Wrist/Hand Anatomy Flashcards
styloid process of middle finger metacarpal
ECU
lunate fossa
lister’s tubercle
ECRB
ECRL
APL
EPB
EPL
what is in the snuff box
fat
radial artery
branch of radial nerve
how do we split up the palmar surface of the hand?
with 4 main lines:
kaplan’s cardinal: from 1st web space through hook of hamate
longitudinal 1: from radial side of D3
longitudinal 2: from ulnar side of D4
transverse: from radial prox crease to ulnar distal crease
superficial arch
digital nerve to D5
hook of hamate
motor branch of ulnar nerve
pisiform
ulnar nerve
tendon of FCR
scaphoid tubercle
crest of trapezium
deep palmar arch
deep branch of ulnar nerve
digital nerve to index
what happens here?
recurrent branch of the median nerve enters the thenar muscle mass
explain the 9 zones of extensor tendon injury
starting with zone I at the DIP, each joint and subsequent interjoint space is labelled a zone. So, for example, the MCP joints will be zone V, and the CMC joints will be VII, the distal radius with radio-ulnar-carpal joints zone VIII, and the last zone (IX) will be proximal radius at the origin of these tendons
what is contained in the 6 compartments of the hand?
1 = APL, EPB
2 = ECRB, ECRL
3 = EPL
4 = EI, ED, PIN
5 = EDM
6 = ECU
what are the 6 flexor tendon injury zones?
1 = FDP to FDS insertion
2 = FDS to A1 pulley (just proximal to metacarpal heads)
3 = A1 pulley to carpal tunnel
4 = carpal tunnel
5 = tendons of forearm flexors
6 = muscles of forearm flexors
normal volar tilt of the distal radius
11°
normal radial inclination
22°
normal radial height
11 mm
what happens as the radius rotates into pronation?
it moves around a fixed ulna, therefore, it shortens with respect to the ulna
what is the sigmoid notch?
the spot on the distal radius where the ulna articulates
list the 5 stabilizers of the DRUJ
TFCC
joint capsule
IO membrane
pronator quadratus
ECU tendon and sheath
while the ECU tendon, ECU sheath, PQ and IO are extrinsic stabilizers of DRUJ, what are the intrinsic stabilizers?
bony contact
superficial radioulnar ligaments
deep radioulnar ligaments
what is the main stabilizer of the DRUJ in supination?
deep dorsal radioulnar ligament stops dorsal subluxation of the radius
what is the main stabilizer of the DRUJ in pronation?
deep volar radioulnar ligament, main restraint to volar subluxation of radius
list the 5 components of the TFCC
articular disc
dorsal and volar radioulnar ligaments
meniscus homolog (disc-carpal ligaments)
volar ulnocarpal ligaments
sheath of ECU
triangular articular disc
ulnolunate ligament
palmar distal radioulnar ligament
ulnocapitate ligament
dorsal distal radioulnar ligament
ulnotriquetral ligament
ECU tendon sheath
triangular articular disc
palmar distal radioulnar ligament
dorsal distal radioulnar ligament
ulnolunate ligament
which carpal bone aligns with the 4th and 5th metacarpals?
hamate
most commonly fractured carpal bone
scaphoid
most commonly dislocated carpal bone
lunate
which tendons attach to the proximal carpal row?
none!
this means they are passive responders to action on the distal row
what is the order of ossification of the carpal bones?
capitate first, then hamate, then clockwise (looking from dorsal surface)
how do the carpal bones move with respect to each other?
well, they are secured by palmar, dorsal and interosseous ligaments between each bone, so very little gliding goes on
they are also stabilized by extrinsic ligaments that span their joints but do not attach here
list the 6 volar extrinsic wrist ligaments
RSC
RSL
LRL
SRL
UL
UT
radioscaphocapitate ligament
long radiolunate ligament
radioscapholunate ligament
short radiolunate ligament
ulnolunate ligament
ulnotriquetral ligament
what is the ligament of testut?
