Pronation Muscles of Anterior Forearm Deep Layer Pronation Muscles of Anterior Forearm Deep Layer/The muscles are largely involved with flexion and pronation. The superficial muscles have their origin on the common flexor tendon. The ulnar nerve and artery are also contained within this compartment. The flexor digitorum superficialis lies in between the other four muscles of the superficial group and the three muscles of the deep group. This is why it is also classified as an intermediate group. 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 https://www.ncbi.nlm.nih.gov/books/NBK507892/ https://www.ncbi.nlm.nih.gov/books/NBK525990/ https://www.ncbi.nlm.nih.gov/books/NBK537258/ https://www.ncbi.nlm.nih.gov/books/NBK499858/ https://www.ncbi.nlm.nih.gov/books/NBK545221/ https://www.ncbi.nlm.nih.gov/books/NBK537056/ https://www.ncbi.nlm.nih.gov/books/NBK482410/ https://teachmeanatomy.info/upper-limb/bones/clavicle/ https://www.kenhub.com/en/library/anatomy/the-clavicle Show More