Pronation Muscles of Anterior Forearm Deep Layer

Muscles of Anterior Compartment of Forearm (Flexors of Forearm)

Superficial layer

Pronator teres

• Function: Pronation of radio-ulnar joint
• Origin: Coronoid process and medial epicondyle of humerus
• Insertion: Lateral surface of the radius
• Innervation: Median nerve (C6, C7)

Flexor carpi radialis

• Function: Flexion and adduction at the wrist
• Origin: Medial epicondyle of humerus
• Insertion: Base of second metacarpal
• Innervation: Median nerve (C6, C7)

Palmaris longus

• Function: Flexion at the wrist, tensing of the palmar aponeurosis
• Origin: Medial epicondyle of humerus
• Insertion: Flexor retinaculum
• Innervation: Median nerve (C7, C8)

Flexor carpi ulnaris

• Function: Flexion and adduction at the wrist
• Origin: Medial epicondyle of humerus and olecranon
• Insertion: Pisiform, hook of hamate and fifth metacarpal
• Innervation: Median nerve (C7, C8)

Intermediate Layer

Flexor digitorum superficialis 

• Function: Flexion of the proximal interphalangeal joint of the second, third, fourth, and fifth finger. Also has a weaker flexion action on the metacarpophalangeal joints of the same fingers
• Origin: Medial epicondyle, coronoid process, and anterior radius
• Insertion: Second, third, fourth, and fifth middle phalanges
• Innervation: Median nerve (C7, C8, T1)

Deep Layer

Flexor digitorum profundus

• Function: Flexion of the distal interphalangeal joint of the second, third, fourth, and fifth finger
• Origin: Medial and the anterior surface of the proximal ulna and interosseous membrane
• Insertion: Second, third, fourth, and fifth distal phalanges
• Innervation: Ulnar nerve (C8, T1) for the medial part, anterior interosseous nerve (C8,T1) for the lateral

Flexor pollicis longus

• Function: Flexion of the interphalangeal joint of the thumb
• Origin: Anterior aspect of radius as well as interosseous membrane
• Insertion: Base of distal phalanx of thumb
• Innervation: Anterior interosseous nerve (C7, C8)

Pronator quadratus

• Function: Pronator of the forearm
• Origin: Anterior aspect of distal ulna
• Insertion: Anterior aspect of the distal radius
• Innervation: Anterior interosseous nerve (C7, C8)

Brachioradialis

• Function: Weak flexor of the forearm
• Origin: Proximal supracondylar ridge on the humerus
• Insertion: Lateral surface of the distal end of radius
• Innervation: Radial nerve (C5, C6, C7)

Muscles of Posterior Compartment of Forearm

Superficial

Extensor carpi radialis longus

• Function: Extension and abduction of the wrist
• Origin: Proximal supracondylar ridge on the humerus
• Insertion: Dorsal base of the second metacarpal
• Innervation: Radial nerve (C6, C7)

Extensor carpi radialis brevis 

• Function: Extension and abduction of the wrist
• Origin: Lateral epicondyle of humerus
• Insertion: Dorsal base of the third metacarpal
• Innervation: Deep branch of the radial nerve (C7, C8)

Extensor digitorum

• Function: Extension of the proximal interphalangeal joint of the second, third, fourth, and fifth fingers. Also has a weaker extension action on the metacarpophalangeal joints of the same fingers
• Origin: Lateral epicondyle of humerus
• Insertion: Extensor expansions on the dorsal aspect of second, third, fourth, and fifth middle and distal phalanges
• Innervation: Posterior interosseous nerve (C7, C8)

Extensor digit minimi

• Function: Extension of the little finger at the metacarpophalangeal joint and interphalangeal joint
• Origin: Lateral epicondyle of humerus
• Insertion: Extensor expansion on the dorsal aspect of fifth phalanx
• Innervation: Posterior interosseous nerve (C7, C8)

Extensor carpi ulnaris

• Function: Extension and adduction of the wrist
• Origin: Lateral epicondyle of the humerus and posterior ulna
• Insertion: Fifth metacarpal base
• Innervation: Posterior interosseous nerve (C7, C8)

Deep Layer

Extensor indices

• Function: Extension of the index finger
• Origin: Dorsal surface of distal ulna and interosseous membrane
• Insertion: Extensor expansion of second finger
• Innervation: Posterior interosseous nerve (C7, C8)

Supinator 

• Function: Supination of the forearm
• Origin: Lateral epicondyle and supinator crest of ulna
• Insertion: Lateral surface of radius
• Innervation: Deep branch of radial nerve (C7, C8)

Abductor policies longus 

• Function: Abduction of the thumb by acting on the carpometacarpal joint and the metacarpophalangeal joint
• Origin: Dorsal aspects of the proximal radius, ulna, and interosseous membrane
• Insertion: Base of the first metacarpal
• Innervation: Posterior interosseous nerve (C7, C8)

