalis cervicis</small>]]
* <small>Multifidus</small>
* <small>Scalene anterior</small>
* <small>Splenius cervicis and capitis</small>
* <small>Sternocleidomastoid</small>
* <small>Inferior oblique (head only)</small>
* <small>Rectus captitis posterior major (head only)</small>
* <small>Longissius capitis</small>
* <small>Spinalis capitis</small>
|}
<ref>Palastanga, N., & Soames, R. (2012). Anatomy and human movement (6th ed.). Edinburgh: Churchill Livingstone.</ref>


''Rotation''
The following tables identify the origin, insertion, innervation and action of key cervical muscles. Muscles with multiple functions are repeated in the relevant tables.
|''All lumbar intervertebral disc joints and zygapophyseal joints combined together:''
''Flexion:60 degrees''


''Extension 25 degrees''
=== Cervical Spine Flexors ===
 
{| class="wikitable"
''Lateral flexion 20-30 degrees''
|+
 
!<small>'''Muscle'''</small>
''Rotation 1-5 degrees''
!<small>'''Origin'''</small>
|''Full extension''
!<small>'''Insertion'''</small>
|''Halfway between flexion and extension''
!<small>'''Innervation'''</small>
!<small>'''Action'''</small>
|-
|<small>'''Rectus capitis anterior'''</small>
|<small>Lateral mass and transverse process of atlas (C1)</small>
|<small>Basilar part of occipital bone</small>
|<small>Anterior rami of 1st and 2nd cervical spinal nerves (C1, C2)</small>
|
* <small>Flexion of the head at the atlanto-occipital joint</small>
|-
|<small>'''Longus colli'''</small>
|<small>Transverse processes of C3-C5 and the vertebral bodies of C5-T3</small>
|<small>Anterior tubercle of C1, the vertebral bodies of C2-C4, and the transverse processes of C5 and C6.</small>
|<small>Anterior rami of the 2nd to 6th cervical spinal nerves (C2-C6)</small>
|
* <small>Unilateral contraction: neck lateral flexion (ipsilateral), neck rotation (contralateral)</small>
* <small>'''Bilateral contraction: neck flexion'''</small>
|-
|<small>'''Longus capitis'''</small>
|<small>Transverse processes of  C3-C6</small>
|<small>Occipital bone</small>
|<small>Anterior rami of 1st to 3rd cervical spinal nerves (C1-C3)</small>
|
* <small>Unilateral contraction: rotation of the head (ipsilateral)</small>
* <small>'''Bilateral contraction: flexion of the head and neck'''</small>
|-
|<small>'''Anterior scalene'''</small>
|<small>Transverse processes of  C3-C6</small>
|<small>First rib</small>
|<small>Anterior rami of 4th to 6th cervical spinal nerves (C4-C6)</small>
|
* <small>Unilateral contraction: neck lateral flexion (ipsilateral), neck rotation (contralateral), elevation of the first rib</small>
* <small>'''Bilateral contraction: neck flexion'''</small>
* Accessory muscle of respiration
|-
|<small>'''Sternocleidomastoid'''</small>
|<small>Manubrium and the medial portion of the clavicle</small>
|<small>Mastoid process of the temporal bone</small>
|<small>Accessory nerve (CN XI), branches of cervical plexus (C2-C3)</small>
|
* <small>Unilateral contraction: '''ipsilateral lateral flexion''', elevation of the chin, contralateral rotation of head</small>
* <small>Bilateral contraction: '''flexes the neck''', extension of the upper vertebral joints, extension of the neck and head, elevation of the head, elevation of the sternum and clavicle, expansion of the thoracic cavity</small>
|-
|<small>'''Rectus capitis lateralis'''</small>
|<small>Transverse process of atlas (C1)</small>
|<small>Jugular process of occipital bone</small>
|<small>Anterior rami of 1st and 2nd cervical spinal nerves (C1-C2)</small>
|
* <small>Lateral flexion of the head (ipsilateral)</small>
* <small>'''Neck flexion'''</small>
* <small>Stabilisation of the atlanto-occipital joint</small>
|}
|}


== ''Cervical Spine Ligaments'' ==
=== '''Cervical Spine Extensors''' ===
 
*
 
Unique to Cervical Spine
 
* [[Ligamentum nuchae|Nuchal ligament]] – a continuation of the supraspinous ligament. It attaches to the tips of the spinous processes from C1-C7, and provides the proximal attachment for the [[rhomboids]] and [[trapezius]].
 
* [[Transverse Ligament of the Atlas|Transverse ligament]] of the [[atlas]] – connects the lateral masses of the atlas, and in doing so anchors the [[Odontoid process|dens]] in place.
 
''(Note: Some texts consider the interspinous ligament to be part of the nuchal ligament).''<ref name=":1" />
{| class="wikitable"
{| class="wikitable"
|+
|+
!'''Key ligaments'''
!<small>'''Muscle'''</small>
!'''Origin'''
!<small>'''Origin'''</small>
!'''Insertion'''
!<small>'''Insertion'''</small>
!'''Action/role'''
!<small>'''Innervation'''</small>
!'''Key palpation points'''
!<small>'''Action'''</small>
|-
|-
|[[Anterior longitudinal ligament]]
|<small>'''Obliquus capitis superior'''</small>
|The anterior portion of the vertebral body at the base of the skull
|<small>Transverse process of the atlas</small>
|The anterior portion of the vertebral body at the sacrum
|<small>Occipital bone</small>
|Limits extension of the vertebral column.
|<small>Suboccipital nerve (posterior ramus of 1st cervical spinal nerve (C1))</small>
Reinforces the intervertebral disc.
|
|
* <small>'''Bilateral contraction: head extension'''</small>
* Unilateral contraction: rotation of head to the ipsilateral side
* <small>Stabilises the atlanto-occipital joint during head movements</small>
|-
|-
|[[Posterior longitudinal ligament]]
|<small>'''Obliquus capitis inferior'''</small>
|The body of C2
|<small>Spinous process of the axis</small>
|Posterior surface of the sacrum
|<small>Tansverse process of atlas</small>
|Limits flexion of the vertebral column.
|<small>Suboccipital nerve (posterior ramus of 1st cervical spinal nerve (C1))</small>
Reinforces the intervertebral disc.
|
|
* <small>'''Bilateral contraction: head extension'''</small>
* <small>Unilateral contraction: rotation of head to the ipsilateral side</small>
* <small>Stabilises the atlanto-axial joint</small>
|-
|-
|[[Ligamentum flavum]]:
|<small>'''Rectus capitis posterior major'''</small>
A series of short ligaments that connect the laminae of each vertebra. There are two ligamenta flava at each vertebra.
|<small>Spinous process of C2</small>
 
|<small>Occipital bone</small>
Each ligament is divided into:
|<small>Suboccipital nerve (posterior ramus of 1st cervical spinal nerve (C1))</small>
 
'''The medial portion:''' passes to the back of the next lower lamina and across the gap between the adjacent vertebrae, fusing with the [[/www.physio-pedia.com/Interspinous ligament|interspinous ligament]]
 
'''The lateral portion:''' passes in front of the [[/www.physio-pedia.com/Facet Joints|facet joint,]] attaches to the anterior aspect of the inferior and superior articular processes and forms the anterior capsule. The most lateral fibres extend beyond the superior articular process to the pedicle below.
|The lower half of the anterior surface of the lamina above
|The posterior surface and upper margin of the lamina below
|Their high elastin content prevents the ligament from buckling into the spinal canal.
Assists with lumbar spine flexion and extension.
 
