Hand & Wrist Flashcards
`Describe the blood supply to the scaphoid? What is the main supply?
Dorsal carpal branch of the radial artery is the main - supplies 80% Also: Superficial palmar branch of the radial artery
Which ligament is violated and must be repaired in the volar approach to the scaphoid?
Radioscaphocapitate ligament
Which ligament is the strongest ligament that resists perilunate dislocations in the wrist?
Long radiolunate ligament
What is the weakest point in the volar wrist?
Space of Poirier
What is the significance of the Space of Poirier?
It is the weakest point in the volar wrist and is where volar lunate dislocations occur most often.
Where is the Space of Poirier located?
Volar wrist at the junction of the Lunate and Trapezium/Trapezoid
Bordered by the Radiocapitate & Radiolunotriquetral ligaments (aka long radiolunate)
What “ligament” in the wrist is actually a neurovascular bundle?
Radioscapholunate ligament
What are the components of the radioscapholunate ligament?
Vascular branches of the anterior interosseous and radial arteries Nerve branches of the anterior interosseous nerve
Where is the radioscapholunate ligament found?
Between the long and short radiolunate ligaments, piercing the joint capsule
What are the components of the TFCC?
Triangular fibrocartilage disc (articular disc)
Meniscus homolog (disc-carpal ligaments)
Volar Ulnocarpal ligaments (ulnolunate & ulnotriquetral)
Dorsal and volar Radioulnar ligaments (palmar & dorsal, each with a superficial & deep component)
ECU subsheath
What is the ligament of Testut?
Radioscapholunate ligament. Actually a neurovascular bundle with no contribution to carpal stability
What are the contents of the anatomical snuffbox?
Radial artery Sensory branch of the radial nerve Wrist joint capsule Fat
What are the borders of the anatomical snuffbox?
Trianglr: Anterior: EPB, ABL Posterior: EPL (extensor compartments 1&3) Base: radial stylus process Floor: scaphoid & trapezium
What are the stabilizers of the DRUJ?
Extrinsic:
ECU tendon & Subsheath
Pronator quadratus
Interosseous membrane
Joint capsule
TFCC
Intrinsic:
Bony contact
Superficial radioulnar ligaments - origina at ulnar styloid
Deep radioulnar ligaments (ligamentum subcruentum) origin at fovea
What are the components of the scapholunate ligament?
Dorsal (strongest) Palmar Proximal (thin, membranous)
What is a lesser arc injury?
Purely ligamentous perilunate injury
What is a greater arc injury?
Fracture around the lunate - scaphoid, capitate, hamate, triquetrum
What are the extrinsic ligaments of the dorsal wrist?
Dorsal radiocarpal ligaments Dorsal intercarpal ligaments
What is Kienbock’s disease?
Avascular necrosis of the lunate.
Why do perilunate dislocations usually NOT end up in AVN?
Because it has a rich blood supply including: Dorsal and volar radial branches Branches of the dorsal and volar intercarpal arch Anterior interosseous artery
How many articulations does the scaphoid have?
5 Radius, capitate, lunate, trapezoid, trapezium
What is intersection syndrome?
Overuse condition affecting the second dorsal compartment - ECRL and ECRB
What is DeQuervain’s tenosynovitis?
Inflammation of the tenosynovium of the abductor pollicis longus and extensor pollicis brevis tendons
Affects 1st dorsal compartment
Diagnosed with Finklestein’s test - Increase in pain when the thumb is held in palm and wrist is ulnarly deviated - Pain is over the radial side of the wrist (1st dorsal compartment)
What is Wartenberg’s Syndrome
Radial neuritis - Neuritis of the superficial branch of the radial nerve - Inflammation due to stretch, compression or direct blow - Compression occurs between the brachioradialis and ECRL
Describe Eaton’s classification of the radiographic stages of thumb CMC OA
1: Normal
2: Joint spacer narrowing, osteophytes 2mm
3: Joint space narrowing, osteophytes >2mm
4: pantrapezial arthritis
What is the bony articulation of the distal radioulnar joint?
