Upper Limb Gross Anatomy 2

Question 1

Describe formation and components of brachial plexus

Answer 1

Formed by ventral primary rami of C5,C6,C7,C8 and T1. Components are: roots, trunks, divisions and cords.

Question 2

Describe branches of brachial plexus

Answer 2

From roots:
C5 gives rise to Dorsal Scapular nerve which innervates rhomboids as well as nerve to serratus anterior. Long thoracic nerve formed from C5,C6 and C7.

From trunks:
Superior trunk gives rise to suprascapular nerve which innervates supraspinatus and infraspinatus muscles. Nerve to subclavius as well.

From cords: 
Lateral - LLM 
Lateral pectoral cord 
Lateral divison of median nerve 
Musculocutaneous nerve

Medial - 4MU
Medial pectoral nerve to pectoralis major and minor
Medial division of median nerve 
Medial cutaneous nerve to arm 
Medial cutaneous nerve to forearm 
Ulnar nerve 

Posterior - ULNAR
Upper scapular nerve to subscapularis
Lower scapular nerve to subscapularis and teres major
Nerve to lattismus dorsi (thoracodorsal nerve)
Axillary nerve
Radial nerve

Question 3

Define nerve plexus

Answer 3

A nerve plexus is formed when peripheral spinal nerve roots merge and split to produce a network of nerves from which new multi-segmental peripheral nerves emerge.

Question 4

What are the 2 main groups of nerves that branch from brachial plexus?

Answer 4

Supraclavicular nerves branch from roots and trunk of plexus while infraclavicular branch from the cords.

Question 5

Describe source and extent of axillary artery

Answer 5

Is a continuation of the subclavian artery into the axilla and begins from outer border of 1st rib to inferior border of teres major.

Question 6

What are the 3 parts of the axillary artery?

Answer 6

Divided in relation to the pectoralis minor muscle. First part is proximal to pectoralis minor, 2nd part is deep/behind muscle and 3rd part is distal to muscle.

Question 7

Describe branches of axillary artery

Answer 7

6 branches in total. 1st part has one branch which is the superior thoracic artery. 2nd part has two branches: thoracoacromial artery and lateral thoracic artery. 3rd part has 3 branches: subscapular artery, posterior circumflex humeral artery and anterior circumflex humeral artery.

Question 8

Describe the origin and course of the brachial artery

Answer 8

Is a continuation of the axillary artery below lower border of teres major muscle. Runs downwards to cubital fossa where it terminates at level of neck of radius by dividing into radial and ulnar arteries.

Question 9

What are the branches of the brachial artery?

Answer 9

Muscular branches
Profunda brachii artery
Nutrient artery to humerus
Superior and inferior ulnar collateral

Question 10

What does the ulnar artery give rise to?

Answer 10

Common interossesous artery which gives rise to the posterior and anterior.

Question 11

Describe origin, course and termination of radial artery

Answer 11

Artery found on lateral side of forearm, forming from smaller terminal branch of brachial artery. Runs along lateral side of front of forearm to reach distal end of radius. At wrist, passes deep to tendons of abductor pollicis longus and extensor pollicis brevis and terminates forming deep palmar arch in palm.

Question 12

Describe origin, course and termination of ulnar artery

Answer 12

Arises as larger terminal branch of brachial artery. Starts in cubital fossa and initially runs obliquely, downwards medially for first 1/3 and then vertically downwards towards medial side in front of forearm to lateral side of pisiform bone. Passes superficial to flexor retinaculum in the wrist and forms superficial palmar arch.

Question 13

Enumerate the veins of the upper limb

Answer 13

Deep veins:
Venae comitantes of radial and ulnar arteries
Venae comitantes of brachial artery
Brachial vein 
Axillary vein 

Superficial veins:
Cephalic vein
Basilic vein
Median vein of forearm

Question 14

What are venae comitantes?

Answer 14

Accompanying veins. Multiple veins form a network of smaller veins with arteries which they accompany. There are connections between the VC. Allow heat exchange and artery pulse promotes venous flow.

Question 15

Describe commencement, course and termination of basilic vein

Answer 15

Begins from medial side of dorsal venous arch of hand. Ascends on medial border of forearm and is joined by median cubital vein just above elbow. Ascends on medial side of biceps and pierces deep fascia in middle of arm. Then ascends medial to brachial artery till lower border of teres major where it continues into axillary vein.

