Practical Class 1: The Vertebral Column and Spinal Cord

Question 1

What structures pass through the transverse foramina of the cervical vertebrae?

Answer 1

• Vertebral artery
• Vertebral vein
• ?Autonomic nerve

Question 2

Describe the features of C1 (atlas).

Answer 2

• No spinous process or body
• Consists of anterior and posterior arches, each with a tubercle and a lateral mass.
• There is a tubercle each on the medial surface of the lateral mass for the transverse ligament, which holds in place the dens of the axis.

Question 3

Describe the features of C2 (axis).

Answer 3

• Has two large flat surfaces, the superior articular facets, upon which the atlas rotates.
• It’s distinguishing feature is the dens (G. tooth), also known as the odontoid process
• This held in position by the transverse ligament of the atlas - prevents horizontal displacement of the atlas.

Question 4

Describe the distinguishing features of the thoracic vertebrae.

Answer 4

• Heart-shaped body with superior and inferior costal demi-facets for articulation with head of rib
• Spinous process - Long and extends postero-inferiorly
• Transverse process – costal facet for articulation with tubercle of rib
• Articular facets – superior faces posteriorly, inferior faces anterior

Question 5

Describe the distinguising features of the lumbar vertebrae.

Answer 5

• Large, kidney-shaped body
• Articular facets - superior face medially, inferior face laterally
• Spinous process short and sturdy

Question 6

What are the features of the zygopophyseal joints?

Answer 6

• Zygapophysial joints occur between superior and inferior articular processes of adjacent vertebrae
• Orientation of articular facets determines types of movements that are possible

Question 7

Describe the structure and function of the inter-vertebral discs.

Answer 7

Consist of:

• Annulus fibrosis – fibrocartilage ring attached to epiphysial rim of vertebral body
• Nucleus pulposus – gelatinous substance that acts as a shock absorber
• Cushion between each vertebrae, allows movement of spinal column but annulus fibrosis also prevent hyperreflexion/extension.
• Thickness determines flexibility

Question 8

What are the attachments and function of the anterior longitudinal ligament?

Answer 8

Attachments - occipital bone and C1 –> sacrum

Function - only ligament to resist hyperextension of vertebral column, connects the posterior of the vertebral body to the back of the annulus fibrosis

Question 9

What are the attachments and function of the ligamentum flava?

Answer 9

Attachments - connect the laminae of adjacent vertebrae, all the way from the second vertebra, axis, to the first segment of the sacrum.

Function - each ligamentum flavum runs between the posterior surface of the lamina on the vertebra below to the anterior surface of the lamina of the vertebra above. The ligamenta flava resist separation of the laminae in flexion and assist in extension back to the anatomical position.

Question 10

What are the attachments of the ligamentum nuchae?

Answer 10

The ligamentum nuchae is a triangular, sheet-like structure in the median sagittal plane:

• The base of the triangle is attached to the skull, from the external occipital protuberance to the foramen magnum.
• The apex is attached to the tip of the spinous process of vertebra CVII.
• The deep side of the triangle is attached to the posterior tubercle of vertebra CI and the spinous processes of the other cervical vertebrae.

Question 11

What is the function of the ligamentum nuchae?

Answer 11

Supports the head. It resists flexion and facilitates returning the head to the anatomical position. The broad lateral surfaces and the posterior edge of the ligament provide attachment for adjacent muscles.

Question 12

What are the attachments of the supraspinous ligament?

Answer 12

Connects and passes along the tips of the vertebral spinous processes from vertebra CVII to the sacrum

Question 13

What are the attachments of the interspinous ligaments?

Answer 13

Connect adjoining spinous processes, attaching from the root to the apex of each process.

Question 14

At which vertebral level does the spinal cord end in the newborn?

Answer 14

L3

Question 15

At which vertebral level does the spinal cord end in the adult?

Answer 15

L1

Question 16

What does the subdural space contain?

Answer 16

Nothing in health. Potential space between dura and arachnoid.

Question 17

What does the arachnoid space contain?

Answer 17

CSF

Question 18

What does the epidural space contain?

Answer 18

Fat, vertebral arteries, venous plexi etc…

Question 19

Where do the anterior and posterior spinal arteries originate?

Answer 19

Vertebral arteries. Travel in anterior median fissure.

Question 20

What is supplied by the anterior spinal artery?

Answer 20

Supplies anterior aspect including lateral corticospinal tract and spinothalamic tract.

Question 21

What is supplied by the posterior spinal arteries?

Answer 21

Supplies posterior aspect (smaller area than anterior) covers dorsal white matter.

Question 22

Describe the venous drainage of the spinal cord.

Answer 22

• Veins that drain the spinal cord form a number of longitudinal channels.
• Two pairs of veins on each side bracket the connections of the posterior and anterior roots to the cord.
• One midline channel parallels the anterior median fissure.
• One midline channel passes along the posterior median sulcus.

These longitudinal channels drain into an extensive internal vertebral plexus in the extradural (epidural) space of the vertebral canal, which then drains into segmentally arranged vessels that connect with major systemic veins, such as the azygos system in the thorax. The internal vertebral plexus also communicates with intracranial veins.

Question 23

What happens to the spinal cord in the lower part of the canal?

Answer 23

Posterior and anterior roots forming spinal nerves emerging between vertebrae in the lower regions of the vertebral column are connected to the spinal cord at higher vertebral levels.

Below the end of the spinal cord, the posterior and anterior roots of lumbar, sacral, and coccygeal nerves pass inferiorly to reach their exit points from the vertebral canal. This terminal cluster of roots is the cauda equina.

Question 24

What is a spinal segment?

Answer 24

The area of the spinal cord that gives rise to the posterior and anterior rootlets, which will form a single pair of spinal nerves.

Question 25

What happens to the spinal nerve as it emerges from an intervertebral foramen?

Answer 25

Each spinal nerve divides, as it emerges from an intervertebral foramen, into two major branches: a small posterior ramus and a much larger anterior ramus.

Question 26

What do the posterior rami supply?

Answer 26

Only intrinsic back muscles and an associated narrow strip of skin on the back.

Question 27

What do the anterior rami supply?

Answer 27

Most other skeletal muscles (the hypaxial muscles) of the body, including those of the limbs and trunk, and most remaining areas of the skin, except for certain regions of the head.

Question 28

From where do the meningeal nerves arise?

Answer 28

Near the point of division into anterior and posterior rami.

Question 29

What is supplied by the (2-4) meningeal nerves?

Answer 29

Dura, ligaments, intervertebral discs, and blood vessels.

Question 30

From where do all major somatic plexuses (cervical, brachial, lumbar, and sacral) arise?

Answer 30

Anterior rami

Question 31

What is the cauda equina?

Answer 31

Bundle of spinal nerves and spinal nerve roots, consisting of the second through fifth lumbar nerve pairs, the first through fifth sacral nerve pairs, and the coccygeal nerve, all of which arise from the lumbar enlargement and the conus medullaris.

Question 32

How many spinal nerves are associated with each region?

Answer 32

Cervical: 8
Thoracic: 12
Lumbar: 5
Sacral: 5
Coccygeal: 1

Question 33

Do cervical spinal nerves emerge superior or inferior to cervical vertebrae?

Answer 33

Superior - Nerve C1 emerges above vertebra C1

Question 34

Do thoracic/lumbar/sacral nerves emerge superior or inferior to their respective vertebrae?

Answer 34

Inferior.

Question 35

From where does nerve C8 emerge?

Answer 35

Superior to T1