DSA11 Singh Spinal Cord Anatomy and Tracts Flashcards
Rexed’s lamina I-V
Pain/temp and touch
Interomediolateral cell column (IMLCC)
Rexed’s lamina VI-VII (C8-L2). Preganglionic sympathetic neurons.
Rexed’s lamina VIII-IX
Ventral horn motor neurons
Rexed’s lamina X
Forms the grey commissure that surrounds the central canal
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
nucleus posterior marginalis
Rexed’s lamina I. Pain/temp & light touch.
nucleus substantia gelatinosa
Rexed’s lamina II (C1-Coc1). Responds to noxious stimuli, pain/temp & light touch. Pain modulation. Homologous to spinal trigeminal nucleus.
nucleus proprius
Rexed’s laminae III & IV (C1-Coc1). Position, light touch. Intersegmental reflex activity.
nucleus dorsalis (thoracis) of Clarke - aka Clarke’s column, aka posterior thoracic nucleus
Rexed’s lamina VII (T1-L3). Gives rise to the (posterior) spinocerebellar tract.
What’s the function of Renshaw cells in the ventral horn of the sc?
Negative feedback. Receive input from alpha motor neurons and inhibit the same group of alpha motor neurons.
Phrenic nucleus
C3-C6. Principal motor nerve to the diaphragm (and some sensory).
Accessory nucleus (in the spine)
C1-C6. Spinal component of CN XI
Which thoracic segments are most vulnerable to infarction? Which artery is occluded?
Upper segments T1-T4; a few segmental branches of the thoracic aorta.
Which lumbosacral segments are most vulnerable to infarction? Which artery is occluded?
Left T12-L4 are all vulnerable; great ventral redicular artery (aka artery of Adamkiewicz).
What are the levels of the cervical enlargement?
C4-T1
What are the levels of the lumbar enlargement?
L1-S2
fasciculus gracilis
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.
fasciculus cuneatus
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.
lateral spinothalamic tract
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.
ventral spinothalamic tract
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.
dorsal spinocerebellar tract
CARRIES: unconscious proprioception (muscle spindle & Golgi tendon organ). Ipsilateral.
ventral spinocerebellar tract
CARRIES: unconscious proprioception (“righting” reflex), fine touch, vibration
lateral corticospinal tract
Pyramidal fibers that decussate (~90%) at base of pyramids and descend contralaterally. Control voluntary, skilled movements.
ventral corticospinal tract
Pyramidal fibers that descend ipsilaterally (~10%).
