Spinal Cord Anatomy Flashcards
How many pairs of spinal nerves?
31
How many cervical spinal nerves?
8
How many thoracic spinal nerves?
12
How many lumbar spinal nerves?
5
How many sacral spinal nerves?
5
How many coccygeal?
1
Which nerves exit ABOVE corresponding vertebra?
C1-C7.
Where does C8 exit?
Below C7, above T1.
Where do T1 and below exit?
Below corresponding vertebrae.
Where does the spinal cord end?
L1-L2.
Where does the subarachnoid space extend to?
Lower border of S2.
Where is LP performed?
Between L3-L4 or L4-L5.
What is herniating through what w/ a vertebral disc herniation?
Nucleus pulposus (soft central disc) hernates through annulus fibrosus (outer ring).
Most common site of vertebral disc herniation?
Posteriorly at L4-L5 or L5-S1.
What tracts of the spinal cord travel in the 11:00-1:00 regions?
Dorsal columns
What tract of the spinal cord travels from 2:00-3:00, or 9:00-10:00?
Lateral corticospinal tract
What tract of the spinal cord travels from 3PM to 6PM? (and 6PM to 9PM?)
Lateral spinothalamic tract, at bottom there’s Anterior spinalthalamic tract.
What is at 6PM of the spinal cord?
Anterior corticospinal tract.
What is the organization of the lateral corticospinal tracts and lateral spinothalamic tracts?
Cervical is Central, Lateral is Legs/Lumbosacral.
What is the organization of the dorsal columns?
Opposite: Lower inside, upper outside.
What are the two parts of the dorsal columns?
Fasciculus gracilis, fasciculus cuneatus
What does the fasciculus gracilus contain?
Lower body. (Ass in the Grass). Cuneatus has upper body.
What are the dorsal columns responsible for?
Pressure, vibration, fine touch, and proprioception.
What are the lateral spinothalamic tracts responsible for?
Pain and temperature.
What are the anterior spinothalamic tracts responsible for?
Crude touch and pressure.
What are the corticospinal tracts responsible for?
Voluntary movement of contralateral limbs.
What is the 1st order neuron of the dorsal columns?
Sensory nerve endings –> cell body in dorsal root ganglion –> enters spinal cord, ascends ipsilaterally in dorsal column.
Where does the 1st order neuron of the dorsal column synapse?
Ipsilateral nucleus cuneatus or gracilus - medulla.
What is the second order neuron of the dorsal column?
Decussates in the medulla, ascends contralaterally in medial lemniscus.
Where does the second order neuron of the dorsal column synapse?
VPL of the thalamus.
Where does the 3rd order neuron of the dorsal column go?
Sensory cortex.
What is the 1st order neuron of the spinothalamic tract?
Sensory nerve ending (A-Delt and C fibers) - cell body in dorsal root ganglion –> enters spinal cord.
Where does the 1st order neuron of the spinothalamic tract synapse?
Ipsilateral gray matter of the spinal cord
What does the second order neuron of the spinothalamic tract do?
Decussates at anterior white commissure –> ascends contralaterally.
Where does the second order neuron of the spinothalamic tract synapse?
VPL, thalamus.
Where does the third order neuron of the spinothalamic tract go?
Sensory cortex
What is the 1st order neuron of the corticospinal tract?
UMN: Cell body in Primary motor cortex. Descends ipsilaterally through internal capsule, most fibers decussate at caudal medulla (pyramidal) –> descends contralaterally
Where does the 1st order neuron of the corticospinal tract synpase?
Cell body of anterior horn in the spinal cord
What is the second order neuron of the corticospinal tract?
LMN: leaves spinal cord.
Where does the second order neuron of the corticospinal tract synpase?
NMJ.
