ICL 4.2: Hand Anatomy & Common Conditions Flashcards
what keeps the distal radial-ulnar joint stable?
triangular fibro-cartilage complex (TFCC)
it lets everything in the wrist rotate
it’s at the tip of the ulnar styloid so if someone says it hurts there the TFCC is probably torn
which bone moves during pronation?
radius
the ulna is stable
what are the characteristics of a normal radial-ulnar joint?
- ulna and radius are about equal length
- radial inclination from the radial styloid to the ulna is about 20 degrees down
- volar tilt of the distal surface of the radius is about 10 degrees down
- no gaps in the joint
what is a Colles’ fracture?
most common fracture
an extra-articular dorsally angulated fracture from a FOOSH that causes the distal radius to get bent backwards
if the radius gets bent backwards, you lose the volar tilt
what’s the pneumonic for the carpal bones?
some lovers try positions that they can’t handle
proximal: scaphoid, lunate, triquetrum, pisiform
distal: trapezium, trapezoid, capitate, hamate
how are your carpals connected?
there’s a distal and proximal row of carpals that are held together by strong ligaments
this means there’s no significant motion within the rows and they all move together as one unit
what causes a scaphoid fracture? how do you treat?
FOOSH
you’ll be tender in the anatomic snuff box
these are unstable and you should be worried because the scaphoid gets it blood supply distal to proximal so the more proximal the fracture, the harder it is to heal
what is carpal instability?
the distal row or proximal row of carpals aren’t moving as a unit, they’re moving on their own
a common thing is tearing the scaphoid-lunate ligament
what is SLAC wrist arthritis?
this is what happens after a scaphoid-lunate ligament tear
over the years the scaphoid is out there unaligned and you get arthritis after 20 years
to treat you take the scaphoid out to prevent scaphoid from rubbing against the radius
what kind of joint is the carpal metacarpal joint of the thumb? what is a common complication with it?
saddle joint
lets your thumb move in any direction!
however, this means that there’s a lot of wear and tear of the thumb CMC joint and usually leads to arthritis –> can take the trapezium out to treat and then a tendon to stabilize the base of the thumb
more common in women
what is a Boxer’s fracture?
5th metacarpal-carpal neck fracture (pinky knuckle break)
usually with young, drunk males that get punching injuries
you don’t do much to treat these because there’s so much motion with the pinky
however, deformity in the more radial MC joints need to be fixed
what is the shape of the metacarpal phalangeal joint?
cam shaped = wider in volar direction
what is Skier’s thumb?
aka Gamekeeper’s thumb
it’s a rupture of the ulnar collateral ligament (UCL) of the thumb in between the thumb and pointer finger
you won’t be able to grip things
often needs to be repaired
what are the different phalanges?
3 in each digit; only 2 in the thumb
proximal = P1
middle = P2
distal = P3
what is a PIP joint dislocation?
most common joint dislocation; usually dorsally
there’s a rupture of the volar plate
what causes MP arthritis vs. IP arthritis?
MP = autoimmune disease (ex. rheumatoid)
IP = osteoarthritis
what are the 4 groups of intrinsic hand muscles?
- interosseous
- lumbricals
- thenar
- hypothenar
what are the interosseous muscles?
they’re between the metacarpals
dorsal ones abduct while palmar adduct
all innervated by ulnar nerve and let you do fine motor skills like typing and playing piano
what are the lumbricals?
the only muscle in the body that originates from a tendon and inserts into a tendon –> flexor digitorum profundus to the radial side of the extensor tendon
they help your hand with power grasp
the ones on the ulnar side are called bipenate and come from 2 tendons; so the lumbricals from the ring and pinky finger come from two tendons and this makes sense because most of your grip strength comes from your pinky and ring finger
the lumbricals of the index and long finger are unipenate
what is the ROM for the thenar and hypothenar muscles?
abductor, flexor, opponens
what is the extensor digitorum communis?
it extends into the MPs of all 4 fingers
it’s 1 muscles with 4 tendon slits
it extends the MP joints but not so much the IP joints
what is the extensor indices proprius?
EIP extends the index MP which lets you point your finger
what is the extensor digit minimi?
EDM extends the pinky MP joint which is what lets you do the bull horn sign with your hand
which tendons are in the 1st extensor compartment?
- abductor policus longus
- extensor policus brevis
they pull your thumb out;abducts
which tendons are in the 2nd extensor compartment?
- extensor carpi radialis longus
- extensor carpi radialis brevis
pull your wrist up
which tendons are in the 6th extensor compartment?
extensor carpi ulnas
what is DeQuervain’s tendonitis?
1st compartment tendonitis:
1. abductor policus longus
- extensor policus brevis
what is intersection syndrome?
tendonitis of the 2nd compartment where the APL and EPB from 1st compartment cross over the ECRL and ECRB of the second compartment:
- extensor carpi radialis longus
- extensor carpi radialis brevis
how do you diagnose tendonitis?
