UL2 - Muscles of the forearm, wrist & hand Flashcards by kanetta kirubakaran

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

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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

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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

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forearm - list the muscles of the anterior deep layer

flexor digitorum profundus
flexor pollicis longus
pronator quadratus

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what muscle groups arise from the common flexor tendon of the forearm?

muscles of the superficial & intermediate layers of the anterior/ flexor forearm compartment
- pronator teres
- flexor carpi ulnaris
- palmaris longus
- flexor carpi radialis
- flexor digitorum superficialis

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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

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forearm - list the muscles of the posterior deep layer (5)

supinator
extensor indicis
abductor pollicis longus
extensor pollicis longus
extensor pollicis brevis

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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

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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

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forearm - what is the general innervation of the posterior compartment? are there any exceptions?

radial nerve - no exceptions

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what nerve innervates the flexor carpi ulnaris?

ulnar nerve

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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

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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

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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

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actions of the pronator teres?

pronation at the proximal & distal radioulnar joints

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actions of the flexor carpi radialis?

wrist flexion
abduction/ radial deviation

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actions of the palmaris longus?

wrist flexion
tenses palmar aponeurosis

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actions of the flexor carpi ulnaris?

wrist flexion
ulnar deviation/ adduction

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is the flexor carpi radialis involved in abduction or adduction?

abduction/ radial deviation

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actions of flexor digitorum superficialis?

wrist flexion
flexion of PIP joints of medial 4 digits (not thumb) - helps gripping

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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

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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

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actions of the flexor pollicis longus?

thumb flexion - flexion of CMC, MCP and IP joints

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innervation of the flexor digitorum profundus?

medial half by ulnar nerve
lateral half by median nerve

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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 retinaculum?

holds tendons in place during wrist & finger flexion

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 - originates 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 thumb extension (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

supinator muscle - origin of two heads? - insertion? - action? - innervation?

origin: - superficial head from lateral epicondyle, radial collateral and annular ligaments - deep head from supinator crest of ulna insertion: lateral proximal 1/3 of the radius action: forearm supination innervation: radial nerve

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

course of the median nerve in the forearm: - median nerve travels over 1) _____ aspect of medial epicondyle - between the 2 heads of 2)_______ - between 3)________ and 4)________ muscles - supplies most of anterior compartment of forearm

1) anterior aspect of medial epicondyle 2) pronator teres (superficial & deep heads) 3) flexor digitorum superficialis 4) flexor digitorum profundus

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

course of the radial nerve in the forearm: - runs deep to 1)_____ muscle - supplies all superficial & deep posterior forearm muscles responsible for 2) _________

1) supinator 2) wrist & digit extension

what nerve supplies the entire forearm muscle compartment?

radial nerve

what posterior forearm muscle inserts on the base of the 5th metacarpal?

extensor carpi ulnaris

Which of the following muscles is the only one in the anterior compartment of the forearm innervated entirely by the ulnar nerve? A) Flexor digitorum profundus B) Flexor carpi ulnaris C) Palmaris longus D) Flexor digitorum superficialis

B) Flexor carpi ulnaris

The muscle that flexes the elbow but is innervated by the radial nerve is: A) Brachialis B) Biceps brachii C) Brachioradialis D) Pronator teres

C) Brachioradialis

A deep laceration to the lateral aspect of the distal forearm severs the anterior interosseous nerve. Which movement is LEAST likely to be affected? A) Pronation B) Thumb flexion C) Flexion of index DIP joint D) Wrist adduction

D) Wrist adduction

A patient is unable to flex the distal interphalangeal joints of the index and middle fingers, but the ring and little fingers are spared. The most likely nerve affected is: A) Ulnar nerve B) Median nerve C) Anterior interosseous nerve D) Radial nerve

C) Anterior interosseous nerve - arises from the median nerve; supplies lateral half of FDP (digits 2 & 3)

Which muscle passes through the carpal tunnel and inserts into the palmar aponeurosis? A) Flexor carpi radialis B) Palmaris longus C) Flexor digitorum superficialis D) Flexor pollicis longus

B) Palmaris longus

The extensor pollicis brevis originates from the __________ and inserts into the __________. A) Radius; distal phalanx of thumb B) Ulna; distal phalanx of thumb C) Radius; proximal phalanx of thumb D) Ulna; proximal phalanx of thumb

