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== Introduction == | == Introduction == | ||
The | The [[Lumbar Anatomy|lumbar spine]] supports much of the upper body's weight. [[Intervertebral disc|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. [[Ligament|Ligaments]] hold the vertebrae in place, and [[Tendon Anatomy|tendon]]<nowiki/>s attach the muscles to the spinal column. | ||
The skeletal support of the abdominal wall includes the vertebral column and lower ribs. The [[Abdominal Muscle Anatomy|abdominal wall]] contains skin, [[fascia]], and [[Muscle Cells (Myocyte)|muscle]]. It provides coverage for the organs, generates intra-abdominal pressure, and moves the vertebral column. This article discusses the key anatomical structures of the lumbar vertebrae and abdominal wall, including the bony structures, articulations, ligaments, muscles, nerves and the vascular supply. | |||
== 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. | ||
[[ | [[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." | ||
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 | 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. | ||
[[ | [[Ligament]]: fibrous connective tissue that holds the bones together. | ||
Open (loose) pack position: position with the least joint congruency where joint stability is reduced. | Open (loose) pack position: position with the least joint congruency where joint stability is reduced. | ||
[[ | [[Cardinal Planes and Axes of Movement|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). | ||
== Lumbar Spine Structure == | == Lumbar Spine Structure == | ||
=== '''Lumbar vertebrae''' === | === '''Lumbar vertebrae''' === | ||
L1-L5 | There are usually five [[Lumbar Vertebrae|lumbar vertebrae]], which are known as L1-L5. However, 10–17.4% of adults present with a 6th lumbar vertebra<ref>Yan YZ, Li QP, Wu CC, Pan XX, Shao ZX, Chen SQ, Wang K, Chen XB, Wang XY. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5966918/pdf/13018_2018_Article_835.pdf Rate of the presence of 11 thoracic vertebrae and 6 lumbar vertebrae in asymptomatic Chinese adult volunteers]. J Orthop Surg Res. 2018 May 23;13(1):124.</ref> (or a sacral vertebra<ref name=":3" />). Having an additional vertebra may influence sagittal parameters. For instance, it may result in a diminished sacral tilt (i.e. the sacrum is in a more vertical position).<ref>Yan YZ, Wang B, Huang XQ, Ru X, Wang XY, Qu HB. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8867438/pdf/OS-14-341.pdf Variation in Global Spinal Sagittal Parameters in Asymptomatic Adults with 11 Thoracic Vertebrae, four Lumbar Vertebrae, and six Lumbar Vertebrae.] Orthop Surg. 2022 Feb;14(2):341-348.</ref> Individuals who have additional lumbar vertebrae may also have fewer thoracic vertebrae (e.g. 11 rather than 12 thoracic vertebrae). | ||
The lumbar vertebrae are located between the 12th thoracic vertebra and the sacrum bone. They are the largest vertebrae of the human body. Each lumbar vertebra contains the following structural elements: | The lumbar vertebrae are located between the 12th (or last) thoracic vertebra and the sacrum bone. They are the largest vertebrae of the human body. Each lumbar vertebra contains the following structural elements: | ||
* Vertebral body | * Vertebral body | ||
** Kidney-shaped | ** Kidney-shaped | ||
** Wider | ** Wider side to side than front to back | ||
** The posterior aspect of the vertebral body changes from concave to convex | ** The posterior aspect of the vertebral body changes from concave to convex | ||
* Vertebral foramen | * Vertebral foramen | ||
** Triangular in shape | ** Triangular in shape | ||
** Larger than in the thoracic vertebrae but smaller than in the cervical vertebrae | ** Larger than in the thoracic vertebrae, but smaller than in the cervical vertebrae | ||
* Two pedicles | * Two pedicles | ||
** Posterior element of the lumbar vertebra | ** Posterior element of the lumbar vertebra | ||
** Attach to the cranial half of the vertebral body | ** Attach to the cranial half of the vertebral body | ||
** | ** Change in shape from L1-L5 | ||
* Two laminae | * Two laminae | ||
** Flat and broad | ** Flat and broad | ||
** Two pedicles and two laminae form the vertebral arch | ** Two pedicles and two laminae form the vertebral arch | ||
** Centrally | ** Centrally connect to the spinous process | ||
* Spinous process | * Spinous process | ||
** Projects perpendicularly from the body | ** Projects perpendicularly from the body | ||
** Short and sturdy | ** Short and sturdy | ||
** | ** Described as "hatchet-shaped" | ||
** | ** Provides an attachment point for muscles and ligaments | ||
* Two transverse processes | * Two transverse processes | ||
** Located on the posterior surface | ** Located on the posterior surface | ||
** Project laterally on each side of the vertebra | ** Project laterally on each side of the vertebra | ||
** Long and slender | ** Long and slender | ||
** | ** Provide attachment points for muscles and ligaments | ||
** L1-L3 | ** L1-L3 project horizontally | ||
**L4-L5 | **L4-L5 project upward | ||
* Four articular processes<ref>Waxenbaum JA, Reddy V, Williams C, Futterman B. [https://www.ncbi.nlm.nih.gov/books/NBK459278/ Anatomy, Back, Lumbar Vertebrae]. 2022 Aug 1. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan–. </ref> | * Four articular processes<ref>Waxenbaum JA, Reddy V, Williams C, Futterman B. [https://www.ncbi.nlm.nih.gov/books/NBK459278/ Anatomy, Back, Lumbar Vertebrae]. 2022 Aug 1. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan–. </ref> | ||
** Two superior articular facets and two inferior articular facets | ** Two superior articular facets and two inferior articular facets | ||
** The point where two facets | ** The point where two facets join is called the zygapophyseal joints | ||
=== Lumbar Lordosis === | === Lumbar Lordosis === | ||