Question 16

Describe commencement, course and termination of cephalic vein

Answer 16

Begins from lateral side of dorsal venous arch of hand. Ascends on lateral part of the forearm and gives rise to median cubital vein just below elbow which links cephalic vein to basilic. Ascends lateral to biceps and pierces deep fascia at lower border of pectoralis major from where it reaches infraclavicular fossa, piercing deltopectoral groove. Then turns to pierce clavipectoral fascia ending in axillary vein.

Question 17

Describe commencement and course of axillary vein

Answer 17

Begins as continuation of basilic vein at lower border of teres major and passes upwards to axilla where it lies medial to axillary artery. At outer border of 1st rib, continues into subclavian vein.

Question 18

What are the 2 lymph nodes of the upper limb?

Answer 18

Cubital nodes – drain distal limb

Axillary nodes – drain limb and breast

Question 19

Describe origin and course of musculocutaneous nerve

Answer 19

Originates from lateral cord of brachial plexus. Arises behind pectoralis minor muscle and lies lateral to axillary artery. Pierces coracobrachialis to reach lateral side of arm. Runs laterally downards between biceps brachii and brachialis muscle. At elbow, pierces deep fascia from where it continues as lateral cutaneous nerve.

Question 20

Describe innervation of musculocutaneous nerve

Answer 20

Muscular: Innervates coracobrachialis, biceps brachii and brachialis.
Cutaneous: Lateral cutaneous nerve of forearm to lateral side of forearm.
Articular: Elbow joint

Question 21

Describe course of ulnar nerve

Answer 21

Is the continuation of medial cord of brachial plexus. In axilla, lies between axillary artery and vein on a deeper plane. Runs down medial side of brachial artery in arm and in midarm, pierces medial intermuscular septum to enter back of arm where it runs along groove on back of medial epicodyle of humerus. Can be palpated here. Enters the forearm by passing between heads of flexor carpi ulnaris, as it lies on medial part of flexor digitorum profundus. Accompanies by ulnar artery on lateral side. Passes into palm superficial to flexor retinaculum and at distal border of FR, divides into superficial and deep branches.

Question 22

Describe innervation of ulnar nerve

Answer 22

In foreram, supplies flexor carpi ulnaris and medial half of flexor digitorum profundus. Palmar cutaneous innervation to hypothenar eminence and dorsal cutaneous branch to medial 1.5 digits excluding dital phalanges. Superficial terminal branch in hand supplies palmaris brevis muscle and medial 1/3 of plam + fingers. Deep branch supplies many more.

Question 23

Describe origin and course of median nerve

Answer 23

Formed in the axilla by two roots: lateral root from lateral cord and medial root from medial cord. Lies anterior and lateral to axillary artery and then brachial artery. At midarm, crosses in front of brachial artery to run medially. Passes through cubital fossa in forearm and leaves between heads of pronator teres before crossing to lateral side and forming anterior interosseous branch. Enters palm through carpal tunnel and ends by dividing into lateral and medial terminal branches but before dividing, gives off recurrent muscular branch from lateral side.

Question 24

Describe innervation of median nerve

Answer 24

Muscular branch to pronator teres. Innervates most of the anterior forearm muscles and some intrinsic hand muscles. Cutaneous innervation of the lateral hand and 3.5 digits. Commonly damaged at the wrist, and also in the distal arm.

Question 25

Describe origin and course of axillary nerve

Answer 25

Arises from posterior cord of brachial plexus. Lies below capsule of shoulder joint and terminates into anterior and posterior segments just behind surgical neck of humerus. Anterior branch runs deep to deltoid muscle. Posterior branch pierces deep fascia to become upper lateral cutaneous nerve of arm.

Question 26

Describe innervation of axillary nerve

Answer 26

Anterior branch supplies deltoid muscle and skin over it. Posterior branch supplies posterior part of deltoid and teres minor muscles.

Question 27

Describe innervation of radial nerve

Answer 27

Innervates all arm and forearm posterior muscles, no intrinsic hand muscles. Cutaneous branches in arm and forearm. Cutaneous innervation of the lateral hand and 3½ digits.