Extensor pollicus longus 

• Function: Extension of the thumb by acting on the carpometacarpal joint, the metacarpophalangeal joint, and the interphalangeal joint.
• Origin: Dorsal aspects of the middle ulna and interosseous membrane
• Insertion: Distal phalanx of 1st finger
• Innervation: Posterior interosseous nerve (C7, C8)

Extensor pollicus brevis

• Function: Extension of the thumb by acting on the carpometacarpal joint and the metacarpophalangeal joint
• Origin: Dorsal aspects of middle radius and interosseous membrane
• Insertion: Distal phalanx of 1st finger
• innervation: Posterior interosseous nerve (C7, C8)

Intrinsic Muscles of Hand

Thenar muscles

Opponents policies 

• Function: Opposition of the thumb
• Origin: Flexor retinaculum  and tubercle of trapezium
• Insertion: Lateral aspect of first metacarpal
• Innervation: Recurrent branch of median nerve (C8, T1)

Abductor policies Brevis

• Function: Abduction of the thumb at the metacarpophalangeal joint
• Origin: Flexor retinaculum  and tubercle of scaphoid
• Insertion: Lateral aspect of proximal phalanx of first finger
• Innervation: Recurrent branch of median nerve (C8, T1)

Flexor pollicus brevis 

• Function: Flexion of the thumb at the metacarpophalangeal joint
• Origin: Flexor retinaculum  and tubercle of trapezium
• Insertion: Lateral aspect of proximal phalanx of first finger
• Innervation: Recurrent branch of median nerve (C8, T1)

Adductor Compartment

Adductor pollicus 

• Function: Adduction of the thumb
• Origin: Second, third metacarpal, and capitate
• Insertion: Proximal phalanx and extensor expansion of 1st finger
• Innervation: Deep branch of ulnar nerve (C8, T1)

Hypothenar Muscles

Abductor digiti minimi

• Function: Abduction of the little finger at the metacarpophalangeal joint
• Origin: Pisiform
• Insertion: Medial aspect of proximal phalanx of fifth finger
• Innervation: Deep branch of ulnar nerve (C8, T1)

Flexor digiti minimi brevis

• Function: Flexion of the little finger at the metacarpophalangeal joint
• Origin: Flexor retinaculum and hook of hamate
• Insertion: Medial aspect of proximal phalanx of fifth finger
• Innervation: Deep branch of ulnar nerve (C8, T1)

Opponens digiti minimi

• Function: Opposition of the little finger
• Origin: Flexor retinaculum and hook of hamate
• Insertion: Medial aspect of fifth metacarpal
• Innervation: Deep branch of ulnar nerve (C8, T1)

Short Muscles

Lubricants 

• Function: Flexion of the metacarpophalangeal joints with extension of the interphalangeal joints
• Origin: Arise from tendons of flexor digitorum profundus. First 2 are unipennate, and the third and fourth are bipennate
• Insertion: Extensor expansions of second, third, fourth, and fifth finger
• Innervation: Median nerve (C8, T1) for the lateral 2 lumbricals, deep branch of ulnar nerve (C8, T1) for the medial 2 lumbricals

Dorsal interossei 

• Function: Abduction of the second, third, and fourth finger away from the axial line
• Origin: Adjacent metacarpals
• Insertion: Extensor expansions and proximal phalanges of the second, third, and fourth fingers
• Innervation: Deep branch of ulnar nerve (C8, T1)

Palmar interossei

• Function: Adduction of the second, third, and fourth finger towards the axial line
• Origin: Palmar surfaces of second, fourth, and fifth metacarpals
• Insertion: Extensor expansions and proximal phalanges of the second, fourth, and fifth fingers
• Innervation: Deep branch of ulnar nerve (C8, T1)

Surgical Considerations

The deltoid is a significant factor when considering the anterior surgical approach to gain access to the shoulder joint.  Some of these technical procedures include, but are not limited to the following:

• Open Bankart repair/capsular reconstructions – indicated in the setting of recurrent anterior (or other directional) instability of the shoulder
• Shoulder arthroplasty – indicated for cases of post-traumatic deformity, advanced degenerative arthritis, and/or avascular necrosis includes hemiarthroplasty, total shoulder arthroplasty (TSA), reverse total shoulder arthroplasty (TSA)
• The long head of the biceps tendon (LHBT) – repair versus tenotomy versus tenodesis procedures  indicated in the setting of either LHBT/bicipital groove instability or advanced/end-stage LHBT tendinopathy and degeneration[rx][rx]
• Rotator cuff repair contemporary –  indications remain somewhat controversial although most of these procedures are now being performed arthroscopically popular approaches (as opposed to the deltopectoral approach) include the mini-open approach (lateral deltoid-splitting approach)

References

Show More