The Posterior Forearm Flashcards
Superficial layer of muscles on the posterior forearm
Brachioradialis Extensor carpi radialis longus Extensor carpi radialis brevis Extensor digitorum Extensor digiti minimi Extensor carpi ulnaris Aconeus
Brachioradialis
Origin: lateral supracondylar ridge of the humerus
Insertion: distal end of the radius near the styloid process
Action: flexes the forearm and partially supinates
Innervation: radial nerve
Extensor carpi radialis longus
Origin: lateral supercondylar ridge
Insertion: base of the second metacarpal
Action: extend and abduct the hand, and weakly flex the forearm
Innervation: radial nerve
Extensor carpi radialis brevis
Origin: lateral epicondyle of the humerus
Insertion: Base of the third metacarpal
Action: Extends and weakly abduct the hand
Innervation: radial nerve
Extensor digitorum
Origin: lateral epicondyle
Insertion: Tendons for digits II, III, IV, and V
Tendons insert on base of the proximal phalanx
Split into a median band and two lateral bands
Extends into the extensor expansion
Action: Extends the MCP, PIP, and DIP joints
Assists in extending the hand and the forearm
Innervation: radial nerve
Extensor digitorum minimi
Origin: lateral epicondyle
Insertion: Joins ED tendon of little finger
Action: extends MIP, PIP, and DIP joints of finger V
Innervation: radial nerve
Extensor Carpi Ulnaris
Origin: lateral epicondyle and posterior border of the ulna
Insertion: base of the fifth metacarpal
Action: extend and adduct the wrist
Assist in extending the forearm
Innervation: radial nerve
Aconeus
Origin: posterior side of the lateral epicondyle
Insertion: lateral side of the proximal ulna
Action: assist the tricep in extending the forearm and stabilizing the elbow joint
Abducts the ulna in the process
Innervation: radial nerve
What are the deep muscles of the posterior arm?
Supinator
Outcropping muscles Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus Extensor indicis
Supinator
Origin: lateral epicondyle, radial collateral ligament, and lateral side of the proximal ulna
Insertion: spirals around proximal part of the radius and inserts on posterior, lateral, and anterior sides
Action: supinate the forearm by swiveling the radius
innervation: radial nerve
Abductor pollicis longus
Origin: posterior side of the interosseous membrane
Insertion: base of the first metacarpal (laterally)
Action: abduct and extend the first CM joint and abduct the hand
Innervation: radial nerve
Extensor pollicis brevis
Origin: posterior side of the interosseous membrane
Insertion: base of the proximal phalanx of the thumb
Action: extends the CM and MCP joint and abducts the hand
Extensor pollicis longus
Origin: posterior aspect of the interosseous membrane
Insertion: base of the distal phalanx of the thumb
Action: extends all of the joints (CM, MCP, and IP) and extends the hand
Extensor indicis
Origin: posterior aspect of the interosseous membrane
Insertion: joins the ED tendon to the the index finger
Action: extends the MCP, DIP, and PIP joint of digit II while also assisting in extending the hand
What is the anatomical snuff box?
Depression between the tendons of the extensor pollicis brevis and the extensor pollicis longus
A fractured scaphoid is tender here
Radial artery passes through: may be difficult to feel pulse due to thick fascia