Compresses the intervertebral discs.
|
|
* <small>Unilateral contraction: head rotation (ipsilateral)</small>
* <small>'''Bilateral contraction: head extension'''</small>
|-
|-
|Intertransverse ligaments
|<small>'''Rectus capitis posterior minor'''</small>
|Transverse processes of the vertebra above
|<small>Posterior tubercle of the atlas</small>
|Transverse processes of the vertebra below
|<small>Occipital bone</small>
|Contributes to the stability of the lumbar spine.
|<small>Suboccipital nerve (posterior ramus of 1st cervical spinal nerve (C1))</small>
Limits lateral flexion.
|
|To palpate the '''transverse process''', position the patient in sitting. The transverse processes of the lumbar spine are most likely located directly in line with the spinous process of the corresponding vertebra. Start by palpating the spinous process of the L1 vertebra and move directly lateral to find the transverse process of L1.
* <small>Head extension</small>
|-
|-
|Supraspinous ligament
|<small>'''Iliocostal cervicis'''</small>
|Tip of spinous processes of the vertebra above from the seventh cervical vertebra to the third or fourth lumbar vertebra
|<small>Ribs 3-6</small>
|Tip of spinous processes of the vertebra below
|<small>Transverse process of C4-C6</small>
|Prevents the separation of the spinous processes during forward flexion, thus limiting lumbar spine flexion
|<small>Dorsal rami of the upper thoracic and lower cervical spinal nerves</small>
|You can palpate the '''spinous processes''' in the centre of the patient's back.
|
Start with finding T12 by palpating the patient's lowest rib and following your finger along the border of the rib towards the centre of the spine.T12 spinous process is in line with the 12th rib that inserts into the spinal segment. Below T12, you can palpate L1 and continue along the spinous process of L2, L3, and L4.
* <small>Laterally flexes and '''extends the lower [[Cervical Anatomy|cervical region]]'''</small>
|-
|-
|Interspinous ligament
|<small>'''Trapezius'''</small>
|Spinous processes of the vertebra above between the ligamenta flava anteriorly and the supraspinous ligament posteriorly
|<small>Occipital bone, nuchal ligament and spinous process C7-T12</small>
|Spinous processes of the vertebra below between the ligamenta flava anteriorly and the supraspinous ligament posteriorly
|<small>Lateral third of the clavicle, acromian and spine of the scapula</small>
|Limits forward flexion of the vertebral column.
|<small>Spinal [[Accessory Nerve Cranial Nerve 11|root of accessory nerve]] (CN XI) (motor)</small>
 
<small>Cervical nerves (C3 and C4) ([[Pain Assessment|pain]] and [[proprioception]])</small>
|
|
* <small>Supports the spinal column to remain erect</small>
* '''Neck extension when scapulae are fixed'''
* Ipsilateral lateral flexion of neck
|-
|-
|** special to C-Spine
|<small>'''Splenius cervicis'''</small>
Nuchal ligament
|<small>Spinous process of T3-T6</small>
|<small>Transverse process of C1-C3</small>
|<small>Dorsal rami of cervical spinal nerves (C5-C8)</small>
|
|
|tips of the spinous process from C1-C7
* <small>'''Acting bilaterally: extend the neck'''</small>
* <small>Acting unilaterally: lateral flexion and rotation of the head and neck to the ipsilateral side</small>
|-
|<small>'''Splenius capitis'''</small>
|<small>Spinous process of C7-T3 and nuchal ligament</small>
|<small>Occipital bone</small>
|<small>Posterior rami of the 2nd and 3rd cervical spinal nerves</small>
|
|
|proximal attachment for rhomboids and trapezius
* <small>'''Acting bilaterally: extension of the head and neck'''</small>
* <small>Acting unilaterally: lateral flexion and rotation of the head and neck to the ipsilateral side</small>
|-
|-
|** special to C-spine
|'''<small>Spinalis capitis</small>'''
Transverse ligament
|<small>Spinous process of C7 and T1</small>
|<small>Occipital bone</small>
|<small>Dorsal rami of spinal nerves</small>
|
|
|connects lateral masses of atlas
* <small>'''Acting bilaterally: extension of the neck'''</small>
|anchors dens in place
* <small>Acting unilaterally: ipsilateral lateral flexion and r</small><small>otation</small>  <small>of the neck</small>
|-
|<small>'''Longissimus capitis'''</small>
|<small>Transverse process of upper 4 thoracic vertebrae and articular process lower three cervical vertebrae</small>
|<small>Mastoid process</small>
|<small>Posterior/dorsal rami of spinal nerves</small>
|
|
* '''<small>Acting bilaterally: extension of neck</small>'''
* <small>Acting unilaterally: ipsilateral lateral flexion and rotation  of the neck</small>
|}
|}
<ref name=":1" />
== ''Muscles of the Lumbar Spine and Abdominal Wall'' ==
''The muscles of the back can be grouped according to their function and location.''
''When grouped according to '''function''', the muscles of the lumbar spine can be organised as follows:''


* ''Flexors: psoas major, psoas minor, internal oblique, external oblique, and rectus abdominis''
<nowiki>**</nowiki> <small>The transversospinal muscles (rotatores, multifidus, semispinalis) are the deep muscle of the spine. They attach between the transverse and spinous process of the vertebrae. They stabilise and extend the spine. The rotatores also provide rotation.</small>
* ''Extensors: quadratus lumborum, interspinales lumborum, multifidus, and the erector spinae (iliocostalis, longissimus)''
* ''Lateral flexors: intertransversarii lumborum, psoas major, quadratus lumborum, erector spinae, internal and external obliques''
* ''Rotators: multifidus, internal and external obliques''


''When grouped according to '''location''', the muscles of the lumbar spine can be divided as follows:''
=== Cervical Spine Lateral Flexors ===
 
* ''The intrinsic (deep) group:''
** ''Superficial layer: erector spinae muscles''
** ''Middle (deep) layer: multifidus''
** ''Deepest layer: interspinales lumborum and intertransversarii lumborum''
* ''The abdominal wall group: transverse abdominis, the internal oblique, rectus abdominis, and the external oblique''
* ''The hip group: psoas major, psoas minor, quadratus lumborum''
 
''The following tables group muscles according to their function. Please note, that when a muscle has multiple functions, it is included in all relevant tables. These tables only list muscle actions associated with the lumbar spine and abdominal wall. If a muscle acts on other joints, these actions are discussed on the relevant page. For example, psoas major is also a major hip flexor - this role is detailed on the [[Functional Anatomy of the Hip|Functional Anatomy of the Hip page]].''
 
