DSA11 Singh Spinal Cord Anatomy and Tracts

Question 1

Rexed’s lamina I-V

Answer 1

Pain/temp and touch

Question 2

Interomediolateral cell column (IMLCC)

Answer 2

Rexed’s lamina VI-VII (C8-L2). Preganglionic sympathetic neurons.

Question 3

Rexed’s lamina VIII-IX

Answer 3

Ventral horn motor neurons

Question 4

Rexed’s lamina X

Answer 4

Forms the grey commissure that surrounds the central canal

Question 5

Identify the relative location of the following tracts/structures on a spinal cord segment:

• fasciculus gracilis
• fasciculus cuneatus
• dorsal spinocerebellar tract
• ventral spinocerebellar tract
• lateral spinothalamic tract
• ventral spinothalamic tract
• lateral corticospinal tract
• ventral corticospinal tract
• medial longitudinal fasciculus
• anterior white commissure

Answer 5

Question 6

nucleus posterior marginalis

Answer 6

Rexed’s lamina I. Pain/temp & light touch.

Question 7

nucleus substantia gelatinosa

Answer 7

Rexed’s lamina II (C1-Coc1). Responds to noxious stimuli, pain/temp & light touch. Pain modulation. Homologous to spinal trigeminal nucleus.

Question 8

nucleus proprius

Answer 8

Rexed’s laminae III & IV (C1-Coc1). Position, light touch. Intersegmental reflex activity.

Question 9

nucleus dorsalis (thoracis) of Clarke - aka Clarke’s column, aka posterior thoracic nucleus

Answer 9

Rexed’s lamina VII (T1-L3). Gives rise to the (posterior) spinocerebellar tract.

Question 10

What’s the function of Renshaw cells in the ventral horn of the sc?

Answer 10

Negative feedback. Receive input from alpha motor neurons and inhibit the same group of alpha motor neurons.

Question 11

Phrenic nucleus

Answer 11

C3-C6. Principal motor nerve to the diaphragm (and some sensory).

Question 12

Accessory nucleus (in the spine)

Answer 12

C1-C6. Spinal component of CN XI

Question 13

Which thoracic segments are most vulnerable to infarction? Which artery is occluded?

Answer 13

Upper segments T1-T4; a few segmental branches of the thoracic aorta.

Question 14

Which lumbosacral segments are most vulnerable to infarction? Which artery is occluded?

Answer 14

Left T12-L4 are all vulnerable; great ventral redicular artery (aka artery of Adamkiewicz).

Question 15

What are the levels of the cervical enlargement?

Answer 15

C4-T1

Question 16

What are the levels of the lumbar enlargement?

Answer 16

L1-S2

Question 17

fasciculus gracilis

Answer 17

SOURCE: Leg. CARRIES: conscious proprioception, epicritic discrimination, and vibration. LOCATION: dorsal column, T6-C1. PATH: Ascends ipsilaterally, synapses in nucleus gracilis, decussates and ascends in medial lemnisus to thalamus, then goes to post-central gyrus.

Question 18

fasciculus cuneatus

Answer 18

SOURCE: Arm. CARRIES: conscious proprioception, epicritic discrimination, and vibration. LOCATION: dorsal column, T6-C1. PATH: Ascends ipsilaterally, synapses in nucleus cuneatus, decussates and ascends in medial lemnisus to thalamus, then goes to post-central gyrus.

Question 19

lateral spinothalamic tract

Answer 19

CARRIES: pain/temp. 1ST: dorsal root ganglion. 2ND: dorsal root. Decussates within 1-2 segments via the anterior white commissure then ascends contralaterally (in lateral spinothalamic tract). 3RD: thalamus to sensory cortex.

Question 20

ventral spinothalamic tract

Answer 20

CARRIES: touch, pressure. 1ST: dorsal root ganglion, ascends or descends ipsilaterally. 2ND: dorsal root. Decussates via the anterior white commissure then ascends contralaterally (in anterior spinothalamic tract). 3RD: thalamus to sensory cortex.

Question 21

dorsal spinocerebellar tract

Answer 21

CARRIES: unconscious proprioception (muscle spindle & Golgi tendon organ). Ipsilateral.

Question 22

ventral spinocerebellar tract

Answer 22

CARRIES: unconscious proprioception (“righting” reflex), fine touch, vibration

Question 23

lateral corticospinal tract

Answer 23

Pyramidal fibers that decussate (~90%) at base of pyramids and descend contralaterally. Control voluntary, skilled movements.

Question 24

ventral corticospinal tract

Answer 24

Pyramidal fibers that descend ipsilaterally (~10%).

Question 25

Outline the venous return of the spinal cord.

Answer 25

Anterior and posterior spinal vv. –> anterior and posterior radicular veins –> internal vertebral venouos plexus –> external vertebral venous plexus

Question 26

Outline the venous neoplastic invasion of vertebrae from the prostate.

Answer 26

Bateson’s plexus (venous) from the prostate communicates with the external vertebral plexus, facilitating neoplastic invasion of vertebrae, the vertebral canal, and/or the spinal cord.

Question 27

What are the spinal levels of the sacral parasympathetics?

Answer 27

S2-S4