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BIOL 2P95 (35)
Lecture

Forearm and Hand

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Department
Biology
Course
BIOL 2P95
Professor
Dirk De Clercq
Semester
Fall

Description
Forearm and Hand Key Points: 1. Each joint only allows certain movements 2. Movement occurs about an axis of rotation (= reference line thru a joint about which movement occurs) 3. Position of muscles with relation to an axis of rotation allows you to know their effect 4. Prime movers = muscles that usually produce movement about an axis 5. Antagonists = muscles that oppose action of prime movers and stabilize joint I. Elbow Joint (humero-ulnar & humero-radial joints) a. Interlocking of bony surfaces => only flexion and extension b. Ligaments restrain abduction/adduction i. Medial: ulnar collateral ligament ii. Lateral: annular ligament c. Flexion is unrestrained; extension restrained by olecranon d. Flexor M: Brachialis (primary), Biceps Brachii (primary), Brachoraidalis, Pronator Teres e. Extensor M: Triceps Brachii (posterior compartment) II. Proximal/Distal Radio-Ulnar Joints a. Radius = lateral (thumb side); Ulna = medial (pinky side) b. Supination = palms face up; anatomical position = lateral rotation i. Limited by ligaments between radius, ulna, and wrist ii. Large size of biceps brachii => we are much stronger at supinating than at pronating our forearm iii. Muscles: Supinator, biceps brachii c. Pronation = palms facing down/posterior = medial rotation i. Medial rotation of humerus adds ~90 degrees to medial rotation ii. Muscles: pronator teres, pronator quadratus III. Wrist Joint (radiocarpal & intercarpal joints) a. Flexion/Extension i. Flexor Muscles 1. pass anterior to mediolateral axis 2. Muscles: Flexor carpi radialis, palmaris longus, flexor carpi ulnaris ii. Extensor Muscles 1. posterior to mediolateral axis 2. Muscles: extensor carpi radialis longus/ brevis, extensor carpi ulnaris b. Abduction/Adduction (occurs about anteroposterior axis) i. Abduction (radial deviation) 1. Flexor carpi radialis, extensor carpi radialis longus/ brevis, abductor pollicis longus ii. Adduction (ulnar deviation) 1. flexor carpi ulnaris, extensor carpi ulnaris iii. Palmaris Longus—NOT an abductor or adductor b/c it passes directly thru the axis of rotation IV. Carpometacarpal & Intermetacarpal Joints a. Generally severely restricted in movement due to ligaments b. NO muscles work on these joints except for digits 1 & 5 c. Digit 1 & 5 have opponens muscles which act to move digits in opposition
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