=== ''Lumbar Spine Flexors'' ===
{| class="wikitable"
{| class="wikitable"
|+
|+
!''Muscle''
!<small>'''Muscle'''</small>
!''Origin''
!<small>'''Origin'''</small>
!''Insertion''
!<small>'''Insertion'''</small>
!''Innervation''
!<small>'''Innervation'''</small>
!''Action''
!<small>'''Action'''</small>
|-
|-
|''Psoas major''
|<small>'''Splenius cervicis'''</small>
|''Vertebral bodies of T12-L4''
|<small>Spinous process of T3-T6</small>
''Intervertebral discs between T12-L4 Transverse processes of L1-L5 vertebrae''
|<small>Transverse process C1-C3</small>
|''Lesser trochanter of femur''
|<small>Dorsal rami of cervical spinal nerves (C5-C8)</small>
|''Anterior rami of spinal nerves L1-L3''
|
|''Contribute to lumbar spine flexion when acting bilaterally and when the insertion point is fixed.''
* <small>'''Acting unilaterally: lateral flexion and rotation of the head and neck to the ipsilateral side'''</small>
* <small>Acting bilaterally: extend the neck</small>
|-
|-
|''Psoas minor''
|<small>'''Splenius capitis'''</small>
|''Vertebral bodies of T12 to L1''
|<small>Spinous process of C7-T3 and nuchal ligament</small>
|''Iliopubic eminence''
|<small>Occipital bone</small>
|''Anterior ramus of spinal nerve L1''
|<small>Posterior rami of the 2nd and 3rd cervical spinal nerves</small>
|''Weak trunk flexor. This muscle is absent in 40% of people.''
|
* <small>'''Acting unilaterally: lateral flexion of the head and neck and rotation of the head to the ipsilateral side'''</small>
* <small>Acting bilaterally: extension of the head and cervical spine</small>
|-
|<small>'''Sternocleidomastoid'''</small>
|<small>Manubrium and the medial portion of the clavicle</small>
|<small>Mastoid process of the temporal bone</small>
|<small>Accessory nerve (CN XI), branches of cervical plexus (C2-C3)</small>
|
* <small>'''Unilateral contraction: ipsilateral lateral flexion''', elevation of the chin, contralateral rotation of head</small>
* <small>Bilateral contraction: flexes the neck, extension of the upper vertebral joints, extension of the neck and head, elevation of the head, elevation of the sternum and clavicle, expansion of the thoracic cavity</small>
|-
|-
|''Internal obliques''
|'''Anterior scalene'''
|''Thoracolumbar fascia''
|<small>Transverse processes of  C3-C6</small>
''Iliac crest Inguinal ligament''
|First rib
|''Lower four ribs''
|<small>Anterior rami of 4th to 6th cervical spinal nerves (C4-C6)</small>
''Linea alba Pubic crest''
|
|''Lower intercostal nerves Branches of the lumbar plexus: iliohypogastric nerve and ilioinguinal nerve''
* <small>'''Unilateral contraction: neck lateral flexion (ipsilateral)''', neck rotation (contralateral), elevation of the first rib</small>
|''Bilateral action: lumbar flexion''
* <small>Bilateral contraction: neck flexion</small>
''Assist in raising intra-abdominal pressure''
* Accessory muscle of respiration
|-
|-
|''External obliques''
|<small>'''Middle scalene'''</small>
|''Ribs five to twelve''
|<small>Posterior tubercles of the transverse processes of C1-C7</small>
|''Linea alba''
|<small>Scalene tubercle of the first rib</small>
''Pubic tubercle Iliac crest''
|<small>Anterior rami of C3-C8</small>
|''Intercostal nerves T7- T11 and the T12 subcostal nerve''
|
|''Bilateral action: lumbar flexion''
* <small>Elevation of the first rib</small>
* <small>'''Ipsilateral contraction causes ipsilateral lateral flexion of the neck'''</small>
* Respiration
|-
|<small>'''Posterior scalene'''</small>
|<small>Posterior tubercles of the transverse processes of C4-C6</small>
|<small>2nd rib</small>
|<small>Anterior rami of C6-C8</small>
|
* <small>Elevation of the second rib</small>
* <small>'''Ipsilateral lateral flexion of the neck'''</small>
* Respiration
|-
|-
|''Rectus abdominis''
|<small>'''Trapezius'''</small>
|''Pubis, pubic symphysis''
|<small>Occipital bone, nuchal ligament and spinous process C7-T12</small>
|''Xiphoid process of the sternum''
|<small>Lateral third of the clavicle, the acromian and the spine of s scapula</small>
''Fifth to seventh costal cartilage''
|<small>Spinal [[Accessory Nerve Cranial Nerve 11|root of accessory nerve]] (CN XI) (motor)</small>
|''Thoracoabdominal nerves''
|''Lumbar spine flexion''
''Assists in raising intra-abdominal pressure''
|}


=== ''Lumbar Spine Extensors'' ===
<small>Cervical nerves (C3 and C4) ([[Pain Assessment|pain]] and [[proprioception]])</small>
{| class="wikitable"
|
|+
* <small>Supports the spinal column to remain erect</small>
!''Muscle''
* <small>Neck extension when scapulae are fixed</small>
!''Origin''
* <small>'''Ipsilateral lateral flexion of the neck'''</small>
!''Insertion''
!''Innervation''
!''Action''
|-
|-
|''Quadratus lumborum''
|<small>'''Rectus capitis lateralis'''</small>
|''Iliac crest''
|<small>Superior surface of the transverse process of atlas</small>
''Iliolumbar ligament''
|<small>Inferior surface of the jugular process of the occipital bone</small>
|''The inferior border of the 12th rib''
|<small>Anterior rami of C1-C2 spinal nerves</small>
''Transverse processes of L1-L4 vertebrae''
|
|''Subcostal nerve''
* <small>'''Lateral flexion of the head (ipsilateral)'''</small>
''Anterior rami of spinal nerves L1-L4''
* <small>Deep neck flexion</small>
|''Bilateral action: trunk extension''
* <small>Stabilisation of the atlanto-occipital joint</small>
|-
|-
|''Interspinales lumborum''
|'''<small>Spinalis capitis</small>'''
|''Superior aspects of spinous processes of L2-L5''
|<small>Spinous process of C7 and T1</small>
|''Inferior aspects of spinous processes of L1-L4''
|<small>Occipital bone</small>
|''Posterior rami of spinal nerves''
|<small>Dorsal rami of spinal nerves</small>
|''Stabilise the lumbar spine Extend the lumbar spine''
|
*<small>Acting bilaterally: extension of the neck</small>
* '''<small>Acting unilaterally: ipsilateral lateral flexion and r</small><small>otation</small>  <small>of the neck</small>'''
|-
|-
|''Multifidus''
|<small>'''Longissimus capitis'''</small>
|''Sacrum''
|<small>Transverse process of upper 4 thoracic vertebrae and articular process lower three cervical vertebrae</small>
''Posterior superior iliac spine''
|<small>Mastoid process</small>
 
|<small>Posterior/dorsal rami of spinal nerves</small>
''The mammillary processes of the lumbar vertebrae''
|
 
*<small>Acting bilaterally: extension of the neck</small>
''Transverse processes of T1-3 Articular processes of C4-C7''
*'''<small>Acting unilaterally: ipsilateral lateral flexion and r</small><small>otation</small>  <small>of the neck</small>'''
|''Spinous processes of the vertebrae above their origin''
|''Medial branches of the posterior rami of the spinal nerves in the corresponding lumbar region''
|''Extends the lumbar spine''
''Provides core stability''
|-
|''Erector spinae: Iliocostalis lumborum (ICL) Longissimus thoracis (LT)''
|''ICL: Iliac crest''
''LT : Lumbar intermuscular aponeurosis, medial part of sacropelvic surface of ilium, posterior sacroiliac ligament''
|''ICL: L1-L4 lumbar transverse processes, angle of 4-12 ribs and thoracolumbar fascia''
''LT: Accessory and transverse processes of vertebrae L1-L5''
|''Dorsal rami of spinal nerves''
|''Bilateral action: lumbar spine extension''
|}
|}