C) Radius; proximal phalanx of thumb

Which muscle lies deepest in the anterior forearm and is solely responsible for pronation near the wrist? A) Pronator teres B) Pronator quadratus C) Supinator D) Flexor digitorum profundus

B) Pronator quadratus

Which posterior forearm muscle originates from the ulna but inserts on the proximal phalanx of the thumb? A) Extensor pollicis longus B) Extensor pollicis brevis C) Abductor pollicis longus D) Extensor indicis

B) Extensor pollicis brevis

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

Which of the following passes deep to the extensor retinaculum and contributes to the anatomical snuffbox? A) Extensor pollicis brevis B) Extensor digiti minimi C) Flexor pollicis longus D) Flexor carpi radialis

A) Extensor pollicis brevis

A penetrating injury severs the nerve running between the two heads of pronator teres. Which action is most likely to be impaired? A) Thumb adduction B) Flexion of the distal phalanx of ring finger C) Pronation of the forearm D) Extension of the wrist

C) Pronation of the forearm - median nerve runs between the two heads of pronator teres; pronator quadratus innervated by anterior interosseus nerve (branch of median nerve) not B - flexion of the distal phalanx of the ring finger is mainly carried out by FDP which is dually innervated

A patient with carpal tunnel syndrome is likely to have weakness in which of the following muscles? A) Adductor pollicis B) Flexor pollicis brevis C) Flexor digiti minimi D) Palmar interossei

B) Flexor pollicis brevis

Which of the following muscles is correctly paired with its innervation? A) Opponens digiti minimi – Median nerve B) Adductor pollicis – Median nerve C) Lumbrical to ring finger – Median nerve D) Abductor digiti minimi – Ulnar nerve

D) Abductor digiti minimi – Ulnar nerve

Which hand muscle group is correctly matched with its action? A) Dorsal interossei – Adduct fingers B) Palmar interossei – Abduct fingers C) Lumbricals – Extend MCP joints D) Lumbricals – Flex MCP and extend IP joints

D) Lumbricals – Flex MCP and extend IP joints

A laceration just distal to the flexor retinaculum cuts the recurrent branch of the median nerve. Which movement is most affected? A) Thumb adduction B) Thumb extension C) Thumb opposition D) Flexion of little finger

C) Thumb opposition - affects opponens pollicis innervation by recurrent branch of median nerve A) Thumb adduction = adductor pollicis = ulnar B) Thumb extension = posterior forearm muscles = radial nerve D) Flexion of little finger = flexor digiti minimi = ulnar

Which of the following explains why a person with an ulnar nerve injury has trouble gripping a pen? A) Paralysis of thenar muscles B) Inability to extend IP joints of fingers C) Paralysis of interossei and medial lumbricals D) Damage to palmar cutaneous branch of median nerve

C) Paralysis of interossei and medial lumbricals - help with MCP flexion and IP extension – key for precision grip.

Which of the following structures passes through the carpal tunnel? A) Ulnar nerve B) Flexor carpi ulnaris tendon C) Flexor digitorum profundus tendons D) Palmar cutaneous branch of the median nerve

C) Flexor digitorum profundus tendons - along with FDS tendons, flexor pollicis longus tendon & median nerve

Which of the following is most likely preserved in carpal tunnel syndrome? A) Sensation over the lateral palm B) Opposition of the thumb C) Flexion at the PIP joints of the fingers D) Abduction of the thumb

A) Sensation over the lateral palm - palmar cutaneous branch of the median nerve supplies the lateral palm and branches before entering the tunnel – so it's not affected in CTS

Which of the following structures does NOT pass through the carpal tunnel? A) Median nerve B) Flexor digitorum superficialis tendons C) Ulnar artery D) Flexor pollicis longus tendon

C) Ulnar artery - ulnar artery, vein and nerve pass superficial to the flexor retinaculum, in Guyon’s canal

A patient has loss of thumb opposition and thenar wasting, but preserved sensation over the palm. What structure is most likely compressed? A) Ulnar nerve B) Superficial branch of the radial nerve C) Palmar cutaneous branch of median nerve D) Median nerve within carpal tunnel

D) Median nerve within carpal tunnel

Which of the following combinations accurately describes the contents of the carpal tunnel? A) Median nerve + FCR tendon + ulnar nerve B) Median nerve + 9 tendons C) Median nerve + 8 tendons + ulnar artery D) Palmar cutaneous branch + FDS + FDP tendons

B) Median nerve + 9 tendons - 4 FDS + 4 FDP + 1 FPL = 9 tendons