NEUROVASCULAR SUPPLY OF THE UPPER LIMB

Question 1

what is the brachial plexus?

Answer 1

a complex inter communicating network of nerves formed by spinal nerves C5, C6, C7, C8, and T1. supplies the upper limb

Question 2

where does the brachial plexus supply? exceptions?

Answer 2

• supplies all SENSORY information to the upper limb and most of the axilla — except for an area of the medial upper arm and axilla (supplied by the intercostobrachial nerve T2)
• supplies all MOTOR information to the muscles of the upper limb and shoulder girdle — except for the trapezius (supplied by the spinal accessory nerve XI)

Question 3

what is the brachial plexus divided into?

Answer 3

roots, trunks (each trunk has anterior and posterior divisions) , divisions, cords

Question 4

what forms the upper/superior trunk?

Answer 4

the roots of C5 and C6

Question 5

what forms the middle trunk?

Answer 5

the roots of C7

Question 6

what forms the lower/inferior trunk?

Answer 6

the roots of C8 and T1

Question 7

what forms the lateral cord?

Answer 7

the anterior divisions of the upper and middle trunks

Question 8

what forms the medial cord?

Answer 8

the anterior division of the inferior trunk continues as the medial cord

Question 9

what forms the posterior cord?

Answer 9

the posterior divisions of all trunks form the posterior cord

Question 10

what forms the long thoracic nerve?

Answer 10

formed by the posterior aspect of the ventral rami of C5, C6, and C7

Question 11

where does the long thoracic nerve pass?

Answer 11

it passes through the apex of the axilla posterior to the other components of the brachial plexus

Question 12

branches of what artery supplies the brachial plexus?

Answer 12

the subclavian artery

Question 13

blood supply of the roots of the brachial plexus

Answer 13

vertebral artery, anterior and posterior spinal arteries

Question 14

blood supply of the trunks and divisions of the brachial plexus

Answer 14

ascending and deep cervical arteries, superior intercostal artery

Question 15

blood supply of the cords of the brachial plexus

Answer 15

axillary artery

Question 16

describe the musculocutaneous nerve

Answer 16

= a major peripheral nerve of the upper limb
= the terminal branch of the lateral cord of the brachial plexus
- nerve roots: C5-C7
- emerges at the inferior border of the pectoralis minor

Question 17

what are the motor and sensory functions of the musculocutaneous nerve?

Answer 17

• MOTOR = innervates the muscles in the anterior compartment of the arm (BBC)
• SENSORY = the nerve gives rise to the lateral cutaneous nerve of the forearm which innervates the skin of the anterolateral aspect of the forearm

Question 18

describe the axillary nerve

Answer 18

= a major peripheral nerve of the upper limb
= a direct continuation of the posterior cord from the brachial plexus
- nerve roots: C5 and C6
- formed within the axilla
- it is posterior to the axillary artery in the axilla and anterior to the subscapularis muscle
- exits axilla at the inferior border of the subscapularis via the quadrangular space
- passes medially to the surgical neck of the humerus where it divides into 3 terminal branches

Question 19

what 3 branches does the axillary nerve divide into?

Answer 19

1. posterior terminal branch — provides motor innervation to the posterior aspect of the deltoid muscle and teres minor. also innervates skin over the inferior part of the deltoid as the upper lateral cutaneous nerve of the arm
2. anterior terminal branch — winds around the surgical neck of the humerus and provides motor innervation to the anterior aspect of the deltoid muscle. terminates with cutaneous branches to the anterior and anterolateral shoulder
3. articular branch — supplies the glenohumeral joint

Question 20

what are the motor and sensory functions of the axillary nerve?

Answer 20

• MOTOR = innervates the teres minor and deltoid muscle
• SENSORY = gives rise to the upper lateral cutaneous nerve of the arm, which innervates the skin over the lower deltoid (regimental badge area)

Question 21

describe the radial nerve

Answer 21

= a major peripheral nerve of the upper limb
= the terminal continuation of the posterior cord of the brachial plexus
- spinal roots C5-T1
- arises in the axilla region, posterior to the axillary artery
- descends down the arm in the radial groove of the humerus
- accompanied by the deep branch of the brachial artery for much of its course
- to enter the forearm, the nerve travels anterior to the lateral epicondyle of the humerus, through the cubital fossa
- the nerve terminates by dividing into 2 branches

Question 22

what 2 branches does the radial nerve divide into?

Answer 22

1. the deep branch (MOTOR) — innervates muscles in the posterior compartment of the forearm
2. the superficial branch (SENSORY) — contributes to the cutaneous innervation of the dorsal hand and fingers

Question 23

what are the motor and sensory functions of the radial nerve?