=== ''Lumbar Spine Lateral Flexors'' ===
=== Cervical Spine Rotators ===
{| class="wikitable"
{| class="wikitable"
|+
|+
!''Muscle''
!'''<small>Muscle</small>'''
!''Origin''
!'''<small>Origin</small>'''
!''Insertion''
!'''<small>Insertion</small>'''
!''Innervation''
!'''<small>Innervation</small>'''
!''Action''
!'''<small>Action</small>'''
|-
|-
|''Intertransversarii lumborum (ITL):''
|<small>'''Rectus capitis posterior major'''</small>
''Lateral (ITLL) Medial (ITLM)''
|<small>Spinous process of C2</small>
|''ITLL: Transverse and accessory processes of L1-L4''
|<small>Occipital bone</small>
''ITLM: Accessory processes of L1-L4''
|<small>Suboccipital nerve (posterior ramus of 1st cervical spinal nerve (C1))</small>
|''ITLL: Transverse process of the following vertebra''
|
''ITLM: Mammillary processes of the following vertebra''
* <small>'''Unilateral contraction: head rotation (ipsilateral)'''</small>
|''Anterior rami of spinal nerves''
* <small>Bilateral contraction: head extension</small>
|''Assists in lateral flexion''
''Stabilises the lumbar spine''
|-
|-
|''Psoas major''
|<small>'''Rectus capitis posterior major'''</small>
|''Vertebral bodies of T12-L4''
|<small>Spinous process of C2</small>
''Intervertebral discs between T12-L4 Transverse processes of L1-L5 vertebrae''
|<small>Occipital bone</small>
|''Lesser trochanter of femur''
|<small>Suboccipital nerve (posterior ramus of 1st cervical spinal nerve (C1))</small>
|''Anterior rami of spinal nerves L1-L3''
|
|''Lateral flexion of the trunk''
* <small>'''Unilateral contraction: head rotation (ipsilateral)'''</small>
* <small>Bilateral contraction: head extension</small>
|-
|-
|''Quadratus lumborum''
|<small>'''Sternocleidomastoid'''</small>
|''Iliac crest''
|<small>Manubrium and the medial portion of the clavicle</small>
''Iliolumbar ligament''
|<small>Mastoid process of the temporal bone</small>
|''The inferior border of the 12th rib''
|<small>Accessory nerve (CN XI), branches of cervical plexus (C2-C3)</small>
''Transverse processes of L1-L4 vertebrae''
|
|''Subcostal nerve''
* <small>Unilateral contraction: ipsilateral lateral flexion, elevation of the chin, c'''ontralateral rotation of head'''</small>
''Anterior rami of spinal nerves L1-L4''
* <small>Bilateral contraction: flexion of the neck, extension of the upper vertebral joints, extension of the neck and head, elevation of the head, elevation of the sternum and clavicle, expansion of thoracic cavity</small>
|''Unilateral action: ipsilateral lumbar spine lateral flexion''
|-
|-
|''Erector spinae:''
|<small>'''Splenius capitis'''</small>
''Iliocostalis (IC) Longissimus (L)''
|<small>Spinous process  ofC7-T3 and nuchal ligament</small>
|''ICL: Iliac crest''
|<small>Occipital bone</small>
''LT : Lumbar intermuscular aponeurosis, medial part of sacropelvic surface of ilium, posterior sacroiliac ligament''
|<small>Posterior rami of the 2nd and 3rd cervical spinal nerves</small>
|''ICL: L1-L4 lumbar transverse processes, angle of 4-12 ribs and thoracolumbar fascia''
|
''LT: Accessory and transverse processes of vertebrae L1-L5''
* <small>Acting unilaterally: lateral flexion of the head and neck and '''rotation of the head to the ipsilateral side'''</small>
|''Dorsal rami of spinal nerves''
|''Unilateral action: ipsilateral side flexion and rotation of the vertebral column''
|-
|-
|''Internal oblique''
|<small>'''Splenius cervicis'''</small>
|''Thoracolumbar fascia''
|<small>Spinous process T3-T6</small>
''Iliac crest Inguinal ligament''
|<small>Transverse process C1-C3</small>
|''Lower four ribs''
|<small>Dorsal rami of cervical spinal nerves (C5-C8)</small>
''Linea alba Pubic crest''
|
|''Lower intercostal nerves''
* <small>Acting unilaterally: lateral flexion and '''rotation of the head and neck to the ipsilateral side'''</small>
''Branches of the lumbar plexus: iliohypogastric nerve and ilioinguinal nerve.''
|''Unilateral action: lumbar spine lateral flexion and/or rotation to the ipsilateral side''
''Assists in raising intra-abdominal pressure''
|-
|-
|''External oblique''
|'''<small>Spinalis capitis</small>'''
|''Ribs five to twelve''
|<small>Spinous process of C7 and T1</small>
|''Linea alba''
|<small>Occipital bone</small>
''Pubic tubercle Iliac crest''
|<small>Dorsal rami of spinal nerves</small>
|''Intercostal nerves T7- T11 and the T12 subcostal nerve''
|
|''Unilateral action: lumbar spine lateral flexion to the ipsilateral side and rotation to the contralateral side''
* <small>Acting bilaterally: extension of the neck</small>
* <small>'''Acting unilaterally: ipsilateral lateral flexion and rotation  of the neck'''</small>
|-
|<small>'''Longissimus capitis'''</small>
|<small>Transverse process of upper 4 thoracic vertebrae and articular process lower three cervical vertebrae</small>
|<small>Mastoid process</small>
|<small>Posterior/dorsal rami of spinal nerves</small>
|
* <small>Acting bilaterally: extension of the neck</small>
* <small>'''Acting unilaterally: ipsilateral lateral flexion and rotation of the neck'''</small>
|}
|}


=== ''Lumbar Spine Rotators'' ===
== Innervation of the Cervical Spine ==
Nerves originating from the cervical plexus innervate the muscles of the neck. Each nerve root in the cervical spine exits above its corresponding nerve root. There are eight pairs of cervical nerves despite there being seven cervical vertebrae. The C8 nerve root exits below the seventh cervical vertebra. The accessory nerve, which is cranial nerve XI innervates sternocleidomastoid and trapezius.<ref name=":0" />
{| class="wikitable"
{| class="wikitable"
|+
|+
!'''''Muscle'''''
!'''<small>Nerve</small>'''
!'''''Origin'''''
!'''<small>Motor</small>'''
!'''''Insertion'''''
!'''<small>Sensory</small>'''
!'''''Innervation'''''
!'''''Action'''''
|-
|-
|''Multifidus''
|'''<small>C1</small>'''
|''Sacrum''
|<small>Flexion of the head and neck</small>
''Posterior superior iliac spine''
<small>Rectus capitus anterior and lateralis, longus capitis</small>
 
|
''The mammillary processes of the lumbar vertebrae''
|''Spinous processes of the vertebrae above their origin''
|''Medial branches of posterior rami of spinal nerves in the corresponding lumbar region.''
|''Rotates the lumbar spine away from the side of the body on which they are located''
''Provides core stability''
|-
|-
|''Internal oblique (IO)''
|'''<small>C2</small>'''
|''Thoracolumbar fascia''
|<small>Flexion of the head and neck</small>
''Iliac crest''
<small>Rectus capitus anterior and lateralis, longus capitus, prevertebral muscles and sternocleidomastoid</small>
 
|<small>Lateral occiput and submandibular area</small>
''Inguinal ligament''
|''Lower four ribs''
''Linea alba''
 
''Pubic crest''
|''Lower intercostal nerves''
''Branches of the lumbar plexus: iliohypogastric nerve and ilioinguinal nerve.''
|''Rotation to the same side''
''Works together with opposite EO to rotate the spine - e.g. right external oblique works with left internal oblique to rotate the spine.''
|-
|-
|''External oblique (EO)''
|'''<small>C3</small>'''
|''Ribs five to twelve''
|<small>Head and neck flexion and rotation</small>
|''Linea alba Pubic tubercle''
''Iliac crest''
|''Intercostal nerves T7- T11 and the T12 subcostal nerve''
|''Rotation to the opposite side''
''Works together with opposite IO to rotate the spine - e.g. right external oblique works with left internal oblique to rotate the spine.''
|}


