EXSS 275L Upper Extremity Muscular Anatomy

1. 
   

subclavius

2. 
   

Deltoid

• origin: anterior (lateral 1/3 of clavicle), medial (acromion), posterior (spine of scapula)

• insertion: deltoid tuberosity of humerus

• innervation: axillary nerve (C5-C6)

• action: anterior (flexion & internal rotation), medial (abduction), posterior (extension & external rotation)

3.

Pectoralis major

• origin: anterior surface of medial clavicle, anterior surface of sternum, costal cartilages of ribs 1-6

• insertion: crest of greater tubercle of humerus (bicipital groove), lateral lip of inter tubercular groove of humerus

• innervation: clavicular head (lateral pectoral nerve (C5-C7)), sternal head (medial pectoral nerve (C8-T1))

• action: adduction, internal rotation, and flexion

4. 
   

Pectoralis minor

• origin: anterior surface of sternum, costal cartilages of ribs 3-5

• insertion: coracoid process of scapula

• innervation: medial pectoral nerve (C8-T1)

• action: draws scapula anteroinferiorly, stabilizes scapula on thoracic wall

5.

Coracobrachialis

• origin: coracoid process of scapula

• insertion: anteromedial surface of the humeral shaft

• innervation: musculocutaneous nerve (C5-C7)

• action: shoulder adduction, flexion

6. 
   

Biceps brachii

• origin: long head (supraglenoid tubercle of scapula), short head (apex of coracoid process of scapula)

• insertion: radial tuberosity of radius, deep fascia of forearm (bicipital aponeurosis)

• innervation: musculocutaneous nerve (C5-C7)

• action: elbow flexion & supination, shoulder flexion (weakly)

7. 
   

Brachialis

• origin: distal half of anterior surface of humerus

• insertion: coronoid process of ulna, tuberosity of ulna

• innervation: musculocutaneous nerve (C5-C7)

• action: elbow flexion

8. 
   

Serratus anterior

Superior:

• origin: ribs 1-2, intercostal fascia

• insertion: anterior surface of superior angle of scapula

Medial:

• origin: ribs 3-6

• insertion: anterior surface of medial border of scapula

Inferior:

• origin: ribs 7-9

• insertion: anterior surface of inferior angle and medial border

innervation: long thoracic nerve (C5-7)

action: scapular protraction and upward rotation

1. 
   

Trapezius

Upper:

• origin: medial third of superior nuchal line, external occipital protuberance, spinous processes of C2-C7 via nuchal ligament

• insertion: descending part (superior fibers), lateral third of clavicle

• action: scapular elevation, extension of head & neck, lateral flexion of head & neck, rotation of head

Middle:

• origin: spinous process of vertebrae T1-T6 via nuchal ligament

• insertion: medial acromial margin, superior crest of spine of scapula

• action: scapular retraction

Lower:

• origin: spinous process if vertebrae T7-T12 via nuchal ligament

• insertion: lateral apex of medial end of scapular spine

• action: scapular depression, retraction, and upward rotation

innervation: spinal accessory nerve (CN XI)

2. 
   

Deltoid

• origin: anterior (lateral third of clavicle), middle (acromion), posterior (spine of scapula)

• insertion: deltoid tuberosity

• innervation: axillary nerve (C5-C6)

• action: abducts arm, anterior- shoulder flexion & internal rotation & horizontal adduction, posterior- shoulder extension & horizontal abduction

3.

Levator scapulae

• origin: transverse processes of vertebrae C1-C4

• insertion: superior angle of scapula, upper medial border of scapula

• innervation: dorsal scapular nerve (C4-C5)

• action: scapular elevation & downward rotation, lateral flexion & extension of neck

4.

rhomboid minor

5

rhomboid major

6.

Supraspinatus

• origin: supraspinatous fossa of scapula

• insertion: greater tubercle of humerus

• innervation: suprascapular nerve (C5-C6)

• action: shoulder abduction

7.

Infraspinatus

• origin: infraspinous fossa of scpaula

• insertion: greater tubercle of humerus

• innervation: suprascapular nerve (C5-C6)

• action: shoulder external rotation

8. 
   

Teres Minor

• origin: lateral border of scapula

• insertion: greater tubercle

• innervation: axillary nerve (C5-C6)

• action: shoulder external rotation and adduction

9. 
   

