SDL - Vertebral Column & Spinal Cord Flashcards
What are the 7 components that make up the back?
the back is the posterior aspect of the trunk and includes:
- skin
- subcutaneous tissue
- vertebral column
- spinal cord and meninges in the vertebral column
- ribs
- nerves and vessels
- muscles
What makes up the vertebral column?
How many vertebrae are in the typical adult vertebral column?
the vertebral column consists of vertebrae separated by intervertebral discs that are bound together by ligaments
the typical adult vertebral column has 33 vertebrae
What are the different types of vertebrae that make up the vertebral column?
7 cervical (C1 - C7 in the neck)
12 thoracic (T1 - 12) articulate with the ribs
5 lumbar (L1 - 5) in the lower back
5 sacral (S1 - S5) fused into the sacrum
4 coccygeal (Co) fused into the coccyx
What are the features of a typical vertebra?
a body anteriorly which supports the vertebral column and is connected to the intervertebral discs
a vertebral arch posteriorly
what are the different parts of the vertebral arch?
pedicle:
- this attaches the transverse process to the body of the vertebra
lamina:
- attaches transverse process to spinous process
paired superior and inferior articular processes:
- protrude posterior to the vertebral notches
spinous and transverse processes:
- for attachment of muscles and ligaments
Label the diagram
What are the smallest vertebrae?
cervical vertebrae
they are the smallest moveable vertebrae and form the bony skeleton of the neck
What is the distinctive feature of the cervical vertebrae?
transverse foramen
these foramina are smaller in C7 than in other cervical vertebrae
they are occasionally absent
What structures pass through the transverse foramina?
- vertebral artery
- vertebral vein
- sympathetic nerves from the inferior cervical ganglion
Which cervical vertebrae have a different structure?
C1 and C2
What is significant about the spinous processes of C3 to C6?
they are short and bifid (divided into 2 parts)
What is significant about the spinous process of C7?
it is known as the vertebra prominens and is very long
it is used as a bony landmark from which to count vertebrae
Label the typical cervical vertebra
What are the unique features of C1 (the atlas) and C2 (the axis)?
- it has NO vertebral body and NO spinous process
- it is ring-like and has an anterior arch, posterior arch and 2 lateral masses
- the anterior arch has a facet for articulation with the dens of the axis
- the posterior arch has a groove for the vertebral artery and C1 spinal nerve
What is the role of the ligament of the atlas?
the anterior arch has a facet for articulation with the dens of the axis
this is secured by the ligament of the atlas that attaches to the lateral masses
What are the unique features of C2 (the axis)?
- the dens rises perpendicularly from the upper surface of the body
- it articulates with anterior arch of the atlas, creating the medial atlanto-axial joint
- they are specialised to allow a greater range of motion
Complete the labelling on the diagrams of C1 and C2
What are the distinguishing features of the thoracic vertebrae?
- vertebral body is heart-shaped
- demi-facets on the sides of each vertebral body articulate with the heads of the ribs
- costal facets on the transverse processes articulate with the tubercles of the ribs (T1 - T10 only)
- spinous processes are long and slant inferiorly
Label the thoracic vertebrae
Label the lumbar vertebra
What are the distinguishing features of the lumbar vertebrae?
- transverse processes are long and slender
- articular processes have nearly vertical facets
- spinous processes are short and broad
What is the purpose of accessory and mammillary processes of the lumbar vertebrae?
accessory processes:
- found on posterior aspect of the base of each transverse process
- site of attachment for deep back muscles
mammillary processes:
- found on the posterior surface of each superior articular process
- site of attachment for deep back muscles
What is significant about the fifth lumbar vertebra?
it has a large vertebral body and transverse processes as it carries the weight of the entire upper body
Label the features of the sacrum and coccyx
What are vertebrae held together by?
- facet joints
- intervertebral discs
- ligaments
What is the purpose of facet joints?
(also called zygapophyseal joints)
they connect the superior and inferior articular processes of adjacent vertebrae
What is the role of intervertebral discs?
intervertebral discs between all non-fused vertebrae provide flexibility to the spine and act as shock absorbers
what is the purpose of the ligaments of the vertebral column?
ligaments bind vertebrae together and give stability to the vertebral column
What are the 2 components of the intervertebral disc?
- annulus fibrosus
- nucleus pulposus
Label the components of the intervertebral disc
What are the functions of the annulus fibrosus and nucleus pulposus?
annulus fibrosus:
- enhances spine’s rotational stability
- helps to resist compressive stress
nucleus pulposus:
- transmits stress and weight from vertebra to vertebra
What are the 5 types of ligaments associated with the vertebral column?
- anterior longitudinal ligament
- posterior longitudinal ligament
- ligamentum flavum
- ligamentum nuchae
- interspinous ligaments
What are the attachments and function of the anterior longitudinal ligament?
attachment/location:
- covers the anterior aspects of the vertebral bodies and intervertebral discs
- attaches to the upper and lower edges of each vertebra, body
function:
- limits extension of the vertebral column and reinforces the intervertebral disc
What are the attachments and functions of the posterior longitudinal ligament?
posterior longitudinal ligament:
- arises from the body of the axis (C2)
- travels downward and posterior to the vertebral bodies and intervertebral discs
- attaches to the back of the sacrum
function:
- limits flexion of the vertebral column
- reinforces intervertebral disc
What is the attachment and function of the ligamentum flavum?
attachments:
- connects the laminae of adjacent vertebrae from C2 to S1
functions:
- resumes the shape of the vertebral column after flexion
- preserves upright posture
- resists excessive separation of the adjacent vertebral laminae
- prevents canal compression
What are the functions and attachments of the ligamentum nuchae?
attachments:
- continuous with the supraspinous ligament
- spans from the occiput to the spine of C7
functions:
- limits flexion
What are the attachments and functions of the interspinous ligaments?
attachments:
- connects the spinous processes (from roots to apexes) from C1 to S1 one segment at a time
- fibres connect with the ligamentum flavum anteriorly
- fibres connect with the supraspinous ligament posteriorly
functions:
- the role of the interspinous ligament is to limit flexion (bending fowards)
- it restricts separation of the spinous processes of the vertebral column
What are the movements possible at the vertebral column?