''Lordosis = the natural curve for the lumbar spine.'' This curve defines lumbar spine alignment in the sagittal plane. However, the pelvis is "the cornerstone of spinal sagittal alignment".<ref name=":0">Diebo BG, Varghese JJ, Lafage R, Schwab FJ, Lafage V. Sagittal alignment of the spine: What do you need to know? Clin Neurol Neurosurg. 2015 Dec;139:295-301.</ref> The curve of the sacrum determines the lumbar curve. | |||
Optimal sagittal alignment of the lumbar spine offers the following benefits during locomotion:<ref name=":0" /> | |||
* Allows the body's centre of mass to be positioned above the hip, knee, and ankle joints | * 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 | * Minimises the muscular force used for postural control | ||
Assessment of | 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 sagittal plane malalignment.<ref>Schwab F, Lafage V, Boyce R, Skalli W, Farcy JP. Gravity line analysis in adult volunteers: age-related correlation with spinal parameters, pelvic parameters, and foot position. Spine (Phila Pa 1976). 2006 Dec 1;31(25):E959-67.</ref> | ||
== Abdominal Wall Structure == | == Abdominal Wall Structure == | ||
The | The skeletal support of the abdominal wall comes from the vertebral column and lower ribs posteriorly. Anteriorly, it connects to the thoracic cage (rib cage) superiorly and the pelvic bones inferiorly. It is defined by the following landmarks: | ||
* superior border = the xiphoid process and costal cartilage of ribs 7–10 | |||
* inferior border = the umbilicus in the middle, and [[Inguinal Ligament|inguinal ligament]], pubic crest and [[Pubic Symphysis Dysfunction|pubic symphysis]] | |||
You can read more about pelvis anatomy [https://www.physio-pedia.com/Functional_Anatomy_of_the_Pelvis#ppm251385 here]. | You can read more about pelvis anatomy [https://www.physio-pedia.com/Functional_Anatomy_of_the_Pelvis#ppm251385 here]. | ||
== Bones, Articulations and Kinematics of the Lumbar Spine == | |||
The | |||
=== Bones and Articulations === | |||
The lumbar spine has two types of joints located between each lumbar vertebra: | |||
# intervertebral disc joint | |||
# zygapophyseal joint or facet joint | |||
{| class="wikitable" | {| class="wikitable" | ||
|+ | |+ | ||
Line 93: | Line 104: | ||
|Intervertebral disc joint | |Intervertebral disc joint | ||
|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. | |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. | ||
|To find each segment of the lumbar spine, position the patient prone. The location of the | |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. | ||
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 | 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"<ref name=":1" />, but the accuracy of palpation is only 36%.<ref name=":1">Feng Q, Zhang L, Zhang M, Wen Y, Zhang P, Wang Y, Zeng Y, Wang J. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7309970/pdf/13018_2020_Article_1750.pdf Morphological parameters of fourth lumbar spinous process palpation: three-dimensional reconstruction of computed tomography.] J Orthop Surg Res. 2020 Jun 22;15(1):227.</ref> | ||
|- | |- | ||
|Articular processes | |Articular processes | ||
|Zygapophyseal joint (Facet joint) | |Zygapophyseal joint (Facet joint) | ||
|Located on the left and right sides of the spine | |Formed between the articular processes of each lumbar vertebra. | ||
Located on the left and right sides of the spine. | |||
The superior articular surface is vertical and concave, and the inferior is vertically convex. | |||
They link one vertical segment to the other. For example, the facet joint between L3 and L4 will connect L3 to L4. | |||
|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 | The superior articular surface is vertical and concave, and the inferior is vertically convex. | ||
Their primary role includes the stabilisation of the spinal motion segment.<ref name=":2">Kapetanakis S, Gkantsinikoudis N. Anatomy of lumbar facet joint: a comprehensive review. Folia Morphol (Warsz). 2021;80(4):799-805. </ref> They also contribute to axial compressive load transmission. | |||
|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.''' | |||
|} | |} | ||
=== | === Kinematics === | ||
The lumbar spine is considered a three-joint complex or | The lumbar spine is considered a three-joint complex or an articular triad.<ref name=":2" /> 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 protect the spine from excessive movements. | ||
The | The spinal motion segment has the following characteristics:<ref>Inoue N, Orías AAE, Segami K. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7002062/pdf/2432-261X-4-0001.pdfv Biomechanics of the Lumbar Facet Joint.] Spine Surg Relat Res. 2019 Apr 26;4(1):1-7. </ref> | ||
* The intervertebral | * The intervertebral disc joint transmits mostly vertical compressive loads | ||
* The facet joints guide and stabilise the motion segment | * The facet joints guide and stabilise the motion segment | ||
* In | * In an erect standing position and erect sitting posture, spine load is also transmitted through the facet joints | ||
{| class="wikitable" | {| class="wikitable" | ||
Line 125: | Line 139: | ||
!Open pack position | !Open pack position | ||
|- | |- | ||
|Intervertebral disc joint | |[[Intervertebral disc|Intervertebral disc joint]] | ||
|Cartilaginous joint, symphysis | |Cartilaginous joint, symphysis | ||
|A single joint: structurally fused but allows very limited, multidirectional movements | |A single joint: structurally fused but allows very limited, multidirectional movements | ||