Teres Major

• origin: inferior angle and lateral border of scapula

• insertion: intertubercular groove of humerus

• innervation: lower subscapular nerve (C5-C7)

• action: shoulder extension, internal rotation, & adduction

10.

latissimus dorsi

11.

triceps brachii

• origin: long head (infraglenoid tubercle of scapula), medial head (posterior surface of humerus), lateral head (posterior surface of humerus)

• insertion: olecranon of ulna

• innervation: radial nerve (C6-C8)

• action: elbow extension (long head: shoulder extension)

Subscapularis

• origin: subscapular fossa of scapula

• insertion: lesser tubercle of humerus

• innervation: upper & lower subscapular nerves (C5-C6)

• action: shoulder internal rotation

AC Joint sprain

AC sprain

• ‘Separated’ shoulder

• Location: distal end of clavicle 

• MOI: direct blow or FOOSH 

• S/s: ‘step off’ deformity, TTP, (+) pain with horizontal adduction  

• Treatment: rest with sling, AC tape, donut pad

Subacromial Impingement Syndrome

rotator cuff tendons and bursa are compressed under acromion during repetitive motions

SLAP Tear

Superior labrum anterior and posterior

• Deep pain inside the shoulder joint

• Popping, clicking, locking, or grinding sensations during movement

• Reduced range of motion and overhead weakness

Rotator Cuff Tear

• MOI: acute: FOOSH, chronic: repetitive throw 

• S/s: pain/weakness when activating injured muscle 

• Treatment: refer (surgery?), RTC and scapular stabilizer rehab

GH Dislocation

• Covers 30% of glenoid fossa → not very stable 

• Subluxation (displacement + replacement) & dislocation 

• Most sprains are anterior 

• MOI: abd & ER (direct or indirect blow) 

• S/s: inability to move, flattened deltoid

1. 
   

Brachioradialis

• Origin: Lateral supracondylar ridge of humerus

• Insertion: Styloid process of radius

• Innervation: Radial nerve (C5–C7)

• Action: Flexes elbow, especially when forearm is in neutral position

2. 
   

Pronator Teres

• Origin: Medial epicondyle of humerus; coronoid process of ulna

• Insertion: Lateral surface of radius

• Innervation: Median nerve (C6–C7)

• Action: Pronates forearm; assists with elbow flexion

3.

Flexor carpi radialis

• Origin: Medial epicondyle of humerus

• Insertion: Base of 2nd metacarpal

• Innervation: Median nerve (C6–C7)

• Action: Flexes and abducts wrist

4. 
   

Palmaris longus

• Origin: Medial epicondyle of humerus

• Insertion: Palmar aponeurosis

• Innervation: Median nerve (C7–C8)

• Action: Flexes wrist; tenses palmar aponeurosis

5.

Flexor carpi ulnaris

• Origin: Medial epicondyle of humerus; olecranon and posterior border of ulna

• Insertion: Pisiform, then via ligaments to hamate and base of 5th metacarpal

• Innervation: Ulnar nerve (C8–T1)

• Action: Flexes and adducts wrist

6.

Flexor digitorum superficialis

• Origin: Medial epicondyle of humerus, coronoid process of ulna, and proximal/anterior radius

• Insertion: Sides of middle phalanges of digits 2–5

• Innervation: Median nerve (C8–T1)

• Action: Flexes PIP joints of digits 2–5; assists with MCP and wrist flexion

1. 
   

Flexor digitorum profundus

• Origin: Proximal ¾ of anterior and medial ulna; interosseous membrane

• Insertion: Bases of distal phalanges of digits 2–5

• Innervation:

  • Digits 2–3: Anterior interosseous nerve (median nerve)

  • Digits 4–5: Ulnar nerve

• Action: Flexes the DIP joints of digits 2–5; assists with wrist flexion

2.

Flexor pollicis longus

• Origin: Anterior surface of radius; interosseous membrane

• Insertion: Base of distal phalanx of thumb

• Innervation: Anterior interosseous nerve (median nerve)

• Action: Flexes the IP joint of the thumb; assists with thumb flexion

3.

Pronator quadratus

• Origin: Distal ¼ of anterior surface of ulna

• Insertion: Distal ¼ of anterior surface of radius

• Innervation: Anterior interosseous nerve (median nerve)

• Action: Pronates the forearm and helps stabilize the distal radioulnar join

1. 
   

Extensor carpi radialis longus

• origin: lateral supracondylar ridge of humerus

• insertion: base of 2nd metacarpal

• innervation: radial nerve (C5-C8)

• action: hand extension & abduction

2.

