extensor muscles of forearm

Question 0

extensor tendons

Answer 0

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

Question 1

functional groups of extensor muscles of forearm

Answer 1

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

Question 2

superficial layer of posterior compartment of forearm

Answer 2

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

Question 3

deep layer of posterior compartment of forearm

Answer 3

supinator

Question 4

outcropping muscles of deep layer of posterior compartment of forearm

Answer 4

abductor policis longus
extensor policis longus
extensor policis brevis
extensor indicis

Question 5

brachioradialis origin

Answer 5

proximal two thirds of lateral supraepicondylar ridge of humerus

Question 6

brachioradialis insertion

Answer 6

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

Question 7

brachioradialis innervation

Answer 7

radial nerve (c5, c6, c7)

Question 8

brachioradialis action

Answer 8

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

Question 9

extensor carpi radialis longus origin

Answer 9

lateral supra-epicondylar ridge of humerus

Question 10

extensor carpi radialis longus insertion

Answer 10

dorsal aspect of base of 2nd metacarpal

Question 11

extensor carpi radialis longus innervation

Answer 11

radial nerve

C6, C7

Question 12

extensor carpi radialis longus action

Answer 12

extends and abduct wrist joint

extensor carpi radialis brevis active during fist clenching

Question 13

extensor carpi radialis brevis origin

Answer 13

lateral epicondyle of humerus (common extensor origin)

Question 14

extensor carpi radialis brevis insertion

Answer 14

dorsal aspect of base of 3rd metacarpal

Question 15

extensor carpi radialis brevis innervation

Answer 15

deep branch of radial nerve C7, C8

Question 16

extensor carpi radialis brevis action

Answer 16

extend and abduct wrist joint

extensor carpi radialis brevis active during fist clenchin

Question 17

extensor digitorum origin

Answer 17

lateral epicondyle of humerus (common extensor origin)

Question 18

extensor digitorum insertion

Answer 18

extensor expansions of medial four fingers

Question 19

extensor digitorum innervation

Answer 19

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

Question 20

extensor digitorum action

Answer 20

extend wrist joint

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

Question 21

extensor digiti minimi origin

Answer 21

lateral epicondyle of humerus (common extensor origin)

Question 22

extensor digiti minimi insertion

Answer 22

extensor expansion of 5th finger

Question 23

extensor digiti minimi innervation

Answer 23

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

Question 24

extensor digiti minimi action

Answer 24

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

Question 25

extensor carpi ulnaris origin

Answer 25

lateral epicondyle of humerus | posterior border of ulna via a shared aponeurosis

Question 26

extensor carpi ulnaris insertion

Answer 26

dorsal aspect of base of 5th metacarpal

Question 27

extensor carpi ulnaris innervation

Answer 27

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

Question 28

extensor carpi ulnaris action

Answer 28

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

Question 29

supinator origin

Answer 29

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

Question 30

supinator insertion

Answer 30

lateral, posterior and anterior surfaces of proximal third of radius

Question 31

supinator innervation

Answer 31

deep branch of radial nerve (c7, C8)

Question 32

supinator action

Answer 32

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

Question 33

abductor policis longus origin

Answer 33

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

Question 34

abductor policis longus insertion

Answer 34

base of 1st metacarpal

Question 35

abductor policis longus innervation

Answer 35

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

Question 36

abductor policis longus action

Answer 36

extends wrist joint | abducts thumb and extends it at carpometacarpal joint

Question 37

extensor policis longus origin

Answer 37

posterior surface of middle third of ulna and interosseus membrane

Question 38

extensor policis longus insertion

Answer 38

dorsal aspect of base of distal phalanx of thumb

Question 39

extensor policis longus innervation

Answer 39

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

Question 40

extensor policis longus action

Answer 40

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

Question 41

extensor policis brevis origin

Answer 41

posterior surface of distal third of radius and interosseus membrane

Question 42

extensor policis brevis distal attachment

Answer 42

dorsal aspect of base of proximal phalanx of thumb

Question 43

extensor policis brevis innervation

Answer 43

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

Question 44

extensor policis brevis action

Answer 44

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

Question 45

extensor indicis origin

Answer 45

posterior surface of distal third of ulna and interosseus membrane

Question 46

extensor indicis insertion

Answer 46

extensor expansion of 2nd finger

Question 47

extensor indicis innervation

Answer 47

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

Question 48

extensor indicis action

Answer 48

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

Question 49

extensor retinaculum

Answer 49

holds extensor tendons in place in the wrist regions | prevents bowstringing of the tendons when the hand is extended at the wrist joint

Question 50

synovial tendon sheaths

Answer 50

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

Question 51

tendinous sheath of extensor digitorum and extensor indicis

Answer 51

common extensor synovial shearg

Question 52

three oblique intertendinous connections

Answer 52

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

Question 53

extensor expansions

Answer 53

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)

Question 54

median and lateral bands

Answer 54

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

Question 55

retinacular ligament

Answer 55

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

Question 56

snuff box

Answer 56

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