Lecture 3 - Spinal Cord, Cerebrum & Motor Tracts

Question 1

how far does the spinal cord extend?

Answer 1

from medulla oblongata to L2

Question 2

what does the spinal cord consist of?

Answer 2

– central gray matter (H shaped) - contains nerve cell bodies, dendrites, central canal and CSF
– white matter (outer region) - contains myelinated and unmyelinated axons to communicate between spinal cord and brain via fibre tracts

Question 3

how does spinal nerve leave the vertebral canal?

Answer 3

Anterior root & posterior root leave spinal cord → roots join → spinal nerve → spinal nerve leaves vertebral canal through the intervertebral foremen.
Each spinal nerve divides into 1. anterior branch and 2. posterior branch which supplies skin & muscle.

Question 4

what is a dermatome?

Answer 4

strip of skin supplied by a single spinal nerve

Question 5

what does the anterior nerve root supply?

Answer 5

motor neurons - muscles

Question 6

what does the posterior nerve root supply?

Answer 6

sensory neurons - skin

Question 7

what are the 5 essential components of a reflex arc?

Answer 7

1. Receptor
2. Sensory neuron
3. Integration centre (interneuron)
4. Motor neuron
5. Effector

Question 8

what are the 2 types of reflex?

Answer 8

monosynaptic - 1 synapse (knee)
polysynaptic - interneuron between sensory and motor neuron (withdrawal)

Question 9

where is the motor area located?

Answer 9

anterior to central sulcus

Question 10

where is the sensory area located?

Answer 10

posterior to central sulcus

Question 11

what are the 2 pathways from brain to muscle?

Answer 11

direct pathway - pyramidal tracts pass through internal capsule
indirect pathway - extrapyramidal tracts do not pass through internal capsule, goes through brain stem nuclei, basal ganglia and cerebellum)

Question 12

what is the corticospinal tract?

Answer 12

UMN -> interneuron -> LMN