Week 9 Wrist and extensors (posterior compartment of the forearm) Flashcards
proximal carpal bones from lateral to medial
-
scaphoid:
boat
-shaped, largest bone in proximal row -
lunate:
moon
-shaped, smooth convex palmar surface (larger than its dorsal surface) -
triquetrum:
pyramidal
-shaped, circular articular surface on palmar surface -
pisiform:
pea
-shaped, sesamoid bone
pisiform lies on the palmar surface of the triquetrum
deep fascia of forearm
- antebrachial fasica
- extensor & flexor compartment demarcated by the:
1. subcutaneous border of ulna: proximally - posteriorly, distally - medially
2. interosseous membrane: posteriorly
3. medial edge of brachioradialis: laterally
joint classification of distal (inferior) radioulnar joint
synovial pivot joint
bones and articular surface of distal (inferior) radioulnar joint
- head of ulna
- ulnar notch
- articular disc (TFCC)
fibrous capsule of distal (inferior) radioulnar joint
weak
synovial membrane of distal (inferior) radioulnar joint
sacciform recess
The sacciform recess is a thin extension of the articular capsule of the proximal radioulnar joint, under the anular ligament of radius.
ligaments of distal (inferior) radioulnar joint
- anterior
- posterior
- interosseous membrane
movements of distal (inferior) radioulnar joint
pronation/ supination
joint classification of wrist (radiocarpal) joint
synovial condyloid joint
bone and articular surface of wrist (radiocarpal) joint
- distal end of the radius (and the articular disc)
- proximal surface of scaphoid, lunate, triquetrum
fibrous capsule of wrist (radiocarpal) joint
general attachment
synovial membrane of wrist (radiocarpal) joint
relatively lax (presents numerous folds)
ligaments of wrist (radiocarpal) joint
- palmar radiocarpal
- dorsal radiocarpal
- palmar ulnaocarpal
- radial collateral
- ulnar collateral
special structures of wrist (radiocarpal) joint
triangular articular disc
nerve supply of wrist (radiocarpal) joint
- anterior interosseous (median)
- posterior interosseous (radial)
- dorsal and deep branches (ulnar)
blood supply of wrist (radiocarpal) joint
dorsal and palmar carpal arches
movements of wrist (radiocarpal) joint
- flexion/ extension
- abduction/ adduction (radial/ ulnar deviation)
- circumduction
muscles groups of wrist (radiocarpal) joint
wrist flexors/ extensors
wrist abductors/ adductors
proximal and distal attachment of anconeus
proximal:
lateral epicondyle of humerus
distal:
- lateral surface of olecranon
- superior part of posterior surface of ulna
innervation of anconeus
radial nerve
muscle action of anconeus
- assists triceps in extending forearm
- stabilises elbow joint
- may abduct ulna during pronation
proximal and distal attachment of brachioradialis
proximal:
proximal 2/3 of lateral supra-epicondylar ridge of humerus
distal:
lateral surface of distal end of radius, proximal to styloid process
innervation of brachioradialis
radial nerve (C5, 6, 7)
main action of brachioradialis
- relatively weak flexion of forearm
- maximal when forearm is in midpronated position
proximal and distal attachment of extensor carpi radialis longus (ECRL)
proximal:
lateral supra-epicondylar ridge of humerus
distal:
dorsal aspect of base of 2nd metacarpal
innervation of ECRL
radial nerve (C6, 7)
main action of ECRL
- extend and abduct hand at the wrist joint
- ECRL active during fist clenching 握拳时活跃
proximal and distal attachment of extensor carpi radialis brevis (ECRB)
proximal:
lateral epicondyle of humerus (common extensor origin)
distal:
dorsal aspect of base of 3rd metacarpal
innervation of ECRB
deep branch of radial nerve (C7, C8)
main action of ECRB
extend and abduct hand at wrist joint
proximal and distal attachment of extensor digitorum (ED)
proximal:
lateral epicondyle of humerus (common extensor origin)
distal:
extensor expansions of medial 4 digits
innervation of extensor digitorum
deep branch of radial nerve (C7, C8)
main action of extensor digitorum
extends medial 4 digits primarily at MCP joints, secondarily at IP joints
proximal and distal attachment of extensor digiti minimi (EDM)
proximal:
lateral epicondyle of humerus (common extensor origin)
distal:
extensor expansion of 5th digit
innervation of EDM
deep branch of radial nerve (C7, C8)
main action of EDM
extends 5th digit primarily at MCP joint, secondarily at IP joint
proximal and distal attachment of extensor carpi ulnaris (ECU)
proximal:
- lateral epicondyle of humerus
- posterior border of ulnar via a shared aponeurosis
distal:
dorsal aspect of base of 5th metacarpal
innervation of ECU
deep branch of radial nerve (C7, C8)
main action of ECU
extends and adducts hand at wrist joint
opposite to ECRL, ECRB
three muscles of common extensor origin
ECRB, ED, EDM
proximal and distal attachment of supinator
proximal:
- lateral epicondyle of humerus
- radial collateral and anular ligaments
- supinator fossa
- crest of ulna
distal:
- lateral, posterior, and anterior surfaces of proximal third
of radius
innervation of supinator
deep branch of radial nerve (C7, C8)
main action of supinator
- supinates forearm
- rotates radius to turn palm anteriorly or superiorly (if elbow is flexed)
proximal and distal attachment of abductor pollicis longus (APL)
proximal:
posterior surface of proximal halves of ulna, radius and interosseous membrane
distal:
base of 1st metacarpal
innervation of APL
posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve
main action of APL
abducts thumb and extends it at CMC joint
proximal and distal attachment of extensor pollicus longus (EPL)
proximal:
posterior surface of middle third of ulna and interosseous membrane
distal:
dorsal aspect of base of distal phalanx of thumb
innervation of EPL
posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve
main action of EPL
- extends distal phalanx of thumb at IP joint
- extends MCP and CPC joint
proximal and distal attachment of extensor pollicis brevis (EPB)
proximal:
posterior surface of distal third of radius and interosseous membrane
distal:
dorsal aspect of base of proximal phalanx of thumb
innervation of EPB
posterior interosseous nerve (C7,C8), continuation of deep branch of radial nerve
main action of EPB
- extends proximal phalanx of thumb at MCP joint
- extends CMC joint
proximal and distal attachment of extensor indicis
proximal:
posterior surface of distal third of ulnar and interosseous membrane
distal:
extensor expansion of 2nd digit
innervation of extensor indicis
posterior interosseous membrane (C7, C8), continuation of deep branch of radial nerve
main action of extensor indicis
- extends 2 digit (enabling its indepedent extension)
- helps extend hand at wrist
course and disribution of the radial nerve
dermatomes of the extensor compartment of the forearm:C7
- cubital fossa: divides into superficial and deep branches
- superficial branch - continues under brachioradialis
- deep branch - pierces supinator
- when emerges from supinator = posterior interosseous nerve (supply all deep extensor muscles, except supinator)
branches of the radia nerve in the extensor compartment of the forearm:
superficial: cutaneous
deep branch: posterior interosseous
arteries of the posterior forearm
ulnar artery courses deep to pronator teres, gives off the common interosseous artery, divides in the cubital fossa
– posterior interosseous artery
superficial veins of the posterior forearm
cephalic, basilic vein
borders, roof, floor and contents of anatomical snuff box
borders:
- laterally: tendon of APL, EPB
- medially: tendon of EPL
roof:
- skin
- superficial radial nerve
- cephalic vein
floor:
- scaphoid
- trapezium
contents:
- radial artery