Line 132: | Line 146: | ||
Frontal | Frontal | ||
Transverse | Transverse | ||
|Single joint: Translating, tilting, rocking and compressing movements | | rowspan="2" |''Single joint:'' Translating, tilting, rocking and compressing movements. | ||
The following movements occur when ''all lumbar intervertebral disc joints and zygapophyseal joints are moving together'' : | |||
Flexion/ | Flexion/extension | ||
Lateral flexion | Lateral flexion | ||
Rotation | Rotation | ||
| | | rowspan="2" |The following movements occur when ''all lumbar intervertebral disc joints and zygapophyseal joints moving together'' : | ||
Flexion 60 degrees | Flexion 60 degrees | ||
Line 151: | Line 168: | ||
| Halfway between flexion and extension | | Halfway between flexion and extension | ||
|- | |- | ||
|Zygapophyseal joint | |Zygapophyseal joint (facet joint) | ||
|Synovial plane joint | |[[Synovial Joints|Synovial]] plane joint | ||
|Facilitate a multiplanar and multidirectional movement of the spine | |Facilitate a multiplanar and multidirectional movement of the spine. | ||
Enable lumbar spine extension, lateral flexion, and rotation in the | Enable lumbar spine extension, lateral flexion, and rotation in the sagittal, transverse and frontal planes. | ||
|Full extension | |Full extension | ||
| Halfway between flexion and extension | | Halfway between flexion and extension | ||
|} | |} | ||
== Lumbar Spine Ligaments | == Lumbar Spine Ligaments == | ||
{| class="wikitable" | {| class="wikitable" | ||
|+ | |+ | ||
Line 182: | Line 188: | ||
|The anterior portion of the vertebral body at the base of the skull | |The anterior portion of the vertebral body at the base of the skull | ||
|The anterior portion of the vertebral body at the sacrum | |The anterior portion of the vertebral body at the sacrum | ||
| | |Limits extension of the vertebral column. | ||
Reinforces the intervertebral disc. | |||
| | | | ||
|- | |- | ||
|[[Posterior longitudinal ligament]] | |[[Posterior longitudinal ligament]] | ||
|The body of | |The body of C2 | ||
|Posterior surface of the sacrum | |Posterior surface of the sacrum | ||
|Limits flexion of the vertebral column | |Limits flexion of the vertebral column. | ||
Reinforces the intervertebral disc | Reinforces the intervertebral disc. | ||
| | | | ||
|- | |- | ||
|[[Ligamentum flavum]]: | |[[Ligamentum flavum]]: | ||
A series of short ligaments that connect the laminae of each vertebra.<ref name=":3">Xuan D. Exploring Lumbar Spine and Abdominal Wall Anatomy Course. Physiopedia Plus, 2023.</ref> There are two ligamenta flava at each vertebra. | |||
'''The lateral portion:''' passes in front of the [[ | Each ligament is divided into: | ||
'''The medial portion:''' passes to the back of the next lower lamina and across the gap between the adjacent vertebrae, fusing with the [[interspinous ligament]] | |||
'''The lateral portion:''' passes in front of the [[Facet Joints|facet joint,]] attaches to the anterior aspect of the inferior and superior articular processes and forms the anterior capsule. 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 lower half of the anterior surface of the lamina above | ||
|The posterior surface and upper margin of the lamina below | |The posterior surface and upper margin of the lamina below | ||
|Assists with lumbar spine flexion and extension | |Their high elastin content prevents the ligament from buckling into the spinal canal.<ref name=":3" /> | ||
Assists with lumbar spine flexion and extension. | |||
Compresses the intervertebral discs. | Compresses the intervertebral discs. | ||
| | | | ||
Line 209: | Line 218: | ||
|Transverse processes of the vertebra above | |Transverse processes of the vertebra above | ||
|Transverse processes of the vertebra below | |Transverse processes of the vertebra below | ||
|Contributes to the stability of the lumbar spine | |Contributes to the stability of the lumbar spine. | ||
Limits lateral flexion. | |||
|To palpate the '''transverse process''', the patient | |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. | ||
|- | |- | ||
|Supraspinous ligament | |Supraspinous ligament | ||
Line 217: | Line 226: | ||
|Tip of spinous processes of the vertebra below | |Tip of spinous processes of the vertebra below | ||
|Prevents the separation of the spinous processes during forward flexion, thus limiting lumbar spine flexion | |Prevents the separation of the spinous processes during forward flexion, thus limiting lumbar spine flexion | ||
|You can palpate the '''spinous processes'' in the centre of the patient's back. | |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. | 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. | ||
|- | |- | ||
Line 228: | Line 237: | ||
== Muscles of the Lumbar Spine and Abdominal Wall == | == Muscles of the Lumbar Spine and Abdominal Wall == | ||
The muscles of the back can be grouped according to their function and | 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 | * Flexors: psoas major, psoas minor, internal oblique, external oblique, and rectus abdominis | ||
Line 237: | Line 246: | ||
* Rotators: multifidus, 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: | |||
* The intrinsic (deep) group | * The intrinsic (deep) group: | ||
** Superficial layer: erector spinae muscles | ** Superficial layer: erector spinae muscles | ||
** Middle (deep) layer: multifidus | ** Middle (deep) layer: multifidus | ||
Line 245: | Line 254: | ||
* The abdominal wall group: transverse abdominis, the internal oblique, rectus abdominis, and the external oblique | * 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 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 === | === Lumbar Spine Flexors === | ||
Line 256: | Line 266: | ||
|- | |- | ||
