Spinal cord anatomy: Difference between revisions

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'''Top Contributors''' - {{Special:Contributors/{{FULLPAGENAME}}}}    
'''Top Contributors''' - {{Special:Contributors/{{FULLPAGENAME}}}}    
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== Introduction  ==
== Introduction  ==
[[File:Spinal cord length.gif|right|frameless|1013x1013px]]The nervous system is divided into the central nervous system ([[Brain Anatomy|brain]] and [[Spinal cord anatomy|spinal cord]] considered upper motor [[Neurone|neurons]]) and the peripheral nervous system (nerves that enter and exit the spinal cord considered lower [[Motor Neurone|motor neurons]]). <ref name="Barker">Barker; Barasi; Neal. Neuroscience at a glance; Blackwell science Ltd; 1999</ref> Information to and from the muscles, glands, organs and sensory receptors are carried through the peripheral nervous system, which is divided into the autonomic nervous system carrying information to and from the organs, and the somatic nervous system carrying information to and from the muscles and the external environment. <ref name=":0" /><ref name=":1">Francisco de Assis Aquino Gondim et al., Topographic and Functional Anatomy of the Spinal Cord, Medshape, 2015</ref> The autonomic nervous system consists of the parasympathetic nervous system that governs the resting function and the sympathetic nervous system that governs excitatory functions. The spinal cord and peripheral nerves provide all impulses to control [[muscle]] contraction, cardiac rhythm, pain and other bodily functions so therefore any lesion to the spinal cord prevents or reduces transmission of this information to and from the brain to the peripheries, affecting movement, sensation and visceral function. <ref name=":1" />
[[File:Spinal cord length.gif|right|frameless|400x400px|alt=]]
The spinal cord is part of the [[Introduction to Neuroanatomy|central nervous system]] and consists of a tightly packed column of nerve tissue that extends downwards from the [[brainstem]] through the central column of the spine. It is a relatively small bundle of tissue (weighing 35g and just about 1cm in diameter) but is crucial in facilitating our [[Activities of Daily Living|daily activities]].
 
The spinal cord carries nerve signals from the [[Brain Anatomy|brain]] to other parts of the body (importantly the [[Muscle|muscles]] we use to move) and receives sensory input from the body, partially processes it, and then transmits that information to the brain.
 
Along with  its role in relaying motor and sensory signals between the brain and periphery, the spinal cord also provides separate neural circuits for many of our [[reflexes]]. Some reflexes eg the knee-jerk are built into the nervous system and bypass the brain, while others can be learned over time.
== Spinal Cord: External ==
[[File:42282-O3EL6G.jpg|Spinal Column <ref name=":3">Designed by Freepik at http://www.freepik.com</ref>|400x400px|frameless|alt=|right]]
Externally, the spinal cord is protected by 33 vertebrae, which sit between a semi-rigid [[intervertebral disc]], which provide a level of flexibility to the vertebral column. Its flexibility is greatest in the [[Cervical Anatomy|cervical]] region and lowest in the [[Thoracic Anatomy|thoracic]] region. The spinal cord (similar to the brain) is protected by three layers of [[Meningitis|meninges]] (membranes). The spinal cord extends from the foramen magnum to the lowest border of the first lumbar vertebra. It is enlarged at two sites, the cervical and lumbar region.
 
The vertebrae (in adults) are arranged in five regions, which provide support and protection for the spinal cord'''.'''  It consists of seven [[Cervical Vertebrae]], twelve [[Thoracic Vertebrae]], five [[Lumbar Vertebrae]], five Sacral (fused in adults to form the [[sacrum]]) and four Coccygeal Vertebrae (fused to form the [[Coccyx Fractures|coccyx]]).<ref name=":2">Rohkamm Reinhard. Color Atlas of Neurology. Thieme; 2014 Sep 2.</ref>
 
== Spinal Cord: Internal ==
[[Image:Spinal Cord Sectional Anatomy.png|300x300px|Spinal Cord Sectional Anatomy <ref>[http://blausen.com/?Topic=360 Spinal Cord]. ''Blausen Medical''. Retrieved on 26 January 2016.</ref>|right|frameless|alt=]]Inside, the spinal cord consists of grey matter and white matter.
 
# The grey matter takes on the shape of a butterfly, with four 'wings' called horns: The horns in the front contain [[Motor Neurone|motor neurons]]; the horns in the back contain sensory neurons which carry sensory information.
# The spinal cord grey matter is surrounded by a column of white matter, containing [[axons]] that allow different parts of the spinal cord to communicate smoothly, with signals passing upwards and downwards conveying eg [[sensation]] and motor signals.
Entry and Exit
 
* Sensory Nerve Fibres enter the Spinal Cord via the&nbsp;Posterior (Dorsal) Root. The cell bodies for these neurons are situated in the Dorsal Root Ganglia.
* Motor and Preganglionic Autonomic Fibres exit via the Anterior (Ventral) Root.


[[Image:Nervous System.jpg|center|Nervous System]]
Below is a good image of the Spinal cord,labelled[[File:Spinal cord labelled.png|right|frameless|441x441px|alt=]]
== Spinal Column ==
The spine or vertebral column bears the weight of the head, neck, trunk and upper extremities. The adult vertebral column typically consists of 33 vertebrae arranged in five regions, which provide support and protection for the spinal cord'''.'''  It consists of seven [[Cervical Vertebrae|Cervical Vertebrae]], twelve [[Thoracic Vertebrae|Thoracic Vertebrae]], five [[Lumbar Vertebrae|Lumbar Vertebrae]], five Sacral and four Coccygeal Vertebrae, The five sacral vertebrae are fused in adults to form the sacrum, and the four coccygeal vertebrae are fused to form the coccyx. Its uppermost vertebrae incorporating the atlas and axis articulate with the head, and the lowermost portion, the sacrum articulates with the [[pelvis]]. Each pair of adjacent vertebrae is separated by a semi-rigid intervertebral disk, which provides a level of flexibility to the vertebral column. Its flexibility is greatest in the cervical region and lowest in the [[Thoracic Anatomy|thoracic]] region. <ref name=":2">Rohkamm Reinhard. Color Atlas of Neurology. Thieme; 2014 Sep 2.</ref>


# central canal
# posterior median sulcus
# gray matter
# white matter
# dorsal root + dorsal root ganglion
# ventral root
# ventral and dorsal nerve rootlets
# anterior spinal artery
# arachnoid mater
# dura mater
== Spinal Canal ==
== Spinal Canal ==
Formed by the vertebral foramina of the vertebral bodies the spinal canal [bound anteriorly by the vertebral bodies and posteriorly by the laminae (vertebral arches)] with reinforcement at the walls through the intervertebral disks and the anterior and posterior longitudinal ligaments. The diameter varies from 12 to 22 mm in the [[Cervical Anatomy|cervical]] region and from 22 to 25 mm in the lumbar region.  
[[File:Spinal canal.png|thumb|Spinal cord sits in the spinal cavity]]
Formed by the vertebral foramina of the vertebral bodies the spinal canal [bound anteriorly by the vertebral bodies and posteriorly by the laminae (vertebral arches)] with reinforcement at the walls through the intervertebral disks and the [[Anterior longitudinal ligament|anterior]] and [[Posterior longitudinal ligament|posterior longitudinal ligaments]]. The diameter varies from 12 to 22 mm in the [[Cervical Anatomy|cervical]] region and from 22 to 25 mm in the lumbar region.  


