May25 M3-Forearm and wrist Flashcards
movements the wrist can do
- flexion
- extension
- ABDuction (radial deviation)
- ADDuction (ulnar deviation)
- supinates and pronates (when forearm (ulna and radius) do) bc articulated
why can’t rotate the wrist (relatively to the forearm)
bc articulated with the ulna and radius
how to really test for pronation-supination function and why
ask patient to flex elbow before the mvmt
-otherwise can be caused by rotation of the humerus and not real pronation, supination
2 different causes for a medial or lateral rotation of the hand and when do epicondyles of the humerus rotate
- medial and lateral rot of humerus at shoulder joint (medial and lat epicondyles of humerus rotate)
- pronation and supination of forearm at radio-ulnar joint (epicondyles of humerus don’t rotate)
function of the anterior compt of the forearm
-flexion of wrist
-flexion of fingers
-pronation-supination
(all the group surrounded with fascia)
innervation to the anterior compt of the forearm (general)
- median n (mostly)
- ulnar n (just a bit)
2 muscles of pronation in the ant compt of the forearm
-pronator teres
-pronator quadratus
(allow flipping radius over the ulna)
pronator teres origin and insertion + specific about its location
medial epicondyle of the humerus to radius
*found in cubital fossa
pronator quadratus origin and insertion
ulna to radius (near the hand)
finger flexors in the ant compt of the forearm
- flexor digitorum superficialis and profundus (fingers)
- flexor pollicis longus (thumb)
FDS muscle origin and insertion
- O: medial epicondyle of the humerus+bit of ulna and radius
- I: middle phalanges of the 4 fingers
- 4 tendons*
FDP muscle origin and insertion
- O: ulna
- I: distal phalanges of the 4 fingers
- 4 tendons* (so FDS + FDP total 8 tendons)
flexor pollicis longus origin and insertion
- O: radius
- I: distal phalanx of the thumb
muscles of wrist flexion in the ant compt of the forearm
lateral to medial starting on pronator teres most laterally:
- flexor carpi radialis
- palmaris longus
- flexor carpi ulnaris
flexor carpi radialis origin and insertion
medial epicondyle of humerus to wrist (runs on radius)
palmaris longus origin and insertion
medial epicondyle of humerus to wrist, forming palmar aponeurosis
flexor carpi ulnaris origin and insertion
medial epicondyle of humerus to wrist (runs on ulna)
what’s the palmar aponeurosis of the palmaris longus
its tendon spreads into a triangular aponeurosis on the wrist
Dupuytren’s contracture is what
- fibrosis of the palmar aponeurosis (becomes more rigid)
- patients have incomplete flexion of their fingers bc of that
golfer elbow is what + cause of that
medial epicondylitis
-inflammation there bc is common attachment for the 3 wrist flexors + pronator teres)
function of the post compt of the forearm
- extension of the fingers
- extension of the wrist
- supination of the forearm
innervation to the post compt of the forearm
all radial n.
supination muscles in the post compt of the forearm
supinator m.
supinator m. O and I
- O: lateral epicondyle of the humerus
- I: radius (bc wants to pull it back on side of ulna)
muscles for extension of the thumb and extension of the index finger
- extensor pollicis longus
- extensor pollicis brevis
- extensor indicis
diff between extensor pollicis longus vs brevis
- longus is more medial so has to travel further to reach the thumb laterally
- longus has to cross a bony process on extensor surface of the radius called Lister’s tubercle
extensor pollicis brevis O and I
- O: radius
- I: thumb (to proximal phalanx bc brevis)
extensor pollicis longus O and I
- O: ulna (makes sense bc starts more medially)
- I: thumb (to distal phalanx bc longus)
extensor indicis O and I
- O: ulna (makes sense bc is medial to extensor pollicis longus)
- I: index finger
muscles for extension of wrist and fingers (3,4,5) in post compt of forearm
most superficial on extensor surface, lateral to medial:
- extensor digitorum
- extensor digiti minimi
- extensor carpi ulnaris
extensor digitorum O, I, shape and fct
-O: lateral epicondyle of the humerus
-I: fingers 2,3,4,5
sends 4 tendons, one to each finger
extensor digiti minimi O and I
- O: lat epicondyle of the humerus
- I: pinky finger
extensor carpi ulnaris m. O and I
- O: lat epicondyle of humerus, ulna
- I: wrist
only 2 fingers with 2 extensor tendons on their dorsal (extensor) surface
- index finger (extensor indicis and extensor digitorum tendons)
- little finger (extensor digitorum and extensor digiti minimi tendons)
what surrounds tendons that forearm muscles send (extensor digitorum, indicis, digiti minimi, pollicis longus and brevis. flexor pollicis longus, flexor digitorum S and P)
synovial sheaths enclose the tendons. (bag with fluid in it that covers the tendon)
clinical relevance of synovial sheaths on tendon
can get a synovial cyst (bump on skin will appear) due to synovial sheath swelling
wrist extensors on the lateral side
extensor carpi radialis longus (more lateral, more on radius side) and extensor carpi radialis brevis (more medial)
extensor carpi radialis longus O and I
- O: humerus
- I: wrist
extensor carpi radialis brevis O and I
-O: lat epicondyle of the humerus to wrist
what’s tennis elbow and how do you get it
lateral epicondylitis
- inflammation there bc is common attachment of the wrist extensors
- origin of extensor carpi ulnaris and extensor carpi radialis longus and brevis
ant compt of forearm how many muscles and diff layers
total: 8
- 5 superficial: lat to med = 1. pronator teres, 2. flexor carpi radialis, 3. palmaris longus, 4. flexor carpi ulnaris. + 5. FDS big on top
- 2 intermediate: lat to med: 1. flexor pollicis longus, 2. FDP below FDS
- 1 deep: 1. pronator quadratus
post compt of forearm how many muscles and the diff layers
total: 11
- 6 superficial: med to lat: 1. extensor carpi ulnaris 2. extensor digiti minimi 3. extensor digitorum 4. extensor carpi radialis brevis and 5. longus 6. brachioradialis
- 5 deep: med to lat: 1. extensor indicis 2. extensor pollicis longus 3. extensor pollicis brevis 4. ABDuctor pollicis longus (next lec) 5. supinato m.
