Lecture 8 - Neuroanatomy: Brachial Plexus & Cranial Nerves

Question 1

What does Innervation mean?

Answer 1

• means nerve “in”

Question 2

What do nerves do?

Answer 2

• they supply sensory and motor nerves in the upper limb

Question 3

What are nerve roots?

Answer 3

• Paired branches that leave the spinal cord at each vertebral segment
• Exit spinal column through the intervertebral foramen

Question 4

What 2 fibres are nerve roots comprised of?

Answer 4

• Efferent (motor) fibres
• Afferent (sensory) fires

Question 5

What is the brachial plexus?

Answer 5

• Plexus = network of nerves or vessels in the body that have web-like formation
• Formed by anterior rami of nerve roots (C4-T1)

Question 6

What are the 5 terminal nerves of the brachial plexus?

Answer 6

• Musculocutaneous nerve
• axillary nerve
• radial nerve
• median nerve
• ulnar nerve

Question 7

What is the Musculocutaneous nerve?

Answer 7

• its root is the ventral rami of C5, C6, & C7
• it Innervates muscles of the anterior brachium:
• biceps brachii
• brachialis
• coracobrachialis

Question 8

What is the axillary nerve?

Answer 8

• it roots at the ventral rami of C5 & C6 & continues as the smaller branch of the posterior cord of the brachial plexus
• it Innervates the deltoid & the teres minor

Question 9

What is the radial nerve?

Answer 9

• it roots from C5, C6, C7, & C8
• it Innervates the triceps brachii, brachioradialis & muscles of the posterior forearm

Question 10

What is the median nerve?

Answer 10

• it roots from C6, C7, C8, & T1
• it Innervates most muscles of the forearm like the Pronator teres, flexor carpi radialis, palmarus longus, flexor digitorum profundus & superficialis
• also Innervates hand muscles like lumbricals (1 & 2), & the thenar group

Question 11

What is the ulnar nerve?

Answer 11

• it roots from the C7, C8, & T1
• it Innervates median muscles of the forearm like the flexor carpi ulnaris, flexor digitorum profundus (medial half), the hypothenar group, lumbricals (3 & 4), & the interossei (dorsal & palmer)

Question 12

What are the 9 peripheral nerves of the brachial plexus?

Answer 12

• long thoracic nerve
• dorsal scapular nerve
• nerve to subclavius
• suprascapular nerve
• lateral pectoral nerve
• medial pectoral nerve
• upper subscapular nerve
• lower subscapular nerve
• Thoracodorsal nerve

Question 13

What is the long thoracic nerve?

Answer 13

• originates at the anterior rami of C5, C6, & C7
• Innervates the Serratus anterior

Question 14

What is the dorsal scapular nerve?

Answer 14

• originates at the ventral rami of C4 & C5
• Innervates the rhomboids major/minor & the levator scapulae

Question 15

What is the nerve to subclavius?

Answer 15

• originates at C5 & C6
• Innervates the subclavius muscle

Question 16

What is the suprascapular nerve?

Answer 16

• originates in the nerve roots of C5 & C6
• it goes through the scapular notch
• Innervates the Supraspinatus & infraspinatus

Question 17

What is the lateral pectoral nerve?

Answer 17

• originates from the lateral cord of the brachial plexus, containing fibres from C5, C6, & C7
• Innervates the Pectoralis major

Question 18

What is the medial pectoral nerve?

Answer 18

• originates from the medial cord of the brachial plexus, containing fibres from C8 & T1
• Innervates the Pectoralis major & minor

Question 19

What is the upper subscapular nerve?

Answer 19

• originates from the ventral rami of C5 & C6
• Innervates the subscapularis muscle

Question 20

What is the lower subscapular nerve?

Answer 20

• originates from the ventral rami of C5 & C6
• Innervates the subscapularis muscle & the teres major

Question 21

What is the Thoracodorsal nerve?

Answer 21

• originates from the posterior cord of the brachial plexus, containing fibres of C6, C7, & C8
• Innervates the latissimus dorsi

Question 22

How many cranial nerves are there?

Answer 22

• 12

Question 23

What is the olfactory nerve?

Answer 23

• the 1st cranial nerve (CN I); also the shortest sensory nerve in your body
• part of your autonomic nervous system
• enables your sense of smell

Question 24

What is the optic nerve?

Answer 24

• known as the 2nd cranial nerve (CNII); optic means vision
• transmits sensory information for vision in the form of electrical impulses from the eye to the brain

Question 25

What is the oculomotor nerve?

Answer 25

- the 3rd cranial nerve (CNIII); motion of the eye - Innervation of eye muscles for for gaze fixation and eye tracking (somatic motor) - Innervation to the lens and pupil (autonomic parasympathetic) - Innervation to the upper eyelid (somatic motor)

Question 26

What is the trochlear nerve?

Answer 26

- the 4th Cranial Nerve (CNIV); with the longest intracranial course, but also the thinnest - trochlear means “pulley” (lift the eye) - enables movement in the eye's superior oblique muscle - This makes it possible to look down & to move your eyes toward your nose or away from it

Question 27

What is the Trigeminal nerve?

Answer 27

- the 5th cranial nerve (CN V); the largest of the cranial nerves - Its primary function is to provide sensory innervation to the face

Question 28

What is the abducens nerve?

Answer 28

- the 6th cranial nerve (CN VI); is purely a somatic motor nerve, It has no sensory function - It is responsible for the abduction of the eyes on the same (ipsilateral) side

Question 29

What is the facial nerve?

Answer 29

- the 7th cranial nerve (CN VII); carries nerve fibers that control facial movement and expression - also carries nerves that are involved in taste to the anterior 2/3 of the tongue and producing tears (lacrimal gland)

Question 30

What is the vestibulocochlear nerve?

Answer 30

Is the 8th cranial nerve (CN VIII); consists of the vestibular and cochlear nerves - Each nerve has distinct nuclei within the brainstem - The vestibular nerve is primarily responsible for maintaining body balance and eye movements - the cochlear nerve is responsible for hearing

Question 31

What is the glossopharyngeal nerve?

Answer 31

- is the 9th cranial nerve (CN IX); It provides motor, parasympathetic and sensory information to your mouth and throat - the nerve helps raise part of your throat, enabling swallowing.

Question 32

What is the vagus nerve?

Answer 32

- is the 10th cranial nerve (CN X); This system controls specific body functions such as your digestion, heart rate and immune system - These functions are involuntary, meaning you can’t consciously control them

Question 33

What is the accessory nerve?

Answer 33

- is the 11th cranial nerve (CN XI); main functions are contracting the trapezius muscle and the sternocleidomastoid

Question 34

What is the hypoglossal nerve?

Answer 34

- is the 12th cranial nerve (CN XII); hypo' meaning under, and 'glossal' meaning tongue - The nerve has a purely somatic motor function, innervating all the extrinsic and intrinsic muscles of the tongue