Sigmoid notch of the radius articulation with the ulna
i.e. “lesser” sigmoid notch
What are the stabilizers of the distal radio-ulnar joint (DRUJ)?
- Bony integrity between sigmoid notch of the radius and ulna - Interosseous membrane - TFCC - Joint capsule - Pronator quadratus - Extensor carpi ulnaris
What are the muscular attachments of the proximal row of the carpal bones?
None
What carpal bones do not contribute to carpal motion?
Pisiform: it’s a sesamoid bone of the flexor carpi ulnaris
The Pisiform is a sesamoid bone for what tendon?
Flexor carpi ulnaris (FCU)
What are the contents of the carpal tunnel?
9 flexor tendons: - 4 for flexor digitorum superficialis - 4 for flexor digitorum profundus - Flexor pollicis longus Median nerve
What are the borders of the carpal tunnel?
Radially: scaphoid & Trapezium Ulnar: Pisiform & hamate Roof: flexor retinaculum/transverse carpal ligament Floor: proximal carpal row & radiocarpal ligaments
During carpal tunnel release, what nerve is most at risk when cutting the transverse carpal ligament? How do you avoid it?
Recurrent motor branch of the median nerve Avoid it by making your cut as ulnar as possible - Ulnar side of the 4th digit when flexed to the palm
What are the borders of Guyon’s Canal?
Roof: volar carpal ligament
Floor: Transverse carpal ligament & hypothenar uscles
Radial: Hook of hamate
Ulnar: Pisiform, pisohamate ligament, abductor digiti minimi muscle belly
How is Guyon’s Canal divided? What is the pathology of damaging each division?
3 zones:
Zone 1: proximal to the bifurcation of the ulnar nerve - Causes mixed motor and sensory symptoms
Zone 2: surrounds deep motor branch of the ulnar nerve - It is more radial - Causes only motor symptoms
Zone 3: Surrounds superficial sensory branch of the ulnar nerve - It is more ulnar - Causes only sensory symptoms
what is the major contributor to the superficial palmar arch?
Ulnar artery - Radial has minor contributions
What is the major contributor to the deep and superficial palmar arches?
Radial artery: deep
ulnar artery: superficial
What muscles attach to the scaphoid>?
None
How much of the scaphoid is covered in articular cartilage?
70%
name the intrinsic hand muscles of the thenar eminence and their function:
Abductor pollicis brevis - Abducts thumb at CMC & MCP Flexor pollicis brevis - Flexes thumb at CMC & MCP Opponens pollicis - Opposition of thumb
What is the innervation of flexor pollicis brevis?
Dual innervation - Superficial: median - Deep: ulnar
What are the intrinsic hand muscles of the hypothenar eminence and their actions?
Abductor digiti minimi brevis - Abducts 5th digit at MCP Flexor digiti minimi - Flexes 5th digit at MCP Opponens digiti minimi - Opposition of 5th digit
Name the intrinsic hand muscles of the hypothenar eminence and their nervous innervation
Abductor digiti minimi Flexor digiti mimini brevis Opponens digiti minimi - All innervated by ulnar nerve
Name the intrinsic muscles of the thenar eminence and their nervous innervation:
Abductor pollicis brevis - Median nerve Flexor pollicis brevis - Dual innevation - Superficial: median nerve - Deep: ulnar nerve Opponens pollicis - Median nerve
What are the muscles of the hand innervated by the median nerve?
LOAF - Lumbricals (radial 2 aka 1 & 2) - Opponens pollicis - Abductor pollicis brevis - Flexor pollicis brevis - note this has dual innervation - Superficial: median - Deep: ulnar
What is the only muscle to originate and insert onto a tendon? Which tendons does it originate and insert into?
Lumbricals - Originate from tendons of flexor digitorum profundus - Insert into extensor expansion on dorsal aspect of each digit’s radial side
What is the function of the dorsal and palmar interossei?
Dorsal: Abduct the fingers Palmar: Adduct the fingers - Remember DAB and PAD
What is the OINA of the palmar interossei?
