November 8 - November 8, 2006 FOREARM AND HAND I....

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November 8, 2006 FOREARM AND HAND I. Introduction – Functions of Forearm and Hand Major functions are grasping and manipulation, which involve: A. Positioning of hand - shoulder mobility, forearm pronation/supination, wrist mobility B. Finger mobility (especially thumb) – opposable thumb (precision grip) II. Bones A. Humerus – need to re-mention 3 features… 1. capitulum 2. medial epicondyle (origin of many of forearm flexors) 3. lateral epicondyle (origin of many of forearm extensors) B. Ulna – distal features 1. head 2. styloid process C. Radius – distal features 1. tuberosity (for biceps brachii) 2. styloid process D. Carpus (‘wrist’) 1. 8 small irregular bones 2. arranged in two rows 3. articulate with each other, radius and metacarpals E. Digits 1. 5 digital rays 2. all have 4 bones except thumb (1 st digit) with 3 3. metacarpals (in palm) 4. phalanges (fingers) – 3 in each digit except thumb with 2 III. Joints A. Proximal and Distal Radioulnar Joints 1. pivot (rotational) type joints 2. allow pronation/supination movements 3. about an axis running proximo-distally through forearm (ulna is stable, radius rotates around it, carrying hand with it) 4. ligaments a. anular (proximal) – holds head of radius against ulna b. interosseous membrane (between shafts) c. articular disc – runs between distal radius and ulna, separating distal ulna from wrist joint cavity & allowing more mobility at wrist B. Wrist Joints 1. Radiocarpal (remember, ulna is separated from carpus by articular disc ): ‘condyloid’ type joint a. flexion/extension – about a ML axis through carpus b. abduction/adduction – about an AP axis through carpus c. circumduction – also occurs at the radiocarpal joint. 2. Intercarpal : ‘plane’ type joints - slight gliding and sliding movements, hand positioning 3. ligaments - many ligaments hold bones tightly together (don’t worry about their names!) C. Finger Joints 1. Carpometacarpal (i.e., at base of metacarpals): plane type in digits 2-5 – slight gliding and sliding movements a. variable degree of movement – digits 2 & 5, more than 3 & 4
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This note was uploaded on 04/22/2008 for the course BIOLOGY 020.152 taught by Professor Pearlman during the Spring '08 term at Johns Hopkins.

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November 8 - November 8, 2006 FOREARM AND HAND I....

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