median n (C5 to T1) location in the forearm
ant compt: pierces pronator teres and runs between FDP and FDS. + sends a branch
branch that the median n sends in the ant forearm
anterior intereosseus nerve (motor branch of the median n.)
what the anterior interosseus nerve (AIN) innervates
FDP, flexor pollicis longus, pronator quadratus
how AIN injury appears clinically
- can’t do the OK sign with index and thumb
- weakness of the grip
what happens if you have a lesion of the median nerve at the level of the elbow
can't do: -pronation -flexion of the fingers -flexion of the wrist (the functions of the ant compt of the forearm)
muscles that the ulnar n. (C8-T1) innervates and that are NOT inn. by the median n.
flexor carpi ulnaris
+ half of FDP that runs on the medial side of the ulna
where ulnar n. travels in the ant compt of the forearm
crosses elbow at the cubital tunnel posterior to the medial epicondyle. in elbow, travels on side of ulna
cubital tunnel syndrome is what
compression of the ulnar n. in the cubital tunnel behind medial epicondyle of the elbow. get specific symptoms
how do you test radial n. (C5 to T1) function clinically
ask patient to extend their wrist or fingers or thumb
what’s Wartenberg’s syndrome
- radial n. injury or compression in the forearm
- forearm extensors are paralyzed
signs of Wartenberg’s syndrome clinically
- wrist drop (can’t extend it)
- can’t supinate
signs of Wartenber’s syndrome clinically if the radial n. injury is more proximal, in the arm
also see incapability of extending the forearm (bc triceps m. does that and inn. by radial n.)
cutaneous inn. that the radial n. provides
posterior arm and a band in the middle of the posterior forearm
what nerve innervates the lateral forearm skin
musculocutaneous n. (C5,C6,C7)
mnemonic for the bones of the wrist
so long the pinky (4 first proximal going towards pinky) here comes the thumb
8 bones of the wrist
- scaphoid lunate triquetrum pisiform
- hamate, capitate, trapezoid, trapezium
bone of the wrist most vulnerable to fracture and why
scaphoid bone bc is aligned with the radius (2nd step of shock transmission in the forearm, if you fall for example)
problem with scaphoid fracture
supplied by an artery, which, during a fracture, can split the bone in 2 regions: one supplied by blood and one not.
not artery that splits. just that region that didn’t receive blood directly before is now separate
what is the artery feeding the scaphoid bone
radial artery and its branches
consequence of one scaphoid region not having blood supply after a fracture
avascular necrosis (in 10-15% of scaphoid bone fractures) in proximal part of the scaphoid
brachius = arm. what’s the name for the wrist in anatomy
carpus
shape of the carpus on a palmar view
has an inwards curvature, a groove is formed by the carpal bones
what structure encloses the carpal tunnel superiorly (on palmar border) and what is it
flexor retinaculum
- ligament
- 4 corners attached to carpal bones (is rectangle shaped)
name of the hole formed by the flexor retinaculum
carpal tunnel/groove of the carpal tunnel
4 bones that have protrusions serving as attachments for the flexor retinaculum
lateral proximal: scaphoid
lateral distal: trapezium
medial proximal: pisiform
medial distal: hamate
structures passing in the carpal tunnel
- 9 tendons (4 of FDS, 4 of FDP + tendon of flexor pollicis longus)
- median nerve
what structures are NOT passing in the carpal tunnel
- ulnar a.
- ulnar n.
- flexor carpi radialis m.
where the ulnar n. passes at the level of the wrist if it’s not in the carpal tunnel
in Guyon’s canal
Guyon’s canal syndrome is what
pathology of the ulnar nerve because of Guyon’s canal problem. caused by hammering or pressing against a bike handlebar
carpal tunnel syndrome is what
- inflammation of flexor retinaculum (will have fluid accum. there, swelling)
- compression of median n. (and all the structures in the carpal tunnel)
- weakness of thumb and loss of sensation around the thumb
clinical case: a nerve is compressed and leads to a person incapable of untightening a screw counterclockwise using the right hand. the pt says they have finger weakness when doing that: ulnar, radial, median or musculocutaneous n.
median n. (pronator teres. + also goes to finger flexors)