Topic 5: Bones, Joints and Muscles of the Wrist and Hand Flashcards
radiocarpal (wrist) joint
classification: synovial, biaxial, condyloid (ellipsoid)
articular surfaces: distal end of radius, distal radioulnar joint articular disc, proximal row of carpal bones (except pisiform)
movements: flexion, extension, abduction, adduction and circumduction
radial (lateral) collateral ligament
from styloid process of radius to scaphoid and trapezium
function: limits adduction of the hand
ulnar (medial) collateral ligament
from styloid process of ulna to triquetrum and pisiform
function: limits abduction of the hand
palmar radiocarpal ligament
from radius to carpal bones on anterior (palmar) side of hand
functions: limits extension of the hand, ensures the hand moves with the forearm during pronation and supination
common carpometacarpal joint
synovial, multiaxial, plane
articular surfaces: distal row of carpals, base of metacarpals
movements: small gliding movements, increasing mobility from lateral to medial
carpometaca
synovial, biaxial, saddle
articular surfaces: trapezium, base of 1st metacarpal
movements: abduction and adduction, circumduction, opposition
metacarpophalangeal joints
classification: synovial, biaxial, condyloid
articular surfaces: head of metacarpals, base of proximal phalanx
movements: flexion, extension, adduction, abduction, circumduction
interphalangeal joints
classification: synovial, uniaxial, hinge
articular surfaces: head of phalanx, base of adjacent phalanx
movements: flexion and extension
pronator teres
anterior suferficial
Origin: medial epicondyle of humerus, coronoid process of ulna
Insertion: middle of convexity on lateral shaft of radius
Actions: pronator of the forearm and flexion of the elbow joint
flexor carpi radialis
anterior, superficial
origin: medial epicondyle of humerus (common flexor origin)
actions: flexion and abduction of wrist joint
palmaris longus
anterior, superficial
origin: medial epicondyle of humerus (common flexor origin)
action: flexion of wrist joint
flexor digitorum superficialis
anterior, superficial
origin: medial epicondyle of humerus (common flexor origin)
actions: flexion of digits 2-5 and wrist joint
flexor carpi ulnaris
anterior, superficial
origin: medial epicondyle of humerus (common flexor origin)
actions: flexion and adduction of wrist joint
pronator quadratus
anterior, deep
origin: medial epicondyle of humerus (common flexor origin)
actions: pronation of forearm
flexor digitorum profundus
anterior, deep
origin: medial epicondyle of humerus (common flexor origin)
actions: flexion of digits 2-5 and wrist joint
flexor pollicis longus
anterior, deep
origin: medial epicondyle of humerus (common flexor origin)
action: flexion of thumb and wrist joint
brachioradialis
Posterior, superficial
Origin: lateral epicondyle of humerus (common extensor origin)
Actions: flexion of forearm (at elbow joint) in mid-prone position
extensor carpi radialis longus
posterior, superficial
Origin: lateral epicondyle of humerus (common extensor origin)
Action: extension and abduction of wrist joint
extensor carpi radialis brevis
posterior, superficial
Origin: lateral epicondyle of humerus (common extensor origin)
action: extension and abduction of wrist
extensor digitorum
posterior, superficial
Origin: lateral epicondyle of humerus (common extensor origin)
Action: extension of digits 2-5 and wrist joint
extensor digiti minimi
posterior, superficial
Origin: lateral epicondyle of humerus (common extensor origin)
actions: extension of digit 5 and wrist joint
extensor carpi ulnaris
posterior, superficial
Origin: lateral epicondyle of humerus (common extensor origin)
actions: extension and adduction of wrist joint
supinator
posterior, deep
Origin: lateral epicondyle of humerus (common extensor origin)
actions: supination of forearm
extensor indicies
posterior, deep
Origin: lateral epicondyle of humerus (common extensor origin)
actions: extension of digit 2 and wrist joint
extensor pollicis longus
posterior, deep
Origin: lateral epicondyle of humerus (common extensor origin)
