Musk system

• The upper limb veins are divided into two groups: superficial veins which lie in the superficial fascia and deep veins which accompany all the large arteries.
• The superficial veins in the upper limb include the dorsal venous arch on the back of the hand, the cephalic vein, the basilic vein, and the median cubital vein which is important for phlebotomy and peripheral venous access.
• The deep veins in the upper limb include the axillary vein, the radial and ulnar veins, and the venae comitantes of the brachial artery, also known as the Brachial veins.
• The cephalic vein arises from the lateral side of the dorsal venous arch on the back of the hand and winds around the lateral border of the forearm, ascending into the cubital fossa and up the front of the arm on the lateral side of the biceps, terminating in the axillary vein.
• The basilic vein arises from the medial side of the dorsal venous arch and winds around the medial border of the forearm, ascending into the cubital fossa and up the front of the arm on the medial side of the biceps, terminating by joining venae comitantes of the brachial artery to form axillary vein.
• The upper arm is enclosed in a sheath of deep fascia which sends medial and lateral intermuscular septa to the medial and lateral supracondylar ridges of the humerus, respectively, dividing the upper arm into an anterior and a posterior fascial compartment.
• The muscles in the anterior fascial compartment of the upper arm include the biceps brachii, coracobrachialis, and brachialis, with the brachial artery as their blood supply and the musculocutaneous nerve as their nerve supply.
• The biceps brachii muscle has two heads: a long head which originates from the supraglenoid tubercle of the scapula and a short head which originates from the coracoid process of the scapula.
• The coracobrachialis muscle originates from the coracoid process of the scapula and inserts on the medial aspect of the shaft of the humerus.
• The brachialis muscle originates from the front of the lower half of the humerus and inserts on the coronoid process of the ulna.
• The brachial artery begins at the lower border of the teres major muscle as a continuation of the axillary artery, terminating at the level of the neck of the radius by dividing into the radial and ulnar arteries.
• The median nerve lies lateral to the artery in the upper part of the arm and then crosses its middle part to become medial in the lower part.
• Profunda brachii artery (Deep artery of arm): passes through spiral groove with radial nerve.
• Superior ulnar collateral artery.
• Inferior ulnar collateral artery.
• Terminal branches of the profunda brachii artery include the radial and ulnar arteries.
• The musculocutaneous nerve leaves the axilla by piercing the coracobrachialis muscle and appears at the lateral margin of the biceps tendon, running down as the lateral cutaneous nerve of the forearm.
• The musculocutaneous nerve has muscular branches to the biceps, coracobrachialis, and brachialis, cutaneous branches to the lateral cutaneous nerve of the forearm, and articular branches to the elbow joint.
• The median nerve arises from the medial and lateral cords of the brachial plexus and has no branches in the upper arm, except for a small vasomotor nerve to the brachial artery.
• The ulnar nerve pierces the medial fascial septum and enters the posterior compartment of the arm, where it has no branches in the upper arm.
• The three heads of the triceps muscle are located in the posterior compartment of the arm, supplied by the radial nerve.
• In the upper arm, the radial nerve immediately enters the posterior compartment of the arm and winds around the back of the arm in the spiral groove of the humerus, re-entering the anterior compartment by piercing the lateral fascial septum.
• In the axilla, the radial nerve has branches to the long and medial heads of the triceps, and the posterior cutaneous nerve of the arm.
• In the spiral groove, the radial nerve has branches to the lateral and medial heads of the triceps and to the anconeus, supplying the lower lateral cutaneous nerve of the arm and the posterior cutaneous nerve of the forearm.
• In the anterior compartment of the arm, the radial nerve has branches to the brachialis, brachioradialis, and extensor carpi radialis longus.
• The cubital fossa is a triangular depression in front of the elbow, bounded laterally by the brachioradialis muscle, medially by the pronator teres muscle, and the base is formed by an imaginary line drawn between the two epicondyles of humerus.
• The floor of the cubital fossa is reinforced by the supinator and brachialis muscles, and the roof is skin and fascia, reinforced by the bicipital aponeurosis.
• The terminal part of the brachial artery, the tendon of the biceps muscle, the median nerve, the radial nerve, and the superficial lymph nodes and median cubital vein are located in the cubital fossa.
• The brachial artery has muscular branches to the anterior compartment of the upper arm and a nutrient artery to the humerus.
• The forearm is divided into three compartments: Anterior, Posterior, and Lateral.
• The muscles of the forearm include a superficial group: pronator teres, flexor carpi radialis, palmaris longus, and flexor carpi ulnaris; an intermediate group: flexor digitorum superficialis; and a deep group: flexor pollicis longus, flexor digitorum profundus, and pronator quadratus.
• The muscles of the forearm are supplied by the ulnar and radial arteries.
• All the muscles of the forearm, except the flexor carpi ulnaris and the medial part of the flexor digitorum profundus, are supplied by the median nerve.
• The action of the muscles of the forearm includes pronation and flexion of the forearm, flexion and abduction of the hand at the wrist joint, flexion of the hand, and flexion of the middle and proximal phalanges and wrist.
• The muscles of the forearm are also supplied by the anterior interosseous nerve.
• The muscles of the forearm include the flexor carpi ulnaris, which flexes and adducts the hand at the wrist joint, and the flexor digitorum profundus, which flexes the distal phalanges of the medial four fingers and then assists in flexion of the middle and proximal phalanges and wrist.
• The ulnar artery is the larger of the two terminal branches of the brachial artery and is the principle source of supply to the forearm.
• The palm enters the hand by passing in front of the flexor retinaculum.
• Branches of the palm include muscular branches to flexor carpi ulnaris and to the medial half of the flexor digitorum profundus, articular branches to the elbow joint, and a palmar cutaneous branch that supplies the skin over the hypothenar eminence.
• The dorsal (posterior) cutaneous branch of the palm is distributed on the posterior surface of the hand and fingers.