Muscles of Upper Extremity

Anterior Axio-Appendicular Muscles

Pectoralis Major/Minor, Subclavius, Serratus Anterior

Pectoralis Major

Origin: anterior surface of medial half of clavicle (clavicular head), anterior surface of sternum, superior six costal cartilages, aponeurosis of external oblique muscle (sternocostal head)

Insertion: lateral lip of intertuberucular groove of humerus

Innervation: lateral and medial pectoral nerves (clavicular head: C5, C6; sternocostal head: C7, C8, T1)

Action: adducts and IR shoulder joint, draws scapula anteriorly and inferiorly; clavicular head flexes shoulder joint, sternocostal head extends joint from flexed position

Pectoralis Minor

Origin: 3rd - 5th ribs near their costal cartilages

Insertion: medial border and superior surface of coracoid process of scapula

Innervation: medial pectoral nerve (C8, T1)

Action: stabilizes scapula by drawing it anteriorly and inferiorly against thoracic wall

Subclavius

Origin: junction of 1st rib and its costal cartilage

Insertion: inferior surface of middle 1/3 of clavicle

Innervation: subclavian nerve (C5, C6)

Action: anchors and depresses clavicle

Serratus Anterior

Origin: external surface of lateral parts of 1st-8th ribs

Insertion: anterior surface of medial border of scapula

Innervation: long thoracic nerve (C5, C6, C7)

Action: protracts scapula and holds it against thoracic wall; rotates scapula

Posterior Axio-appendicular muscles

Superficial: Trapezius, Latissimus Dorsi

Deep: Levator Scapulae, Rhomboid Major/Minor

Trapezius

Origin: medial 1/3 of superior nuchal line, external occiputal protuberance, nuchal ligament, spinous processes of C7-T12 vertebrae

Insertion: lateral 1/3 of clavicle, acromion and spine of scapula

Innervation: spinal accessory nerve (CN XI; motor fibers) and C3, C4 spinal nerves (pain and proprioceptive fibers)

Action: elevates scapula (descending/superior part), depresses scapula (ascending/inferior part), protract scapula (all parts); descending and ascending word together to rotate glenoid cavity superiorly

Latissimus Dorsi

Origin: spinous processes of inferior six thoracic vertebrae, thoracolumbar fascia, iliac crest, inferior 3 or 4 ribs

Insertion: floor of intertubercular groove of humerus

Innervation: thoracodorsal nerve (C6, C7, C8)

Action: extends, adducts, and IR shoulder joint; raises body toward arms during climbing

Levator Scapulae

Origin: posterior tubercles of transverse processes of C1-C4 vertebrae

Insertion: medial border of scapula superior to root of spine (superior angle)

Innervation: dorsal scapular (C5) and cervical (C3,C4) spinal nerves

Action: elevates scapula and tilts glenoid cavity inferiorly by rotating scapula

Rhomboids (Major and Minor)

Origin: nuchal ligament and spinous processes of C7-T1 vertebrae (minor) spinous proceses of T2-T5 vertebrae (major)

Insertion: triangular area at medial end of scapular spine (minor), medial border of scapula from level of spine to inferior angle (major)

Innervation: dorsal scapular nerve (C4, C5)

Action: retract scapula and rotate it to depress glenoid cavity; fix scapula to thoracic wall

Deltoid

Origin: lateral 1/3 of clavicle; acromion and spine of scapula

Insertion: deltoid tuberosity of humerus

Innervation: axillary nerve (C5, C6)

Action: flexes and IR shoulder joint (clavicular/anterior), abducts shoulder joint (acromial/middle), extends and ER shoulder joint (spinal/posterior)

Supraspinatus

Origin: supraspinous fossa of scapula

Insertion: superior facet of greater tubercle of humerus

Innervation: suprascapular nerve (C4, C5, C6)

Action: initiates and assists deltoid in abducting shoulder joint (0 to 15 degrees) and acts with other rotator cuff muscles