- anywhere in the body, the tendon will have point tenderness
- if you stretch the tendon it’ll hurt
- pain with resistance
what is the Finklestein test?
stretching tendons –> the examiner grasps the thumb and ulnar deviates the hand sharply. If sharp pain occurs along the distal radius, de Quervain’s tenosynovitis is likely
specifically used for Dequervain’s tendonitis of the 1st extensor compartment
what is the extensor mechanism?
your long extensor tendon goes right over your MP joint and it extends the MP joint
it does this via the little bands that come off of the extensor tendon called sagittal bands that wrap around the base o the proximal phalanx which lift the finger up –> your extensor tendon doesn’t have any insertion at all on the proximal phalanx
the sagittal bands also keep the extensor tendon on the midline
then the extensor tendon keeps going and divides into 3 slips –> the central slip inserts on the base of the middle phalanx P2 and extends the PIP joint
the lateral two slips run along the edges then come together and insert on P3 and they extend the DIP
what is a mallet deformity?
avulsion of the extensor tendon from P3
so you lose extension at the DIP joint
ex. when you jam your finger and the tendon rips off P3 so nothing is keeping your DIP straight so your finger droops
the good news is that the tendon doesn’t retract so you can just treat it with splints
what is a Boutonniere deformity?
avulsion of the central slip of the extensor mechanism from the P2 base
so you get loss of extension at the PIP
PIP joint will flex but the extensor mechanism at the DIP joint is fine so it’ll overflex and the tip of your finger will start to curve up
what is a swan neck deformity?
hyper-extension at the PIP and flexion of the DIP
could be caused by chronic mallet finger that doesn’t get fixed and eventually causes hyper-extension of PIP
usually because of autoimmune diseases like lupus and rheumatoid arthritis
what is your flexor digitorum profundus?
starts in the forearm and then it inserts on P3 of digits 2-5 but the long, ring and small fingers usually function together while the index finger is independent
flexes DIP joint of the fingers
involved in power grip
what is your flexor digitorum superficialis?
inserts on the P2 of digits 2-5 and flexes the PIP joint
it splits into two slips over P1 area and then the flexor digitorum profundus goes through that and that’s called Camper’s chiasm
involves in fine motor skills
what are annular pulleys?
part of the flexor sheath of the fingers = flexor digitorum superficialis and profundus
annular pulleys 1,3,5 are tendons at the joints of your fingers that let your joints bend
annular pulleys 2 and 4 are functionally important to prevent bowstringing; they hold the tendons next to the bones when you extend your fingers
what is the function of the flexor sheath?
- stabilizes the tendons and allows them to slide
- gives the nutrition and makes synovial fluid
tendons = flexor digitorum superficialis and profundus
what is jersey finger?
flexor digitoum profundus avulsion
common on ring fingers
pt. won’t be able to make a fist
flexor injuries always get fixed with surgery!
what are trigger fingers?
a tendonitis that happens where the tendon enters the flexor sheath
the tendon gets irritated as it’s going through the sheets and as it’s going through A1 pulley it gets caught and your finger gets caught and stays flexed at PIP
just stretch it out or sometimes you have to cut A1 pulley
what is carpal tunnel?
transverse carpal ligament is the roof and the carpals are the base of the carpal tunnel where median nerve passes through
median nerve gives you sensation and fine motor and lets you oppose your thumb!!!
causes numbness, night pain, and lots of dropping things
*numbness is ONLY in the fingers, not in the palm
what’s inside the carpal tunnel?
10 structures:
4 FDP tendons
4 FDS tendons
FPL
median nerve
your FCR tendon is NOT in your carpal tunnel
how do you diagnose carpal tunnel?
- Tinnel’s test
- Phalen’s test
- Durkin’s test (squeeze the nerve)
how do you treat carpal tunnel?
- splints
- stretching
- corticosteroid injection
- surgical release
what are the long term effects of carpal tunnel?
hour glass contristriction and then the nerve stops working and then the muscles stop working = thenar muscle wasting
what is cubital tunnel syndrome?
cubital tunnel aka your funny bone
you’ll get numbest in the ulnar distribution = pinky
you’ll also have pain, waking up at night, loss of motor skills
you diagnose with Tinnel’s test on ulnar nerve in the elbow area
how do you treat cubital tunnel syndrome?
- splint so you don’t bent elbow
- avoid pressure on elbow
- usually get surgical release to decompress
how can the radial nerve get injured? what is Wartenberg syndrome?
- injury with humeral fracture along surgical neck
2. Wartenberg syndrome = compression of the superficial radial nerve at the wrist (handcuffs)
which artery mainly supplies the hand?
ulnar nerve (78%)
what’s the path of the radial artery through the hand?
goes dorsal through the anatomic snuff box, dorsal to thumb metacarpal and forms deep arch
what is the path of the ulnar artery through the hand?
goes through Guyon’s canal with ulnar nerve then forms the superficial arch of the palm
what is ulnar hammer syndrome?
clotting of the ulnar artery in Guyon’s canal
you’ll get pain in hypothenar region and numbness in ulnar distribution
you get it from using your hand as a hammer like carpenters
what is Raynaud’s disease?
vasospasm of the digital arteries
more common women and in the cold
associated with lots of autoimmune diseases
what is the function of the palmar fascia?
it sticks your skin to your palm!
what is Dupuytren’s disease?
thickening and contracture o the palmar fascia and you get nodules in the palm
causes flexion usually of the ring finger
more common in white males
what kinds of incisions are done during hand surgery?
avoid straight longitudinal incisions on flexor surfaces
scars that are straight don’t bend well when you bend your fingers
what is cellulitis?
superficial soft tissue infection; red, swollen, tender
can treat with IV antibiotics, rest, etc
what is Felon infection?
subcutaneous abscess of distal pulp space of fingertips
what is paronychia?
infection around the nail bed
you get it from picking at your nails or biting them
what is pyogenic flexor tenosynovitis?
infection that goes along the flexor
you have the flexor sheath that surrounds your flexor tendon so it can spread up your forearm
what are the 2 parts of the nail bed?
- germinal matrix = white part = makes nail (nails doesn’t stick to germinal matrix)
- serile matrix = pink part = this is what sticks to nail plate
what is a ganglion?
sac of fluid that comes from your joint
can happen anywhere in the body but wrist is the most common
what is bursitis?
inflammation of bursa
bursa is a thin fluid filled sac that allows soft tissues to move smoothly over bony prominences; usually very thin
ex. olecran bursitis
treat with rest, avoid direct pressure, ice, drainage
