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extensor muscles of forearm Flashcards

0
Q

extensor tendons

A

held in place in the wrist region by the extensor retinaculum which prevents bowstringing of the tendons when the hand is extended at the wrist joint.
as the tendons pass over the dorsum of the wrist, they are covered with synovial tendon sheaths, which reduce friction for the extensor tendons as they traverse the osseofibrous tunnels, formed by the attachment of the extensor retinaculum to the distal radius and ulna

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1
Q

functional groups of extensor muscles of forearm

A
  1. muscles that extend and abduct or adduct the hand of the wrist joint: extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB) and extensor carpi ulnaris (ECU)
  2. muscles that extend the medial four digits: extensory digitorum, extensor indicis and extensor digiti minimi (EDM)
  3. muscles that extend or abduct the thumb: abductor policis longus, extensory policis brevis and extensory policis longus
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2
Q

superficial layer of posterior compartment of forearm

A

extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, and extensor carpi ulnaris, brachioradialis, extensor carpi radialis longus

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3
Q

deep layer of posterior compartment of forearm

A

supinator

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4
Q

outcropping muscles of deep layer of posterior compartment of forearm

A

abductor policis longus
extensor policis longus
extensor policis brevis
extensor indicis

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5
Q

brachioradialis origin

A

proximal two thirds of lateral supraepicondylar ridge of humerus

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6
Q

brachioradialis insertion

A

lateral surface of dustal end of radius, proximal to styloid process

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7
Q

brachioradialis innervation

A

radial nerve (c5, c6, c7)

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8
Q

brachioradialis action

A

relatively weak flexion of elbow joint, maximal when forearm is in midpronated position

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9
Q

extensor carpi radialis longus origin

A

lateral supra-epicondylar ridge of humerus

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10
Q

extensor carpi radialis longus insertion

A

dorsal aspect of base of 2nd metacarpal

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11
Q

extensor carpi radialis longus innervation

A

radial nerve

C6, C7

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12
Q

extensor carpi radialis longus action

A

extends and abduct wrist joint

extensor carpi radialis brevis active during fist clenching

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13
Q

extensor carpi radialis brevis origin

A

lateral epicondyle of humerus (common extensor origin)

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14
Q

extensor carpi radialis brevis insertion

A

dorsal aspect of base of 3rd metacarpal

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15
Q

extensor carpi radialis brevis innervation

A

deep branch of radial nerve C7, C8

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16
Q

extensor carpi radialis brevis action

A

extend and abduct wrist joint

extensor carpi radialis brevis active during fist clenchin

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17
Q

extensor digitorum origin

A

lateral epicondyle of humerus (common extensor origin)

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18
Q

extensor digitorum insertion

A

extensor expansions of medial four fingers

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19
Q

extensor digitorum innervation

A

posterior interosseus nerve (C7, C8), continuation of deep branch of radial nerve

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20
Q

extensor digitorum action

A

extend wrist joint

extend medial four fingers primarily at metacarpophalangeal joints, secondarily at interphalangeal joints

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21
Q

extensor digiti minimi origin

A

lateral epicondyle of humerus (common extensor origin)

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22
Q

extensor digiti minimi insertion

A

extensor expansion of 5th finger

23
Q

extensor digiti minimi innervation

A

posterior interosseus nerve (C7, C8), continuation of deep branch of radial nerve

24
Q

extensor digiti minimi action

A

extends wrist joint

extends 5th finger primarily at metacarpophalngeal joint, secondarily at interphalangeal joint

25
Q

extensor carpi ulnaris origin

A

lateral epicondyle of humerus

posterior border of ulna via a shared aponeurosis

26
Q

extensor carpi ulnaris insertion

A

dorsal aspect of base of 5th metacarpal

27
Q

extensor carpi ulnaris innervation

A

posterior interosseus nerve (c7, c8), continuation of deep branch of radial nerve

28
Q

extensor carpi ulnaris action

A

extends and adducts wrist joint (also active during fist clenching)

29
Q

supinator origin

A

lateral epicondyle of humerus, radial collateral and anular ligaments, supinator fossa, crest of ulna