Infraspinatus

Origin: infraspinous fossa of scapula

Insertion: middle facet of greater tubercle of humerus

Innervation: suprascapular nerve (C5, C6)

Action: ER shoulder joint; helps hold humeral head in glenoid cavity of scapula

Teres Minor

Origin: middle part of lateral border of scapula

Insertion: inferior facet of greater tubercle of humerus

Innervation: axillary nerve (C5, C6)

Action: ER shoulder joint; helps hold humeral head in glenoid cavity of scapula

Teres Major

Origin: inferior part of lateral border of scapula and posterior surface of inferior angle of scapula

Insertion: medial lip of intertubercular groove of humerus

Innervation: lower subscapular nerve (C5, C6)

Action: adducts and IR shoulder joint

Subscapularis

Origin: subscapular fossa (most of the anterior surface of scapula)

Insertion: lesser tubercle of humerus

Innervation: upper and lower subscapular nerve (C5, C6, C7)

Action: IR and adducts shoudlers joint; helps hold humeral head in glenoid cavity

Biceps Brachii

Origin: tip of coracoid process of scapula (short head) supraglenoid tubercle of scapula (long head)

Insertion: tuberosity of radius and fascia of forearm via bicipital aponeurosis

Innervation: musculocutaneous nerve (C5, C6)

Action: supinates forearm and, when it is supinated, flexes elbow joint; flexes shoulder joint; short head resists dislocation of shoulder

Brachialis

Origin: distal half of anterior surface of humerus

Insertion: coronoid process and tuberosity of ulna

Innervation: musculocutaneous nerve (C5, C6)

Action: flexes elbow joint in all positions

Coracobrachialis

Origin: tip of coracoid process of scapula

Insertion: middle 1/3 of medial surface of humerus

Innervation: musculocutaneous nerve (C5, C6, C7)

Action: helps flex and adduct shoulder joint; resists dislocation of shoulder

Triceps Brachii

Origin: infraglenoid tubercle of scapula (long head), posterior surface of humerus, superior to radial groove (lateral head), posterior surface of humerus, inferior to radial groove (medial head)

Insertion: proximal end of olecranon of ulna and fascia of forearm

Innervation: radial nerve (C6, C7, C8)

Action: chief extensor of elbow joint; long head extends shoulder joint and resists dislocation of humerus (especially important during abduction)

Anconeus

Origin: lateral epicondyle of humerus

Insertion: lateral surface of olecranon and superior part of posterior surface of ulna

Innervation: radial nerve (C7, C8, T1)

Action: assists triceps in extending elbow joint; stabilizes elbow joint; adducts ulna during pronation

Superficial Anterior Forearm Muscle

Pronater Teres, Flexor Carpi Radialis, Palmaris Longus, Flexor Carpi Ulnaris (Pass, Fail, Pass, Fail)

Pronator Teres

Origin: coronoid process of ulna (ulnar head) medial epicondyle of humerus (humeral head)

Insertion: middle of convexity of lateral surface of radius

Innervation: median nerve (C6, C7)

Action: pronates and flexes forearm

Flexor Carpi Radialis

Origin: medial epicondyle of humerus

Insertion: base of 2nd (3rd) metacarpal

Innervation: median nerve (C6, C7)

Action: flexes and abducts hand at wrist

Palmaris Longus

Origin: medial epicondyle of humerus

Insertion: distal half of flexor retinaculum, palmar aponeurosis

Innervation: median nerve (C7, C8)

Action: flexes hand (at wrist) and tenses palmar aponeurosis

Flexor Carpi Ulnaris

Origin: medial epicondyle of humerus, olecranon and posterior border of ulna (via aponeurosis)

Insertion: pisiform, hook of hamate, 5th metacarpal

Innervation: ulnar nerve (C7, C8)

Action: flexes and adducts hand at wrist

Intermediate Anterior Forearm Muscles

Flexor Digitorum Superficialis (Fail again)