== ''Innervation of the Lumbar Spine and Abdominal Wall'' ==
<small>Longus capitus, longus colli, prevertebral muscles and sternocleidomastoid, diaphragm, levator scapulae, trapezius and scalenus medius</small>
{| class="wikitable"
|<small>Lateral occiput and lateral neck, overlapping C2</small>
|+
!'''''Nerve'''''
!'''''Origin'''''
!'''''Branches'''''
!'''''Motor fibres'''''
!'''''Sensory fibres'''''
|-
|-
|''Intercostal''
|<small>'''C4'''</small>
|''Lumbar plexus''
|<small>Head and neck flexion and rotation</small>
|''Muscular, collateral, lateral cutaneous, anterior cutaneous, and''
<small>Longus capitus, longus colli, levator scapulae, scaleni, trapezius, diaphragm</small>
''communicating branches''
|<small>Lower lateral neck and medial shoulder area</small>
|''External obliques''
''Internal obliques''
|''Skin over the anterior abdomen''
|-
|-
|''Subcostal''
|'''<small>C5</small>'''
|''Anterior ramus of the spinal nerve T12''
|<small>Deltoid, biceps, bicep tendon reflex</small>
|''Muscular, cutaneous, communicating and collateral branches''
|<small>Clavicle level and lateral arm</small>
|''Quadratus lumborum''
''External oblique''
|''The skin of the region under the umbilicus''
|-
|-
|''Iliohypogastric''
|'''<small>C6</small>'''
|''Lumbar plexus''
|<small>Biceps, wrist extensors (brachioradialis tendon reflex)</small>
|''Lateral cutaneous branch''
|<small>Lateral forearm, thumb, index and half of 2nd finger</small>
''Anterior cutaneous branch''
|''Internal oblique''
|''External abdominal oblique, transversus abdominis, internal abdominal oblique''
''The skin of the suprapubic region''
|-
|-
|''Ilioinguinal''
|'''<small>C7</small>'''
|''Lumbar plexus''
|<small>Wrist flexors, triceps (triceps tendon reflex)</small>
|''Anterior labial nerves''
|<small>Second finger</small>
''Anterior scrotal nerves''
|''Internal oblique''
|
|-
|-
|''Dorsal (posterior) rami of spinal nerves''
|'''<small>C8</small>'''
|''Spinal nerves''
|<small>Finger flexors, interossei</small>
|''Medial''
|<small>Medial forearm, ring and little finger</small>
''Intermediate''
 
''Lateral''
|''Interspinales lumborum''
''Multifidus''
 
''Erector spinae''
|''The skin of the back''
|-
|-
|''Ventral (anterior) rami of L1-L4''
|<small>'''T1'''</small>
|''Spinal nerves''
|<small>Interossei</small>
|
|<small>Medial arm</small>
|''Intertransversarii lumborum''
''Psoas major''
 
''Psoas minor''
|''Ventrolateral body surface Structures in the body wall''
|}
|}


== ''Vascular Supply of the Lumbar Spine and Abdominal Wall'' ==
== Vascular Supply of the Cervical Spine ==
{| class="wikitable"
Vertebral arteries, veins and nerves pass through the transverse foramina of the cervical vertebrae except for in C7, where the vertebral artery passes around the vertebra instead of through the transverse foramen.<ref name=":1" /> The neural components sit posterior to the vertebral artery.<ref>Joshi N, Klinger N, Halalmeh DR, Tubbs RS, Moisi MD. [https://www.cureus.com/articles/26181-the-neural-sulcus-of-the-cervical-vertebrae-a-review-of-its-anatomy-and-surgical-perspectives#!/ The Neural Sulcus of the Cervical Vertebrae: A Review of Its Anatomy and Surgical Perspectives]. Cureus. 2020 Jan 18;12(1)</ref>
|+
!''Artery''
!''Origin''
!''Branches''
!''Supply''
|-
|''Lumbar artery (LA):''
''Left (LLA)''


''Right (RLA)''
The cervical spine vascular supply is primarily provided by the vertebral arteries on each side of the spine. These arteries arise from the subclavian arteries, which originate directly from the arch of the [[aorta]] on the right and the brachiocephalic trunk on the left.
|''Abdominal aorta''
|''Medial''
''Middle''


''Lateral''
<nowiki>**</nowiki> The common carotid artery bifurcates into the internal and external carotid arteries at the C3 segmental level. Only the external carotid artery provides any blood supply to the neck.
|''Skin and muscles of the posterior abdominal wall''
''Joints of the lumbar spine''


''The lumbar portion of the deep back muscles''
== Clinical Relevance ==


''Lower two-thirds of the spinal cord''
* Atlanto-axial instability (AAI) can have serious neurological consequences:
|-
** conditions with the potential for AAI include:
|''Internal thoracic artery''
*** rheumatoid arthritis
|''Subclavian artery''
*** Down syndrome:
|''Anterior collaterals''
**** laxity in the transverse ligament is present in 14-22% of individuals with Down syndrome.
''Posterior collaterals''


''Terminal branches''
* A tight [[sternocleidomastoid]] muscle can cause torticollis.
|''The superior aspect of the abdominal wall''
* Disc herniation:
|-
** disc herniations in the cervical spine are a lot less common than in the lumbar spine
|''External iliac artery''
** typical locations:
|''Common iliac artery''
*** C5-C6
|''Inferior epigastric,''
*** C6-C7
''Deep circumflex iliac arteries''
* Because the prevertebral cervical muscles stabilise the neck, dysfunction in these muscles can cause cervicogenic pain
|''Lower abdominal wall''
* Trigger points that develop in the suboccipital muscles can refer pain to the head, causing cervicogenic headaches<ref name=":3">Xuan D.  Exploring Cervical Spine Anatomy Course. Plus, 2023.</ref>
|}


== ''Clinical Relevance'' ==
== Resources ==


# ''Disc herniations are a common low back condition. They occur when the nucleus pulposus displaces from the intervertebral space. According to Yoon et al., when there is imaging confirmation of lumbar disc herniation that is "consistent with clinical findings, and failure to improve after six weeks of conservative care", surgical intervention may be required. You can read more about the management of disc herniation symptoms [[Disc Herniation|here.]]''
* [[Functional Anatomy of the Thoracic Spine and Rib Cage]]
# ''Spinal stenosis is a narrowing of the spinal canal. Spinal stenosis can be caused by a range of conditions, such as tumours or bone spurs. You can learn about low back pain assessment and prognosis by taking this course.''
* [[Functional Anatomy of the Lumbar Spine and Abdominal Wall]]
# ''Diastasis recti is a very common condition where the linea alba stretches and produces a gap between the two sides of the rectus abdominis muscle. Learn more about diastasis recti [[Diastasis recti abdominis|here]].''
* [[Cervical Deep Neck Extensors]]
* [[Cervical Deep Neck Flexors]]


== References ==
== References ==
<references />
[[Category:Anatomy]]
[[Category:Cervical Spine]]
[[Category:Musculoskeletal/Orthopaedics]]
[[Category:Neurology]]
[[Category:Course Pages]]
[[Category:Plus Content]]

Latest revision as of 10:49, 1 September 2023

Original Editor - Robin Tacchetti based on the course by Daphne Xuan
Top Contributors - Robin Tacchetti, Jess Bell, Kim Jackson, Tarina van der Stockt, Vidya Acharya and Ewa Jaraczewska


Introduction[edit | edit source]

The cervical spine supports the weight of the head and enables head and neck movement.[1] [2] Intervertebral discs maintain the spaces between the vertebrae. These discs act like shock absorbers throughout the spinal column to cushion the bones as the body moves. Ligaments hold the vertebrae in place, and tendons attach the muscles to the spinal column. The cervical spine is subjected to a range of extrinsic factors such as repetitive movements, whole-body vibrations and static load.[3]

Cervical spine

Key Terms[edit | edit source]

Axes: lines around which an object rotates. The rotation axis is a line that passes through the centre of mass. There are three axes of rotation: sagittal passing from posterior to anterior, frontal passing from left to right, and vertical passing from inferior to superior. The rotation axes of the foot joints are perpendicular to the cardinal planes. Therefore, motion at these joints results in rotations within three planes. Example: supination involves inversion, internal rotation, and plantarflexion.

Bursae: reduce friction between the moving parts of the body joints. A bursa is a fluid-filled sac. There are four types of bursae: adventitious, subcutaneous, synovial, and sub-muscular.

Capsule: one of the characteristics of the synovial joints. It is a fibrous connective tissue which forms a band that seals the joint space, provides passive and active stability and may even form articular surfaces for the joint. The capsular pattern is "the proportional motion restriction in range of motion during passive exercises due to tightness of the joint capsule."

