Muscles of the Arm - Flexors and Extensors

Muscles of the Arm - Flexors/Extensors

Coracobrachialis: Originates at the coracoid process, inserts on the middle third of the medial surface of the humerus, and is innervated by the musculocutaneous nerve. Its action is to flex and adduct the arm.
Biceps brachii: Has a long head originating at the supraglenoid tubercle and a short head at the coracoid process. It inserts at the radial tuberosity, is innervated by the musculocutaneous nerve, and flexes the arm and forearm, as well as supinating the forearm.
Brachialis: Originates on the lower anterior surface of the humerus, inserts at the coronoid process of the ulna and ulnar tuberosity, is innervated by the musculocutaneous nerve, and flexes the forearm.
Triceps: Comprised of three heads (long, lateral, and medial) originating at the infraglenoid tubercle, superior to the radial groove on the humerus, and inferior to the radial groove, respectively. Inserts at the olecranon process of the ulna, is innervated by the radial nerve, and extends the forearm.
Anconeus: Originates on the lateral epicondyle of the humerus, inserts on the olecranon and upper posterior surface of the ulna, is innervated by the radial nerve, and extends the forearm.

Muscles of the Forearm - Flexors/Extensors (Anterior)

Pronator teres: Originates at the medial epicondyle and coronoid process of the ulna and humerus, inserts on the middle of the lateral side of the radius, is innervated by the median nerve, and pronates and flexes the forearm.
Flexor carpi radialis: Originates at the medial epicondyle of the humerus, inserts on the bases of the second and third metacarpals, is innervated by the median nerve, and flexes the forearm and abducts the hand.
Palmaris longus: Originates at the medial epicondyle of the humerus, inserts on the flexor retinaculum, palmar aponeurosis, is innervated by the median nerve and flexes the forearm.
Flexor carpi ulnaris: Originates at the medial epicondyle (humeral head), medial olecranon, and posterior border of the ulna (ulnar head), inserts at the pisiform, hook of hamate, and base of the fifth metacarpal, is innervated by the ulnar nerve, and flexes the forearm and adducts the hand.
Flexor digitorum superficialis: Originates at the medial epicondyle, coronoid process, and oblique line of the radius, inserts at the middle phalanges of fingers, is innervated by the median nerve and flexes the proximal interphalangeal joints, flexes the hand and forearm.
Flexor digitorum profundus: Originates at the anteromedial surface of the ulna and interosseous membrane, inserts on the bases of the distal phalanges of the fingers, is innervated by the ulnar and median nerve and flexes the distal interphalangeal joints and hand.
Flexor pollicis longus: Originates at the anterior surface of the radius, interosseous membrane, and coronoid process, inserts at the base of the distal phalanx of the thumb, is innervated by the median nerve, and flexes the thumb
Pronator quadratus: Originates from the anterior surface of distal ulna, inserts on the anterior surface of distal radius, is innervated by the median nerve, and pronates the forearm.

Muscles of the Forearm - Flexors/Extensors (Posterior)

Brachioradialis: Originates at the lateral supracondylar ridge of the humerus, inserts at the base of the radial styloid process, is innervated by radial nerve, and flexes the forearm.
Extensor carpi radialis longus: Originates at the lateral supracondylar ridge of the humerus, inserts at the dorsum of the base of the second metacarpal, is innervated by the radial nerve, and extends and abducts the hand.
Extensor carpi radialis brevis: Originates at the lateral epicondyle of the humerus, inserts at the posterior base of the third metacarpal, is innervated by the radial nerve, and extends and abducts the hand.
Extensor digitorum: Originates at the lateral epicondyle of the humerus, inserts at the extensor expansions, middle and distal phalanges, is innervated by the radial nerve, and extends the fingers and hand.
Extensor digiti minimi: Originates from a common extensor tendon and interosseous membrane, inserts at the extensor expansion and bases of the middle and distal phalanges, is innervated by the radial nerve, and extends the little finger.
Extensor carpi ulnaris: Originates at the lateral epicondyle and posterior surfaces of the ulna, inserts at the base of the fifth metacarpal, is innervated by the radial nerve, and extends and adducts the hand.
Supinator: Originates at the lateral epicondyle, radial collateral and annular ligaments, supinator fossa, and crest of the ulna, inserts at the lateral surface of the upper part of the radius, is innervated by radial nerve, and supinates the forearm.
Abductor pollicis longus: Originates at the interosseous membrane, middle third of the posterior surfaces of the radius and ulna, inserts at the lateral surface of the base of the first metacarpal, is innervated by radial nerve, and abducts the thumb and hand.
Extensor pollicis longus: Originates at the interosseous membrane and middle third of the posterior surface of the ulna, inserts at the base of the distal phalanx of the thumb, is innervated by the radial nerve, and extends the distal phalanx of the thumb and abducts the hand.
Extensor pollicis brevis: Originates at the interosseous membrane and posterior surface of the middle third of the radius, inserts at the base of the proximal phalanx of the thumb, is innervated by radial nerve, and extends the proximal phalanx of the thumb and abducts the hand.
Extensor indicis: Originates at the posterior surface of the ulna and interosseous membrane, inserts at the extensor expansion of the index finger, is innervated by radial nerve, and extends the index finger.

Cubital Fossa

Boundaries: Medial: Pronator teres muscle, Lateral: Brachioradialis muscle, Superior/Base: Imaginary horizontal lines between humeral epicondyles, Roof: Fascial roof of arm and forearm, strengthened by the bicipital aponeurosis, Floor: Brachialis and Supinator muscles.
Contents: Radial nerve, biceps brachii tendon, brachial artery, and median nerve (lateral to medial).
Clinical Application: Venipuncture (median cubital vein or basilic vein), cardiac catheter insertion.