O: They originate on the side facing the long finger
1st: ulnar side of 2nd MC
2nd: radial side of 4th MC
3rd: radial side of 5th MC
I: Extensor expansion of 2,4,5 digits
N: ulnar
A: adduction of 1,2,4,5th digits
nb: adduction/abduction is named relative to long finger
What is the OINA of the dorsal interossei?
O:
1st medial head: radial side of 2nd MC
1st lateral head: ulnar side of 1st MC
2nd, 3rd, 4th: space between the MC bones
I:
1st: radial sid of 2nd proximal phalanx
2nd: radial side of 3rd PP
3rd: ulnar side of 3rd PP
4th ulnar side of 4th PP
N: ulnar
A: ABduction of 2,3,5 fingers (away from midline)
What are the O, I, N, A of the lumbricals?
O: tendons of flexor digitorum profundus
I: extensor expansion on dorsal aspect of each digit’s radial side
N: 1/2: median, 3/4: ulnar
A: flexion of MCP of digist 2-5 - Extension of DIP & PIP of digits 2-5
What is the OINA of the palmaris brevis?
O: Flexor retinaculum I: Palmar surface of skin on ulnar side of hand N: Ulnar A: Wrinkles skin on ulnar side of hand
Describe the safe position of the hand. Why is it safe?
Intrinsic plus position: - Wrist extended 10 deg - MCP Flexion to 70 deg - IP extended It’s safe b/c with the MCPs in flexion, the collaterals are tight (at their longest) - So they will not get tight in a shortened position (short/lax in extension)
What are the components of the extensor hood?
Central tendon
Lateral Bands
Dorsal/palmar interossei
Lumbricals
Oblique retinacular ligaments
Sagittal bands
Works on both the MCP and IP joints
Describe the flexor zones of the hand?
1: Distal of FDS insertion (Jersey finger) 2: DIP to distal palmar crease (no man’s land) 3: Palm (Assoc w/ neurovasc injury) 4: Carpal tunnel (post-op adhesions) 5: Wrist to forearm: (Assoc w/ neurovasc injury) Thumb: Early ROM NOT better, like other fingers - T1, T2, T3
Describe the pulley system of the fingers and thumb
Fingers:
5 annular pulleys: - A1, A3, A5 at MCP, PIP, DIP - A2, A4 at proximal and distal phalanx. These are most important in preventing bowstringing
3 cruciate pulleys - C1: at distal end of proximal phalanx - C2: at middle phalanx - C3: at distal end of middle phalanx
Thumb: A1 at MCP, A2 at IP Oblique between them at proximal phalanx
Where does the superficial branch of the radial nerve emerge from at the wrist?
Beneath brachioradialis 7-9cm proximal to rad styloid tip
What is the most common place for the palmar cutaneous branch of the median nerve to emerge? What is its location with respect to FCR and the carpal tunnel?
Ulnar to FCR - Travels outside the carpal tunnel, so not affected by CTS (you get sparing)
Space of Parona - where is it?
space between pron quadratus and flextor tendons - continuous with carpal tunnel and palmar space
Stener’s lesion
Ulnar collateral ligament tear with interposed adductor pollicis tendon - prevents healing so is an indiation for surgical repair
Normally, the UCL is deep to the adductor pollicis tendon
A Stener lesion is characterised by slippage of the torn end of the ulnar collateral ligament superficial to the adductor aponeurosis / adductor pollicis muscle
AKA the tendon/aponeurosis is now interposed between the ulnar collateral ligament and the MCP joint
This prevents healing and is an indication for surgical repair.
Froment’s sign
Ulnar nerve injury
Wartenberg’s sign
Ulnar nerve injury - Ulnar drift of small finger due to unopposed function of EDM (radial) with paralysis of palmar interossei (ulnar)
EDM attaches ulnarly so will have an ulnar/abduction moment, pulling small finger ulnarly
vs: Wartenburg’s syndrome: superficial radial nerve injury
Why is a flexor tendon sheath infection a medical emergency?
B/c the most common anatomical variants have flexor sheaths 1 & 5 communicating with the wrist/carpal tunnel, so infection can easily propagate up the wrist
What is the most common variation of the recurrent branch of the median nerve?