How do these vary?
the arrangement of the vertebral column, with many small bones separated by intervertebral discs, permits a wide range of movements of the back
- flexion
- lateral flexion
- extension
- rotation
these movements are possible to different extents in different regions of the vertebral column
What are the 2 groups of muscles of the back?
superficial (or extrinsic)
deep (or intrinsic)
What are the extrinsic (superficial) back muscles?
What is their innervation?
- rhomboid major and minor
- levator scapulae
- trapezius
- latissimus dorsi
they are innervated by the ventral rami of spinal nerves
trapezius is innervated by the accessory nerve
What is the innervation of the intrinsic (deep) back muscles?
How can they be divided?
dorsal (posterior) rami of spinal nerves
they can be divided into superficial, intermediate and deep
What are the muscles in the superficial group of intrinsic back muscles?
- splenius muscles on the posterolateral surfaces of the neck
- splenius capitis
- splenius cervicis
what are the following superficial intrinsic back muscles?
What are the functions of splenius capitis?
acting bilaterally:
- extension of the head and cervical spine
acting unilaterally:
- lateral flexion of the head and neck
- rotation of the head to the same side
- it also assists in supporting the head in the erect position
What are the functions of splenius cervicis?
acting bilaterally:
- they extend the neck
acting unilaterally:
- they laterally flex and rotate the head and neck to the same side
- they also assist in supporting the head in the erect position
What muscle is part of the intermediate group of deep back muscles?
What is its composition like?
the large erector spinae muscles that lie on either side of the vertebral column
it is composed of 3 separate muscles and acts as the chief extensor of the vertebral column
What are the 3 muscles that make up erector spinae?
from midline to most lateral:
- vertebral column
- spinalis
- longissimus
- iliocostalis
Label the constituents of erector spinae
What muscles form part of the deep group of intrisic back muscles?
Where do they originate from?
deep to erector spinae there is a group of much smaller muscles that originate from the transverse processes of the vertebrae
and insert onto the spinous process of more superior vertebrae
this is the transversospinalis group
it consists of semispinalis, multifidus and rotatores
What are the primary contents of the vertebral canal?
- spinal cord
- spinal nerve roots
- their meningeal coverings
At which vertebral level does the spinal cord end in a newborn and an adult?
What does this mean for the lower spinal nerve roots in adults?
the vertebral column ends at L1 - L2
at birth, the vertebral column ends at L3
the lower spinal nerve roots in adults form the cauda equina
they travel down the vertebral column to exit below their respective vertebrae
Label the diagram of the spinal cord
What is contained within the subdural and subarachnoid space?
subdural space:
- potential space between arachnoid and dura mater
- does not contain any bridging veins (unlike cranial subdural space) so haemorrhage in this area is rare
subarachnoid space:
- space between the arachnoid and the pia mater
- filled with cerebrospinal fluid
What is contained within the epidural space in the spinal cord?
this is a space between the dura and vertebra
it contains fat
What is the arterial supply to the spinal cord?
the spinal cord receives its arterial supply from three small, longitudinally running arteries
these are one anterior and two posterior spinal arteries
Where do the anterior and posterior spinal arteries originate?
anterior spinal artery:
- originates from vertebral artery
- travel in the anterior median fissure
posterior spinal artery:
- originate from the vertebral artery or posteroinferior cerebellar artery
- they anastamose with each other in the pia mater
Which areas of the spinal cord are supplied by the anterior and posterior spinal arteries?
anterior spinal artery:
- supplies anterior portion of spinal cord
posterior spinal artery:
- supplies grey and white posterior columns of the spinal cord
What arteries reinforce the anterior and posterior spinal arteries?
the anterior and posterior spinal arteries are small and are reinforced by radicular branches of the intercostal and lumbar arteries
these enter the vertebral canal through the intervertebral foramina
Complete the labelling of the blood supply to the spinal cord
Label the venous drainage of the spinal cord
What is the venous drainage of the spinal cord like?
venous drainage is via three anterior and three posterior spinal veins
these are valveless and form an anastomosing network along the surface of the spinal cord
they also receive venous blood from the radicular veins
What do the spinal veins drain into?
they drain into the internal and external vertebral plexuses
these empty into the systemic segmental veins
the internal vertebral plexus also empties into the dural venous sinuses superiorly
At each vertebral level, what venous connections are present?
at each vertebral level there are connections with thoracic, abdominal and intercostal veins and the external vertebral venous plexus
Where does blood pass into after flowing through a spinal vein?
spinal veins have no valves
blood passes directly into the systemic venous system
What is significant about the continuity of the vertebral venous plexuses with the prostatic plexus?
the continuity of the vertebral venous plexuses with the prostatic plexus is probably the path along which prostatic neoplastic cells metastasize to the central nervous system
label the components of the venous drainage of the spinal cord
what is the passage of the spinal nerve like in the upper part of the vertebral canal?
in the upper part of the vertebral canal, each spinal nerve has a short course before emerging through the intervertebral foramen as the anterior primary ramus and posterior primary ramus
what happens to spinal nerves in the lower part of the spinal canal?
the roots of the sacral nerves begin inside the vertebral column at the level of the L1 vertebra
they descend into the sacrum
this is where the cauda equina begins
Label the diagram