Contains: 
Contains: 
* Spinal cord  
* Spinal cord
* Meninges,
* Meninges
* Blood vessels,
*[[Cardiovascular System|Blood vessels]]
* Spinal nerve roots and surrounding fatty and connective tissues. <ref name=":0">Moore KL, Agur AM, Dalley AF. Essential Clinical Anatomy. Philadelphia: Lippincott Williams & Wilkins; 2002 Mar.</ref><ref name=":2" />
*[[Spinal Nerves|Spinal nerve]] roots and surrounding fatty and [[Connective Tissue Disorders|connective]] tissues. <ref name=":0">Moore KL, Agur AM, Dalley AF. Essential Clinical Anatomy. Philadelphia: Lippincott Williams & Wilkins; 2002 Mar.</ref><ref name=":2" />


== Spinal Cord ==
== Spinal Cord ==
The spinal cord is the major conduit and [[Reflexes|reflex]] centre between the peripheral nerves and the brain and transmits motor information from the brain to the muscles, tissues and organs, and sensory information from these areas back to the brain. <ref name=":0" /><ref name=":1" />  
[[File:Cauda equina.jpeg|thumb|1.Conus medullaris 2. Filum terminale 3. Cauda Equina]]
The spinal cord is the major conduit and [[Reflexes|reflex]] centre between the peripheral nerves and the brain and transmits motor information from the brain to the muscles, tissues and organs, and sensory information from these areas back to the brain. <ref name=":1">Francisco de Assis Aquino Gondim et al., Topographic and Functional Anatomy of the Spinal Cord, Medshape, 2015</ref> It is, in an adult, approximately 45 cm long, cylindrical  and slightly flattened anteriorly and posteriorly.<ref name=":0" />.


The spinal cord in an adult is approximately a 45 cm long, cylindrical structure that is slightly flattened anteriorly and posteriorly. <ref name=":0" />
Its upper end is continuous with the medulla, the transition is defined to occur just above the level of exit of the first pair of cervical nerves.
* The spinal cord lies within the vertebral canal, extending from the foramen magnum to the lowest border of the first lumbar vertebra. It is enlarged at two sites, the cervical and lumbar region.
* Its upper end is continuous with the medulla, the transition is defined to occur just above the level of exit of the first pair of cervical nerves.  
* Its tapering lower end, the conus medullaris, terminates at the level of the L3 vertebra in neonates, and at the level of the L1-2 intervertebral disk in adults.
* The conus medullaris is continuous at its lower end with the threadlike filum terminale, composed mainly of [[Glial Cells|glial]] and connective tissue, which, in turn, runs through the lumbar sac amidst the posterior and anterior roots of the spinal nerves, collectively called the Cauda Equina (“horse’s tail”), and then attaches to the dorsal surface of the coccyx. <ref name=":2" />
Sensory Nerve Fibres enter the Spinal Cord via the&nbsp;Posterior (Dorsal) Root. The cell bodies for these neurons are situated in the Dorsal Root Ganglia. Motor and Preganglionic Autonomic Fibres exit via the Anterior (Ventral) Root.<div class="col-md-6">[[File:42282-O3EL6G.jpg|Spinal Column <ref>Designed by Freepik at http://www.freepik.com</ref>|400x400px|left|frameless]]
</div>
  <div class="col-md-6">[[Image:Spinal Cord Sectional Anatomy.png|400x400px|Spinal Cord Sectional Anatomy <ref>[http://blausen.com/?Topic=360 Spinal Cord]. ''Blausen Medical''. Retrieved on 26 January 2016.</ref>|right|frameless]]</div>
</div>


== Spinal Nerves ==
Its tapering lower end, the conus medullaris, terminates at the level of the L3 vertebra in neonates, and at the level of the L1-2 intervertebral disk in adults. It then becomes the cauda equina<ref name=":3" />
Emerging from the spinal cord are 31 pairs of anterior and posterior nerve roots. The cervical, thoracic, lumbar, and sacral portions of the spinal cord are defined according to the segmental division of the vertebral column and spinal nerves. There are eight cervical*, twelve thoracic, five lumbar, five sacral and one coccygeal. At each level an anterior pair of nerve roots carries motor nerves, while a posterior pair of nerve roots carries only sensory nerves. The anterior and posterior roots join to form two spinal nerves, one on either side of the spine, which then exit the vertebral canal through the intervertebral foramina. Once outside the intervertebral foramina they form peripheral nerves. <ref name=":2" />  