Closed pack position: the position with the most congruency of the joint surfaces. In this position, joint stability increases. For example, the closed pack position for the interphalangeal joints is full extension.

Degrees of freedom: the direction of joint movement or rotation; there is a maximum of six degrees of freedom, including three translations and three rotations.

Ligament: fibrous connective tissue that holds the bones together.

Open (loose) pack position: position with the least joint congruency where joint stability is reduced.

Planes of movement: describe how the body moves. Up and down movements (flexion/extension) occur in the sagittal plane. Sideway movements (abduction/adduction) occur in the frontal plane. The transverse plane movements are rotational (internal and external rotation).

Cervical Spine Structure[edit | edit source]

Cervical Vertebrae[edit | edit source]

There are seven cervical vertebrae, which are known as C1-C7. Their role is to support the head and neck and to promote head movement. The cervical spine is only exposed to small weight-bearing loads. Therefore, the cervical vertebral bodies do not need to be large and "an increased range of motion takes priority over vertebral size and rigidity".[2] However, because of this increased range of motion at the cervical spine, there is a heightened injury risk for the spinal cord and the associated neurovascular structures.[2]

The cervical vertebral bodies (C3-C6) have unique characteristics:[2][4]

  • vertebral bodies are smaller compared to the rest of the spine
  • vertebral foramen is triangular
  • spinous process is bifid (i..e. it splits into two distally)
  • there are openings in the transverse processes which allow passage for the vertebral artery, vein, and sympathetic nerves

The Atlas (C1), Axis (C2) and C7 have further distinguishing features:

Atlas (C1)
  • has no vertebral body or spinous process
  • instead, it has lateral masses for articulation with the occiput of the head and the second cervical vertebra (the Axis)
Atlas - C1

Axis (C2)
  • has a bony projection from the anterior portion called the dens, or the odontoid process, which articulates with the atlas
  • it is the primary weight-bearing bone of upper cervical region
Axis - C2

C7
  • singular spinous process
  • larger spinous process
  • spinous process is not bifid
C3-C6

**In supine, it may be difficult to palpate the spinous process of C3-C6 in individuals with normal cervical lordosis.

Intervertebral Discs (IVD)[edit | edit source]

The intervertebral discs make up 25% of the height of the entire spine. However, in the cervical region, they make up 40% of the height. This increased height relative to vertebral body height provides a mobility advantage.[5]

The nucleus pulposus of the cervical discs is gelatinous in children and young people. However, it dries out by the age of 30 years and becomes a firm, fibrocartilaginous plate.[6]

Intervertebral disc

The following are characteristics of the cervical spine intervertebral discs:

  • thicker anteriorly than posteriorly
  • concave superior surface
  • convex inferior surface
  • movement limited by the uncinate process
  • anteroposterior translation does occur

** Due to the location of the uncinate process, posterolateral disc herniations are less frequent.

Cervical Lordosis[edit | edit source]

Typically, the cervical spine has a lordotic curvature. A lordotic posture can resist large compressive loads. It also helps to decrease stress on vertebral end plates. Compressive loads are distributed differently in the cervical spine than in the thoracic and lumbar spine. In the cervical spine, the anterior column absorbs 36% of the load, and the posterior facet (zygapophyseal) joints absorb 64%.[7]

Kinematics and Joints of the Cervical Spine[edit | edit source]

Range of Motion in Cervical Spine

The cervical spine is the most mobile part of the vertebral column.

Flexion range of motion is usually around 40 degrees, and extension is around 50 degrees. The largest contributors to flexion/extension are:

  • C4/C5 and C5/C6 in sitting
  • C6/C7 in supine

C7/T1 contributes the least to flexion/extension.

Lateral flexion range of motion is normally close to 30 degrees. C3/C4 and C6/C7 allow for the most movement in this plane of motion.

Cervical rotation range of motion is usually close to 70 degrees. Flexibility in this plane is mainly achieved through the C1/C2 segment.[8]

Joints of the Cervical Spine[5][9]
Joint Location/Articulations Function Orientation/Composition
Intervertebral Disc Joint
  • Between the vertebral bodies
  • Bear weight
  • Facilitate motion
  • Absorb shock
Facet (Zygapophyseal) Joints
  • Formed by articulations between the superior and inferior articular processes of adjacent vertebrae
  • Guide motion at the segmental level
  • Determine the direction of motion
  • Upper cervical spine = horizontal
  • Lower cervical spine = more vertical
Uncovertebral Joint
  • Between the five lower cervical vertebral bodies
  • Anteromedially to the nerve root
  • Posteromedially to the vertebral artery
  • Control movement
  • Limit lateral flexion
Atlanto-Axial Joint
  • Between the atlas and axis
  • Two lateral: interior facets of the lateral masses of C1 and superior facets of C2
  • One medial: between the dens of C2 and the articular facet of C1
  • Cervical rotation (60% of cervical rotation occurs at this joint)
  • Lateral: plane-type synovial joint
  • Medial: pivot-type synovial joint
Atlanto-Occipital Joint
  • Between the spine and cranium
  • Between the superior facets of the lateral masses of the atlas and the occipital condyles
  • Flexion and extension of the head on the neck
  • Lateral flexion
  • Condyloid-type synovial joint

Spinal Ligaments[edit | edit source]

Ligaments present throughout the entire vertebral column:

  1. Anterior longitudinal ligament: anterior surface of the vertebral bodies; limits extension of the spine
  2. Posterior longitudinal ligament: posterior surface of the vertebral bodies; limits flexion of the spine
  3. Ligamentum flavum: connects the laminae of each vertebrae; series of short ligaments
  4. Intertransverse ligament: a series of short ligaments that connect the laminae of each vertebrae; preserves upright posture and prevents hyperflexion of the spine[10]
Ligaments Unique to the Cervical Spine
Ligament Origin Insertion Role/Function
Nuchal ligament Occiput Tips of the spinous process from C1-C7 Limits hyperflexion
Transverse ligament Attaches to lateral masses of atlas Anchors dens in place
Apical ligament Dens of the axis Foramen magnum Connects the dens of the axis to the foramen magnum

Stabilises the skull on the spine

Alar ligament Dens of the axis Occiput Connects the dens of the axis to the occiput

Limits atlanto-axial rotation

Cruciform or cruciate ligament

1. Superior longitudinal band

2. Inferior longitudinal band

3. Transverse band

  1. Superior: transverse band
  2. Inferior: transverse band
  3. Transverse: dens of the axis
  1. Superior: foramen magnum
  2. Inferior: second vertebral body
  3. Transverse: between the lateral masses of the atlas
 Holds dens in place

** ligaments in spinal column

Muscles of the Cervical Spine[edit | edit source]

The muscles of the cervical spine can be divided by location or by function.

Anterior vertebral muscles

Anterior (Prevertebral) Vertebral Muscles[edit | edit source]

These muscles are also known as the deep cervical (neck) flexors.

Lateral Vertebral Muscles[edit | edit source]

Scalenes

Lateral view of cervical muscles

Posterior Vertebral Muscles[edit | edit source]

These can be further divided into intrinsic and extrinsic muscles.

Extrinsic muscles[edit | edit source]

Intrinsic muscles[edit | edit source]

Posterior muscles of the cervical spine

Movement[edit | edit source]

Motion Flexion Extension Lateral Flexion Rotation
Muscles
  • Scalene anterior, medius and posterior
  • Sternocleidomastoid
  • Splenius capitis
  • Trapezius
  • Erector spinae
  • Rectus capitis lateralis (head only)
  • Spinalis capitis
  • Semispinalis cervicis
  • Multifidus
  • Scalene anterior
  • Splenius cervicis and capitis
  • Sternocleidomastoid
  • Inferior oblique (head only)
  • Rectus captitis posterior major (head only)
  • Longissius capitis
  • Spinalis capitis

[11]

The following tables identify the origin, insertion, innervation and action of key cervical muscles. Muscles with multiple functions are repeated in the relevant tables.

