brachial plexus

Question 1

what is the brachial plexus?

Answer 1

a network of nerve fibres which supply the skin and musculature of the upper limb

Question 2

where is the brachial plexus found?

Answer 2

it begins at the root of the neck, passes through the axilla and runs through the entire upper extremity

Question 3

what forms the brachial plexus?

Answer 3

-anterior rami (divisions) of the cervical spine nerves C5, C6, C7 and C8 and the first thoracic nerve T1

Question 4

what are the 5 divisions that the brachial plexus can be split into?

Answer 4

Read That Damn Cadaver Book

Roots, Trunks, Divisions, Cords and Branches

Question 5

what are the ‘roots’ in the brachial plexus?

Answer 5

-when talking about the ‘roots’ we are referring to the anterior rami of C5, C6, C7, C8 and T1

Question 6

where do paired spinal nerves arise?

Answer 6

-at each vertebral level

Question 7

where do paired spinal nerves leave the spinal cord?

Answer 7

-via the intervertebral foramina

Question 8

what role do the anterior and posterior rami of C5-T1 have?

Answer 8

anterior rami- make up brachial plexus which is responsible for supplying the skin and musculature of the upper limb

posterior rami- supply the skin and musculature of the intrinsic back muscles

Question 9

what do C5-T1 have to pass through to enter the base of the neck?

Answer 9

anterior and medical scalene muscles

Question 10

what are the trunks formed by the brachial plexus?

Answer 10

• superior trunk
• middle trunk
• inferior trunk

Question 11

what makes up the superior trunk of brachial plexus?

Answer 11

-combination of C5 and C6

Question 12

what makes up the middle trunk of the brachial plexus?

Answer 12

C7

Question 13

what makes up the inferior trunk of the brachial plexus?

Answer 13

-combination of C8 and T1

Question 14

where are the trunks of the brachial plexus found?

Answer 14

-they run laterally, crossing the posterior triangle of the neck

Question 15

what doe each trunk divid into?

Answer 15

• 2 divisions
• anterior division which travels towards the body
• posterior division which travels to the back of the body

(as there are 3 trunks there are then 3 anterior and 3 posterior divisions)

Question 16

where are the anterior and posterior divisions of the brachial plexus found?

Answer 16

-they leave the posterior triangle of the neck and pass into the axilla before they recombine into the cords of the brachial plexus

Question 17

where do the anterior and posterior divisions recombine to form 3 cords?

Answer 17

in the axilla

Question 18

what are the 3 cords named after?

Answer 18

-theyre named by they’re position relative to the axillary artery

Question 19

what is the lateral cord formed by?

Answer 19

• the anterior division of the superior trunk (C5, C6)

- the anterior division of the middle trunk (C7)

Question 20

what is the posterior cord formed by?

Answer 20

• the posterior division of the superior trunk (C5, C6)
• the posterior division of the medial trunk (C7)
• the posterior division of the inferior trunk (C8, T1)

Question 21

the is the medial cord formed by?

Answer 21

-the anterior division of the inferior trunk (C8, T1)

Question 22

what do the cords give rise to?

Answer 22

-the major branches of the brachial plexus

Question 23

what branches come from the lateral cord?

Answer 23

• muscocutaenous

- median

Question 24

what branches come from the posterior cord ?

Answer 24

• axillary

- radial

Question 25

what branches come from the medial cord?

Answer 25

- median | - ulnar

Question 26

what are the roots of the muscocutaenous nerve?

Answer 26

-C5, C6, C7

Question 27

what are the motor functions of the musculocutaneous nerve?

Answer 27

-innervates the brachial, biceps brachia and corabrachialis muscles

Question 28

what is the sensory function of the muscocultaneous nerve?

Answer 28

-gives off the lateral cutaneous branch of the forearm, which innervates the lateral half of the anterior forearm and a small portion of the posterior forearm

Question 29

what is the arterial supply to the anterior compartment of teh upper arm?

Answer 29

brachial artery

Question 30

what is the function of the biceps brachii?

Answer 30

- supination of the forearm | - it also flexes the arm at the elbow and at the shoulder

Question 31

what are the roots of the axillary nerve?

Answer 31

C5 and C6

Question 32

what is the motor function of the axillary nerve?

Answer 32

-innervates teres minor and deltoid

Question 33

what is the sensory function of the axillary nerve?

Answer 33

-gives off the superior lateral cutaneous nerve of the arm, which innervates the inferior region of the deltoid ('regimental badge area')

Question 34

what are the roots of the median nerve?

Answer 34

C6-T1 | some people however have strands of C5 as well

Question 35

what is the motor function of the median nerve?

Answer 35

supplies LOAF: - lateral two lumbrical (associated with index and middle fingers) - opponens pollicis brevis - abductor pollicis brevis - flexor pollicis brevis Most of the flexor muscles in the forearm: - palmaris longus - flexor carpi radialis - pronator teres - flexor digitorum superficialis - flexor pollicis longus - lateral half of flexor digitorum profundus - pronator Quadratus

Question 36

what is the sensory function of the median nerve?

Answer 36

- it gives off the palmar cutaneous branch which innervates the lateral part of the palm - it also gives off the digital cutaneous branch which innervates the lateral three and a half fingers on the anterior (palmar) surface of the hand

Question 37

what are the roots of the radial nerve?

Answer 37

C5 to T1

Question 38

what is the motor function of teh radial nerve?

Answer 38

- innervates the triceps brachii | - innervates the muscles of the posterior compartment of the arm

Question 39

what is the sensory function of teh radial nerve?

Answer 39

- innervates the posterior aspect of arm and forearm | - innervates the posterolateral aspect of the hand

Question 40

what are the roots of the ulnar nerve?

Answer 40

-C8 and T1

Question 41

what is the motor function of the ulnar nerve?

Answer 41

innervates: - all the muscles of the hand apart from LOAF (lateral two lumbricals, opponens pollicis brevis, abductor pollicis brevis and flexor pollicis brevis) - flexor carpi ulnas - medial half of flexor digitorum profundus

Question 42

what is the sensory function of the ulnar nerve?

Answer 42

-innervates the anterior and posterior surfaces of the medial one and a half fingers and associated palm area