UL2 - Muscles of the forearm, wrist & hand Flashcards
list the compartments & layers within each compartment of the forearm - how many muscles in each layer?
anterior compartment - (flexors) has muscles for flexing the wrist and fingers; three layers:
- superficial = 4
- intermediate = 1
- deep = 3
posterior compartment - (extensors) has muscles for extending the wrist & fingers; two layers:
- superficial = 6
- deep = 5
forearm - list the muscles of the anterior superficial layer. where do they arise from?
pronator teres
flexor carpi radialis
palmaris longus
flexor carpi ulnaris
arise from the common flexor tendon at the medial epicondyle of the humerus
forearm - list the muscle of the anterior intermediate layer. where does it arise from?
flexor digitorum superficialis
arises from the common flexor tendon at the medial epicondyle
forearm - list the muscles of the anterior deep layer
flexor digitorum profundus
flexor pollicis longus
pronator quadratus
what muscle groups arise from the common flexor tendon of the forearm?
muscles of the superficial & intermediate layers of the anterior/ flexor forearm compartment (5 muscles total)
forearm - list the muscles from the posterior superficial layer (6)
brachioradialis - separates the anterior & posterior compartments
extensor carpi radialis longus
extensor carpi radialis brevis
extensor digitorum
extensor digiti minimi
extensor carpi ulnaris
forearm - list the muscles of the posterior deep layer (5)
supinator
extensor indicis
abductor pollicis longus
extensor pollicis longus
extensor pollicis brevis
what muscles arise from the common extensor tendon of the forearm?
four muscles from the posterior superficial layer of the forearm
- extensor carpi radialis brevis
- extensor digitorum
- extensor digiti minimi
- extensor carpi ulnaris
forearm - what is the general innervation of the anterior compartment of the forearm? what muscles are the exceptions?
general innervation by the median nerve
exceptions:
- flexor carpi ulnaris (superficial layer) = innervated by ulnar nerve
- flexor digitorum profundus (deep layer) = medial half innervated by ulnar nerve, lateral half by median nerve
forearm - what is the general innervation of the posterior compartment? are there any exceptions?
radial nerve
no exceptions
what nerve innervates the flexor carpi ulnaris?
ulnar nerve
the pronator teres has two heads - where do they originate from? where do they insert?
humeral head - from common flexor tendon at the medial epicondyle
ulnar head - from the coronoid process (ulna)
fibres converge & insert on the midshaft of the humerus
muscles of the wrist flexor group in the anterior superficial forearm muscle compartment? (3)
palmaris longus
flexor carpi radialis
flexor carpi ulnaris
NOT pronator teres
the flexor carpi ulnaris has two heads - where do they originate from? where do they insert?
humeral head- common flexor tendon
ulnar head - olecranon process of ulna & proximal 2/3 of ulnar body
inserts on pisiform, hook of hamate and 5th metacarpal base
which muscle of the forearm inserts on the palmar aponeurosis of the hand? what action is it involved in?
palmaris longus - involved in wrist flexion & tenses palmar aponeurosis for grip
actions of the pronator teres?
pronation at the proximal & distal radioulnar joints
actions of the flexor carpi radialis?
wrist flexion
abduction/ radial deviation
actions of the palmaris longus?
wrist flexion
tenses palmar aponeurosis
actions of the flexor carpi ulnaris?
wrist flexion
ulnar deviation/ adduction
is the flexor carpi radialis involved in abduction or adduction?
abduction/ radial deviation
actions of flexor digitorum superficialis?
wrist flexion
flexion of PIP joints of medial 4 digits (not thumb) - helps gripping
course of flexor digitorum superficialis?
two heads - humeroulnar head form common flexor tendon & radial head from oblique line of radius
muscle passes down anterior forearm - deep to flexor retinaculum - divides into 4 tendons & each insert on the middle phalanx of the medial 4 digits
does the flexor digitorum superficialis pass superficial or deep to the flexor retinaculum? what happens following this?
deep to it - then splits into 4 tendons which insert on the middle phalanx of the medial 4 digits
actions of the flexor pollicis longus?
thumb flexion - flexion of CMC, MCP and IP joints
innervation of the flexor digitorum profundus?
medial half by ulnar nerve
lateral half by median nerve
actions of the flexor digitorum profundus?
wrist flexion
flexion of distal IP joints of medial 4 digits
actions of pronator quadratus?
pronation of forearm
which two muscles of the anterior forearm compartment pronate the forearm?
pronator teres
pronator quadratus
function of the flexor retinacuum?
holds tendons in place during wrist & finger flexion
origins of the flexor digitorum profundus & flexor pollicis longus?