30
Q

supinator insertion

A

lateral, posterior and anterior surfaces of proximal third of radius

31
Q

supinator innervation

A

deep branch of radial nerve (c7, C8)

32
Q

supinator action

A

supinates forearm; rotates radius to turn palm anteriorly or superiorly (if elbow is flexed)

33
Q

abductor policis longus origin

A

posterior surface of proximal halves of ulna, radius, and interosseus membrane

34
Q

abductor policis longus insertion

A

base of 1st metacarpal

35
Q

abductor policis longus innervation

A

posterior interosseus nerve (c7, c8), continuation of deep branch of radial nerve

36
Q

abductor policis longus action

A

extends wrist joint

abducts thumb and extends it at carpometacarpal joint

37
Q

extensor policis longus origin

A

posterior surface of middle third of ulna and interosseus membrane

38
Q

extensor policis longus insertion

A

dorsal aspect of base of distal phalanx of thumb

39
Q

extensor policis longus innervation

A

posterior interosseus nerve (c7, c8), continuation of deep branch of radial nerve

40
Q

extensor policis longus action

A

extends wrist joint

extends distal phalanx of thumb at interphalangeal joint: extends metacarpophalangeal and carpometacarpal joints

41
Q

extensor policis brevis origin

A

posterior surface of distal third of radius and interosseus membrane

42
Q

extensor policis brevis distal attachment

A

dorsal aspect of base of proximal phalanx of thumb

43
Q

extensor policis brevis innervation

A

posterior interosseus nerve (c7, c8), continuation of deep branch of radial nerve

44
Q

extensor policis brevis action

A

extends wrist joint

extends proximal phalanx of thumb at metacarpophalangeal joint; extends carpometacarpal joint

45
Q

extensor indicis origin

A

posterior surface of distal third of ulna and interosseus membrane

46
Q

extensor indicis insertion

A

extensor expansion of 2nd finger

47
Q

extensor indicis innervation

A

posterior interosseus nerve (c7, c8), continuation of deep branch of radial nerve

48
Q

extensor indicis action

A

extends wrist joint
extends 2nd finger (enabling its independent extension)
helps extend hand at wrist

49
Q

extensor retinaculum

A

holds extensor tendons in place in the wrist regions

prevents bowstringing of the tendons when the hand is extended at the wrist joint

50
Q

synovial tendon sheaths

A

covers tendons as they pass over the dorsum of the wrist
reduce friction for the extensor tendons as they traverse the osseo-fibroys tunnels formed by the attachment of the extensor retinaculum to the distal radius and ulna

51
Q

tendinous sheath of extensor digitorum and extensor indicis

A

common extensor synovial shearg

52
Q

three oblique intertendinous connections

A

restrict independent extension of the fingersadjacent tends linked proximal to the metacarpophalangeal joints by tendons

53
Q

extensor expansions

A

distal ends of metacarpals and along phalanges, four tendons of extensor digitorum flatter
each one is a triangular tendinous aponeurosis that wraps around the dorsum and sides of a head of the metacarpal and base of the proximal phalanx
hood over head of metacarpal is anchored on each side to the palmar ligament (a thickened portion of the fibrous layer of the joint capsule of the metacarpophalangeal joints)

54
Q

median and lateral bands

A

extensor digitorum tendon divides into a median band which passes t the base of the middle phalanx and two lateral bands which pass to the base of the distal phlanx

55
Q

retinacular ligament

A

delicate fibrous band that runs from proximal phalanx and fibrous digital sheath obliquely across middle phalanx and two interphalangeal joints
becomes taut during flexion of distal interphalangeal joint. taut ligament pulls proximal interphalangeal joint into flexion. on extending proximal joint, the distal joint is pulled by the retinacular ligment into nearly complete extension

56
Q

snuff box

A

laterally: tendons of the APL and EPB
medially: tendon of EPL
visible as a hollow on the lateral aspect of the wrist when the thumb is extended fully
radial artery lies on the floor
radial styloid process can be palpated proximally and the base of the 1st metacarpal can be palpated distally in the snuff box
scaphoid and trapezium can be felt in the floor of the snuff box between the radial styloid process and the 1st metacarpal

Gross (31 decks)

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