Cervical Spine Flexors[edit | edit source]

Muscle Origin Insertion Innervation Action
Rectus capitis anterior Lateral mass and transverse process of atlas (C1) Basilar part of occipital bone Anterior rami of 1st and 2nd cervical spinal nerves (C1, C2)
  • Flexion of the head at the atlanto-occipital joint
Longus colli Transverse processes of C3-C5 and the vertebral bodies of C5-T3 Anterior tubercle of C1, the vertebral bodies of C2-C4, and the transverse processes of C5 and C6. Anterior rami of the 2nd to 6th cervical spinal nerves (C2-C6)
  • Unilateral contraction: neck lateral flexion (ipsilateral), neck rotation (contralateral)
  • Bilateral contraction: neck flexion
Longus capitis Transverse processes of C3-C6 Occipital bone Anterior rami of 1st to 3rd cervical spinal nerves (C1-C3)
  • Unilateral contraction: rotation of the head (ipsilateral)
  • Bilateral contraction: flexion of the head and neck
Anterior scalene Transverse processes of C3-C6 First rib Anterior rami of 4th to 6th cervical spinal nerves (C4-C6)
  • Unilateral contraction: neck lateral flexion (ipsilateral), neck rotation (contralateral), elevation of the first rib
  • Bilateral contraction: neck flexion
  • Accessory muscle of respiration
Sternocleidomastoid Manubrium and the medial portion of the clavicle Mastoid process of the temporal bone Accessory nerve (CN XI), branches of cervical plexus (C2-C3)
  • Unilateral contraction: ipsilateral lateral flexion, elevation of the chin, contralateral rotation of head
  • Bilateral contraction: flexes the neck, extension of the upper vertebral joints, extension of the neck and head, elevation of the head, elevation of the sternum and clavicle, expansion of the thoracic cavity
Rectus capitis lateralis Transverse process of atlas (C1) Jugular process of occipital bone Anterior rami of 1st and 2nd cervical spinal nerves (C1-C2)
  • Lateral flexion of the head (ipsilateral)
  • Neck flexion
  • Stabilisation of the atlanto-occipital joint

Cervical Spine Extensors[edit | edit source]

Muscle Origin Insertion Innervation Action
Obliquus capitis superior Transverse process of the atlas Occipital bone Suboccipital nerve (posterior ramus of 1st cervical spinal nerve (C1))
  • Bilateral contraction: head extension
  • Unilateral contraction: rotation of head to the ipsilateral side
  • Stabilises the atlanto-occipital joint during head movements
Obliquus capitis inferior Spinous process of the axis Tansverse process of atlas Suboccipital nerve (posterior ramus of 1st cervical spinal nerve (C1))
  • Bilateral contraction: head extension
  • Unilateral contraction: rotation of head to the ipsilateral side
  • Stabilises the atlanto-axial joint
Rectus capitis posterior major Spinous process of C2 Occipital bone Suboccipital nerve (posterior ramus of 1st cervical spinal nerve (C1))
  • Unilateral contraction: head rotation (ipsilateral)
  • Bilateral contraction: head extension
Rectus capitis posterior minor Posterior tubercle of the atlas Occipital bone Suboccipital nerve (posterior ramus of 1st cervical spinal nerve (C1))
  • Head extension
Iliocostal cervicis Ribs 3-6 Transverse process of C4-C6 Dorsal rami of the upper thoracic and lower cervical spinal nerves
Trapezius Occipital bone, nuchal ligament and spinous process C7-T12 Lateral third of the clavicle, acromian and spine of the scapula Spinal root of accessory nerve (CN XI) (motor)

Cervical nerves (C3 and C4) (pain and proprioception)

  • Supports the spinal column to remain erect
  • Neck extension when scapulae are fixed
  • Ipsilateral lateral flexion of neck
Splenius cervicis Spinous process of T3-T6 Transverse process of C1-C3 Dorsal rami of cervical spinal nerves (C5-C8)
  • Acting bilaterally: extend the neck
  • Acting unilaterally: lateral flexion and rotation of the head and neck to the ipsilateral side
Splenius capitis Spinous process of C7-T3 and nuchal ligament Occipital bone Posterior rami of the 2nd and 3rd cervical spinal nerves
  • Acting bilaterally: extension of the head and neck
  • Acting unilaterally: lateral flexion and rotation of the head and neck to the ipsilateral side
Spinalis capitis Spinous process of C7 and T1 Occipital bone Dorsal rami of spinal nerves
  • Acting bilaterally: extension of the neck
  • Acting unilaterally: ipsilateral lateral flexion and rotation of the neck
Longissimus capitis Transverse process of upper 4 thoracic vertebrae and articular process lower three cervical vertebrae Mastoid process Posterior/dorsal rami of spinal nerves
  • Acting bilaterally: extension of neck
  • Acting unilaterally: ipsilateral lateral flexion and rotation of the neck

** The transversospinal muscles (rotatores, multifidus, semispinalis) are the deep muscle of the spine. They attach between the transverse and spinous process of the vertebrae. They stabilise and extend the spine. The rotatores also provide rotation.

Cervical Spine Lateral Flexors[edit | edit source]

Muscle Origin Insertion Innervation Action
Splenius cervicis Spinous process of T3-T6 Transverse process C1-C3 Dorsal rami of cervical spinal nerves (C5-C8)
  • Acting unilaterally: lateral flexion and rotation of the head and neck to the ipsilateral side
  • Acting bilaterally: extend the neck
Splenius capitis Spinous process of C7-T3 and nuchal ligament Occipital bone Posterior rami of the 2nd and 3rd cervical spinal nerves
  • Acting unilaterally: lateral flexion of the head and neck and rotation of the head to the ipsilateral side
  • Acting bilaterally: extension of the head and cervical spine
Sternocleidomastoid Manubrium and the medial portion of the clavicle Mastoid process of the temporal bone Accessory nerve (CN XI), branches of cervical plexus (C2-C3)
  • Unilateral contraction: ipsilateral lateral flexion, elevation of the chin, contralateral rotation of head
  • Bilateral contraction: flexes the neck, extension of the upper vertebral joints, extension of the neck and head, elevation of the head, elevation of the sternum and clavicle, expansion of the thoracic cavity
Anterior scalene Transverse processes of C3-C6 First rib Anterior rami of 4th to 6th cervical spinal nerves (C4-C6)
  • Unilateral contraction: neck lateral flexion (ipsilateral), neck rotation (contralateral), elevation of the first rib
  • Bilateral contraction: neck flexion
  • Accessory muscle of respiration
Middle scalene Posterior tubercles of the transverse processes of C1-C7 Scalene tubercle of the first rib Anterior rami of C3-C8
  • Elevation of the first rib
  • Ipsilateral contraction causes ipsilateral lateral flexion of the neck
  • Respiration
Posterior scalene Posterior tubercles of the transverse processes of C4-C6 2nd rib Anterior rami of C6-C8
  • Elevation of the second rib
  • Ipsilateral lateral flexion of the neck
  • Respiration
Trapezius Occipital bone, nuchal ligament and spinous process C7-T12 Lateral third of the clavicle, the acromian and the spine of s scapula Spinal root of accessory nerve (CN XI) (motor)

Cervical nerves (C3 and C4) (pain and proprioception)

  • Supports the spinal column to remain erect
  • Neck extension when scapulae are fixed
  • Ipsilateral lateral flexion of the neck
Rectus capitis lateralis Superior surface of the transverse process of atlas Inferior surface of the jugular process of the occipital bone Anterior rami of C1-C2 spinal nerves
  • Lateral flexion of the head (ipsilateral)
  • Deep neck flexion
  • Stabilisation of the atlanto-occipital joint
Spinalis capitis Spinous process of C7 and T1 Occipital bone Dorsal rami of spinal nerves
  • Acting bilaterally: extension of the neck
  • Acting unilaterally: ipsilateral lateral flexion and rotation of the neck
Longissimus capitis Transverse process of upper 4 thoracic vertebrae and articular process lower three cervical vertebrae Mastoid process Posterior/dorsal rami of spinal nerves
  • Acting bilaterally: extension of the neck
  • Acting unilaterally: ipsilateral lateral flexion and rotation of the neck