RSL
*this is actually an NV bundle that does not contribute to carpal stability
strongest volar extrinsic ligament of the wrist
RSC
*must repair in volar approach to the scaphoid
what is the primary restraint to perilunate dislocations?
long RL ligament
keystone of the wrist
lunate
what happens with disruption of the proximal row of carpal bones?
dissociative carpal instability
what happens with disruption between proximal and distal carpal rows?
non-dissociative disruption
what is the space of poirier?
where the palmar capsule between capitate and lunate is torn
what can you infer from a lesser arc injury?
that it is ligamentous
what can you infer from a greater arc injury?
there is a # around the lunate
what is significant about this space?
this is the space of poirier
the lunate can displace through it
4 stages of progressive perilunar instability
scapholunate failure
capitolunate failure
lunotriquetral failure
dorsal radiocarpal ligament failure
*clockwise from scaphoid
volar CT
volar TT
volar STT
volar SC
volar SL
volar LT
volar TH
volar TC
volar CH
dorsal CT
dorsal CH
dorsal LT
dorsal SL
dorsal TT
3 parts of the SL ligament
which part is strongest?
dorsal (strongest)
palmar
proximal
2 dorsal general ligaments
dorsal radiocarpal ligament (DRC - also called DRTriquetral)
dorsal intercarpal ligament (DIC)
function of the DRC
to stabilize the lunotriquetral joint
function of the DIC
to stabilize the proximal pole of the scaphoid
function of the SL ligament
resists dorsal intercalated segment instability
2 components of the LT ligament
volar (strongest)
dorsal
function of the LT ligament
resists volar intercalated segment instability
which CMC joints can abduct and adduct as well as flex and extend?
1st and 5th
extensor hood
deep transverse metacarpal ligament
volar plate
pulley
FDP
FDS
palmar carpal ligament
flexor retinaculum
what are the attachments of the transverse carpal ligament?
hook of hamate and pisiform ulnarly to scaphoid tubercle and trapezial tuberosity radially
trapezial tubercle
scaphoid tubercle
FCR tendon
FCU tendon
pisiform
hook of hamate
contents of the carpal tunnel
8 flexor tendons of FDS and FDP
median nerve
FPL
FPL
FCR
boundaries of Guyon’s canal
roof: volar carpal ligament
floor: flexor retinaculum
radial: hamate
ulnar: pisiform
contents of Guyon’s canal
ulnar nerve
ulnar artery
explain the 3 zones of Guyon’s canal
I: proximal to the ulnar nerve bifurcation
II: deep motor branch as it passes hook of hamate
III: superficial sensory branch on the other side of the canal
what is the septum of legueu and juvara?
deep palmar fascia that connects the metacarpal heads to the palmar skin
interossei tendon
*note these are dorsal to DTML
deep transverse metacarpal ligament
lumbrical tendon
*note these are volar to DTML
cleland’s ligament
lateral digital sheath
spiral band
natatory ligament
grayson’s ligament
which two fascia bands are NOT affected in Dupuytren’s contracture?
transverse fibers
Cleland’s ligament
how can a ‘horseshoe’ abscess arise in the hand?
when there is a variant in flexor tendon sheath as below (normally only the 5th digit is completely communicating with the sheath of the wrist)
3 potential spaces in the hand
thenar
midpalmar
hypothenar
which potential space superficial to PQ communicates with the midpalmar and thenar spaces?
Parona’s space
APB origin and insertion
originates from:
scaphoid tuberosity
trapezium ridge
transverse carpal ligament
inserts on:
lateral base of proximal 1st phalanx
FPB origin and insertion
origin:
trapezium
trapezoid
capitate
insertion:
radial side of base of 1st proximal phalanx
innervation of FPB
superficial is median
deep is ulnar
OP origin and insertion
origin:
trapezium
transverse carpal ligament
insertion:
radial side of 1st metacarpal shaft
AddP origin and insertion
origin:
capitate
base of 2/3 metacarpals
more of the 3rd shaft
insertion:
ulnar side of base of 1st proximal phalanx
Abd DM origin and insertion
origin:
pisiform
insertion:
ulnar side base of 5th proximal phalanx
FDM origin and insertion
origin:
hamate
transverse carpal ligament
insertion:
ulnar side of proximal 5th phalanx
ODM origin and insertion
origin:
hook of hamate
transverse carpal ligament
insertion:
ulnar border of 5th metacarpal
where do the palmar interossei originate and insert?
what to they do?
there are only 3*: ulnar side of 2, radial side of 4 and 5
they all insert on the extensor expansions of the digits from which they arose
discuss the dorsal interossei
arise from the space between metacarpals and insert on the proximal part of the proximal phalanx of radial 2, both sides 3, ulnar 4
the only muscle in the body to originate and insert from and to tendon
lumbricals:
they orginate from the tendons of FDP and insert into the extensor expansion of each digit on the radial side
odd in that they both flex MCP and extend DIP and PIP
palmaris brevis origin and insertion
origin:
flexor retinaculum
insertion:
palmar surface skin on ulnar side of hand
what is the ‘safe’ position of the wrist and hand?
wrist in 30° extension
MCP 70° flexion
IP neutral
Lister’s tubercle
which tendons are in compartment 1?