|Psoas major | |Psoas major | ||
|Vertebral bodies of T12-L4 | |Vertebral bodies of T12-L4 | ||
Intervertebral discs between T12-L4 | |||
Transverse processes of L1-L5 vertebrae | |||
|Lesser trochanter of femur | |Lesser trochanter of femur | ||
|Anterior rami of spinal nerves L1-L3 | |Anterior rami of spinal nerves L1-L3 | ||
| | |Contribute to lumbar spine flexion when acting bilaterally and when the insertion point is fixed.<ref name=":3" /> | ||
|- | |- | ||
|Psoas minor | |Psoas minor | ||
Line 265: | Line 277: | ||
|Iliopubic eminence | |Iliopubic eminence | ||
|Anterior ramus of spinal nerve L1 | |Anterior ramus of spinal nerve L1 | ||
|Weak trunk flexor. | |Weak trunk flexor. This muscle is absent in 40% of people.<ref name=":3" /> | ||
|- | |- | ||
|Internal obliques | |Internal obliques | ||
|Thoracolumbar fascia | |Thoracolumbar fascia | ||
Iliac crest | Iliac crest | ||
Inguinal ligament | Inguinal ligament | ||
Line 274: | Line 286: | ||
Linea alba | Linea alba | ||
Pubic crest | Pubic crest | ||
|Lower intercostal nerves Branches of the lumbar plexus: iliohypogastric nerve and ilioinguinal nerve | |Lower intercostal nerves Branches of the lumbar plexus: iliohypogastric nerve and ilioinguinal nerve | ||
|Bilateral action: lumbar flexion | |Bilateral action: lumbar flexion | ||
Assist in raising intra-abdominal pressure | |||
|- | |- | ||
|External obliques | |External obliques | ||
|Ribs five to twelve | |Ribs five to twelve | ||
|Linea alba Pubic tubercle | |Linea alba | ||
Pubic tubercle | |||
Iliac crest | Iliac crest | ||
|Intercostal nerves T7- T11 and the T12 subcostal nerve | |Intercostal nerves T7- T11 and the T12 subcostal nerve | ||
Line 286: | Line 299: | ||
|- | |- | ||
|Rectus abdominis | |Rectus abdominis | ||
|Pubis | |Pubis, pubic symphysis | ||
|Xiphoid process of the sternum | |||
|Xiphoid process of the sternum | Costal cartilage of ribs 5-7 | ||
|Thoracoabdominal nerves | |Thoracoabdominal nerves | ||
|Lumbar spine flexion | |Lumbar spine flexion | ||
Line 317: | Line 329: | ||
|Inferior aspects of spinous processes of L1-L4 | |Inferior aspects of spinous processes of L1-L4 | ||
|Posterior rami of spinal nerves | |Posterior rami of spinal nerves | ||
|Stabilise the lumbar spine | |Stabilise the lumbar spine Extend the lumbar spine | ||
|- | |- | ||
|Multifidus | |Multifidus | ||
|Sacrum | |Sacrum | ||
Posterior superior iliac spine | Posterior superior iliac spine | ||
The mammillary processes of the lumbar vertebrae | The mammillary processes of the lumbar vertebrae | ||
Transverse processes of T1-3 Articular processes of C4-C7 | |||
|Spinous processes of the vertebrae above their origin | |Spinous processes of the vertebrae above their origin | ||
|Medial branches of posterior rami of spinal nerves in the corresponding lumbar region | |Medial branches of the posterior rami of the spinal nerves in the corresponding lumbar region | ||
|Extends the lumbar spine | |Extends the lumbar spine | ||
Provides core stability | Provides core stability | ||
|- | |- | ||
|Erector spinae: Iliocostalis lumborum (ICL) Longissimus thoracis (LT) | |Erector spinae: Iliocostalis lumborum (ICL) Longissimus thoracis (LT) | ||
Spinalis (not involved in the lumbar spine motion) | |||
|''ICL'': Iliac crest | |''ICL'': Iliac crest | ||
''LT'' : Lumbar intermuscular aponeurosis, medial part of sacropelvic surface of ilium, posterior sacroiliac ligament | ''LT'' : Lumbar intermuscular aponeurosis, medial part of sacropelvic surface of ilium, posterior sacroiliac ligament | ||
Line 358: | Line 374: | ||
|- | |- | ||
|Psoas major | |Psoas major | ||
|Vertebral bodies of T12-L4 | |Vertebral bodies of T12-L4 | ||
Intervertebral discs between T12-L4 | |||
Transverse processes of L1-L5 vertebrae | |||
|Lesser trochanter of femur | |Lesser trochanter of femur | ||
|Anterior rami of spinal nerves L1-L3 | |Anterior rami of spinal nerves L1-L3 | ||
Line 382: | Line 400: | ||
|- | |- | ||
|Internal oblique | |Internal oblique | ||
|Thoracolumbar fascia | |Thoracolumbar fascia | ||
Iliac crest | Iliac crest | ||
Inguinal ligament | Inguinal ligament | ||
|Lower four ribs | |Lower four ribs | ||
Line 395: | Line 413: | ||
|External oblique | |External oblique | ||
|Ribs five to twelve | |Ribs five to twelve | ||
|Linea alba Pubic tubercle | |Linea alba | ||
Pubic tubercle | |||
Iliac crest | Iliac crest | ||
|Intercostal nerves T7- T11 and the T12 subcostal nerve | |Intercostal nerves T7- T11 and the T12 subcostal nerve | ||
Line 412: | Line 431: | ||
|Multifidus | |Multifidus | ||
|Sacrum | |Sacrum | ||
Posterior superior iliac spine | Posterior superior iliac spine | ||
The mammillary processes of the lumbar vertebrae | The mammillary processes of the lumbar vertebrae | ||
|Spinous processes of the vertebrae above their origin | |Spinous processes of the vertebrae above their origin | ||
Line 422: | Line 442: | ||
|Thoracolumbar fascia | |Thoracolumbar fascia | ||
Iliac crest | Iliac crest | ||
Inguinal ligament | Inguinal ligament | ||
|Lower four ribs | |Lower four ribs | ||
Linea alba | Linea alba | ||
Pubic crest | Pubic crest | ||
|Lower intercostal nerves | |Lower intercostal nerves | ||
Branches of the lumbar plexus: iliohypogastric nerve and ilioinguinal nerve. | Branches of the lumbar plexus: iliohypogastric nerve and ilioinguinal nerve. | ||
|Rotation to the | |Rotation to the ''ipsilateral'' 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) | |External oblique (EO) | ||
Line 436: | Line 458: | ||
Iliac crest | Iliac crest | ||
|Intercostal nerves T7- T11 and the T12 subcostal nerve | |Intercostal nerves T7- T11 and the T12 subcostal nerve | ||
|Rotation to the | |Rotation to the ''contralateral'' side | ||