Cervical Spine Rotators[edit | edit source]

Muscle Origin Insertion Innervation Action
Rectus capitis posterior major Spinous process of C2 Occipital bone Suboccipital nerve (posterior ramus of 1st cervical spinal nerve (C1))
  • Unilateral contraction: head rotation (ipsilateral)
  • Bilateral contraction: head extension
Rectus capitis posterior major Spinous process of C2 Occipital bone Suboccipital nerve (posterior ramus of 1st cervical spinal nerve (C1))
  • Unilateral contraction: head rotation (ipsilateral)
  • Bilateral contraction: head extension
Sternocleidomastoid Manubrium and the medial portion of the clavicle Mastoid process of the temporal bone Accessory nerve (CN XI), branches of cervical plexus (C2-C3)
  • Unilateral contraction: ipsilateral lateral flexion, elevation of the chin, contralateral rotation of head
  • Bilateral contraction: flexion of the neck, extension of the upper vertebral joints, extension of the neck and head, elevation of the head, elevation of the sternum and clavicle, expansion of thoracic cavity
Splenius capitis Spinous process ofC7-T3 and nuchal ligament Occipital bone Posterior rami of the 2nd and 3rd cervical spinal nerves
  • Acting unilaterally: lateral flexion of the head and neck and rotation of the head to the ipsilateral side
Splenius cervicis Spinous process T3-T6 Transverse process C1-C3 Dorsal rami of cervical spinal nerves (C5-C8)
  • Acting unilaterally: lateral flexion and rotation of the head and neck to the ipsilateral side
Spinalis capitis Spinous process of C7 and T1 Occipital bone Dorsal rami of spinal nerves
  • Acting bilaterally: extension of the neck
  • Acting unilaterally: ipsilateral lateral flexion and rotation of the neck
Longissimus capitis Transverse process of upper 4 thoracic vertebrae and articular process lower three cervical vertebrae Mastoid process Posterior/dorsal rami of spinal nerves
  • Acting bilaterally: extension of the neck
  • Acting unilaterally: ipsilateral lateral flexion and rotation of the neck

Innervation of the Cervical Spine[edit | edit source]

Nerves originating from the cervical plexus innervate the muscles of the neck. Each nerve root in the cervical spine exits above its corresponding nerve root. There are eight pairs of cervical nerves despite there being seven cervical vertebrae. The C8 nerve root exits below the seventh cervical vertebra. The accessory nerve, which is cranial nerve XI innervates sternocleidomastoid and trapezius.[2]

Nerve Motor Sensory
C1 Flexion of the head and neck

Rectus capitus anterior and lateralis, longus capitis

C2 Flexion of the head and neck

Rectus capitus anterior and lateralis, longus capitus, prevertebral muscles and sternocleidomastoid

Lateral occiput and submandibular area
C3 Head and neck flexion and rotation

Longus capitus, longus colli, prevertebral muscles and sternocleidomastoid, diaphragm, levator scapulae, trapezius and scalenus medius

Lateral occiput and lateral neck, overlapping C2
C4 Head and neck flexion and rotation

Longus capitus, longus colli, levator scapulae, scaleni, trapezius, diaphragm

Lower lateral neck and medial shoulder area
C5 Deltoid, biceps, bicep tendon reflex Clavicle level and lateral arm
C6 Biceps, wrist extensors (brachioradialis tendon reflex) Lateral forearm, thumb, index and half of 2nd finger
C7 Wrist flexors, triceps (triceps tendon reflex) Second finger
C8 Finger flexors, interossei Medial forearm, ring and little finger
T1 Interossei Medial arm

Vascular Supply of the Cervical Spine[edit | edit source]

Vertebral arteries, veins and nerves pass through the transverse foramina of the cervical vertebrae except for in C7, where the vertebral artery passes around the vertebra instead of through the transverse foramen.[4] The neural components sit posterior to the vertebral artery.[12]

The cervical spine vascular supply is primarily provided by the vertebral arteries on each side of the spine. These arteries arise from the subclavian arteries, which originate directly from the arch of the aorta on the right and the brachiocephalic trunk on the left.

** The common carotid artery bifurcates into the internal and external carotid arteries at the C3 segmental level. Only the external carotid artery provides any blood supply to the neck.

Clinical Relevance[edit | edit source]

  • Atlanto-axial instability (AAI) can have serious neurological consequences:
    • conditions with the potential for AAI include:
      • rheumatoid arthritis
      • Down syndrome:
        • laxity in the transverse ligament is present in 14-22% of individuals with Down syndrome.
  • A tight sternocleidomastoid muscle can cause torticollis.
  • Disc herniation:
    • disc herniations in the cervical spine are a lot less common than in the lumbar spine
    • typical locations:
      • C5-C6
      • C6-C7
  • Because the prevertebral cervical muscles stabilise the neck, dysfunction in these muscles can cause cervicogenic pain
  • Trigger points that develop in the suboccipital muscles can refer pain to the head, causing cervicogenic headaches[10]

Resources[edit | edit source]

References[edit | edit source]

  1. ↑ Frost BA, Camarero-Espinosa S, Foster EJ. Materials for the spine: anatomy, problems, and solutions. Materials. 2019 Jan;12(2):253
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Kaiser JT, Reddy V, Lugo-Pico JG. Anatomy, Head and Neck: Cervical Vertebrae. [Updated 2022 Oct 6]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539734/
  3. ↑ Petersen JA, Brauer C, Thygesen LC, Flachs EM, Lund CB, Thomsen JF. Prospective, population-based study of occupational movements and postures of the neck as risk factors for cervical disc herniation. BMJ open. 2022 Feb 1;12(2):e053999.
  4. ↑ 4.0 4.1 Teach me anatomy The cervical Spine Available from:https://teachmeanatomy.info/neck/bones/cervical-spine/
  5. ↑ 5.0 5.1 Learn muscles . Cervical spine joints. Available from: https://learnmuscles.com/blog/2017/08/01/cervical-spinal-joints/ (last accessed 29.1.2020)
  6. ↑ Peng B, Bogduk N. Cervical discs as a source of neck pain. An analysis of the evidence. Pain Medicine. 2019 Mar 1;20(3):446-55.
  7. ↑ Guo GM, Li J, Diao QX, Zhu TH, Song ZX, Guo YY, Gao YZ. Cervical lordosis in asymptomatic individuals: a meta-analysis. Journal of orthopaedic surgery and research. 2018 Dec;13(1):1-7.
  8. ↑ Lindenmann S, Tsagkaris C, Farshad M, Widmer J. Kinematics of the Cervical Spine Under Healthy and Degenerative Conditions: A Systematic Review. Annals of Biomedical Engineering. 2022 Dec 10:1-29.
  9. ↑ RSNA Joints of Luschka Available from: https://pubs.rsna.org/doi/10.1148/66.2.181 (last accessed 28.1.2020)
  10. ↑ 10.0 10.1 Xuan D. Exploring Cervical Spine Anatomy Course. Plus, 2023.
  11. ↑ Palastanga, N., & Soames, R. (2012). Anatomy and human movement (6th ed.). Edinburgh: Churchill Livingstone.
  12. ↑ Joshi N, Klinger N, Halalmeh DR, Tubbs RS, Moisi MD. The Neural Sulcus of the Cervical Vertebrae: A Review of Its Anatomy and Surgical Perspectives. Cureus. 2020 Jan 18;12(1)
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