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Insertion: To the coracoid process.
Origin: Three heads: long from the infraglenoid tubercle, lateral from
Action: Depresses the tip of the shoulder.
the humerus above the spiral line, and medial from the back of the
Nerve supply: Medial and lateral pectoral nerves.
• Deltoid • Triceps
lower part of the humerus.
Origin: From the lateral third of the clavicle, the acromion and the Insertion: Into the olecranon.
spine of the scapula. Action: Extensor of the elbow.
Insertion: To the deltoid tubercle on the lateral surface of the humerus. Nerve supply: Radial nerve.
Actions: Abduction of the upper limb (assisted by supraspinatus and • Pronator teres
serratus anterior), flexion (anterior fibres) and extension (posterior Origin: From the common flexor origin on the medial epicondyle of the
fibres) of the arm. humerus.
Nerve supply: Axillary nerve. Insertion: To the lateral surface of the shaft of the radius.
• Teres major Action: Pronation of the forearm.
Origin: From the lower angle of the scapula. Nerve supply: Median nerve.
Insertion: To the medial lip of the intertubercular sulcus. • Flexor carpi radialis
Actions: Adduction and medial rotation of the arm. Origin: From the common flexor origin.
Nerve supply: Lower subscapular nerve. Insertion: To the base of metacarpals 2 and 3.
• The rotator cuff Actions: Flexion and abduction of wrist.
Consists of subscapularis, supraspinatus, infraspinatus and teres Nerve supply: Median nerve.
minor. Acting together, these muscles maintain the stability of the • Palmaris longus
shoulder joint as well as having their own individual actions, as Origin: From the common flexor origin.
follows: Insertion: To the flexor retinaculum and the palmar aponeurosis.
• Subscapularis Action: Flexor of the wrist. (Often absent.)
Origin: From the subscapular fossa. Nerve supply: Median nerve.
Insertion: Passes in front of the shoulder joint to the lesser tuberos- • Flexor carpi ulnaris
ity of the humerus. Origin: From the common flexor origin and the posterior border of the
Action: Medial rotation of the arm. ulna.
Nerve supply: Subscapular nerves. Insertion: To the pisiform and thence by the pisometacarpal ligament
• Supraspinatus to the 5th metacarpal.
Origin: From the supraspinous fossa. Actions: Flexion and adduction of the wrist.
Insertion: To the top of the greater tuberosity of the humerus. Nerve supply: Ulnar nerve.
Action: Initiates abduction of the arm. • Flexor digitorum superficialis
Nerve supply: Suprascapular nerve. Origin: From the common flexor origin and the shaft of the radius.
• Infraspinatus Insertion: To the sides of the middle phalanges of the four fingers. The
Origin: From the infraspinous fossa. tendons are perforated by the tendons of flexor digitorum profundus.
Insertion: To the back of the greater tuberosity. Actions: Flexion of the proximal two phalanges and of the wrist.
Action: Lateral rotation of the arm. Nerve supply: Median nerve.
Nerve supply: Suprascapular nerve. • Flexor pollicis longus
• Teres minor Origin: From the front of the shaft of the radius.
Origin: From the lateral border of the scapula. Insertion: To the distal phalanx of the thumb.
Insertion: To the humerus below infraspinatus. Actions: Flexion of all the joints of the thumb.
Action: Lateral rotation of the arm. Nerve supply: Median nerve.
Nerve supply: Axillary nerve. • Flexor digitorum profundus
• Coracobrachialis Origin: From the front of the shaft of the ulna and its posterior border.
Origin: From the coracoid process along with the short head of biceps. Insertion: To the distal phalanges of the four fingers, the tendons pass-
Insertion: To the medial side of the humerus. ing through those of flexor digitorum superficialis.
Action: Moves the arm upwards and medially. Actions: Flexion of the fingers and the wrist.
Nerve supply: Musculocutaneous nerve. Nerve supply: Half by the median nerve and half by the ulnar nerve.
• Biceps brachii • Pronator quadratus
Origin: Long head from the supraglenoid tubercle and short head from Origin: From the lower end of the front of the radius.
the coracoid process (with coracobrachialis). Insertion: To the lower end of the ulna.
Insertion: To the radial tuberosity and, via the bicipital aponeurosis, Action: Pronator of the forearm.
into the deep fascia of the forearm. Nerve supply: Median nerve.
Actions: Flexion and supination of the forearm. • Brachioradialis
Nerve supply: Musculocutaneous nerve. Origin: From the lateral supracondylar ridge of the humerus.
• Brachialis Insertion: To the lower end of the radius.
Origin: From the front of the lower part of the humerus. Action: Flexion of the elbow.
Insertion: To the tubercle on the ulna just below the coronoid process. Nerve supply: Radial nerve.
Action: Flexion of the elbow. • Extensor carpi radialis longus and brevis
Nerve supply: Musculocutaneous nerve and radial nerve. Origin: From the lateral supracondylar ridge of the humerus.
Muscle index 163