Works with opposite IO to rotate the spine - e.g. right external oblique works with left internal oblique to rotate the spine. | |||
|} | |} | ||
Line 449: | Line 471: | ||
!'''Sensory fibres''' | !'''Sensory fibres''' | ||
|- | |- | ||
|Intercostal | |Intercostal | ||
|Lumbar plexus | |Lumbar plexus | ||
|Muscular, collateral, lateral cutaneous, anterior cutaneous, and | |Muscular, collateral, lateral cutaneous, anterior cutaneous, and | ||
Line 457: | Line 479: | ||
|Skin over the anterior abdomen | |Skin over the anterior abdomen | ||
|- | |- | ||
|Subcostal | |Subcostal | ||
|Anterior ramus of the spinal nerve T12 | |Anterior ramus of the spinal nerve T12 | ||
|Muscular, cutaneous, communicating and collateral branches | |Muscular, cutaneous, communicating and collateral branches | ||
Line 464: | Line 486: | ||
|The skin of the region under the umbilicus | |The skin of the region under the umbilicus | ||
|- | |- | ||
|Iliohypogastric | |Iliohypogastric | ||
|Lumbar plexus | |Lumbar plexus | ||
|Lateral cutaneous branch | |Lateral cutaneous branch | ||
Line 472: | Line 494: | ||
The skin of the suprapubic region | The skin of the suprapubic region | ||
|- | |- | ||
|Ilioinguinal | |Ilioinguinal | ||
|Lumbar plexus | |Lumbar plexus | ||
|Anterior labial nerves | |Anterior labial nerves | ||
Line 482: | Line 504: | ||
|Spinal nerves | |Spinal nerves | ||
|Medial | |Medial | ||
Intermediate | Intermediate | ||
Lateral | Lateral | ||
|Interspinales lumborum | |Interspinales lumborum | ||
Multifidus | Multifidus | ||
Erector spinae | Erector spinae | ||
|The skin of the back | |The skin of the back | ||
|- | |- | ||
|Ventral (anterior) rami of L1-L4 | |Ventral (anterior) rami of L1-L4 | ||
Line 494: | Line 518: | ||
|Intertransversarii lumborum | |Intertransversarii lumborum | ||
Psoas major | Psoas major | ||
Psoas minor | Psoas minor | ||
| | |The skin of the ventrolateral body walls | ||
|} | |} | ||
Line 509: | Line 534: | ||
|Lumbar artery (LA): | |Lumbar artery (LA): | ||
Left (LLA) | Left (LLA) | ||
Right (RLA) | Right (RLA) | ||
|Abdominal aorta | |Abdominal aorta | ||
|Medial | |Medial | ||
Middle | Middle | ||
Lateral | Lateral | ||
|Skin and muscles of the posterior abdominal wall | |Skin and muscles of the posterior abdominal wall | ||
Joints of the lumbar spine | Joints of the lumbar spine | ||
The lumbar portion of the deep back muscles | |||
The lumbar portion of the deep back muscles | |||
Lower two-thirds of the spinal cord | Lower two-thirds of the spinal cord | ||
|- | |- | ||
Line 523: | Line 552: | ||
|Anterior collaterals | |Anterior collaterals | ||
Posterior collaterals | Posterior collaterals | ||
Terminal branches | Terminal branches | ||
|The superior aspect of the abdominal wall | |The superior aspect of the abdominal wall | ||
Line 535: | Line 565: | ||
== Clinical Relevance == | == Clinical Relevance == | ||
# Disc herniations are common low back | # Disc herniations are a common low back condition. They occur when the nucleus pulposus displaces from the intervertebral space. According to Yoon et al.,<ref name=":4" /> 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.<ref name=":4">Yoon WW, Koch J. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8246101/pdf/eor-6-526.pdf Herniated discs: when is surgery necessary?] EFORT Open Rev. 2021 Jun 28;6(6):526-530.</ref> You can read more about the management of disc herniation symptoms [[Disc Herniation|here.]] | ||
# Spinal stenosis is a narrowing of the spinal canal. | # Spinal stenosis is a narrowing of the spinal canal. A range of conditions, such as tumours or bone spurs, can cause spinal stenosis. You can learn about low back pain assessment and prognosis [https://members.physio-pedia.com/learn/low-back-pain-assessment-and-prognosis-promopage/ here.] | ||
# Diastasis recti | # Diastasis recti occurs when the linea alba stretches and produces a gap between the two sides of the rectus abdominis muscle (e.g. in pregnancy, obesity).<ref name=":3" /> Learn more about this common condition<ref>Cavalli M, Aiolfi A, Bruni PG, Manfredini L, Lombardo F, Bonfanti MT, Bona D, Campanelli G. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8370915/pdf/10029_2021_Article_2468.pdf Prevalence and risk factors for diastasis recti abdominis: a review and proposal of a new anatomical variation.] Hernia. 2021 Aug;25(4):883-890. </ref> [[Diastasis Recti Abdominis|here]]. | ||
# Non-specific low back pain is low back pain that is not attributed to a specific pathology. You can learn about lumbar spine assessment by completing [https://members.physio-pedia.com/learn/an-introduction-to-clearing-the-lumbar-spine-promopage/ An Introduction to Clearing the Lumbar Spine] and [https://members.physio-pedia.com/considerations-for-lumbar-assessment-course/ Considerations for Lumbar Assessment]. | |||
== Resources == | == Resources == | ||
Line 553: | Line 584: | ||
[[Category:Lumbar Spine]] | [[Category:Lumbar Spine]] | ||
[[Category:Course Pages]] | [[Category:Course Pages]] | ||
[[Category:Plus Content]] |
Latest revision as of 02:49, 28 August 2023
Top Contributors - Ewa Jaraczewska, Jess Bell, Robin Tacchetti, Kim Jackson and Lucinda hampton
Introduction[edit | edit source]
The lumbar spine supports much of the upper body's weight. 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 skeletal support of the abdominal wall includes the vertebral column and lower ribs. The abdominal wall contains skin, fascia, and muscle. It provides coverage for the organs, generates intra-abdominal pressure, and moves the vertebral column. This article discusses the key anatomical structures of the lumbar vertebrae and abdominal wall, including the bony structures, articulations, ligaments, muscles, nerves and the vascular supply.