Extensor carpi radialis brevis

• origin: lateral epicondyle of humerus

• insertion: base of 3rd metacarpal

• innervation: radial nerve (C5-C8)

• action: hand extension & abduction

3.

Extensor digitorum

• origin: lateral epicondyle of humerus

• insertion: digits 2-5

• innervation: posterior interosseous nerve (C7-C8)

• action: finger extension of digits 2-5

4. 
   

Extensor digiti minimi

• origin: lateral epicondyle of humerus

• insertion: digit 5

• innervation: posterior interosseous nerve (C7-C8)

• action: finger extension (digit 5)

5.

Extensor carpi ulnaris

• origin: lateral epicondyle of humerus, posterior border of ulna

• insertion: base of 5th metacarpal

• innervation: posterior interosseous nerve (C7-C8)

• action: hand extension and adduction

1.

Supinator

• origin: lateral epicondyle of humerus, RCL, annular ligament, supinator crest of ulna

• insertion: lateral, posterior, and anterior surface of proximal 3rd of radius

• innervation: posterior interosseous nerve (C7-C8)

• action: forearm supination

2. 
   

Abductor pollicis longus

• origin: posterior surface of proximal half of radius, ulna and interosseous membrane

• insertion: base of 1st metacarpal (trapezium)

• innervation: posterior interosseous nerve (C7-C8)

• action: hand extension, thumb abduction & extension

3

Extensor pollicis brevis

• origin: posterior surface of distal third of radius & interosseous membrane

• insertion: posterior aspect of base of proximal phalanx of thumb

• innervation: posterior interosseous nerve (C7-C8)

• action: thumb extension

4.

Extensor pollicis longus

• origin: posterior surface of middle third of ulna & interosseous membrane

• insertion: posterior aspect of base of distal phalanx of thumb

• innervation: posterior interosseous nerve (C7-C8)

• action: thumb extension (weak hand extension)

5.

Extensor indicis

• origin: posterior surface of distal third of ulna & interosseous membrane

• insertion: extensor expansion of index finger

• innervation: posterior interosseous nerve (C7-C8)

• action: index finger extension (weak hand extension)

Carpal Tunnel

Borders:

• radial; scaphoid and lunate

• ulnar: pisiform and hook of hamate

• top: flexor retinaculum

Contents:

• flexor digitorum profundus

• flexor digitorum superficialis

• flexor pollicis longus

• median nerve

Palmaris brevis

• origin: palmar aponeurosis and flexor retinaculum

• insertion: skin of hypothenar eminence

• innervation: superficial branch of ulnar nerve (C8–T1)

• action: wrinkles/tenses skin of palm; assists grip

1. 
   

Lumbricals

• origin: tendons of flexor digitorum profundus

• insertion: lateral sides of extensor expansions of digits 2–5

• innervation: 1st–2nd: Median nerve; 3rd–4th: Deep branch of ulnar nerve

• action: flex MCP joints and extend IP joints

2.

Interossei dorsales

• origin: adjacent sides of metacarpals

• insertion: bases of proximal phalanges and extensor expansions of digits 2–4

• innervation: deep branch of ulnar nerve (C8–T1)

• action: abduct fingers; assist MCP flexion and IP extension

3.

Interossei palmares

• origin: palmar surfaces of metacarpals 2, 4, 5

• insertion: bases of proximal phalanges/extensor expansions of digits 2, 4, 5

• innervation: deep branch of ulnar nerve (C8–T1)

• action: adduct fingers; assist MCP flexion and IP extension

4. 
   

Abductor digiti minimi

• origin: pisiform, pisohamate ligament, flexor retinaculum

• insertion: base of proximal phalanx of 5th digit

• innervation: deep branch of ulnar nerve (C8–T1)

• action: abducts little finger; assists MCP flexion

5.

Flexor digiti minimi brevis

• origin: hook of hamate and flexor retinaculum

• insertion: base of proximal phalanx of 5th digit

• innervation: deep branch of ulnar nerve (C8–T1)

• action: flexes little finger at MCP

6.

Opponens digiti minimi

• origin: hook of hamate and flexor retinaculum

• insertion: medial/ulnar border of 5th metacarpal

• innervation: deep branch of ulnar nerve (C8–T1)

• action: opposes little finger; draws 5th metacarpal forward/rotates it