FDP: proximal 1/2 of ulna
FPL: anterior radius & interosseus membrane
action of the brachioradialis?
elbow flexion in mid-pronation
the brachioradialis muscle is considered part of the posterior compartment of the forearm. why is this contradictory? why is it still considered posterior?
contradictory as it acts to flex the elbow & its muscle belly and tendon pass more anteriorly
still posterior as its origin from the lateral supracondylar ridge & nerve supply by the radial nerve is similar to other posterior forearm muscles
which two muscles of the posterior superficial layer don’t originate from the common extensor tendon? where do they originate from instead?
brachioradialis & extensor carpi radialis longus - originate from the lateral supracondylar ridge instead
action of the extensor carpi radialis longus?
wrist extension
radial deviation/abduction
action of the extensor carpi radialis brevis?
wrist extension
radial deviation/abduction
actions of the extensor carpi ulnaris?
wrist extension
ulnar deviation/adduction
actions of the extensor digitorum?
wrist extension
extension of MCP, DIP & PIP joints of medial 4 digits (NOT thumb)
actions of extensor digiti minimi?
wrist extension
extension of little finger via MCP & IP joints
actions of supinator?
forearm supination
actions of extensor indicis?
wrist extension
index finger extension (2nd digit)
action of abductor pollicis longus?
wrist extension
abduction of thumb
CMC joint extension
actions of extensor pollicis longus?
wrist extension
CMC joint extension
thumb extension of proximal phalanx at first MCP joint
actions of extensor pollicis brevis?
wrist extension
CMC & MCP joint extension
extends distal phalanx of thumb at first IP joint
significance of the extensor retinaculum?
holds tendons of posterior/extensor muscles in place - prevents them from bowing out during finger & wrist extension
the supinator muscle has two heads - what are their origins & where do they insert?
superficial head from lateral epicondyle, radial collateral and annular ligaments; deep head from supinator crest of ulna
insert on the lateral proximal 1/3 of the radius
main actions of the abductor pollicis longus, extensor pollicis longus & extensor pollicis brevis?
APL: wrist extension & thumb abduction via CMC joint extension
EPL: wrist extension & extends proximal phalanx of thumb via 1st MCP joint
EPB: wrist extension & extends distal phalanx of thumb via 1st IP joint
flexor retinaculum forms the roof of what clinically important space?
carpal tunnel
how does the radial nerve run in relation to the supinator muscle?
runs DEEP to the muscle
how are the tendons of the flexor digitorum superficialis & flexor digitorum profundus related to each other?
tendons of FDS split into lateral & medial slips near the proximal phalanges - allows the tendons of FDP to pass through
FDS tendons attach to the middle phalanges & FDP tendons insert on distal phalanges
what muscle forms the extensor expansion? why?
extensor digitorum - gives off fibrous connections that split to form slips & allow the muscle to extend the digits by attaching onto the middle and distal phalanges of digits
what does the interconnecting nature of the extensor digitorum mean in terms of digit movement?
less individual dexterity of extensor muscle for fingers
what common overuse injury involves inflammation of the common extensor tendon? how does it happen?
lateral epicondylitis/ tennis elbow - happens when tendons attached to the lateral epicondyle become inflamed from forearm overuse
what muscle is most affected during tennis elbow?
extensor carpi radialis
what are the 5 intrinsic hand muscle groups?
thenar
hypothenar
central/lumbricals
adductor
interosseus
difference between the extrinsic & intrinsic hand muscles
extrinsic hand muscles originate form the forearm - e.g. extensor pollicis longus & brevis, flexor pollicis longus
intrinsic hand muscles originate, insert and act entirely on the hand - 5 groups
name the muscles of the thenar group (3) - what do they each do?
abductor pollicis brevis = thumb abduction
flexor pollicis brevis = thumb flexion
opponens pollicis = opposition of the thumb
innervation to thenar group muscles?
recurrent branch of median nerve
what clinical condition occurs due to compression of the median nerve as it passes through the carpal tunnel? effect of this condition?
severe carpal tunnel syndrome
leads to muscle wasting of the thenar eminence & difficulty with thumb movements
what are the muscles of the hypothenar group? what do they each do?
abductor digiti minimi = abducts little finger/ 5th digit
flexor digiti minimi = flexes little finger
opponens digiti minimi = opposition of little finger
what nerve innervates the hypothenar group of muscles?
(deep branch of) ulnar nerve
name the single muscle in the adductor hand group - what does it do?
adductor pollicis - adducts thumb/ pulls thumb towards palm
what nerve innervates the adductor pollicis?
deep branch of the ulnar nerve
origin & insertion of the lumbrical muscles?
origin - tendon of flexor digitorum profundus
insertion - extensor expansion on the dorsal aspect of the medial 4 digits
actions of the lumbrical muscles?
MCP joint flexion
IP joint extension
what nerves innervate the lumbrical muscles?
index & middle finger lumbricals (1st and 2nd) - median nerve
3rd and 4th lumbricals - deep branch of the ulnar nerve
what do the interossei muscles help the lumbricals do?
flex MCP joints
extend IP joints
what are the two types of interossei muscles? what types of muscles are they?
palmar - unipennate (3 muscles)
dorsal - bipennate (4 muscles)
origin and insertion of interossei muscles?
origin - spaces in between metacarpals
insertion - extensor expansion & base of proximal phalanx
what nerve innervates the interosseus group of hand muscles?
deep branch of the ulnar nerve
what groups/ specific hand muscles aren’t innervated by the deep branch of the ulnar nerve? what are they innervated by instead?
thenar eminence muscles - recurrent branch of the median nerve
1st and 2nd lumbricals - median nerve
which clinical condition is associated with muscle wasting of the thenar eminence?
severe carpal tunnel syndrome