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).
Lumbar Spine Structure[edit | edit source]
Lumbar vertebrae[edit | edit source]
There are usually five lumbar vertebrae, which are known as L1-L5. However, 10–17.4% of adults present with a 6th lumbar vertebra[1] (or a sacral vertebra[2]). Having an additional vertebra may influence sagittal parameters. For instance, it may result in a diminished sacral tilt (i.e. the sacrum is in a more vertical position).[3] Individuals who have additional lumbar vertebrae may also have fewer thoracic vertebrae (e.g. 11 rather than 12 thoracic vertebrae).
The lumbar vertebrae are located between the 12th (or last) thoracic vertebra and the sacrum bone. They are the largest vertebrae of the human body. Each lumbar vertebra contains the following structural elements:
- Vertebral body
- Kidney-shaped
- Wider side to side than front to back
- The posterior aspect of the vertebral body changes from concave to convex
- Vertebral foramen
- Triangular in shape
- Larger than in the thoracic vertebrae, but smaller than in the cervical vertebrae
- Two pedicles
- Posterior element of the lumbar vertebra
- Attach to the cranial half of the vertebral body
- Change in shape from L1-L5
- Two laminae
- Flat and broad
- Two pedicles and two laminae form the vertebral arch
- Centrally connect to the spinous process
- Spinous process
- Projects perpendicularly from the body
- Short and sturdy
- Described as "hatchet-shaped"
- Provides an attachment point for muscles and ligaments
- Two transverse processes
- Located on the posterior surface
- Project laterally on each side of the vertebra
- Long and slender
- Provide attachment points for muscles and ligaments
- L1-L3 project horizontally
- L4-L5 project upward
- Four articular processes[4]
- Two superior articular facets and two inferior articular facets
- The point where two facets join is called the zygapophyseal joints
Lumbar Lordosis[edit | edit source]
Lordosis = the natural curve for the lumbar spine. This curve defines lumbar spine alignment in the sagittal plane. However, the pelvis is "the cornerstone of spinal sagittal alignment".[5] The curve of the sacrum determines the lumbar curve.
Optimal sagittal alignment of the lumbar spine offers the following benefits during locomotion:[5]
- 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 sagittal plane malalignment.[6]
Abdominal Wall Structure[edit | edit source]
The skeletal support of the abdominal wall comes from the vertebral column and lower ribs posteriorly. Anteriorly, it connects to the thoracic cage (rib cage) superiorly and the pelvic bones inferiorly. It is defined by the following landmarks:
- superior border = the xiphoid process and costal cartilage of ribs 7–10
- inferior border = the umbilicus in the middle, and inguinal ligament, pubic crest and pubic symphysis
You can read more about pelvis anatomy here.
Bones, Articulations and Kinematics of the Lumbar Spine[edit | edit source]
Bones and Articulations[edit | edit source]
The lumbar spine has two types of joints located between each lumbar vertebra:
- intervertebral disc joint
- zygapophyseal joint or facet joint
Bones | Articulations | Characteristics | Key palpation points |
---|---|---|---|
Vertebral body | Intervertebral disc joint | 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. | 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.
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"[7], but the accuracy of palpation is only 36%.[7] |
Articular processes | 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. The superior articular surface is vertical and concave, and the inferior is vertically convex. Their primary role includes the stabilisation of the spinal motion segment.[8] They also contribute to axial compressive load transmission. |
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. |
Kinematics[edit | edit source]
The lumbar spine is considered a three-joint complex or an articular triad.[8] 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 protect the spine from excessive movements.
The spinal motion segment has the following characteristics:[9]
- The intervertebral disc joint transmits mostly vertical compressive loads
- The facet joints guide and stabilise the motion segment
- In an erect standing position and erect sitting posture, spine load is also transmitted through the facet joints
Joint | Type of joint | Plane of movement | Motion | Kinematics | Closed pack position | Open pack position |
---|---|---|---|---|---|---|
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.
The following movements occur when all lumbar intervertebral disc joints and zygapophyseal joints are moving together : Flexion/extension Lateral flexion Rotation |
The following movements occur when all lumbar intervertebral disc joints and zygapophyseal joints moving together :
Flexion 60 degrees Extension 25 degrees Lateral flexion 20-30 degrees Rotation 1-5 degrees |
Full extension | Halfway between flexion and extension |
Zygapophyseal joint (facet joint) | Synovial plane joint | Facilitate a multiplanar and multidirectional movement of the spine.
Enable lumbar spine extension, lateral flexion, and rotation in the sagittal, transverse and frontal planes. |
Full extension | Halfway between flexion and extension |
Lumbar Spine Ligaments[edit | edit source]
Key ligaments | Origin | Insertion | Action/role | Key palpation points |
---|---|---|---|---|
Anterior longitudinal ligament | The anterior portion of the vertebral body at the base of the skull | The anterior portion of the vertebral body at the sacrum | Limits extension of the vertebral column.
Reinforces the intervertebral disc. |
|
Posterior longitudinal ligament | The body of C2 | Posterior surface of the sacrum | Limits flexion of the vertebral column.