Flexor Digitorum Superficialis

Origin: medial epicondyle of humerus and coronoid process of ulna (humeroulnar head) oblique line of radius (radial head)

Insertion: shafts (bodies) of middle phalanges of medial four digits

Innervation: median nerve (C7, C8, T1)

Action: flexes wrist joint; flexes proximal interphalangeal joints of middle four digits; acting more strongly, it also flexes proximal phalanges at metacarpophalangeal joints (MCP)

Deep Anterior Forearm Muscles

Flexor Digitorum Profundus, Flexor Pollicis Longus, Pronator Quadratus (Pass 3 times)

Flexor Digitorum Profundus

Origin: proximal three quarters of medial and anterior surface of ulna and interosseous membrane

Insertion: bases of distal phalanges of 2nd-5th digits

Innervation: median nerve (C8, T1) (lateral part; digits 2-3) ulnar nerve (C8, T1) (medial part; digits 4-5)

Action: flexes wrist joint; flexes distal interphalangeal joints of digits 2-5; assists with wrist flexion

Flexor Pollicis Longus

Origin: anterior surface of radius and adjacent interosseous membrane

Insertion: base of distal phalanx of thumb

Innervation: anterior interosseous nerve, from median nerve (C8, T1)

Action: flexes wrist; flexes metacarpophalangeal (MCP) and interphalangeal (IP) joints of thumb

Pronator Quadratus

Origin: distal ¼ of anterior surface of ulna

Insertion: distal ¼ of anterior surface of radius

Innervation: anterior interosseous nerve, from median nerve (C8, T1)

Action: pronates forearm; deep fibers bind radius and ulna together

Superficial Posterior Forearm Muscles

Brachioradialis, Extensor Carpi Radialis Longus, Extensor Carpi Radialis Brevis, Extensor Digitorum, Extensor Digiti Minimi, Extensor Carpi Ulnaris

Brachioradialis

Origin: proximal 2/3 of lateral supracondylar ridge of humerus

Insertion: lateral surface of distal end of radius proximal to styloid process

Innervation: radial nerve (C5, C6, C7)

Action: relatively weak flexion of elbow joint, maximal when forearm is in midpronated position

Extensor Carpi Radialis Longus

Origin: lateral supraepicondylar ridge of humerus

Insertion: dorsal aspect of base of 2nd metacarpal

Innervation: radial nerve (C6, C7)

Action: extend and abduct wrist joint

Extensor Carpi Radialis Brevis

Origin: lateral epicondyle of humerus

Insertion: dorsal aspect of base of 3rd metacarpal

Innervation: deep branch of radial nerve (C7, C8)

Action: extend and abduct wrist joint; active during fist clenching

Extensor Digitorum

Origin: lateral epicondyle of humerus

Insertion: extensor expansions of medial four digits

Innervation: posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve

Action: extends wrist joint, extends medial four fingers primarily at metacarpophalangeal (MCP) joints, secondarily at interphalangeal (IP) joints

Extensor Digiti Minimi

Origin: lateral epicondyle of humerus

Insertion: extensor expansion of 5th digit

Innervation: posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve

Action: extends wrist joint, extends 5th finger primarily at metacarpophalangeal (MCP) joint, secondarily at interphalageal (IP) joint

Extensor Carpi Ulnaris

Origin: lateral epicondyle of humerus; posterior border of ulna via a shared aponeurosis

Insertion: dorsal aspect of base of 5th metacarpal

Innervation: posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve

Action: extends and adducts wrist joint; active during fist clenching

Deep Posterior Forearm Muscles

Supinator

Supinator

Origin: lateral epicondyle of humerus, radial collateral and annular ligaments, supinator fossa, crest of ulna

Insertion: lateral, posterior, and anterior surfaces of proximal 1/3 of radius

Innervation: deep branch of radial nerve (C7, C8)

Action: supinates forearm, rotates radius to turn palm anteriorly or superiorly (if elbow is flexed)