Nerves of the upper limb: brachial plexus

Question 1

the brachial plexus is made from the ventral rami from ___. (spinal level)

Answer 1

C5-T1

Question 2

the ventral root provides ____ function.
the dorsal root provides ____ function.

Answer 2

ventral = motor
dorsal = sensory

Question 3

where are the cell bodies located for all sensory components of the PNS?

Answer 3

dorsal root ganglion

Question 4

are spinal nerves motor, sensory, or mixed?

Answer 4

ventral and dorsal roots come together to form spinal nerves, so spinal nerves are MIXED –> then splits into dorsal and ventral rami which are still mixed nerves

Question 5

describe the different ways a nerve can be damaged

Answer 5

Avulsion - pulled so hard they are displaced from spinal cord (can happen during childbirth)
Laceration - cut through the nerve
Compression - pusing agianst (crutches, saterday night palsy)
stretch/traction - trama to nerve but not completely out of spinal cord

Question 6

Musculocutaneuous nerve
- motor innervation and action
- sensory innervation
- what happens if damaged?

Answer 6

I: pierces/innervated corticobrachialis, biceps brachii and brachialis
A: flexion at elbow
S: lateral antebrachial cutaneous nerve (sensation to portion of forearm (on radial side))

damage - cant flex at elbow and cant feel sensation on lateral aspect of forearm

Question 7

which nerve is damaged in carpal tunnel syndrome? Why/how is it damaged?

Answer 7

median nerve

damaged dt overuse of tendons leading to inflammation –> inflammation of the tendons in the carpal tunnel compresses the median nerve –> poor nerve conduction resulting in muscle weakness and sensory problems

Question 8

axillary nerve - what does it innervate, action?

Answer 8

I: deltoid muscle
A: aBduction of the shoulder

Question 9

radial nerve - what does it innervate, sensory portion?

Answer 9

I: triceps muscle and all 12 muscles on the posterior aspect of the arm (extensor muscles)
S: provides sensory info from the back part of the arm/forearm

Question 10

what are the terminal branches of the posterior cord of the brachial plexus?

Answer 10

axillary and radial nerve
- posterior cord affects shoulder, extensors of the wrists and fingers

Question 11

what is a dermatome?

Answer 11

the area of skin supplied by the cutaneous branches from a SINGLE SPINAL NERVE (can be supplied by multiple nerve, but they all eventually combine at same spinal level

Question 12

C5 and C6 come together to form the ____ trunk

Answer 12

superior

Question 13

does C7 combine with another ventral rami to make up the middle cord

Answer 13

no; C7 continues alone to form the middle cord

Question 14

C8 and T1 combine to form the ___

Answer 14

inferior trunk

Question 15

Anterior divisions go towards the ___ part of the limb. the muscles in this portion of the arm/forearm mainly act as ___

Answer 15

anterior divisions go towards the ANTERIOR part of the limb to muscls that mainly act as FLEXORS

Question 16

Posterior divisions go towards the ___ part of the limb. the muscles in this portion of the arm/forearm mainly act as ___

Answer 16

posterior divisions go towards the POSTERIOR part of the limb to muscls that mainly act as EXTENSORS

Question 17

anterior divisions go to the ____ cord(s); posterior division goes to the ___ cord(s)

Answer 17

anterior divisions –> lateral and medial cords
posterior divisions –> posterior cord

Question 18

injuries where the shoulder is pushed down typically injures which trunk?

Answer 18

push down = upper trunk damage

Question 19

injuries where the shoulder is pulled upwards typically injurs which trunk?

Answer 19

lower trunk