<nowiki>*</nowiki>While there are eight pairs of cervical spinal nerves there are only seven cervical vertebrae. This disparity occurs because the first pair of cervical spinal nerves exits ''above'' the first cervical vertebra just below the skull. However, the eighth pair of cervical spinal nerves exits ''below'' the last cervical vertebra.* <ref name=":0" />
The cauda equina
=== Muscle Innervation ===
==== Upper Limb <ref name=":3">Harvey L. Management of Spinal Cord Injuries: A Guide for Physiotherapists. Elsevier Health Sciences; 2008 Jan 10</ref> ====
{| class="wikitable"
! rowspan="2" |'''Joint'''
! rowspan="2" |'''Movement'''
! rowspan="2" |'''Muscles'''
! colspan="7" |'''Innervation'''
|-
!'''C3'''
!'''C4'''
!'''C5'''
!'''C6'''
!'''C7'''
!'''C8'''
!'''T1'''
|-
| rowspan="6" |'''Scapula'''
| rowspan="2" |Elevation
|[[Trapezius|Upper Trapezius]]
|O
|X
|
|
|
|
|
|-
|[[Levator Scapulae|Levator Scapula]]
|O
|O
|O
|
|
|
|
|-
|Depression
|[[Trapezius|Lower Trapezius]]
|O
|X
|
|
|
|
|
|-
| rowspan="2" |Retraction
|[[Trapezius|Middle Trapezius]]
|O
|X
|
|
|
|
|
|-
|[[Rhomboids]]
|
|O
|O
|
|
|
|
|-
|Protraction
|[[Serratus Anterior]]
|
|
|X
|O
|O
|
|
|-
| rowspan="25" |'''Shoulder'''
| rowspan="4" |Flexion
|[[Deltoid|Anterior Deltoid]]
|
|
|X
|O
|
|
|
|-
|[[Pectoralis major|Pectoralis Major]] (Clavicular Head)
|
|
|X
|O
|
|
|
|-
|[[Pectoralis major|Pectoralis Major]] (Sternocostal Head)
|
|
|
|O
|X
|O
|O
|-
|[[Coracobrachialis Muscle|Corachobrachialis]]
|
|
|O
|O
|O
|
|
|-
| rowspan="5" |Extension
|[[Deltoid|Posterior Deltoid]]
|
|
|X
|O
|
|
|
|-
|[[Infraspinatus]]
|
|
|X
|O
|
|
|
|-
|[[Teres Minor]]
|
|
|X
|O
|
|
|
|-
|[[Teres Major]]
|
|
|O
|X
|O
|
|
|-
|[[Latissimus Dorsi Muscle|Latissimus Dorsi]]
|
|
|
|O
|X
|O
|
|-
| rowspan="2" |Abduction
|[[Deltoid|Middle Deltoid]]
|
|
|X
|O
|
|
|
|-
|[[Supraspinatus]]
|
|
|X
|O
|
|
|
|-
| rowspan="3" |Adduction
|[[Pectoralis major|Pectoralis Major]] (Sternocostal Head)
|
|
|
|O
|X
|O
|O
|-
|[[Latissimus Dorsi Muscle|Latissimus Dorsi]]
|
|
|
|O
|X
|O
|
|-
|[[Coracobrachialis Muscle|Corachobrachialis]]
|
|
|O
|O
|O
|
|
|-
|Horizontal Abduction
|[[Deltoid|Posterior Deltoid]]
|
|
|X
|O
|
|
|
|-
| rowspan="3" |Horizontal Adduction
|[[Pectoralis major|Pectoralis Major]] (Clavicular Head)
|
|
|X
|O
|
|
|
|-
|[[Pectoralis Minor]]
|
|
|O
|O
|X
|X
|O
|-
|[[Deltoid|Anterior Deltoid]]
|
|
|X
|O
|
|
|
|-
| rowspan="4" |Internal Rotation
|[[Subscapularis]]
|
|
|O
|X
|
|
|
|-
|[[Teres Major]]
|
|
|O
|O
|O
|
|
|-
|[[Latissimus Dorsi Muscle|Latissimus Dorsi]]
|
|
|
|O
|X
|O
|
|-
|[[Deltoid|Anterior Deltoid]]
|
|
|X
|O
|
|
|
|-
| rowspan="3" |External Rotation
|[[Infraspinatus]]
|
|
|X
|O
|
|
|
|-
|[[Teres Minor]]
|
|
|X
|O
|
|
|
|-
|[[Deltoid|Posterior Deltoid]]
|
|
|X
|O
|
|
|
|-
| rowspan="8" |'''Elbow'''
| rowspan="3" |Flexion
|[[Biceps brachii|Biceps Brachii]]
|
|
|O
|O
|
|
|
|-
|[[Brachialis]]
|
|
|O
|X
|O
|
|
|-
|[[Brachioradialis]]
|
|
|O
|X
|
|
|
|-
|Extension
|[[Triceps brachii|Triceps]]
|
|
|
|O
|X
|O
|
|-
| rowspan="2" |Supination
|[[Biceps brachii|Biceps Brachii]]
|
|
|O
|O
|
|
|
|-
|[[Supinator]]
|
|
|
|X
|O
|
|
|-
| rowspan="2" |Pronation
|[[Pronator Quadratus]]
|
|
|
|
|O
|X
|
|-
|[[Pronator Teres]]
|
|
|
|O
|X
|
|
|-
| rowspan="11" |'''Wrist'''
| rowspan="3" |Flexion
|[[Flexor Carpi Radialis]]
|
|
|
|O
|O
|
|
|-
|[[Palmaris Longus]]
|
|
|
|
|O
|O
|
|-
|[[Flexor Carpi Ulnaris Muscle|Flexor Carpi Ulnaris]]
|
|
|
|
|O
|X
|O
|-
| rowspan="3" |Extension
|[[Extensor carpi radialis longus|Extensor Carpi Radialis Longus]]
|
|
|O
|X
|
|
|
|-
|[[Extensor Carpi Radialis Brevis]]
|
|
|
|
|X
|O
|
|-
|[[Extensor Carpi Ulnaris]]
|
|
|
|
|X
|O
|
|-
| rowspan="3" |Radial Deviation
|[[Extensor carpi radialis longus|Extensor Carpi Radialis Longus]]
|
|
|O
|X
|
|
|
|-
|[[Extensor Carpi Radialis Brevis]]
|
|
|
|
|X
|O
|
|-
|[[Flexor Carpi Radialis]]
|
|
|
|O
|O
|
|
|-
| rowspan="2" |Ulnar Deviation
|[[Extensor Carpi Ulnaris]]
|
|
|
|
|X
|O
|
|-
|[[Flexor Carpi Ulnaris Muscle|Flexor Carpi Ulnaris]]
|
|
|
|
|O
|X
|O
|-
| rowspan="13" |'''Fingers'''
|Flexion (MCP/PIP)
|[[Flexor Digitorum Superficialis]]
|
|
|
|
|O
|X
|O
|-
| rowspan="3" |Flexion (DIP)
|[[Flexor Digitorum Profundus]]
|
|
|
|
|O
|X
|O
|-
|[[Dorsal Interossei of the Hand|Dorsal Interossei]]
|
|
|
|
|
|O
|X
|-
|Palmar Interossei
|
|
|
|
|
|O
|
|-
|Flexion (MCP)
|Flexor Digiti Minimi Brevis
|
|
|
|
|
|O
|X
|-
| rowspan="3" |Extension (MCP/PIP/DIP)
|Extensor Digitorum
|
|
|
|
|X
|O
|
|-
|Extensor Indicis
|
|
|
|
|X
|O
|
|-
|Extensor Digiti Minimi
|
|
|
|
|X
|O
|
|-
|Extension (PIP/DIP)
|Lumbricals
|
|
|
|
|
|O
|X
|-
| rowspan="2" |Abduction
|[[Dorsal Interossei of the Hand|Dorsal Interossei]]
|
|
|
|
|
|O
|X
|-
|Abductor Digiti Minimi
|
|
|
|
|
|O
|X
|-
|Adduction
|Palmar Interossei
|
|
|
|
|
|O
|X
|-
|Opposition
|Opponens Digiti Minimi
|
|
|
|
|
|O
|X
|-
| rowspan="9" |'''Thumb'''
|Flexion (IP)
|Flexor Pollicis Longus
|
|
|
|
|O
|X
|
|-
|Flexion / Rotation (MCP)
|Flexor Pollicis Brevis
|
|
|
|
|
|O
|X
|-
|Extension (MCP)
|Extensor Pollicis Brevis
|
|
|
|
|X
|O
|
|-
|Extension (IP)
|Extensor Pollicis Longus
|
|
|
|
|X
|O
|
|-
|Abduction
|Abductor Pollicis Longus
|
|
|
|
|X
|O
|
|-
|Abduction / Rotation
|Abductor Pollicis Brevis
|
|
|
|
|
|O
|X
|-
|Adduction / Rotation
|Adductor Pollicis
|
|
|
|
|
|O
|X
|-
|Adduction / Flexion (IP)
|Palmar Interossei
|
|
|
|
|
|O
|X
|-
|Opposition
|Opponens Pollicis
|
|
|
|
|
|O
|X
|}


