Lecture 15 - Spinal Cord Anatomy

Question 1

Descending vs Ascending Tracts

Answer 1

Descending tracts: (motor commands)
* Lateral Corticospinal Tract
* Ventral Corticospinal Tract

Ascending tracts: (to brain, sensory)
* Dorsal Column Medial Lemniscus Tract
* Ventral Spinothalamic Tract

Question 2

Dermetones

Answer 2

Areas of skin innervated by certain nerves

Face does not count as it uses cranial nerves

Question 3

Overview

Answer 3

Dorsal root = sensory info
Ventral root = relay information

Does not chose left or right but diffuses into two different tracks at a fork

Question 4

Descending spinal tracts

Answer 4

M1: Primary motor cortex, sends info into CNS by action potientals

1. Lateral Corticospinal Tract
   =contralateral
   =switches sides
   = appendicular muscles
   = left to right
2. Ventral Corticospinal Tract
   =ipsylateral
   = same side
   =core muscles
   =stays left

decussate = switch sides

Ventral = innervates bilaterally, innervates both sides at point of attachment
Lateral = one side

Caudal medulla= lower medulla, alpha motor neuron as well

Question 5

Track of Lateral Corticospinal and Ventral Corticospinal Tracts

Answer 5

Cortex (M1 Area)

to Thalamus

to Brainstem (caudal medulla), lateral = decussate but ventral = right through

to spinal cord

Question 6

Overview

Answer 6

Lateral = one side innervated

Ventral = both sides

a beta = cutaneous receptors
a delta or c axon = info through dorsal,

synapse at level of spine it enters

Question 7

Ascending spinal tracts: Dorsal Column Medial Lemniscus Tract

Answer 7

Descussation: DCML and LCT

Level at which it enters: VCST and VST

Cutaneous receptors
GTO’s
Joint receptors
Ia, II, Ib, AB axon
primary, secondary, GTO, cutaneous

D(spine) CM(medial) lemniscus tract

order 1,2,3: change of direction

1: dorsal rot ganglion
2. caudal medulla
3. thalamus

Question 8

Ascending spinal tracts: Ventral Spinothalamic Tract

Answer 8

Pain and tempt sensory input travels up spinal cord along the spinothalamic tracts

Third order: Ventral postier lateral nucleus of thalamus

all info goes into S1

a theta =mylinated, C axon = not

Question 9

Comparing ascenidng tracts

Answer 9

DCML decussates at caudal medulla

VST decussates immediately at spinal cord