Extra ligamentous, distal to the carpal tunnel (46-95%)
What is the last muscle innervated by the median nerve proper?
Second lumbrical
Where does the dorsal branch of the ulnar nerve branch off?
5-12cm, average 9cm
What nerves branch off the ulnar nerve proximal to the elbow?
Usually none, but if any, are just articular branches
What is a Riche-Cannieu anastamosis?
Ulnar to median anastmosis in the hand. classically deep br of ulnar n to recurrent median.
i.e. ulnar n supplying thenar muscles
Name the contents of the extensor compartments
1: ABL/EPB 2: ECRB/ECRL 3: EPL 4: EDC/EIP (PIN) 5: EDM 6: ECU
Which is more distal, superficial or deep palmar arch?
Superficial - it is at the distal transverse palmar crease
Where is the superficial and deep palmar arches?
Superficial: distal transverse palmar crease Deep: Kaplan’s cardinal line
Describe the extensor zones of the hand and wrist
Odd numbers are at the joints:
I: DIP
III: PIP
V: MCP
VII: radiocarpal
IX: forarm muscle belly
Name the contents of the extensor compartment of the wrist
I: APL/EPB
2: ECRB/ECRL
3: EPL
4: EDC/EIP (PIN)
5: EDM
6: ECU
Name a syndrome or pathology for each extensor compartment of the wrist
1: De Quervain’s tenosynovitis
2: Intersection syndrome
3: Drummer’s wrist or traumatic rupture with DR #
4: Extensor tenosynovitis
5: Vaughn-Jackson’ syndrome (common in RA0
6: Snapping ECU
Describe the flexor tenson injury zones:
Fingers:
1: FDP to FDS insertion
2: FDS to A1 pulley
3: A1 pulley to carpal tunnel
4: Carpal tunnel
5: Tendons of forearm flexors
6: Muscle bellies of forearm flexors
Thumb:
1: Distal to IP
2: IP to A1 pulley
3: thenar eminence
4: carpal tunnel
5: tendons of forearm flexors
6: muscle bellies of forearm flexors
In what position is the radius shortest compared to the ulna (or the ulna longest compared to the radius)?
In pronation
THINK: supination is anatomic position so bones are uncrossed. In pronation, radius must cross over ulna, shortening it compared with the ulna
That’s why positive ulnar variance is mostly detected in pronation x-rays
What ligaments are the main restraint to subluxation of the DRUJ in supination and pronation?
Supination:
Deep dorsal radioulnar ligament is the main restraint to dorsal subluxation of the radius
Pronation:
Deep volar radioulnar ligament is the main restraint to volar subluxation of the radius
Name the 9 palmar and 5 dorsal intrinsic carpal ligaments
see picture
Palmar:
scapholunate
lunotriquetral
triquetrohamate
triquetrocapitate
capitohamate
capitotrapezoidal
trapeziotrapezoidal
scaphotrapeziotrapezoidal
scaphocapitate
Dorsal:
scapholunate
lunotriquetral
trapeziotrapezoidal
capitotrapezoidal
capitohamate
What carpal bones do the following MC align with?
1st MC
2 MC
3 MC
4/5th MC
1st MC: Trapezium
2nd MC: Trapezoid
3rd MC: Capitate
4th/5th MC: Hamate
Name the Volar extrensic Wrist ligaments (6)
Radioscaphocapitate
Radioscapholunate
Long radiolunate
Short radioluate
Ulnolunate
Ulnotriquetral
What is the strongest wrist ligament?
Radioscaphocapitate
**Note that the long radiolunate is the primary restraint to perilunate dislocations but not the strongest volar wrist ligament
What are the components of the scapholunate ligament?
Dorsal (strongest)
Palmar
Membranous (intraosseous, proximal)
Name the extrinsic dorsal wrist ligaments
Dorsal radiocarpal
Dorsal intercarpal
These converge on the triquetrum and can be used in the Mayo ligament sparing approaach that Gammon uses
What type of joints are the 1st - 5th CMC joints?
1st: saddle
2-4: plane/synovial
5th???