==== Lower Limb <ref name=":3" /> ====
* Is the name given to the roots of the spinal nerves that extend beyond the termination of the spinal cord at the first lumbar vertebra in the form of a bundle of filaments within the spinal canal resembling a horse's tail<ref>Merriam webster Cauda equina Available:https://www.merriam-webster.com/medical/cauda%20equina (accessed 29.4.2022)</ref> 
{| class="wikitable"
* Has approximately 10 fiber pairs at its base: 3 to 5 lumbar fiber pairs; 5 sacral fiber pairs, and 1 coccygeal nerve.
! rowspan="2" |'''Joint'''
* Primary function of the cauda equina is to send and receive messages between the lower limbs and the pelvic organs, which consist of the bladder, the rectum, and the internal genital organs<ref>Healthline Cauda equina Available: https://www.healthline.com/human-body-maps/cauda-equina#1<nowiki/>(accessed 29.4.2022)</ref>.
! rowspan="2" |'''Movement'''
! rowspan="2" |'''Muscles'''
! colspan="8" |'''Innervation'''
|-
!L1
!L2
!L3
!L4
!L5
!S1
!S2
!S3
|-
| rowspan="30" |'''Hip'''
| rowspan="6" |Flexion
|[[Psoas Major]]
|X
|X
|O
|
|
|
|
|
|-
|[[Iliacus]]
|
|X
|O
|
|
|
|
|
|-
|Pectineus
|
|X
|O
|
|
|
|
|
|-
|[[Rectus Femoris]]
|
|O
|X
|X
|
|
|
|
|-
|Adductor Longus
|
|X
|X
|O
|
|
|
|
|-
|[[Sartorius]]
|
|O
|O
|
|
|
|
|
|-
| rowspan="5" |Extension
|[[Gluteus Maximus]]
|
|
|
|
|X
|X
|O
|
|-
|[[Adductor Magnus]]
|
|X
|X
|O
|
|
|
|
|-
|[[Semimembranosus]]
|
|
|
|
|O
|X
|O
|
|-
|[[Semitendinosus]]
|
|
|
|
|O
|X
|O
|
|-
|[[Biceps Femoris]]
|
|
|
|
|O
|X
|O
|
|-
| rowspan="4" |Internal Rotation
|[[Iliacus]]
|
|X
|O
|
|
|
|
|
|-
|[[Gluteus Medius]]
|
|
|
|X
|X
|O
|
|
|-
|[[Gluteus Minimus]]
|
|
|
|X
|X
|O
|
|
|-
|[[Tensor Fascia Lata|Tensor Fascia Latae]]
|
|
|
|X
|X
|O
|
|
|-
| rowspan="7" |External Rotation
|Superior Gemelli
|
|
|
|
|O
|O
|
|
|-
|Inferior Gemelli
|
|
|
|
|O
|O
|
|
|-
|[[Quadratus Femoris]]
|
|
|
|
|O
|O
|
|
|-
|[[Piriformis]]
|
|
|
|
|O
|X
|O
|
|-
|[[Obturator Internus]]
|
|
|
|
|O
|X
|
|
|-
|[[Obturator Externus]]
|
|
|O
|X
|
|
|
|
|-
|[[Sartorius]]
|
|O
|O
|
|
|
|
|
|-
| rowspan="4" |Adduction
|[[Gracilis]]
|
|X
|O
|
|
|
|
|
|-
|Adductor Longus
|
|X
|X
|O
|
|
|
|
|-
|Adductor Magnus
|
|X
|X
|O
|
|
|
|
|-
|Pectineus
|
|X
|O
|
|
|
|
|
|-
| rowspan="4" |Abduction
|[[Tensor Fascia Lata|Tensor Fascia Latae]]
|
|
|
|X
|X
|O
|
|
|-
|[[Gluteus Medius]]
|
|
|
|X
|X
|O
|
|
|-
|[[Gluteus Minimus]]
|
|
|
|X
|X
|O
|
|
|-
|[[Piriformis]]
|
|
|
|
|O
|X
|O
|
|-
| rowspan="8" |'''Knee'''
| rowspan="4" |Flexion
|[[Semimembranosus]]
|
|
|
|
|O
|X
|O
|
|-
|[[Semitendinosus]]
|
|
|
|
|O
|X
|O
|
|-
|[[Biceps Femoris]]
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|
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|O
|X
|O
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|-
|[[Gastrocnemius]]
|
|
|
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|O
|O
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|-
| rowspan="4" |Extension
|[[Rectus Femoris]]
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|O
|X
|X
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|
|
|
|-
|[[Vastus Lateralis]]
|
|O
|X
|X
|
|
|
|
|-
|[[Vastus Intermedius]]
|
|O
|X
|X
|
|
|
|
|-
|[[Vastus Medialis]]
|
|O
|X
|X
|
|
|
|
|-
| rowspan="15" |'''Ankle'''
| rowspan="4" |Dorsiflexion
|[[Tibialis Anterior]]
|
|
|
|X
|O
|
|
|
|-
|Extensor Digitorum Longus
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|
|
|
|X
|O
|
|
|-
|[[Extensor Hallucis Longus]]
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|
|
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|X
|O
|
|
|-
|[[Peroneus Tertius]]
|
|
|
|
|O
|O
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|
|-
| rowspan="6" |Plantarflexion
|[[Gastrocnemius]]
|
|
|
|
|
|O
|O
|
|-
|[[Soleus]]
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|
|
|
|
|O
|O
|
|-
|[[Flexor hallucis longus|Flexor Digitorum Longus]]
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|
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|
|O
|X
|X
|
|-
|[[Flexor hallucis longus|Flexor Hallucis Longus]]
|
|
|
|
|O
|X
|X
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|-
|Peroneus Longus
|
|
|
|
|O
|O
|
|
|-
|[[Tibialis Posterior]]
|
|
|
|O
|O
|
|
|
|-
| rowspan="2" |Inversion
|[[Tibialis Anterior]]
|
|
|
|X
|O
|
|
|
|-
|[[Tibialis Posterior]]
|
|
|
|O
|O
|
|
|
|-
| rowspan="3" |Eversion
|Peroneus Longus
|
|
|
|
|O
|O
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|-
|Peroneus Brevis
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|
|
|
|O
|O
|
|
|-
|[[Peroneus Tertius]]
|
|
|
|
|O
|O
|
|
|-
| rowspan="17" |'''Toes'''
| rowspan="9" |Flexion
|[[Flexor hallucis longus|Flexor Digitorum Longus]]
|
|
|
|
|O
|X
|X
|
|-
|[[Flexor hallucis longus|Flexor Hallucis Longus]]
|
|
|
|
|O
|X
|X
|
|-
|[[Flexor Hallucis Brevis]]
|
|
|
|
|
|O
|O
|
|-
|Flexor Digitorum Brevis
|
|
|
|
|
|O
|O
|
|-
|Flexor Digitorum Accessorius
|
|
|
|
|
|
|O
|O
|-
|Flexor Digiti Minimi Brevis
|
|
|
|
|
|
|O
|O
|-
|Abductor Hallucis
|
|
|
|
|
|O
|O
|
|-
|Abductor Digiti Minimi
|
|
|
|
|
|
|O
|O
|-
|Lumbricals
|
|
|
|
|
|O
|O
|O
|-
| rowspan="3" |Extension
|Extensor Digitorum Longus
|
|
|
|
|X
|O
|
|
|-
|[[Extensor Digitorum Brevis]]
|
|
|
|
|O
|O
|
|
|-
|[[Extensor Hallucis Longus]]
|
|
|
|
|X
|O
|
|
|-
| rowspan="3" |Abduction
|Abductor Hallucis
|
|
|
|
|
|O
|O
|
|-
|Abductor Digiti Minimi
|
|
|
|
|
|
|O
|O
|-
|Dorsal Interossei
|
|
|
|
|
|
|O
|O
|-
| rowspan="2" |Adduction
|Plantar Interossei
|
|
|
|
|
|
|O
|O
|-
|Adductor Hallucis
|
|
|
|
|
|
|O
|O
|}
X - Main Nerves Innervating Muscle         


