Wrist Flashcards
What is Ulnar and Palmar tilt of the Radius
Ulnar Tilt
- distal end of radius angles 25 degrees toward ulnar direction
- allows for more UD than RD -> RD is limited by lateral carpal bones and radial styloid process
Palmar Tilt
- distal surface of radius angles 10 degrees in palmar direction
- partly accounts for greater wrist flexion than extension
What makes up the TFCC and what does it do?
major stabilizer of the ulnar side of wrist
absorb forces between ulnar and triquetrum and lunate
1. Articular disc (triangular fibrocartilage)
- fill in space to sit better
2. Distal RU jt capsular ligaments
- Dorsal RU lig
- Volar RU lig
3. Palmar ulnocarpal lig
- Ulnotriquetral
- Ulnolunate
4. Ulnar collateral ligament
5. Fascial sheath enclosing ECU tendon
What carpal bones make up the proximal row?
Radial to Ulnar
-scaphoid
-lunate
-triquetrum
-pisiform
looser
What carpal bones make up the distal row?
Radial to Ulnar
-trapezium
-trapezoid
-capitate
-hamate
bound tightly by ligaments
What makes up the Radiocarpal (RC) jt?
-bones?
-Concave or convex?
- Open and closed pack
scaphoid
Lunate
Triquetrum
convex proximally, concave distally (makes a U)
- distal radius is concave
Open packed: neutral w/ slight UD
Closed pack: full flexion with RD
What makes up the midcarpal (MC) jt?
Scaphoid, lunate, and triquetrum ARTICULATE WITH trapezium, trapezoid, capitate, and hamate
- Scaphoid: trapezium, trapezoid on top & capitate medially
- Lunate: capitate, hamate
- Triquetrum: hamate
Radiocarpal Jt ROM
Wrist flexion: 80 degrees
Wrist extension: 70 degrees
UD: 30 degrees
RD: 20 degrees
Compressive loading
Scaphoid and lunate: 80% of load
TFCC: 20% of load
What are the Ulnar Variances?
Ulnar Zero: normal relationship length of radius and ulna
-> 80% radius, 20% ulna
Ulnar Negative: shorter ulna in comparison to radius (more space btwn carpal bones)
-> DECREASE ULNAR LOAD, increase radial load
-> THICKER TFCC
Ulnar Positive: Longer ulna in relation to radius (less space btwn carpal bones)
-> INCREASES ULNAR LOAD, decrease radial load
-> THINNER TFCC
Scaphoid
Articulates with…
- radius, lunate, capitate, trapezoid, and trapezium
Medial surface is deeply concave and articulates with capitate
most commonly fractured
Lunate
Articulates with…
- radius, scaphoid, capitate, hamate and triquetrum
Most unstable carpal bone
Wedged btwn scaphoid and triquetrum
Deeply concave surface articulates with capaitate
most commonly dislocated
Capitate
Largest Carpal bone, located in the center
- Rigidly joined with 3 MC -> allows capitate and 3rd MC to moved as one (longitudinal stability)
Axis of rotation for all wrist motions passes through capitate
Trapezium
Distal saddle shaped articulates with base of 1st MC
- allows for greater ROM of thumb
ATHROKINEMATICS of Wrist
EXTENSION
Dorsal roll, palmar slide
RC jt
- convex surface of lunate rolls dorsally on radius, slides palmarly
MC jt
- head of capitate rolls dorsally on lunate, slides palmarly
ATHROKINEMATICS of Wrist
FLEXION
Palmar roll, dorsal slide
RC jt
- convex surface of lunate rolls palmarly on radius, slides dorsally
MC jt
- head of capitate rolls palmarly on lunate, slides dorsally
ATHROKINEMATICS of Wrist
UD/ADD
Ulnar roll, dorsal slide
RC jt.
- scaphoid, lunate, and triquetrum roll in ulnar direction, slide radially
MC jt.
- capitate rolls in an ulnar direction, slides slightly radially
ATHROKINEMATICS of Wrist
RD/ABD
Radial roll, ulnar slide
RC jt.
- scaphoid, lunate, and triquetrum roll in radial direction, slide ulnarly
MC jt.
- capitate rolls in radial direction, slides ulnarly
What is in the 1st Dorsal Compartment
- extensor pollicis brevis
- abductor pollicis longus
APL & EPB (2)
What is in 2nd Dorsal Compartment
- extensor carpi radialis longus
- extensor carpi radialis brevis
ECRL & ECLB (2)
What is in 3rd Dorsal Compartment
- extensor pollicis longus
EPL (1)
What is in 4th Dorsal Compartment
- extensor digitorum
- extensor indicis
ED & EI (2)
What is in 5th Dorsal Compartment
- extensor digiti mini
EDM (1)
What is in 6th Dorsal Compartment
- extensor carpi ulnaris
ECU (1)
Wrist Flexors
Flexors can generate more torque than wrist extensors
-> related to greater CSA
FCU has greatest wrist flexion torque based on MA and CSA
During active wrist flexion
- FCR and FCU work together as synergistic to oppose each other’s RD and UD
Radial Deviators
RD muscles generate more isometric torque than UD
active wrist extension is coupled with RD
In neutral wrist position…
- ECRL and APL have largest product of CSA and MA for RD torque
EPB has greatest MA of all radial deviators (farthest away from center)
APL and EPB provide stability
Ulnar Deviators
MA of ECU and FCU set them up to generate the most torque for UD (farther away from center)
What does the flexor retinaculum (transverse carpal ligament) do?
- attachment site for thenar and hypothnar muscles
- helps maintain transverse carpal arch
- acts as restrain against bowstringing of extrinsic flexor tendons
- protects median nerve
- forms carpal tunnel
Structures deep to flexor retinaculum
- FDS
-FDP
-FPL
-FCR
-Median nerve
What is the tunnel of guyon?
Superficial to flexor retinaculum
functions as a passageway for the ulnar nerve and artery into hand
Roof
- palmar carpal ligament
- palmaris brevis muscle
- palmar aponeurosis
Floor
- Transverse carpal ligament (flexor retinaculum)
- pisohamte lig
- pisometacarpal lig
