MMB 020 Forearm II PDF

MMB, 020 Forearm II Anatomy Division staff  Posterior compartment of the forearm ▪ Muscles in the posterior compartment extend the wrist and digits and supinate the hand. ▪ There are 12 muscles in this compartment arranged in superficial and deep groups.  Superficial...

MMB, 020 Forearm II Anatomy Division staff  Posterior compartment of the forearm ▪ Muscles in the posterior compartment extend the wrist and digits and supinate the hand. ▪ There are 12 muscles in this compartment arranged in superficial and deep groups.  Superficial group : (7 muscles) arrnged as follows: ▪ A short one is called 2 1)anconeus 3 1 ▪ And 6 long muscles arranged as follow : 4 three run along the lateral border of the forearm: 2) brachioradialis 6 5 7 3) extensor carpi radialis longus 4) extensor carpi radialis brevis. three muscles run along the posterior surface of the forearm: 5) Extensor digitorum 6) Extensor digiti minimi 7) Extensor carpi ulnaris  Anconeus (has a triangularShape) Small muscle on the back of elbow Origion: from the lateral epicondyle of the humerus insertion: into the posterolateral surface of the olecranon Action : Assists in extension of the elbow.  Brachioradialis Anterior view Origin :from lateral supraondylar ridge. Insertion :into the base of the styloid process of radius. Action : Flex the elbow in mid prone position. Posterior view Extensor carpi radialis longus Extensor carpi radialis brevis Origin :from lateral Origin :from the supracondylar common extensor origin. ridge. Insertion :into base of Insertion :into the third metacarpal second metacarpal bone. bone. Action : Action : Extends and Extends and abducts the abducts the hand at hand at the wrist joint. the wrist joint.  Extensor digitorum Extensor Digitorum Origin :from the common extensor origin. Insertion through extensor expansion. Action : Extends the MP and IP joints of the medial four fingers.  Extensor digiti minimi Extensor carpi ulnaris Origin :from the common extensor Origin :from the origin. common extensor origin Insertion :its Insertion :into fifth tendon joins the metacarpel bone. extensor Action : expansion of the little finger. Extends and adducts the hand at the wrist joint. Action : Extends all the joints of the little finger Tennis elbow, or lateral epicondylitis, is a painful condition of the elbow caused by overuse. It is an inflammation of the tendons that join the forearm muscles on the outside of the elbow. This leads to pain and tenderness on the outside of the elbow.  Deep group They are 5 muscles one is short and four long muscles. The short one is called 1)supinator and 4 long muscles arranged as follow : 3 go to the thumb (pollex): 2) abductor pollicis longus 3) extensor pollicis brevis 4) extensor pollicis longus. One go to the index finger: 5) extensor indicis.  supinator Origin :by two heads : Insertion :into lateral surface of radius. Action : Supinates the extended arm.  Abductor pollicis longus Origin :from the posterior surface of radius &ulna Insertion :into first metacarpal bone of the thumb. Action :abducts and extends the thumb at the carpometacarpal joint.  Extensor pollicis brevis Extensor pollicis longus Origin :from the Origin :from the posterior posterior surface of surface of ulna radius Insertion :into base of Insertion :into base distal phalanx of the of proximal phalanx thumb. of the thumb. Action :extends the distal Action :extends the phalanx of the thumb. proximal phalanx of the thumb.  Extensor indicis Origin :from the posterior surface of ulna Insertion :into the extensor expansion of the index. Action :extends the joints of the index finger. www.studyblue.com  Nerve supply of the extensor group Anconeus ,brachioradialis,and extensor carpi radialis longus are supplied by radial nerve ,while the remaining muscles are supplied by posterior interosseous nerve of the radial nerve.  Posterior interosseous nerve : Course : ▪ It arises from the radial nerve in the front of the lateral epicondyle of humerus as the deep terminal branch of the radial nerve. ▪ It perforates the supinator muscle to reach the posterior compartment ▪ it passes deep to the extensor retinaculum (in the 4th compartment) to the back of the carpus Distribution: https://www.semanticscholar.org Thank you