O - Accessory Nerves Innervating Muscle<div align="justify">
== Spinal Nerves ==
== Spinal Motorneurons ==
[[File:Spinal nerve.png|thumb|472x472px|Spinal Nerve]]The term spinal nerve generally refers to a mixed spinal nerve that carries motor, sensory, and autonomic signals between the spinal cord and the body.
Alpha and Gamma motor neurons are both found in the anterior (ventral) horn. Alpha motor neurons are the largest motor neurons in the nervous system and innervate skeletal muscle. Gamma Motorneurons innervate intrafusal muscle fibres of the [[Muscle spindles|muscle spindle]]. Motor neurons are arranged somatotopically across the anterior horn. The more medially placed motor neurons innervate proximal muscles while laterally placed motor neurons innervate distal muscles. <ref name=":0" /><ref name=":2" />


== Blood Supply ==
Humans have 31 left–right pairs of spinal nerves, each roughly corresponding to a segment of the vertebral column. There are eight cervical*, twelve thoracic, five lumbar, five sacral and one coccygeal.  
The majority of the spinal cord blood supply is provided by the segmental spinal arteries, with further supply coming from the vertebral arteries via a single anterior spinal artery and paired posterior spinal arteries. The segmental and spinal arteries are linked by numerous anastomoses. <ref name=":0" /><ref name=":2" />


=== Segmental Arteries ===
The spinal nerves are relatively large nerves that are formed by the merging of two nerve roots: a sensory nerve root and a motor nerve root.
<div align="justify">
[[File:Spinal Cord.jpeg|thumb|Spinal cord and spinal nerves]]
<div align="justify">
Sensory nerve roots emerge from the back of the spinal cord and the motor nerve roots from the front of the spinal cord. As they join, they form the spinal nerves on the sides of the spinal cord<ref>Very well health Spinal Nerves Available:https://www.verywellhealth.com/spinal-nerves-anatomy-4682599 (accessed 29.4.2022)</ref>.
The segmental arteries give off radicular branches, cervical and thoracolumbar, which enter the intervertebral foramen and supply the anterior and posterior roots and spinal ganglion of the corresponding level. The spinal cord itself is supplied by unpaired medullary arteries that originate from segmental arteries. <ref name=":0" /><ref name=":2" />


=== Spinal Arteries ===
The anterior and posterior roots join to form two spinal nerves, one on either side of the spine, which then exit the vertebral canal through the intervertebral foramina. Once outside the intervertebral foramina they form peripheral nerves. <ref name=":2" />  
<div align="justify">
<div align="justify">
<div align="justify">
The spinal arteries, arising from the vertebral artery, run longitudinally down the spinal cord. The unpaired anterior spinal artery lies in the anterior median fissure of the spinal cord and extends from the level of the lower brainstem to the tip of the conus medullaris, with the diameter steadily increasing below the T2 level. It supplies the ventral medial surface of the medulla and anterior 2/3 of the spinal cord. The paired posterior spinal arteries supply the dorsal columns and the all but the base of the dorsal horns bilaterally. There are reinforcing branches from other arteries along the length of the cord and numerous anastomoses of the spinal arteries produce a vasocorona around the spinal cord. If occlusion occurs, it is normally of the anterior spinal artery, producing loss of power and spinothalamic sensory deficit, but dorsal column sensory capabilities are maintained. <ref name=":0" /><ref name=":2" />
=== Spinal Veins ===
Blood from within the spinal cord travels through the intramedullary veins, to the anterior and posterior spinal veins, which form a reticulated network in the pia mater around the circumference of the cord throughout its length. The anterior two-thirds of the gray matter drain via the anterior spinal vein, while the posterior and lateral spinal veins drain the rest of the spinal cord. These vessels empty by way of the radicular veins into the external and internal vertebral venous plexuses, groups of valveless veins that extend from the coccyx to the base of the skull. The vertebral and deep cervical veins drain venous blood from the cervical spine into the superior vena cava; the posterior intercostal and lumbar veins drain venous supply from the thoracic and lumbar spine into the azygos and hemiazygos veins; and the median and lateral sacral veins drain venous supply from the sacrum into the common iliac vein. <ref name=":0" /><ref name=":2" />


