Musculature of the Upper Extremity

Muscles Attaching the Axial Skeleton to the Shoulder Girdle
- Trapezius
- origin: ligamentum niche, spines of C7 and T1-T12
- insertion: spine of scapula, acromion process, lateral 1/3 clavicle
- action: retracts scapula; upper elevates, lower depresses scapula
- nerve: spinal accessory nerve (CN XI)
- Levator Scapulae
- origin: C1-C4 (transverse processes)
- insertion: medial border of scapula
- action: elevates scapula
- nerve: dorsal scapular nerve
- Rhomboids (Major and Minor)
- origin: C7-T1 (minor), T2-5 (major)
- insertion: medial border of scapula
- action: retract, elevate
- nerve: dorsal scapular
- Serratus Anterior
- origin: lateral surface of ribs 1-8
- insertion: medial border of scapula
- action: protracts, laterally rotates scapula
- nerve: long thoracic
- Pectoralis minor
- origin: ribs 3-5
- insertion: coracoid process
- action: protrction
- nerve: medial pectoral
Muscles Inserting on the Humerus
- Pectoralis Major
- origin: medial 2/3 clavicle, sternum
- insertion: greater tubercle
- action: flexion, adduction, internal rotation
- nerve: medial and lateral pectoral nerves
- Latissimus Dorsi
- origin: spinous processes T6-T12
- insertion: floor of bicipital groove
- action: extension, adduction, internal rotation
- nerve: thoracodorsal
- Deltoid
- origin: spine of scapula, acromion process, lateral 1/3 clavicle
- insertion: deltoid tuberosity
- action: flexion, internal rotation (anterior); abduction (middle); extension and external rotation (posterior)
- nerve: axillary
- Subscapularis
- origin: subscapular fossa
- insertion: lesser tubercle
- action: internal rotation
- nerve: upper and lower subscapular
- supraspinatus
- origin: supraspinos fossa
- insertion: greater tubercle
- action: abduction
- nerve: suprascapular
- Infraspinous
- origin: infraspinous fossa
- insertion: greater tubercle
- action: external rotation
- nerve: suprascapular
- teres minor
- origin: lateral border of scapula
- insertion: greater tubercle
- action: external rotation
- nerve: axillary
- teres major
- origin: inferior angle and posterior angle
- insertion: lesser tubercle
- action: internal rotation
- nerve: lower subscapular
Muscles of the Arm
- Anterior
- Coracobrachialis
  - origin: coracoid process
  - insertion: medial aspect of humerus
  - action: shoulder flexion, adduction
  - nerve: musculocutaneous
- biceps brachii
  - origin (long head): supraglenoid tubercle
  - origin (short head): coracoid process
  - insertion: radial tuberosity
  - action: shoulder flexion, elbow flexion, forearm supination
  - nerve: musculocutaneous
- brachialis
  - origin: lower half of humerus
  - insertion: ulnar tuberosity
  - action: elbow flexion
  - nerve: musculocutaneous
- Posterior
- Triceps Brachii
  - origin (long head): infraglenoid tubercle
  - origin (lateral head): posterior surface of humerus
  - origin (medial head): posterior surface (below radial groove)
  - insertion: olecranon
  - action: shoulder extension (long head); elbow extension
  - nerve: radial
- anconeus
  - origin: lateral epicondyle
  - insertion: olecranon process
  - action: elbow tension
  - nerve: radial
Forearm Muscles
- Anterior (flexor) group/ superficial: all originate from medial epicondyle
- pronator teres
  - action: pronation
  - nerve: median
- flexor carpi radialis
  - action: wrist flexion, abduction (radial deviation)
  - nerve: median
- palmaris longus
  - action: wrist flexion
  - nerve: median
- flexor digitorum superficialis
  - action: wrist flexion, flexion of digits 2-5 (except dip)
  - nerve: medial
- flexor carpi ulnaris
  - action: wrist flexion, adduction (ulnar deviation)
  - nerve: ulnar
- Anterior (flexor) group/ deep
- flexor pollicus longus
  - action: wrist flexion, flexion of thumb (cmc, mcp, ip)
  - nerve: median
- flexor digitorum profundus
  - action: wrist flexion, flexion of digits 2-5 (map, pip, dip)
  - nerve (radial half): median
  - nerve (ulnar half): ulnar
- pronator quadratus
  - action: pronation
  - nerve: median
- Posterior (extensor) group/ superficial: all originate at lateral epicondyle
- brachioradialis
  - action: elbow flexion
  - nerve: radial
- extensor carpi radialis longus and brevis
  - action: wrist extension and abduction (radial deviation)
  - nerve: radial
- extensor digitorum
  - action: wrist extension and extension of digits 2-5 (mcp, pip, dip)
  - nerve: radial
- extensor digiti minimi
  - action: extension of 5th digit (mcp, pip, dip)
  - nerve: radial
- extensor carpi ulnaris
  - action: wrist extension, adduction (ulnar deviation)
  - nerve: radial
- Posterior (extensor) group/ deep
- abductor pollicus longus
  - action: abducts thumb (cmc)
  - nerve: radial
- extensor pollicus brevis
  - action: extends thumb (cmc, mcp)
  - nerve: radial
- extensor pollicus longus
  - action: extends thumb (cmc, mcp, ip)
  - nerve: radial
- extensor indicis
  - action: extends 2nd digit
  - nerve: radial
- supinator
  - action: supinates forearm
  - nerve: radial
Hand Muscles
- Thenar (lateral group)
- abductor pollicus brevis
  - action: abducts thumb (cmc)
  - nerve: median
- flexor pollicus brevis
  - action: flexes thumb (mcp)
  - nerve: median
- opponens pollicus
  - action: flexion, abduction of thumb (cmc)
  - nerve: median
- adductor pollicus
  - action: adduction thumb
  - nerve: ulnar
- Hypothenar (medial) group
- abductor digiti minimi
  - action: abduction 5th digit (mcp)
  - nerve: ulnar
- flexor digiti minimi (brevis)
  - action: flexion (mcp)
  - nerve: ulnar
- opponens digiti minimi
  - action: opposition (gliding at cmc)
  - nerve: ulnar
- Lumbricales (1-4)
- action: flexion digits 2-5 at mcps’s with extension of pip/dip
- nerve: 1-2 median; 3-4 ulnar
- Interosseous muscles
- dorsal interossei (4)
  - action: abduction of digits 2-4 (mcp)
  - nerve: ulnar
- palmar interossei
  - action: adduction of digits 2,4,5
  - nerve: ulnar