What are the components of the deep flexor retinaculum of the wrist?
Starts as: antebrachial fascia
Becomes: Transverse carpal ligament
Becomes Thenar & Hypothnar aponeurosis/Deep palmar fascia
What are the components of the superficial wrist retinaculum?
Carpal ligament and palmar ligament
What are the contents of the Guyon’s canal?
Ulnar nerve
Ulnar artery
Name the bands affected & not affected by Dupuytren’s Disease
Affected:
Pretendinous
Spiral
Natatory
Lateral
Grayson’s
Not Affected:
Trasnverse fibers
Cleland’s ligaments
(Some say only Cleland’s is not affected)
What are the positions of Grayson’s and Clelands Ligaments with respect to each other
Grayson’s: (grip) are volar to the NV bundle
Cleland’s (ceiling) are dorsal to the NV bundle
What are the variants of the flexor tendon sheath anatomy?
Why is this important?
Communication between 1st, 5th flexors (most common)
Communication between 1st, 2nd, 5th flexors
No communication between 1st and anywhere else
Can get horseshoe abscesses if there is communication between the 2st/5th digists
Name the potential spaces in the hand (3) and forearm (1)
Hand:
Midpalmar space
Thenar space
Hypothenar space
Forearm:
Parona’s space
Describe Parona’s Space
Potential space superficial to pronator quadratus
Contiguous with the midpalmar and thenar spaces (also potnetial spaces)
Name the intrinsic hand muscles of the thenar eminence:
Abductor pollicis brevis
Flexor pollicis brevis
Opponens pollicis
Adductor pollicis
Name the intrinsic hand muscles of the hypothenar eminence:
Abductor digiti minimi
Flexor digiti minimi
Opponens digiti minimi
Name the OINA of Abductor Pollicis Brevis
O: Scaphoid tuberosity, trapezium ridge, TCL
I: Proximal 1st phalanx, lateral base
N: Median
F: ABduction of CMC & MCP of thumb
Name the OINA of Flexor Pollicis Brevis
O:
- Superficial Head: trapezium
- Deep Head: trapezoid, capitate and palmar ligaments of distal carpal bones
I: Base of 1st proximal phalanx on radial side & extensor expansion
N:
Superficial: median
Deep: ulnar
F: CMC & MCP thumb flexion
What is the innervation of flexor pollicis brevis?
Superficial head: median nerve
Deep head: ulnar nerve
What is the OINA of opponens pollicis?
O: Trapezium & TCL
I: 1st MC shaft, radial side
N: median
A: Opposition
Name the OINA for adductor pollicis
O:
Oblique head: capitate, base of 2/3 MC
Transverse head: proximal 2/3 of palmar surface of 3rd MC
I: base of 1st proximal phalanx, ulnar side
N: ulnar nerve
A: adduction of 1st CMC
Name the OINA for abductor digiti minimi:
O: pisiform
I: base of 5th proximal phalanx, ulnar side
N: ulnar
A: Abduction of 5th MCP/digit
Describe the OINA for flexor digiti minimi
O: hamate, TCL
I: Proximal 5th phalanx, ulnar side
N: ulnar
A: flexion of 5th digit/MCP
Name the OINA for opponens digiti minimi
O: hook of hamate, TCL
I: 5th MC - entire ulnar border
N: ulnar
A: 5th MCP flexion and rotation of entire 5th digit
What is a test you can do for ?Boutonniere’s Deformity
how do you do it?
Elson’s Test:
Tests for central slip rupture
Flex PIP to 90 deg over a table edge
get them to actively extend PIPJ
if they can, then central slip is intact
if they cannot, then central slip is disrupted - lateral bands sublux volar to axis of PIPJ and pull on extensor tendon will cause flexion instead
Name the OINA of the lumbricals
O: Tendons of FDP
I: extensor expansion on dorsal aspect of each digitit’s radial side
N:
1,2: median
3,4: ulnar
A:
MCP flexion 2-5th digits
DIP & PIP extension of 2-5th digits
How do the lumbricals exert their function?