== Associated Pathways ==
<nowiki>*</nowiki>While there are eight pairs of cervical spinal nerves there are only seven cervical vertebrae. This disparity occurs because the first pair of cervical spinal nerves exits ''above'' the first cervical vertebra just below the skull. However, the eighth pair of cervical spinal nerves exits ''below'' the last cervical vertebra.* <ref name=":0" />


=== Ascending Sensory Pathway ===
== Spinal Cord Muscle Innervation ==
Information detected by sensory receptors in the periphery is transmitted along ascending neural tracts in the spinal cord. Located in the white matter of the spinal cord, the ascending sensory tracts arise from either the the cells of the spinal ganglia or the intrinsic neurons within the grey matter that receive primary sensory input. There are many sensory tracts and pathways carrying different types of sensory information from the periphery to the cerebral cortex. In humans the major sensory pathways include:
For each spinal cord level and muscles innervated see [[Spinal Cord Muscle Innervation]]
* Spinothalamic Tract  The [[Spinothalamic tract|spinothalamic tracts]] sit within the dorsal horn laminae I,III,IV,Vof the spinal cord. Most of the fibres cross the midline at or near the level they enter the spinal cord. The lateral spinothalamic tract carries information about pain and temperature, and the anterior spinothalamic tract carries information about crude touch.
* Dorsal Column or Medial Lemniscal Pathway  The largest ascending tract, the fasciculi gracilis and cuneatus, arise from the spinal ganglion cells and ascend in the dorsal funiculus to the medulla oblongata. The gracile and cuneate tracts carry information about proprioception and light touch. The ''gracile tract'' is positioned medially and predominantly carries sensory fibres from the lower body below T6, while the ''cuneate tract'' is positioned laterally and predominantly carries fibres from the upper body above T6. The fibres within the gracile and cuneate tracts cross completely in the brainstem and form the medial lemniscus, which in turn projects to the anterior basal nuclear complex of the thalamus. Conveys proprioception, light touch and vibration.
* Spinocerebellar Tract  From spinal cord interneurons. It has two tracts a) Posterior Spinocerebellar Tract, which relays via inferior cerebellar peduncle and b) Anterior Spinocerebellar Tract relays via superior cerebellar peduncle to the cerebellum. It conveys proprioceptive information and on-going activity in the spinal cord interneurons.


=== Descending Motor Pathways ===
=== Spinal Motorneurons ===
The descending pathways, convey the motor commands and are involved in the control of movement. In humans, the major motor pathways include:
Alpha and Gamma [[Motor Neurone|motor neurons]] are both found in the anterior (ventral) horn. 


==== [[Corticospinal Tract|Corticospinal (Pyramidal) Tract]] ====
# Alpha motor neurons are the largest motor neurons in the nervous system and innervate skeletal muscle. 
[[Extrapyramidal and Pyramidal Tracts|Extrapyramidal and Pyramidal tracts]]<div align="justify">
# Gamma Motorneurons innervate intrafusal muscle fibres of the [[Muscle spindles|muscle spindle]]. 
<div align="justify">
<div align="justify">
<div align="justify">
<div align="justify">
Carries information from the cerebral cortex to the spinal cord. Also called the pyramidal tract as it is the only point where all the fibres are collected together without contamination by other fibre tracts in the medullary pyramids of the brain stem. Primary motor cortex is the main source of input to this tract, but the premotor and supplementary motor cortex also contribute fibres. Its projections are primarily contralateral and have a strong influence on the activity of groups of spinal motoneurones, which innervate distal muscles of the hands and feet. Most of the fibers, approximately 85%, cross the midline in the decussation of the pyramids in the brain stem and then descend through the spinal cord in the lateral corticospinal tract, while the other 15% cross within the spinal cord at the level they terminate and are carried within the medial corticospinal tract. According to Harvey (2008), the cervical upper motor neurons are centrally located within the corticospinal tract while the lumbar and sacral neurons are peripherally located, which explains neurological patterns of loss seen with certain types of incomplete spinal cord injuries where the peripheral rim of the spinal cord is undamaged. <ref name=":3" />


==== [[Reticulospinal Tract]] ====
Motor neurons are arranged somatotopically across the anterior horn. The more medially placed motor neurons innervate proximal muscles while laterally placed motor neurons innervate distal muscles. <ref name=":0" /><ref name=":2" />
<div align="justify">
<div align="justify">
<div align="justify">
<div align="justify">
<div align="justify">
This tract begins in the caudal reticular formation in the pons and medulla. The fibres from the medullary portion descend in the dorsolateral funiculus of the cord near the corticospinal fibres, whereas the fibres from the pontine region travel in the ventromedial portion of the spinal cord. These pathways are predominantly bilateral and have the largest density of projections to axial and proximal muscles. Provides both excitable and inhibitory effects on the interneurons in the spinal cord, and to a lesser extent, it also acts on the motor neurons. Its main action is to dampen down activity in the spinal cord. without this pathway, there is increased extensor tone observed. <ref name=":3" />
==== [[Vestibulospinal Tract]] ====
Originates from Deiters nucleus in the medulla and innervates the extensor and axial muscles. The vestibulospinal tracts receive limited input from the cortical motor areas as they arise in the vestibular nuclei, which receive main input from the balance organs of the ear. Their projections to the spinal cord are mostly bilateral and to proximal and axial muscles. It is involved in balance control and posture. <ref name=":3" />
==== [[Rubrospinal Tract]] ====
Originates from the magnocellular part of the red nucleus in the brain. It projects towards common structures with the CoST, particularly those involved with distal motor control. There is debate as to how significant this tract is in humans, is quite prominent in the cat. <ref name=":3" /> 



=== Autonomic Pathways ===
== Associated Pathways ==
Autonomic nerves are also carried by the spinal cord. Sympathetic nerves exit the vertebral canal via thoraco-lumbar spinal nerves, and parasympathetic nerves exit via sacral spinal nerves. As a result individuals with a cervical lesion lose supraspinal control of the entire sympathetic nervous system and of the sacral part of the parasympathetic nervous system. Individuals with thoracic, lumbar or sacral lesions lose varying amounts of supraspinal control of the sympathetic and parasympathetic nervous system as determined by the level of the lesion. Some parasympathetic fibres are carried within cranial nerves and are unaffected by spinal cord injury. <ref name=":3" /> 
[[File:Brain and spinal cord tracts.jpeg|thumb|336x336px|Brain and spinal cord tracts]]
The central nervous system uses ascending and descending pathways to communicate with the external environment. See [[Central Nervous System Pathways]].  
== Blood Supply ==
The majority of the spinal cord [[Blood Physiology|blood]] supply is provided by the segmental spinal arteries, with further supply coming from the [[Vertebral Artery|vertebral arteries]] via a single anterior spinal artery and paired posterior spinal arteries. The segmental and spinal arteries are linked by numerous anastomoses. <ref name=":0" /><ref name=":2" />