APL
EPB
(from radial to ulnar)
which tendons are in compartment 2?
ECRL
ECRB
which tendons are in compartment 3?
EPL
which tendons are in compartment 4?
EI
ED
which tendons are in compartment 5?
EDM
which tendons are in compartment 6?
ECU
through which extensor compartment of the wrist does the dorsal branch of PIN lie?
4th
which is the only extensor tendon of the wrist with a true sheath?
ECU
what are the juntura tendinae?
the connections that help stabilize the extensor tendons in flexion between the individual tendons of ED
also known as intertendinous connections or retaining ligaments
what is the extensor hood?
a combinatorial structure made up of:
ED tendons
DI and PI tendons
lumbricals
central tendon
oblique retinacular ligaments
sagittal bands
central slip
lateral slip
central slip
lumbrical
dorsal and volar interossei respectively
sagittal band
transverse retinacular ligament
oblique retinacular ligament
where does the common extensor tendon insert? how does it move the entire finger?
at the base of the middle phalanx
the lateral slips extend farther to attach to the base of the distal phalanx
which side of the digits do the lumbricals attach to?
radial only!
what are the medial and lateral interosseous bands?
the confluence of the lumbrical and interosseous tendons that merge
MIB joins the central slip at PIP
LIB joins the lateral slip at DIP
what does the sagittal band do?
attaches the ED tendon to sides of volar plate limiting proximal excursion of ED in extension and stabilizing it in flexion
what causes a swan-neck deformity?
rupture of the transverse retaining ligament, which will release the ED tendon from its connection to the volar plate causing dorsomedial displacement of this tendon resulting in hyperextended PIP, relative elongation of ED resulting in DIP flexion (swan-necking)
function of the oblique retinacular ligament
links extension of PIP to extension and flexion of DIP
i.e. when one goes the other must follow
what causes a boutonniere deformity?
incompetence of the triangular ligament between the 2 lateral bands on the dorsum of the middle phalanx
what would happen if the triangular ligament contracted (as opposed to rupturing)?
a fixed swan-neck deformity
4 causes of dorsal subluxation of transverse retinacular ligament
RA
PIP joint effusion
volar plate laxity
TRL laxity
rupture of the distal extensor tendon
mallet finger
besides triangular ligament rupture, what else could cause boutonniere deformity?
central slip rupture at PIP
what is elson’s test?
essentially just looking for a boutonniere deformity
list the pulley system in a finger
flexor surface to prevent bowstringing:
A1 = MCP
A2 = proximal proximal phalanx
C1 = distal proximal phalanx
A3 = PIP
C2 = proximal middle phalanx
A4 = middle middle phalanx
C3 = distal middle phalanx
A5 = DIP
*note ‘A’ just means annular, ‘C’ means cruiciate*
*thumb has only A1 = MCP, A2 = IP, and oblique between them
how do the flexor tendons receive a blood supply?
diffusion and vincular system
each tendon has a short (near insertion) and long (more proximal) vinculum
dorsal intercarpal arch
2,3 intercompartmental supraretinacular artery
1,2 intercompartmental supraretinacular artery
% of scaphoid covered in articular cartilage
75%
blood supply of the scaphoid
80% from the dorsal carpal branch of the radial artery
20% from the superficial palmar branch of the radial artery
what is Keinbock disease?
AVN of the lunate
to which arches do the radial and ulnar arteries contribute most?
radial = deep
ulnar = superficial
which 3rd major artery supplies the hand?
the anterior interosseous artery, which bifurcates into dorsal and palmar branches at PQ
where does the digital nerve give off its dorsal cutaneous branch?
mid P2
*note that the digital nerve itself is the most volar structure in the finger
which nerve to the hand leaves the median before the carpal tunnel?
the palmar cutaneous branch of the median nerve
what is wartenberg’s syndrome?
entrapment of the superficial radial nerve (sensory) as it exits the deep forearm 8 cm proximal to the wrist between BR and ECRL
dorsal roof
ventral floor
hyponychium
sterile matrix
lunula
eponychium
germinal matrix
how do you best check median nerve motor function?
1st MCP abduction (last muscle to be innervated by median nerve)
how do you best check ulnar nerve motor function?
2nd MCP abduction (adductor pollicus last muscle)
what is Gamekeeper’s thumb (aka Stener’s lesion)?
injury to UCL of 1st MCP
where UCL flips over adductor pollicus after avulsion off proximal phalanx
won’t reattach if in this position
results in a radial deviation of 1st MCP joint
order of ossification of the carpal bones