They relax it’s own antagonist (FDP) when they are contracting
It originates from the FDP muscel tendon
When it is relaxed, and the FDP contracts, the IP joint flexes
When the lumbricals contract, it extends the IP joint by relaxation of the FDP tendon distal to the lumbrical origin and by proximal pull on the lateral band and dorsal aponeurosis
Descirbe the pathoanatomy of a swan neck deformity
Lesion: Hyperextension of PIP + flexion of DIP
Primary lesion: Lax volar plate caused by:
- Trauma
- Generalized Laxity
- RA
Secondary lesion: Imbalance of forces on PIP joint (PIP extension > PIP flexion). Causes:
- Mallet finger: leads to transfer of DIP extension force into PIP extension forces
- FDS rupture: eads to unopposed PIP extension combined with loss of integrity of the volar plate
- Intrinsic contracture
- MCPJ volar subluxation: in RA
What is the intrinsic plus position?
What is the principle behind this position?
Safe position for immobilization of the hand
Wrist in 30deg extension
MCP 70deg flexion
IP neural
Princip;s”
Wrist in extension: optimal position for grip strength
MCP flexion: MCP collateral ligament at their longest in 90 deg flexion, but this is painful so only do 70 deg
PIP collateral ligaments: at same length throughout ROM but flexors arestronger than extensors and gaining PIP flexion is easier than gaining back extension
What are the junctura tendinae?
Intertendinous connections
Transverse connections between EDC tendons
EIP & EDM not typically involved, therefore allowing for independent extension of D2 and D5
Passive stabilization of extensor tendon over MC head in full flexion (fist)
What allows for independent motion of the index and small fingers (most of the time)?
Generally, no junctura tendinae between EIP and EDM so they get independent motion
What are the components of the extensor hood?
Combination of:
EDC tendons –> central slip
DI and PI tendons & Lumbricals –> lateral bands
Oblique retinacular ligaments
Sagittal bands
Triangular ligament
Describe the pathoanatomy of a Boutonniere Deformity:
Force causing hyperflexion at PIP joint
Central slip rupture –> more force going through terminal slip –> hyperextenio of DIP, Volar subluxation of alteral bands –> PIP hyperflexion
Triangular ligament rupture –> subluxation of lateral bands –> hyperflexion of PIP –> increased extension force through DIP
What is Camper’s Chiasm?
Where FDP passes through the 2 slips of FDS located at the PIP joint
Describe the blood supply to the flexor tendons
From Diffusion and Vascular supply from vincular system
- Each tendon has a short and long vinculum
What is the blood supply to the Lunate?
Dorsal plexus: from radial and anterior interosseous arteries
Volar plexus: from radial, ulnar, anterior interossoues, recurrent branches of deep palmar arch
3 different vascular patterns within lunate (see picture attached)
“I” has greatest risk of AVN
Name the course of the radial artery
Arises from the bifurcation of the brachial artery in the cubital fossa
Runs distally on anterior forearm winding laterally around the wrist radial to FCR
Passes through the anatomical snuff box
Then between the heads of the first dorsal interosseous muscle
It passes anteriorly between the heads of the adductor pollicis & winds around 1st MC between heads of oblique and transverse opponens pollicis
Gives off major contributions fo deep palmar arch, which joins with deep branch of ulnar artery
Name the course of the ulnar artery
From brachial artery
Arises just distal to cubital fossa (5-9cm)
Deep proximally: covered by the PT, FCR, FDS; It lies on Brachialis FDP
The median nerve is in relation with the medial side of the artery for about 2.5 cm. and then crosses the vessel, being separated from it by the ulnar head of the Pronator teres.
Distally in forearm, it sits on FDP being covered by the integument and the superficial and deep fasciæ, and sits between the FCU & FDS
Runs with 2 venæ comitantes
Covered in middle 1/3 by FCU
Ulnar nerve is ulnar in distal 2/3
Palmar cutaneous branch of the nerve descends on the lower part of the vessel to the palm of the hand.