{| width="400" cellspacing="1" cellpadding="1" border="0" align="center"
'''Segmental Arteries:''' The segmental [[arteries]] give off radicular branches, cervical and thoracolumbar, which enter the intervertebral foramen and supply the anterior and posterior roots and spinal ganglion of the corresponding level. The spinal cord itself is supplied by unpaired medullary arteries that originate from segmental arteries. <ref name=":0" /><ref name=":2" />
|-
| {{#ev:youtube|5B87zsAKmWc|350}}<ref>Handwritten tutorials. Spinal Pathways 1 - Spinal Cord Anatomy and Organisation. Available from: http://www.youtube.com/watch?v=5B87zsAKmWc [last accessed 29/08/16] </ref>
|}


'''Spinal Arteries:''' The spinal arteries, arising from the vertebral artery, run longitudinally down the spinal cord. The unpaired anterior spinal artery lies in the anterior median fissure of the spinal cord and extends from the level of the lower brainstem to the tip of the conus medullaris, with the diameter steadily increasing below the T2 level. It supplies the ventral medial surface of the medulla and anterior 2/3 of the spinal cord. The paired posterior spinal arteries supply the dorsal columns and the all but the base of the dorsal horns bilaterally. There are reinforcing branches from other arteries along the length of the cord and numerous anastomoses of the spinal arteries produce a vasocorona around the spinal cord. If occlusion occurs, it is normally of the anterior spinal artery, producing loss of power and spinothalamic sensory deficit, but dorsal column sensory capabilities are maintained. <ref name=":0" /><ref name=":2" />[[File:Spinal cord posterior.jpeg|thumb|Posterior spinal cord Great Posterior Radiculomedullary Artery]]'''Spinal Veins:''' Blood from within the spinal cord travels through the intramedullary [[veins]], to the anterior and posterior spinal veins, which form a reticulated network in the pia mater around the circumference of the cord throughout its length. The anterior two-thirds of the gray matter drain via the anterior spinal vein, while the posterior and lateral spinal veins drain the rest of the spinal cord. These vessels empty by way of the radicular veins into the external and internal vertebral venous plexuses, groups of valveless veins that extend from the coccyx to the base of the skull. The vertebral and deep cervical veins drain venous blood from the cervical spine into the superior vena cava; the posterior intercostal and lumbar veins drain venous supply from the thoracic and lumbar spine into the azygos and hemiazygos veins; and the median and lateral sacral veins drain venous supply from the sacrum into the common iliac vein. <ref name=":0" /><ref name=":2" />
== References ==
== References ==
<references />  
<references />  
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[[Category:Spinal Cord Injuries]]  
[[Category:Spinal Cord Injuries]]  
[[Category:Anatomy]]
[[Category:Anatomy]]
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[[Category:Spinal Cord - Anatomy]]
[[Category:Spinal Cord - Anatomy]]

Latest revision as of 18:31, 17 January 2023

Original Editor - Naomi O'Reilly

Top Contributors - Naomi O'Reilly, Lucinda hampton, Kim Jackson, Nikhil Benhur Abburi, Vidya Acharya, Aminat Abolade, Admin, Tarina van der Stockt, Jess Bell, Ewa Jaraczewska and Rucha Gadgil  

Introduction[edit | edit source]

The spinal cord is part of the central nervous system and consists of a tightly packed column of nerve tissue that extends downwards from the brainstem through the central column of the spine. It is a relatively small bundle of tissue (weighing 35g and just about 1cm in diameter) but is crucial in facilitating our daily activities.

The spinal cord carries nerve signals from the brain to other parts of the body (importantly the muscles we use to move) and receives sensory input from the body, partially processes it, and then transmits that information to the brain.

Along with its role in relaying motor and sensory signals between the brain and periphery, the spinal cord also provides separate neural circuits for many of our reflexes. Some reflexes eg the knee-jerk are built into the nervous system and bypass the brain, while others can be learned over time.

Spinal Cord: External[edit | edit source]

Externally, the spinal cord is protected by 33 vertebrae, which sit between a semi-rigid intervertebral disc, which provide a level of flexibility to the vertebral column. Its flexibility is greatest in the cervical region and lowest in the thoracic region. The spinal cord (similar to the brain) is protected by three layers of meninges (membranes). The spinal cord extends from the foramen magnum to the lowest border of the first lumbar vertebra. It is enlarged at two sites, the cervical and lumbar region.

The vertebrae (in adults) are arranged in five regions, which provide support and protection for the spinal cord.  It consists of seven Cervical Vertebrae, twelve Thoracic Vertebrae, five Lumbar Vertebrae, five Sacral (fused in adults to form the sacrum) and four Coccygeal Vertebrae (fused to form the coccyx).[2]

Spinal Cord: Internal[edit | edit source]

Inside, the spinal cord consists of grey matter and white matter.

  1. The grey matter takes on the shape of a butterfly, with four 'wings' called horns: The horns in the front contain motor neurons; the horns in the back contain sensory neurons which carry sensory information.
  2. The spinal cord grey matter is surrounded by a column of white matter, containing axons that allow different parts of the spinal cord to communicate smoothly, with signals passing upwards and downwards conveying eg sensation and motor signals.

Entry and Exit

  • Sensory Nerve Fibres enter the Spinal Cord via the Posterior (Dorsal) Root. The cell bodies for these neurons are situated in the Dorsal Root Ganglia.
  • Motor and Preganglionic Autonomic Fibres exit via the Anterior (Ventral) Root.

Below is a good image of the Spinal cord,labelled

  1. central canal
  2. posterior median sulcus
  3. gray matter
  4. white matter
  5. dorsal root + dorsal root ganglion
  6. ventral root
  7. ventral and dorsal nerve rootlets
  8. anterior spinal artery
  9. arachnoid mater
  10. dura mater

Spinal Canal[edit | edit source]

Spinal cord sits in the spinal cavity

Formed by the vertebral foramina of the vertebral bodies the spinal canal [bound anteriorly by the vertebral bodies and posteriorly by the laminae (vertebral arches)] with reinforcement at the walls through the intervertebral disks and the anterior and posterior longitudinal ligaments. The diameter varies from 12 to 22 mm in the cervical region and from 22 to 25 mm in the lumbar region.