Answer 23

• MOTOR = muscles in the posterior arm and posterior forearm (triceps brachii and extensor muscles in the forearm)
• SENSORY = innervates most of the skin of the posterior forearm, the lateral aspect of the dorsum of the hand and the dorsal surface of the hand and fingers

Question 24

describe the median nerve

Answer 24

= a major peripheral nerve of the upper limb
= derived from the median and lateral cords of the brachial plexus
- nerve roots: C6-T1 (also fibres from C5 in some individuals)
- runs through the anterior portion of the arm and forearm, before finishing its path at the hand and fingers
- exits exiles and travels with the brachial artery down the shaft of the humerus into the cubital fossa
- foes through carpal tunnel into hand

Question 25

what are the motor and sensory functions of the median nerve?

Answer 25

- MOTOR = innervates the majority of the muscles in the anterior forearm and some intrinsic hand muscles - SENSORY = responsible for cutaneous innervation of part of the hand

Question 26

sensory innervation by the median nerve is achieved via what 2 branches?

Answer 26

1. the palmar cutaneous branch — arises in the forearm and travels into the hand. innervates the lateral aspect of the palm. does not travel through carpal tunnel 2. the palmar digital cutaneous branch — arises in the hand. innervates the palmar surface and fingertips of the lateral 3 and 1/2 digits

Question 27

describe the ulnar nerve

Answer 27

= a major peripheral nerve of the upper limb = a continuation of the medial cord of the brachial plexus - spinal roots: C8-T1 - descends in a pane between the axillary artery (lateral) and axillary vein (medial) - proceeds down the medial aspect of the arm, medial to the brachial artery

Question 28

what are the motor and sensory functions of the ulnar nerve?

Answer 28

- MOTOR = flexor carpi ulnaris and medial half of flexor digitorum profundus of anterior forearm. intrinsic muscles of the hand (apart from the thenar muscles and 2 lateral lumbricals) - SENSORY = medial 1 and a 1/2 fingers and the associated palm area

Question 29

describe the subclavian artery

Answer 29

where arterial supply to the upper limb begins

Question 30

where does the subclavian artery arise from on the RHS?

Answer 30

arises from the brachiocephalic trunk

Question 31

where does the subclavian artery arise from on the LHS?

Answer 31

arises directly from the arch of the aorta

Question 32

how many parts is the subclavian artery divided into and where are they?

Answer 32

3 PARTS 1. 1st part = origin of the subclavian artery to the medial border or the anterior scalene 2. 2nd part = posterior to the anterior scalene 3. 3rd part = lateral border of the anterior scalene to the lateral border of the 1st rib

Question 33

what does the subclavian artery become and where?

Answer 33

renamed the axillary artery at the lateral border of the 1st rib where it enters the axilla

Question 34

where is the axillary artery and how many parts is it divided into?

Answer 34

= lies deep to the pectoralis minor and is enclosed in the axillary sheath (covers teh artery and the 3 cords of the brachial plexus) - divided inti 3 parts based on its position relative to pectoralis minor

Question 35

describe the parts of the axillary artery

Answer 35

- 1st part = proximal to PM - 2nd part = posterior to PM - 3rd part = distal to PM

Question 36

what does the axillary artery become and where?

Answer 36

at the lower border of the teres major muscle the axillary artery is renamed the brachial artery

Question 37

describe the brachial artery

Answer 37

= a continuation of the axillary artery past the lower border of teres major - MAIN BLOOD SUPPLY OF THE ARM - the brachial artery proper descends down the arm - as it moves through the cubital fossa, underneath the bicipital aponeurosis, the brachial artery terminates by bifurcation into the radial and ulnar arteries

Question 38

where are the radial and ulnar arteries formed?

Answer 38

formed by the bifurcation of the brachial artery within the cubital fossa

Question 39

describe the radial artery

Answer 39

supplies the posterolateral aspect of the forearm. it contributes to anastomotic networks surrounding the elbow joint and carpal bones

Question 40

describe the ulnar artery

Answer 40

supplies the anteromedial aspect of the forearm. it contributes to anastomotic networks surrounding the elbow joint

Question 41

where do the ulnar and radial arteries anatomise and what do they become?

Answer 41

anatomise in the hand by forming 2 arches — the superficial and deep palmar arches

Question 42

what is the deep palmar arch mainly formed from?

Answer 42

the terminal part of the radial artery

Question 43

where does the deep palmar arch lie?

Answer 43

lies upon the bases of metacarpal bones and on the interossei of the hand

Question 44

what emerges from the deep palmar arch?

Answer 44

palmar metacarpal arteries

Question 45

what is the superficial palmar arch predominately formed from?

Answer 45

ulnar artery