Lecture 20

Question 1

What is the external anatomy of the spinal cord?

Answer 1

• Starts at foramen magnum, ends at inferior border of 1st lumbar vertebra (L1)
• within a sac made of meninges that fits inside spinal cavity
• spinal cavity within vertebrae, extends to coccygeal vertebrae

Question 2

What is the anterior and posterior of the vertebrae called? Where does the spinal cord go?

Answer 2

anterior = ventral
posterior = dorsal
spinal cord in spinal canal

Question 3

What are the non-neural structures associated with the spinal cord?

Answer 3

• extends within meningeal sac filled with CSF
• end is a tapered cone called conus medularis, non-neural tissue
• filum terminale extends to end of spinal cavity, made of fibrous, non-neural tissue, anchors spinal cord

Question 4

What are the numbers of nerve pairs for each part of the spinal cord?

Answer 4

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

Question 5

How are the spinal nerves named? What is the exception?

Answer 5

• named by vertebra they exit below
• exception is 1st cervical spinal nerve as exits between skull and first cervical vertebra

Question 6

What is cauda equina?

Answer 6

The large collection of long nerves inferior to end of spinal cord

Question 7

Name the parts of the internal anatomy of the spinal cord.

Answer 7

• dorsal median sulcrus
• central canal
• ventral median fissure
• dorsal horn (cell bodies)
• ventral horn (cell bodies)
• lateral horn (cell bodies)
• dorsal column (axons)
• lateral column (axons)
• ventral column (axons)
• dorsal nerve root (axons)
• dorsal root ganglion (cell bodies)
• ventral nerve root (axons)
• spinal nerve

Question 8

The dorsal and ventral sides of the spinal cord are in charge of what types of flow of information?

Answer 8

Dorsal = sensory/afferent
Ventral = motor/efferent

Question 9

How does the flow of efferent information from the spinal cord work?

Answer 9

somatic motor neurons -> ventral nerve root -> skeletal muscle

Question 10

What is the flow of afferent information into the spinal cord?

Answer 10

dorsal root ganglion -> dorsal nerve root -> spinal column

Question 11

What is the structure of a peripheral nerve?

Answer 11

• axons covered in endoneurium
• endoneurium covered axons bundled into fasicles
• fasicles covered with perineurium
• fasicles bundle together to form a nerve
• nerves covered by epineurium

Question 12

What does the dorsal ramus do?

Answer 12

• efferent to back
• afferent from back

Question 13

What does the ventral ramus do?

Answer 13

• efferent to ventral body
• afferent from ventral body

Question 14

What are the rami communicans?

Answer 14

• sympathetic nervous system
• only T1-L2