Reinforces the intervertebral disc. |
|
Ligamentum flavum:
A series of short ligaments that connect the laminae of each vertebra.[2] There are two ligamenta flava at each vertebra. Each ligament is divided into: The medial portion: passes to the back of the next lower lamina and across the gap between the adjacent vertebrae, fusing with the interspinous ligament The lateral portion: passes in front of the facet joint, attaches to the anterior aspect of the inferior and superior articular processes and forms the anterior capsule. 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.[2]
Assists with lumbar spine flexion and extension. Compresses the intervertebral discs. |
|
Intertransverse ligaments | Transverse processes of the vertebra above | Transverse processes of the vertebra below | Contributes to the stability of the lumbar spine.
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. |
Supraspinous ligament | Tip of spinous processes of the vertebra above from the seventh cervical vertebra to the third or fourth lumbar vertebra | Tip of spinous processes of the vertebra below | Prevents the separation of the spinous processes during forward flexion, thus limiting lumbar spine flexion | 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. |
Interspinous ligament | Spinous processes of the vertebra above between the ligamenta flava anteriorly and the supraspinous ligament posteriorly | Spinous processes of the vertebra below between the ligamenta flava anteriorly and the supraspinous ligament posteriorly | Limits forward flexion of the vertebral column. |
Muscles of the Lumbar Spine and Abdominal Wall[edit | edit source]
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
- 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:
- 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 page.
Lumbar Spine Flexors[edit | edit source]
Muscle | Origin | Insertion | Innervation | Action |
---|---|---|---|---|
Psoas major | Vertebral bodies of T12-L4
Intervertebral discs between T12-L4 Transverse processes of L1-L5 vertebrae |
Lesser trochanter of femur | Anterior rami of spinal nerves L1-L3 | Contribute to lumbar spine flexion when acting bilaterally and when the insertion point is fixed.[2] |
Psoas minor | Vertebral bodies of T12 to L1 | Iliopubic eminence | Anterior ramus of spinal nerve L1 | Weak trunk flexor. This muscle is absent in 40% of people.[2] |
Internal obliques | Thoracolumbar fascia
Iliac crest Inguinal ligament |
Lower four ribs
Linea alba Pubic crest |
Lower intercostal nerves Branches of the lumbar plexus: iliohypogastric nerve and ilioinguinal nerve | Bilateral action: lumbar flexion
Assist in raising intra-abdominal pressure |
External obliques | Ribs five to twelve | Linea alba
Pubic tubercle Iliac crest |
Intercostal nerves T7- T11 and the T12 subcostal nerve | Bilateral action: lumbar flexion |
Rectus abdominis | Pubis, pubic symphysis | Xiphoid process of the sternum
Costal cartilage of ribs 5-7 |
Thoracoabdominal nerves | Lumbar spine flexion
Assists in raising intra-abdominal pressure |
Lumbar Spine Extensors[edit | edit source]
Muscle | Origin | Insertion | Innervation | Action |
---|---|---|---|---|
Quadratus lumborum | Iliac crest
Iliolumbar ligament |
The inferior border of the 12th rib
Transverse processes of L1-L4 vertebrae |
Subcostal nerve
Anterior rami of spinal nerves L1-L4 |
Bilateral action: trunk extension |
Interspinales lumborum | Superior aspects of spinous processes of L2-L5 | Inferior aspects of spinous processes of L1-L4 | Posterior rami of spinal nerves | Stabilise the lumbar spine Extend the lumbar spine |
Multifidus | Sacrum
Posterior superior iliac spine The mammillary processes of the lumbar vertebrae Transverse processes of T1-3 Articular processes of C4-C7 |
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)
Spinalis (not involved in the lumbar spine motion) |
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[edit | edit source]
Muscle | Origin | Insertion | Innervation | Action |
---|---|---|---|---|
Intertransversarii lumborum (ITL):
Lateral (ITLL) Medial (ITLM) |
ITLL: Transverse and accessory processes of L1-L4
ITLM: Accessory processes of L1-L4 |
ITLL: Transverse process of the following vertebra
ITLM: Mammillary processes of the following vertebra |
Anterior rami of spinal nerves | Assists in lateral flexion
Stabilises the lumbar spine |
Psoas major | Vertebral bodies of T12-L4
Intervertebral discs between T12-L4 Transverse processes of L1-L5 vertebrae |
Lesser trochanter of femur | Anterior rami of spinal nerves L1-L3 | Lateral flexion of the trunk |
Quadratus lumborum | Iliac crest
Iliolumbar ligament |
The inferior border of the 12th rib
Transverse processes of L1-L4 vertebrae |
Subcostal nerve
Anterior rami of spinal nerves L1-L4 |
Unilateral action: ipsilateral lumbar spine lateral flexion |
Erector spinae:
Iliocostalis (IC) Longissimus (L) |
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 | Unilateral action: ipsilateral side flexion and rotation of the vertebral column |
Internal oblique | Thoracolumbar fascia
Iliac crest Inguinal ligament |
Lower four ribs
Linea alba Pubic crest |
Lower intercostal nerves
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 | Ribs five to twelve | Linea alba
Pubic tubercle Iliac crest |
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 |
Lumbar Spine Rotators[edit | edit source]
Muscle | Origin | Insertion | Innervation | Action |
---|---|---|---|---|
Multifidus | Sacrum
Posterior superior iliac spine 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) | Thoracolumbar fascia
