Snell MOINA

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Arm Muscles

• Deltoid

  • Origin: Lateral third of clavicle, acromion, spine of scapula

  • Insertion: Middle of lateral surface of humerus

  • Nerve Supply: Axillary nerve (C5, 6)

  • Action: Abducts arm; anterior fibers flex and medially rotate, posterior fibers extend and laterally rotate arm.

• Supraspinatus

  • Origin: Supraspinous fossa of scapula

  • Insertion: Greater tuberosity of humerus

  • Nerve Supply: Suprascapular nerve (C4, 5, 6)

  • Action: Abducts arm and stabilizes shoulder joint.

• Infraspinatus

  • Origin: Infraspinous fossa of scapula

  • Insertion: Greater tuberosity of humerus

  • Nerve Supply: Suprascapular nerve (C4, 5, 6)

  • Action: Laterally rotates arm and stabilizes shoulder joint.

• Teres Major

  • Origin: Lower third of lateral border of scapula

  • Insertion: Medial lip of bicipital groove of humerus

  • Nerve Supply: Lower subscapular nerve (C6, 7)

  • Action: Medially rotates and adducts arm; stabilizes shoulder joint.

• Teres Minor

  • Origin: Upper two-thirds of lateral border of scapula

  • Insertion: Greater tuberosity of humerus

  • Nerve Supply: Axillary nerve (C4, 5, 6)

  • Action: Laterally rotates arm and stabilizes shoulder joint.

• Subscapularis

  • Origin: Subscapular fossa of scapula

  • Insertion: Lesser tuberosity of humerus

  • Nerve Supply: Upper and lower subscapular nerves (C5, 6, 7)

  • Action: Medially rotates arm and stabilizes shoulder joint.

Anterior Compartment of Arm

• Biceps Brachii

  • Long Head: Supraglenoid tubercle of scapula; Insertion: Tuberosity of radius; Nerve: Musculocutaneous nerve (C5, 6); Action: Supinates forearm and flexor of elbow joint.

  • Short Head: Coracoid process of scapula; Insertion: Tuberosity of radius; Nerve: Musculocutaneous nerve (C5, 6, 7); Action: Flexes arm and weakly adducts.

• Coracobrachialis

  • Origin: Coracoid process of scapula

  • Insertion: Medial aspect of shaft of humerus

  • Nerve Supply: Musculocutaneous nerve (C5, 6, 7)

  • Action: Flexes arm; weak adductor.

• Brachialis

  • Origin: Front of lower half of humerus

  • Insertion: Coronoid process of ulna

  • Nerve Supply: Musculocutaneous nerve (C5, 6)

  • Action: Flexor of elbow joint.

Posterior Compartment of Arm

• Triceps

  • Long Head: Infraglenoid tubercle of scapula; Insertion: Olecranon process of ulna; Nerve: Radial nerve (C6, 7, 8); Action: Extensor of elbow joint.

  • Lateral Head: Upper half of posterior surface of shaft of humerus; Insertion: Olecranon process of ulna; Nerve: Radial nerve; Action: Extensor.

  • Medial Head: Lower half of posterior surface of shaft of humerus; Insertion: Olecranon process of ulna; Nerve: Radial nerve; Action: Extensor.

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Osseofascial Compartment - Forearm Muscles

• Pronator Teres

  • Humeral Head: Medial epicondyle of humerus; Insertion: Lateral aspect of shaft of radius; Nerve: Median nerve (C6, 7); Action: Pronation and flexion of forearm.

  • Ulnar Head: Medial border of coronoid process of ulna.

• Flexor Carpi Radialis

  • Origin: Medial epicondyle of humerus

  • Insertion: Bases of second and third metacarpal bones

  • Nerve Supply: Median nerve (C6, 7)

  • Action: Flexes and abducts hand at wrist joint.

• Palmaris Longus

  • Origin: Medial epicondyle of humerus

  • Insertion: Flexor retinaculum and palmar aponeurosis

  • Nerve Supply: Median nerve (C7, 8)

  • Action: Flexes hand.

• Flexor Carpi Ulnaris

  • Humeral Head: Medial epicondyle of humerus; Insertion: Pisiform bone, hook of hamate, base at fifth metacarpal bone; Nerve: Ulnar nerve (C8; T1); Action: Flexes and adducts hand at wrist joint.

  • Ulnar Head: Medial aspect of olecranon process and posterior border of ulna.

• Flexor Digitorum Superficialis

  • Humeroulnar Head: Medial epicondyle of humerus; Insertion: Middle phalanx of medial four fingers; Nerve: Median nerve (C7, 8; T1); Action: Flexes middle phalanx of fingers, assists in flexing proximal phalanx and hand.

  • Radial Head: Oblique line on anterior surface of shaft of radius.

• Flexor Pollicis Longus

  • Origin: Anterior surface of shaft of radius

  • Insertion: Distal phalanx of thumb

  • Nerve Supply: Anterior interosseous branch of median nerve (C8; T1)

  • Action: Flexes distal phalanx of thumb.

• Flexor Digitorum Profundus

  • Origin: Anterior and medial surfaces of ulna

  • Insertion: Distal phalanges of medial four fingers

  • Nerve Supply: Ulnar (medial half; C8; T1) and median (lateral half) nerves

  • Action: Flexes distal phalanges and assists in flexion of middle, proximal phalanges and wrist.

• Pronator Quadratus

  • Origin: Anterior surface of shaft of the ulna

  • Insertion: Anterior surface of shaft of radius

  • Nerve Supply: Anterior interosseous branch of median nerve (C8; T1)

  • Action: Pronates forearm.

• Brachioradialis

  • Origin: Lateral supracondylar ridge of humerus

  • Insertion: Base of styloid process of radius

  • Nerve Supply: Radial nerve (C5, 6, 7)

  • Action: Flexes forearm at elbow joint; rotates forearm to mid-prone position.

• Extensor Carpi Radialis Longus

  • Origin: Lateral supracondylar ridge of humerus

  • Insertion: Posterior surface of base of second metacarpal bone

  • Nerve Supply: Radial nerve (C6, 7)

  • Action: Extends and abducts hand at wrist joint.