Neuro - Anat & Phys (Spinal Anatomy & Motor Signs) Flashcards
Pg. 464-466 in First Aid 2014 Sections include: -Spinal nerves -Spinal cord - lower extent -Spinal cord & associated tracts -Spinal tract anatomy & functions -Motor neuron signs
How many spinal nerves are there? List them by category.
There are 31 spinal nerves in total: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal.; Think: “31, just like 31 flavors of Baskin-Robbins ice cream!”
Where do spinal nerves exit?
Nerves C1-C7 exit above the corresponding vertebra. All other nerves exit below (e.g., C3 exits above the 3rd cervical vertebra; L2 exits below the 2nd lumbar vertebra)
What is Vertebral disc herniation? Where does it usually occur?
Vertebral disc herniation - nucleus pulposus (soft central disc) herniates through annulus fibrosus (outer ring); usually occurs posterolaterally at L4-L5 or L5-S1
What is the lower extent of the spinal cord in adults?
In adults, spinal cord extends to lower border of L1-L2 vertebrae.
What is the lower extent of the subarachnoid space?
Subarachnoid space (which contains the CSF) extends to lower border of S2 vertebra
Where is a Lumbar puncture usually performed?
Lumbar puncture is usually performed between L3-L4 or L4-L5 (level of cauda equina);
What is the goal of a lumbar puncture? How is this accomplished?
Goal of lumbar puncture is to obtain sample of CSF without damaging spinal cord. Think: “To keep the cord alive, keep the spinal needle between L3 and L5.”
Where are legs located in the lateral corticospinal tracts? In what other tract are they located in the same place?
Legs (Lumbosacral) are Lateral in Lateral corticospinal, spinothalamic tracts
How is the dorsal column (somatotopically) organized?
Dorsal column is organized as you are, with hands at sides. Arms outside, legs inside.
What function does lateral corticospinal tract serve? What is another tract that serves this same function?
DESCENDING: (1) Lateral corticospinal tract (2) Anterior corticospinal tract; Voluntary motor
What function(s) does the dorsal column serve?
ASCENDING: Dorsal column - Pressure, vibration, touch, proprioception
What are 2 ascending tracts near the anterior of the spinal cord? What are their functions?
ASCENDING:(1) Lateral spinothalamic tract - Pain, temperature; (2) Anterior spinothalamic tract - Crude touch, pressure
What are the names of the white matter in the dorsal column associated with the lower body/legs versus upper body/arms?
(1) Fasciculus gracilis (lower body, legs) (2) Fasciculus cuneatus (upper body, arms)
Draw the spinal cord and label its associated tracts: (1) ASCENDING: Dorsal column (2) ASCENDING: Lateral spinothalamic tract (3) ASCENDING: Anterior spinothalamic tract (4) DESCENDING: Lateral corticospinal tract (5) DESCENDING: Anterior corticospinal tract (6) Fasciculus gracilis (7) Fasciculus cuneatus (8) Gray matter (9) Anterior horn (10) Posterior horn (11) Intermediate horn sympathetics (T1-L2/L3) (12) White matter.
See p. 465 in First Aid 2014 for visual
What is the orientation of cervical versus sacral in the Lateral corticospinal tract? What other tract shares this same orientation?
Cervical = medial; Sacral = lateral; Lateral spinothalamic tract
What should you remember about ascending tracts?
Remember, ascending tracts synapse and then cross
What kind of tract is the Dorsal column? What is its function?
Ascending: pressure, vibration, fine touch, and proprioception
What kind of tract is the Spinothalamic tract? What is (are) its function(s) ?
Ascending; Lateral - Pain, temperature; Anterior - Crude touch, pressure
What kind of tract is the Lateral corticospinal tract? What is its function?
Descending: Voluntary movement of contralateral limbs.
What is the route taken by the Dorsal column? Include neurons and synapses in order.
1ST-ORDER NEURON: Sensory nerve ending –> cell body in dorsal root ganglion –> enters spinal cord, ascends ipsilaterally in dorsal column; SYNAPSE 1: Ipsilateral nucleus cuneatus or gracilis (medulla); 2ND-ORDER NEURON: Decussates in medulla –> ascends contralaterally in medial lemniscus; SYNAPSE 2: VPL (thalamus); 3RD-ORDER NEURON: Sensory cortex
What is the route taken by the Spinothalamic tract? Include neurons and synapses in order.
1ST-ORDER NEURON: Sensory nerve ending (Adelta and C fibers) (cell body in dorsal root ganglion) –> enters spinal cord; SYNAPSE 1: Ipsilateral gray matter (spinal cord); 2ND-ORDER NEURON: Decussates at anterior white commissure –> ascends contralaterally; SYNAPSE 2: VPL (thalamus); 3RD-ORDER NEURON: Sensory cortex
What is the route taken by the Lateral corticospinal tract? Include neurons and synapses in order.
1ST-ORDER NEURON: UMN: cell body in primary motor cortex –> descends ipsilaterally (through internal capsule), most fibers decussate at caudal medulla (pyramidal decussation) –> descends contralaterally; SYNAPSE 1: Cell body of anterior horn (spinal cord); 2ND-ORDER NEURON: LMN: leaves spinal cord; SYNAPSE 2: NMJ
What is the 1st-order neuron for the Dorsal column, and where does it travel?
1ST-ORDER NEURON: Sensory nerve ending –> cell body in dorsal root ganglion –> enters spinal cord, ascends ipsilaterally in dorsal column
What is the 2nd-order neuron for the Dorsal column, and where does it travel?
From synapse 1 (ipsilateral nucleus cuneatus or gracilis (medulla)), 2ND-ORDER NEURON: Decussates in medulla –> ascends contralaterally in medial lemniscus