Contains: 

Spinal Cord[edit | edit source]

1.Conus medullaris 2. Filum terminale 3. Cauda Equina

The spinal cord is the major conduit and reflex centre between the peripheral nerves and the brain and transmits motor information from the brain to the muscles, tissues and organs, and sensory information from these areas back to the brain. [5] It is, in an adult, approximately 45 cm long, cylindrical and slightly flattened anteriorly and posteriorly.[4].

Its upper end is continuous with the medulla, the transition is defined to occur just above the level of exit of the first pair of cervical nerves.

Its tapering lower end, the conus medullaris, terminates at the level of the L3 vertebra in neonates, and at the level of the L1-2 intervertebral disk in adults. It then becomes the cauda equina[1]

The cauda equina

  • Is the name given to the roots of the spinal nerves that extend beyond the termination of the spinal cord at the first lumbar vertebra in the form of a bundle of filaments within the spinal canal resembling a horse's tail[6] 
  • Has approximately 10 fiber pairs at its base: 3 to 5 lumbar fiber pairs; 5 sacral fiber pairs, and 1 coccygeal nerve.
  • Primary function of the cauda equina is to send and receive messages between the lower limbs and the pelvic organs, which consist of the bladder, the rectum, and the internal genital organs[7].

Spinal Nerves[edit | edit source]

Spinal Nerve

The term spinal nerve generally refers to a mixed spinal nerve that carries motor, sensory, and autonomic signals between the spinal cord and the body.

Humans have 31 left–right pairs of spinal nerves, each roughly corresponding to a segment of the vertebral column. There are eight cervical*, twelve thoracic, five lumbar, five sacral and one coccygeal.

The spinal nerves are relatively large nerves that are formed by the merging of two nerve roots: a sensory nerve root and a motor nerve root.

Spinal cord and spinal nerves

Sensory nerve roots emerge from the back of the spinal cord and the motor nerve roots from the front of the spinal cord. As they join, they form the spinal nerves on the sides of the spinal cord[8].

The anterior and posterior roots join to form two spinal nerves, one on either side of the spine, which then exit the vertebral canal through the intervertebral foramina. Once outside the intervertebral foramina they form peripheral nerves. [2]

*While there are eight pairs of cervical spinal nerves there are only seven cervical vertebrae. This disparity occurs because the first pair of cervical spinal nerves exits above the first cervical vertebra just below the skull. However, the eighth pair of cervical spinal nerves exits below the last cervical vertebra.* [4]

Spinal Cord Muscle Innervation[edit | edit source]

For each spinal cord level and muscles innervated see Spinal Cord Muscle Innervation

Spinal Motorneurons[edit | edit source]

Alpha and Gamma motor neurons are both found in the anterior (ventral) horn. 

  1. Alpha motor neurons are the largest motor neurons in the nervous system and innervate skeletal muscle. 
  2. Gamma Motorneurons innervate intrafusal muscle fibres of the muscle spindle. 

Motor neurons are arranged somatotopically across the anterior horn. The more medially placed motor neurons innervate proximal muscles while laterally placed motor neurons innervate distal muscles. [4][2]

Associated Pathways[edit | edit source]

Brain and spinal cord tracts

The central nervous system uses ascending and descending pathways to communicate with the external environment. See Central Nervous System Pathways.

Blood Supply[edit | edit source]

The majority of the spinal cord blood supply is provided by the segmental spinal arteries, with further supply coming from the vertebral arteries via a single anterior spinal artery and paired posterior spinal arteries. The segmental and spinal arteries are linked by numerous anastomoses. [4][2]

Segmental Arteries: The segmental arteries give off radicular branches, cervical and thoracolumbar, which enter the intervertebral foramen and supply the anterior and posterior roots and spinal ganglion of the corresponding level. The spinal cord itself is supplied by unpaired medullary arteries that originate from segmental arteries. [4][2]

Spinal Arteries: The spinal arteries, arising from the vertebral artery, run longitudinally down the spinal cord. The unpaired anterior spinal artery lies in the anterior median fissure of the spinal cord and extends from the level of the lower brainstem to the tip of the conus medullaris, with the diameter steadily increasing below the T2 level. It supplies the ventral medial surface of the medulla and anterior 2/3 of the spinal cord. The paired posterior spinal arteries supply the dorsal columns and the all but the base of the dorsal horns bilaterally. There are reinforcing branches from other arteries along the length of the cord and numerous anastomoses of the spinal arteries produce a vasocorona around the spinal cord. If occlusion occurs, it is normally of the anterior spinal artery, producing loss of power and spinothalamic sensory deficit, but dorsal column sensory capabilities are maintained. [4][2]

Posterior spinal cord Great Posterior Radiculomedullary Artery

Spinal Veins: Blood from within the spinal cord travels through the intramedullary veins, to the anterior and posterior spinal veins, which form a reticulated network in the pia mater around the circumference of the cord throughout its length. The anterior two-thirds of the gray matter drain via the anterior spinal vein, while the posterior and lateral spinal veins drain the rest of the spinal cord. These vessels empty by way of the radicular veins into the external and internal vertebral venous plexuses, groups of valveless veins that extend from the coccyx to the base of the skull. The vertebral and deep cervical veins drain venous blood from the cervical spine into the superior vena cava; the posterior intercostal and lumbar veins drain venous supply from the thoracic and lumbar spine into the azygos and hemiazygos veins; and the median and lateral sacral veins drain venous supply from the sacrum into the common iliac vein. [4][2]

References[edit | edit source]

  1. ↑ 1.0 1.1 Designed by Freepik at http://www.freepik.com
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Rohkamm Reinhard. Color Atlas of Neurology. Thieme; 2014 Sep 2.
  3. ↑ Spinal Cord. Blausen Medical. Retrieved on 26 January 2016.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Moore KL, Agur AM, Dalley AF. Essential Clinical Anatomy. Philadelphia: Lippincott Williams & Wilkins; 2002 Mar.
  5. ↑ Francisco de Assis Aquino Gondim et al., Topographic and Functional Anatomy of the Spinal Cord, Medshape, 2015
  6. ↑ Merriam webster Cauda equina Available:https://www.merriam-webster.com/medical/cauda%20equina (accessed 29.4.2022)
  7. ↑ Healthline Cauda equina Available: https://www.healthline.com/human-body-maps/cauda-equina#1(accessed 29.4.2022)
  8. ↑ Very well health Spinal Nerves Available:https://www.verywellhealth.com/spinal-nerves-anatomy-4682599 (accessed 29.4.2022)
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