Lesson 4

Brachium

Brachium - arm

• A. Bony landmarks • 1. humerus – a. lateral epicondyle - radial side – b. medial epicondyle - ulnar side • 2. ulna – a. olecranon process – elbow – b. styloid process of ulna - dorsomedial point of wrist • 3. radius – a. styloid process of radius - lateral point of wrist • 4. Interosseous membrane: fibrous connective membrane, between radius and ulna

Cutaneous nerves

• (A)1. Medial brachial cutaneous nerve: middle of arm medial side - to skin over olecranon • (A) 2. Medial antebrachial cutaneous nerve: appears just inferior to medial brachial nerve on medial arm, splits: – a. anterior branch - skin of anteromedial forearm – b. posterior branch - skin of posteromedial forearm • (A) 3. Lateral antebrachial cutaneous nerve: continuation of musculocutaneous - appears just above inside of elbow, near cephalic vein - to skin of lateral & anterolateral forearm - also has anterior & posterior branches • (P) 4. Superior lateral brachial cutaneous nerve - a branch off the axillary nerve - to skin over inferior half of deltoid

Cutaneous nerves

• (P) 5. Posterior brachial cutaneous nerve - branches off the radial nerve up in the axilla - to skin on dorsal arm inferior to deltoid • (P) 6. Inferior lateral brachial cutaneous nerve = superior terminal branch - of radial nerve - a small branch ~2 inches above lateral epicondyle - to skin of lower lateral & anterolateral arm • (P) 7. Posterior antebrachial cutaneous nerve = inferior terminal branch of radial nerve - large - appears just below, posterior to lateral epicondyle - to skin on dorsal, lateral forearm • (P) 8. Superficial radial nerve - lateral border, distal forearm, just proximal to wrist - from under lateral border of brachioradialis - innervates skin on lateral dorsum of hand, thumb, proximal 2/3 of 1st 2-3 fingers (lateral side of middle or ring finger) • (A) 9. Posterior cutaneous branch of the ulnar nerve: - medial border, distal forearm, just proximal to wrist - innervates skin on medial dorsum of hand, last 2 fingers (medial side of ring finger)

Veins

• 1. cephalic vein: lateral (radial side) - all the way from wrist to deltopectoral groove, to axillary vein • 2. basilic vein: medial (ulnar side) - goes deep, joins venae comitantes (deep) & brachial artery • 3. median cubital vein: crosses over, connects cephalic with basilic - common site for drawing blood • 4. dorsal venous arch: back of hand - often used for an IV

Arteries

• Brachial artery: extension/continuation of axillary artery, splits into two terminal branches (radial and ulnar) • Branches – 1. profunda brachii artery ('deep'): largest, most superior branch; follows radial nerve - posterior descending branch (splits into radial collateral artery and middle collateral artery) – 2. two ulnar collateral arteries: branch off brachial below profunda & above elbow - superior ulnar collateral: mid-arm; follows ulnar nerve post. to medial epicondyle - inferior ulnar collateral: from ~2 in. proximal to elbow, anterior to medial epicondyle

Artery

• 3. radial artery: lateral, anterior to elbow, crosses anterior to biceps tendon & supinator muscle; overlapped by brachioradialis muscle – radial recurrent: a branch toward lateral epicondyle, anastomoses with profunda branch • 4. ulnar artery: medial, anterior to elbow, goes deep to pronator teres muscle – anterior ulnar recurrent – posterior ulnar recurrent – common interosseous artery - divides into anterior and posterior interosseous arteries (interosseous recurrent artery -- branch off posterior interosseous or common interosseous artery)

Anastomeses

• ** Collateral elbow circulation - is created by anastomoses between recurrents & collaterals: • including: radial recurrent; ulnar recurrents (anterior & posterior) ulnar collaterals (superior & inferior), recurrent interosseous and descending branch of profunda brachii

Coracobrachialis

• • • •

ORIGIN

apex of coracoid process of scapula

INSERTION

medial surface of middle of shaft of humerus, opposite deltoid tuberosity

ACTION

flexes and adducts the shoulder

NERVE

musculocutaneous - C

6, 7

BICEPS BRACHII

• • • •

ORIGIN

short head: apex of coracoid process of scapula long head: supraglenoid tubercle of scapula (just above the fossa)

INSERTION

short, long heads: tuberosity of radius, and aponeurosis of biceps brachii (laterous fibrosus)

ACTION

Flexes the shoulder joint, and the long head may assist abduction if the humerus is laterally rotated.

With the origin fixed: flexes the elbow, moving forearm towards the humerus and supinates forearm With insertion fixed: flexes the elbow joint moving the humerus toward the forearm as in pull-up or chinning exercises

NERVE

musculocutaneous nerve -

C5, C6

BRACHIALIS

• • • •

ORIGIN

humerus - distal 1/2, anterior surface of humerus, and medial and lateral intermuscular septa

INSERTION

ulna - coronoid process, ulnar tuberosity

ACTION

With origin fixed: flexes the elbow joint moving the forearm toward the humerus With insertion fixed: flexes the elbow joint moving the humerus toward the forearm as in pull-up or chinning exercises.

NERVE

musculocutaneous nerve + a small branch of radial nerve -

C5, C6

TRICEPS

• • • •

ORIGIN

– long head: scapula - infraglenoid tubercle – lateral head: humerus - lateral and posterior surfaces of proximal 1/2 of humerus; and lateral intermuscular septum – medial head: humerus - distal 2/3 of medial and posterior surfaces of humerus below the radial groove, and from medial intermuscular septum

INSERTION

ulna - posterior surface olecranon process; antebrachial fascia

ACTION

extends the elbow joint; long head also assist in abduction and extension of the shoulder joint

NERVE

radial nerve - C6,

C7, C8,

T1

ANCONEUS

• • • •

ORIGIN

humerus - lateral epicondyle; on posterior surface

INSERTION

ulna - olecranon process, on lateral side; & proximal 1/4 of ulna, posterior surface

ACTION

extends the elbow joint, and may stabilize the ulna during pronation and supination

NERVE

radial nerve -

C7, C8

, T1