Human Movement and Sensation

Question 1

External anatomy of spinal cord structure

Answer 1

Starts at foramen magnum (base of skull), ends at inferior border of 1st lumbar vertebra, within a sac made of meninges, spinal cavity within vertebrae

Question 2

Position of spinal cord

Answer 2

Spinal cord sits inside meninges which are surrounded by thin layer of fat in the spinal canal

Question 3

What is the conus medularis?

Answer 3

End of the spinal cord which is shaped as a tapered cone made out of non neural tissue
Attachment point for filum terminale

Question 4

What is the filum terminale?

Answer 4

Extends from the conus medularis to the end of the spinal cord, it anchors/holds the signal cord in place. Made out of fibrous non-neural tissue

Question 5

How many spinal cord segments are there?

Answer 5

31 Segments, each made up of a pair- one on LHS and one on RHS
Cervical : 8 pairs
Thoracic : 12 pairs
Lumbar : 5 pairs
Sacral : 5 pairs
Coccygeal : 1 pair

Question 6

What are exit points in the spinal nerve

Answer 6

Spinal nerves are named by the vertebra they exit, the first spinal nerve exits between the first cervical vertebra and skull hence why there are 8 cervical spinal nerves but only 7 cervical verterbrae

Question 7

Spinal nerves exit points in relation to levels

Answer 7

Exit the column at the level appropriate to their origin
This is why meninge sack exists past the end of the spinal cord

Question 8

What are components of the internal anatomy of the spinal cord?

Answer 8

In CNS: Median sulcus, white matter, grey matter, central canal, dorsal horn, dorsal column, lateral column, lateral horn, ventral horn, ventral column
In PNS: dorsal nerve root, dorsal root ganglion, spinal nerve, ventral nerve root

Question 9

Flow of efferent information - out of the spinal cord

Answer 9

Motor commands to effectors in the body, somatic motor neurons -> ventral nerve root -> skeletal muscle (effector)

Question 10

What would happen if there was damage to the ventral horn?

Answer 10

Paralysis of muscles supplied by somatic motor neurons from this spinal cord segment, on same side only as damage

Question 11

Flow of afferent information - into the spinal cord

Answer 11

Cell bodies of sensory neurons are in dorsal root ganglion, input zone in body associates with receptors for sensory stimulus, output zone enters the spinal cord through dorsal roots

Question 12

What would happen if there was damage to the afferent flow pathway?

Answer 12

Loss of sensation from regions of the body supported by the sensory neurons from this spinal cord segment, same side as damage only

Question 13

What parts of the spinal cord carry afferent information?

Answer 13

Dorsal nerve roots
Spinal nerve

Question 14

What parts of the spinal cord carry efferent information?

Answer 14

Ventral nerve roots
Spinal nerve

Question 15

Structure of a peripheral nerve

Answer 15

Individual axons may be myelinated or unmylienated
Axons are covered with endoneurium
Endoneurium covered axons are bundled together to form a fascicle
Fascicles are covered with perineurium and bundle with each other and with blood vessels to form a nerve which are curved by epineurium