Iliac crest 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 ipsilateral 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) | Ribs five to twelve | Linea alba Pubic tubercle
Iliac crest |
Intercostal nerves T7- T11 and the T12 subcostal nerve | Rotation to the contralateral side
Works 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[edit | edit source]
Nerve | Origin | Branches | Motor fibres | Sensory fibres |
---|---|---|---|---|
Intercostal | Lumbar plexus | Muscular, collateral, lateral cutaneous, anterior cutaneous, and
communicating branches |
External obliques
Internal obliques |
Skin over the anterior abdomen |
Subcostal | Anterior ramus of the spinal nerve T12 | Muscular, cutaneous, communicating and collateral branches | Quadratus lumborum
External oblique |
The skin of the region under the umbilicus |
Iliohypogastric | Lumbar plexus | Lateral cutaneous branch
Anterior cutaneous branch |
Internal oblique | External abdominal oblique, transversus abdominis, internal abdominal oblique
The skin of the suprapubic region |
Ilioinguinal | Lumbar plexus | Anterior labial nerves
Anterior scrotal nerves |
Internal oblique | |
Dorsal (posterior) rami of spinal nerves | Spinal nerves | Medial
Intermediate Lateral |
Interspinales lumborum
Multifidus Erector spinae |
The skin of the back |
Ventral (anterior) rami of L1-L4 | Spinal nerves | Intertransversarii lumborum
Psoas major Psoas minor |
The skin of the ventrolateral body walls |
Vascular Supply of the Lumbar Spine and Abdominal Wall[edit | edit source]
Artery | Origin | Branches | Supply |
---|---|---|---|
Lumbar artery (LA):
Left (LLA) Right (RLA) |
Abdominal aorta | Medial
Middle Lateral |
Skin and muscles of the posterior abdominal wall
Joints of the lumbar spine The lumbar portion of the deep back muscles Lower two-thirds of the spinal cord |
Internal thoracic artery | Subclavian artery | Anterior collaterals
Posterior collaterals Terminal branches |
The superior aspect of the abdominal wall |
External iliac artery | Common iliac artery | Inferior epigastric,
Deep circumflex iliac arteries |
Lower abdominal wall |
Clinical Relevance[edit | edit source]
- Disc herniations are a common low back condition. They occur when the nucleus pulposus displaces from the intervertebral space. According to Yoon et al.,[10] 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.[10] You can read more about the management of disc herniation symptoms here.
- Spinal stenosis is a narrowing of the spinal canal. A range of conditions, such as tumours or bone spurs, can cause spinal stenosis. You can learn about low back pain assessment and prognosis here.
- Diastasis recti occurs when the linea alba stretches and produces a gap between the two sides of the rectus abdominis muscle (e.g. in pregnancy, obesity).[2] Learn more about this common condition[11] here.
- Non-specific low back pain is low back pain that is not attributed to a specific pathology. You can learn about lumbar spine assessment by completing An Introduction to Clearing the Lumbar Spine and Considerations for Lumbar Assessment.
Resources[edit | edit source]
- Inoue N, Orías AAE, Segami K. Biomechanics of the Lumbar Facet Joint. Spine Surg Relat Res. 2019 Apr 26;4(1):1-7.
- Kostov S, Dineva S, Kornovski Y, Slavchev S, Ivanova Y, Yordanov A. Vascular Anatomy and Variations of the Anterior Abdominal Wall - Significance in Abdominal Surgery. Prague Med Rep. 2023;124(2):108-142.
- Clinical Physio. Lumbar Spine Palpation
References[edit | edit source]
- ↑ Yan YZ, Li QP, Wu CC, Pan XX, Shao ZX, Chen SQ, Wang K, Chen XB, Wang XY. Rate of the presence of 11 thoracic vertebrae and 6 lumbar vertebrae in asymptomatic Chinese adult volunteers. J Orthop Surg Res. 2018 May 23;13(1):124.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Xuan D. Exploring Lumbar Spine and Abdominal Wall Anatomy Course. Physiopedia Plus, 2023.
- ↑ Yan YZ, Wang B, Huang XQ, Ru X, Wang XY, Qu HB. Variation in Global Spinal Sagittal Parameters in Asymptomatic Adults with 11 Thoracic Vertebrae, four Lumbar Vertebrae, and six Lumbar Vertebrae. Orthop Surg. 2022 Feb;14(2):341-348.
- ↑ Waxenbaum JA, Reddy V, Williams C, Futterman B. Anatomy, Back, Lumbar Vertebrae. 2022 Aug 1. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan–.
- ↑ 5.0 5.1 Diebo BG, Varghese JJ, Lafage R, Schwab FJ, Lafage V. Sagittal alignment of the spine: What do you need to know? Clin Neurol Neurosurg. 2015 Dec;139:295-301.
- ↑ Schwab F, Lafage V, Boyce R, Skalli W, Farcy JP. Gravity line analysis in adult volunteers: age-related correlation with spinal parameters, pelvic parameters, and foot position. Spine (Phila Pa 1976). 2006 Dec 1;31(25):E959-67.
- ↑ 7.0 7.1 Feng Q, Zhang L, Zhang M, Wen Y, Zhang P, Wang Y, Zeng Y, Wang J. Morphological parameters of fourth lumbar spinous process palpation: three-dimensional reconstruction of computed tomography. J Orthop Surg Res. 2020 Jun 22;15(1):227.
- ↑ 8.0 8.1 Kapetanakis S, Gkantsinikoudis N. Anatomy of lumbar facet joint: a comprehensive review. Folia Morphol (Warsz). 2021;80(4):799-805.
- ↑ Inoue N, Orías AAE, Segami K. Biomechanics of the Lumbar Facet Joint. Spine Surg Relat Res. 2019 Apr 26;4(1):1-7.
- ↑ 10.0 10.1 Yoon WW, Koch J. Herniated discs: when is surgery necessary? EFORT Open Rev. 2021 Jun 28;6(6):526-530.
- ↑ Cavalli M, Aiolfi A, Bruni PG, Manfredini L, Lombardo F, Bonfanti MT, Bona D, Campanelli G. Prevalence and risk factors for diastasis recti abdominis: a review and proposal of a new anatomical variation. Hernia. 2021 Aug;25(4):883-890.
- ↑ Clinical Physio. Lumbar Spine Palpation. Available from: https://www.youtube.com/watch?v=XrQP3AeDjiM [last accessed 25/6/2023]