Brachialis deep to biceps brachii and is most powerful flexor of forearm at the

Brachialis deep to biceps brachii and is most

This preview shows page 15 - 17 out of 22 pages.

e. Brachialis -deep to biceps brachii and is most powerful flexor of forearm at the elbow joint -‘workhorse’ of the elbow flexors -origin= distal, anterior surface of humerus -insertion= ulnar tuberosity and coronoid process of ulna -action= flexes forearm at elbow joint -innervation= musculocutaneous and radial nerves f. Brachioradialis -lower down than biceps and brachialis- mostly along radius -action= flexes forearm at the elbow joint, especially when a quick movement is required or when a weight is lifted slowly during flexion of the forearm; supinates and pronates forearm at radioulnar joints to neutral position Posterior (Extensor) Compartment: Forearm Extensors a. Triceps brachii -large muscle on posterior surface of arm -more powerful of extensors at elbow joint -three heads of origin: long head from scapula, lateral and medial heads from humerus -long head crosses the shoulder joint -origin= long head originates from infraglenoid tubercle (projection inferior to glenoid cavity of scapula); lateral head originates from lateral and posterior surface of humerus; medial head originates from entire posterior surface of humerus inferior to a groove for the radial nerve -insertion= olecranon of ulna -action= extends forearm at elbow joint and extends arm at shoulder joint -innervation= radial nerve g. Anconeus (not part of Posterior compartment) -small muscle located on lateral part of posterior aspect of elbow -assists triceps brachii in extending the forearm at the elbow joint Forearm Pronators -these muscles pronate forearm at radioulnar joints -innervated by median nerve a. Pronator teres h. Pronator quadratus -distal portion of shaft of ulna -shaped like a square Forearm Supinator a. Supinator -supinates forearm at radioulnar joints -innervated by deep radial nerve Muscles of the Forearm that Move the Wrist, Hand, Thumb, and Digits -extrinsic muscles of the hand act on the digits and originate outside the hand and insert within it -tendons of the forearm muscles that attach to the wrist or into the hand, along with BVs and nerves are held close to bones by strong fasciae -tendons surrounded by tendon sheaths
Image of page 15
-wrist has deep fascia thickened into fibrous retinacula - flexor retinaculum is located over palmar surface of carpal bones; the long flexor tendons of the digits and wrist and the median nerve pass deep to the flexor retinaculum - extensor retinaculum is located over dorsal surface of carpal bones; extensor tendons of wrist and digits pass deep to it Anterior (Flexor) Compartment: -originate on the humerus -typically insert on the carpals, metacarpals, and phalanges -function primarily as flexors -bellies of these muscles are the bulk of the forearm 1. Superficial Anterior (Flexor) Compartment of the Forearm -flex and abduct hand at wrist joint; flex middle phalanx -listed muscles are arranged lateral to medial a. Flexor carpi radialis i. Palmaris longus -missing in 10% of individuals (usually in left forearm) -commonly used for tendon repair j. Flexor carpi ulnaris -ulnar nerve and artery are just lateral to the tendon of this muscle at the wrist k. Flexor digitorum superficialis
Image of page 16
Image of page 17

You've reached the end of your free preview.

Want to read all 22 pages?

  • Fall '18
  • Cesar M
  • Brachial plexus, Muscles of the upper limb

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

Stuck? We have tutors online 24/7 who can help you get unstuck.
A+ icon
Ask Expert Tutors You can ask You can ask You can ask (will expire )
Answers in as fast as 15 minutes