Major contributions to superficial palmar arch
Course of the Anterior interossoues artery
Comes down the forearm on palmar surface of the IoM
Accompanied by palmar interosseous branch of the median nerve & overlapped by FDP & FPL giving off muscular branches and nutrient vessels to radius/ulna
At the upper border of the pronator quadratus, it pierces the IoM, winding to dorsal forearm to anastomosewith the dorsal interosseous artery.
It then descends with the terminal part of the dorsal interosseous nerve to the dorsal wrist to join dorsal carpal network.
Before it pierces the interosseous membrane the anterior interosseous sends a branch downward behind the pronator quadratus muscle to join the palmar carpal network.
Digital nerve: volar or dorsal in the finger?
Nerve becomes the most volar structure in the finger
It gives off dorsal branches to innervate dorsal skin starting at ~mid P2
Name the anatomic variants of the Million Dollar Nerve
Recurrent Motor branch of the Median Nerve
Variants:
Extraligamentous: most common
Subligamentous: next
Transligamentous: Rarest
Describe the course of the palmar cutaneous branch of the median nerve. What common surgery to you have to watch out for it
Arises from radial border of median nerve approximately 5 to 6 cm proximal to distal transverse flexion crease of the wrist;
- it runs along the median nerve for 2 to 3 cm, and then runs along the ulnar border of the flexor carpi radialis tendon;
- in some cases it may run along the ulnar side of the palmaris longus tendon;
- when the tendon enters the flexor retinaculum comparment, the nerve passes between the two layers of the forearm fascia into the root of the palmar aponeurosis;
- after 5-10 mm, the nerve divides into three terminal branches which cross the midpalmar aponeurosis to supply deep layers of dermis
Watch out for it during Carpal Tunnel Approach and with any incision ulnar to FCR
Where can you find the dorsal cutaneous branch of the ulnar nerve?
emerges from under FCU and becomes subcutaneous 5cm proximal to pisiform
0.2-2cm proximal to the ulnar styloid at the subcutaneous border of the ulna
What is the terminal branch of the ulnar nerve and what does it supply?
Deep branch of ulnar nerve
Supplies 1st dorsal interossei last
describe path of superficial radial nerve at the level of the wrist/hand:
emerges where?
branches where?
emerges from under BR, 7-9cm proximal to radial styloid tip on dorsoradial aspect of wrist
branches out 5cm proximal to radial styloid tip into terminal branches
dorsal extrinsic wrist ligaments: what and where?
dorsal intercarpal ligament: between scaphoid and triquetrum
dorsal radiocarpal ligament: between radius (ulnar side) and triquetrum
lunotiquetral ligament: what part is strongest?
volar
Name the compartments of the hand
(not wrist)
there are 10
Thenar compartment
Adductor pollicis
Hypothenar compartment - may have subcompartments
4x dorsal interossei compartments
3x palmar interossei compartments
Describe the motion of the proximal carpal row with ulnar and radial deviation of the wrist
Radial deviation: Proximal row flexes (think scaphoid)
Ulnar deviation: proximal row extends
What structure is at risk during trigger thumb release?
Radial digital nerve because of it’s oblique orientation overlying the A1 pulley
What is the last muscle to be reinnervated after PIN injury? Bonus marks for full order of reinnervation.
Last to reinnervate: EIP
Order of reinnervation: Goes proximal to distal:
ECU, EDC, EDM, APL, EPL, EPB, EIP
The ulnar nerve is (radial/ulnar) and (volar/dorsal) to the artery at the level of the wrist
Ulnar nerve is ulnar and dorsal to the artery at the level of the wrist
What amount of wrist flexion and extension occur through the midcarpal joint?
70 degrees
What is the main function of the midcarpal joint?
radial and ulnar deviation
What is a Martin-Gruber Anastomosis?
median to ulnar n anastomosis in the forearm, somtimes AIN to ulnar.
i.e. median/AIN supplies muscles normally supplied by ulnar n, so with ulnar palsy can still have intrinsic hand function
order of carpal bone ossification?
capitate, hamate, triquetrum, lunate, scaphoid, trapezium, trapezoid, pisiform
i.e. starting with capitate, go clockwise on right wrist dorsum, with pisiform at end