actions: extension of thumb and wrist joint
extensor pollicis brevis
posterior, deep
Origin: lateral epicondyle of humerus (common extensor origin)
actions: extension of thumb and wrist joint
flexor pollicis brevis
Attachments:
- Superficial head: flexor retinaculum and trapezium bone
- Deep head: trapezoid and capitate bones
Innervation: median nerve
Actions: flexion of the thumb, opposition, thumb adduction
muscle of thenar eminence
abductor pollicis longus
posterior, deep
Origin: lateral epicondyle of humerus (common extensor origin)
actions: abduction of thumb and extension of wrist joint
abductor pollicis brevis
Attachments: middle third of radius and ulna, base of first metacarpal bone
Innervation: radial nerve
Actions: abduction of the thumb, extension of the thumb, radial deviation
Muscle of thenar eminence
opponens pollicis
Attachments: trapezium bone, first metacarpal bone
Innervation: median nerve
Actions: opposition of thumb, flexion of thumb
Muscle of thenar eminence
flexor digiti minimi
Attachments: hook of hamate, base of the proximal phalanx of the little finger
Innervations: ulnar nerve
Actions: flexion of little finger, opposition
Muscle of hypothenar eminence
abductor digiti minimi
Attachments: pisiform bone, base of the proximal phalanx of the little finger
Innervations: ulnar nerve
Actions: abduction of pinky, flexion and opposition
Muscle of hypothenar eminence
opponens digiti minimi
Attachments: hook of hamate, 5th metacarpal bone
Innervations: ulnar nerve
Actions: opposition, flexion
Muscle of hypothenar eminence
adductor pollicis
Attachments:
- Oblique head: Bases of the 2nd and 3rd metacarpal bones, capitate and adjacent carpal bones, base of the proximal phalanx
- Transverse head: Anterior surface of the shaft of the 3rd metacarpal bone, base of the proximal phalanx
Innervation: Ulnar nerve
Actions: adduction of thumb
lumbricals
Attachments: tendons of the flexor digitorum profundus and extensor expansions
Innervation: median or ulnar nerve
Actions: flexion of MCP and extension of IP joints
dorsal interossei
Attachments: metacarpal bones, base of the proximal phalanx
Innervation: ulnar nerve
Actions: abduction of fingers
palmar interossei
Attachments: metacarpal bones, base of proximal phalanx
Innervations: ulnar nerve
Actions: adduction of fingers
position of function of the hand
wrist: slight dorsiflexion
fingers: slight flexion of IP joints, flexion at MCP joints
thumb: opposed and slightly flexed
advantages: stable wrist position, ligaments taut, allows prehensile grip, reduces prehensile grip
normal digital sweep
- path taken by the fingers as the hand closes
- long path desirable: allows grip of large objects
- lumbricals and interossei moderate effect of long flexors and long extensors
flexor retinaculum
- scaphoid and trapezium to pisiform and hamate
- functions: prevent bowstringing, protect underlying structures
extensor retinaculum
- attachments: radius, ulna, pisiform, triquetrum, ulnar collateral ligament
- run to carpal bones and form seperate tunnels for extensor tendonds
palmar aponeurosis
- triangular shaped sheet of fascia, extends from the flexor retinaculum, to the deep transverse metacarpal ligaments
- protects underlying vessels and nerves
- anchors skin
- aids grip
dorsal digital expansion
- forms an aponeurosis over the posterior surface of each finger
- receives attachment from ED, lumbricals, interossei
- simultaneous extension of the interphalangeal joints in each finger when releasing grip
intertendinous connections
- Fibrous connections between bads of the extensor digitorum muscles just proximal to the MCP joints
- Prevents independent extension of any one finger, ensures hand opens as a unit when releasing grip
precision grip
- small objects
- lateral digits only
- thumb opposed, flexion of MCP of fingers, IPs may be flexed or extended
e.g. pinch, lateral, lumbrical
power grip
- large objects
- whole hand
- thumb abducting and adducting, flexion at all finger joints, palm cupped, wrist dorsiflexion
e.g. cylindrical, spherical, hook and lateral
