Anterior Forearm Flashcards
what demarcates the posteromedial boundary separating the flexor-pronator (anterior) and extensor-pronator (posterior) compartments?
posterior border of ulna
where can pulsations of the radial artery be palpated?
superficial to the cubital fossa
where does the anterolateral boundary lie?
cubital fossa, anterior to radial styloid
how far distal is the radial styloid process from the ulnar styloid process?
1cm
what does not participate in the wrist (radoiocarpal) joint?
ulna
what is the most common fracture of the forearm?
colles fracture (complete transverse fracture of distal 2cm of radius)
how does Colles fracture manifest?
forced dorsiflection of the hand
dinner fork deformity
what happens to the radial styloid process during a Colles fracture?
it projects proximal to the ulnar styloid process (since the radius is shortened)
flexors are what?
anterior - median nerve
extensors are what?
posterior - radial nerve
what is the antebrachial fascia that goes posteriorly?
extensor retinaculum
what is the antebrachial fascia that goes anteriorly?
palmar carpal ligament
what is the antebrachial fascia inferior to the palmar carpal ligament?
flexor retinaculum (transverse carpal ligament)
what antebrachial fascia helps make the carpal tunnel
flexor retinaculum
what passes through the carpal tunnel?
- median nerve
- flexor tendons
what is the deep fascia beyond the extensor retinaculum and flexor retinaculum?
palmar fascia
what is the thick, triangular, tendinous central part of the palmar fascia that overlies the central part of the palm?
palmar aponeurosis
what is the apex of the palmar aponeurosis?
palmaris longus
anterior compartment innervation
- median nerve
- ulnar nerve (1 and a half anterior forearm muscles)
posterior compartment innervation
deep radial nerve
superficial flexor-pronator muscles
- pronator teres
- flexor carpi radialis
- palmaris longus
- flexor carpi ulnaris
superior flexor-pronator muscle attachment
common flexor tendon to medial epicondyle
intermediate flexor-pronator muscle
- flexor digitorum superficialis
- humeral head
deep flexor-pronator muscles
- flexor digitorum profundus
- flexor pollicis longus
- pronator quadratus
what does the lateral border of the pronator teres form?
medial boundary of cubital fossa
compression of the median nerve with pain and tenderness in proximal aspect of the anterior forearm
pronator syndrome
flexor carpi radialis action
- flexion (with flexor carpi ulnaris)
- abduction of wrist (with extensor carpi radials longus/brevis)
- flexion/abduction combo when alone (anterolateral)
what is a good guide to the radial artery?
flexor carpi radialis
what does the FCR pass through?
-lateral part of flexor retinaculum
-vertical groove in trapezium
(has own synovial tendinous sheath of FCR)
which forearm muscle is sometimes absent?
palmaris longus
what is a good guide to the median nerve?
palmaris longus
flexor carpi ulnaris action
- flexes wrist with FCR
- ADducts with ECR
where does the ulnar nerve enter the forearm?
between humeral and ulnar heads
which muscle is fully innervated by the ulnar nerve?
FCU
what syndrome compresses the ulnar nerve?
cubital tunnel syndrome
flexor digitorum superficialis attachement
common flexor origin
what is the largest superficial muscle in the forearm?
FDS
FDS innervation
- median nerve
- ulnar nerve
what encloses the FDS and FDP tendons in the carpal tunnel?
synovial common flexor sheath
FDS action
- flexes middle phalanges of medial 4 fingers at PIPs
- flexes proximal phalanges at MCP joints and wrist joint
which is the only muscle that can flex the distal interphalangeal joints of the fingers?
flexor digitorum profundus
which muscle can flex DIP, PIP, MCP, and wrist joint?
flexor digitorum profundus
which tendon is flat and passes deep to the flexor retinaculum on the lateral side of the common flexor sheath?
flexor pollicis
which is the only muscle that flexes the distal phalanx of the thumb?
flexor pollicis
which muscle flexes the proximal phalanx at the MCP joint and 1st metacarpal at the carpometacarpal joint?
flexor pollicis
which is the deepest muscle in the anterior forearm?
pronator quadratus
pronator quadratura action
pronation (with pronator teres)
main forearm arteries
radial and ulnar arteries
branches of which arteries participate in the periarticular anastomosis of the elbow?
branches of the ulnar artery
what supplies the muscles of the medial and central forearm and common flexor sheath?
branches of ulnar artery
what do anterior ulnar recurrent arteries anastomose with?
inferior ulnar collateral arteries
what do posterior ulnar recurrent arteries anastomose with?
superior ulnar collateral arteries
what does the radial recurrent artery anastamose with?
radial collateral artery (branch of the deep artery of the arm)
in 3% of people, what does the ulnar artery do?
descends superficial to the flexor muscles
need to be careful drawing blood and inserting drugs
fractured medial epicondyle and other ulnar nerve injuries cause what?
- difficulty making a fist
- no extension of interphalangeal joints
- atrophy of interosseous muscles
- numbness and paresthesia middle part of palm and medial one and a half fingers
“claw hand”
what kind of innervation does radial nerve serve?
- motor and sensory in arm and forearm
- ONLY sensory in hand
2 branches of forearm radial nerve
- sensory/cutaneous = superficial branch
- motor = deep radial/posterior interossesous nerve branch
humeral shaft fracture
radial nerve
-wrist drop
