Wrist Flashcards
Describe the shape of the scaphoid bone in the sagittal plane
It has a “waist” region midway between the proximal and distal poles
The distal radius shows an ulnar tilt (anterior view) of how many degrees?
25 degrees
Ulnar tilt of the radius allows the wrist and hand to rotate farther into ___ deviation rather than ____ deviation.
ulnar
radial
Radial deviation of the wrist is limited by impingement of what against the styloid process of the radius?
lateral side of carpus against
The distal radius shows an palmar tilt (medial view) of how many degrees?
10 degrees
The 10 degrees of palmar tilt at the distal radius allows for greater movement of what motion?
greater amounts of flexion than extension at wrist
The distal articular surface of the radius is con__ in both the ML and AP directions
concave
What are a few unique characteristics of the radial articular cartilage?
There are facets from indentations made by scaphoid and lunate bones
What are the most common type of radial fractures?
Fractures of distal end of radius with dorsal displacement of distal fragment
What is the MOI for a radius fracture?
A fall over an outstretched hand
Do the palmar or dorsal side of the carpal bones form a concavity?
palmar
What ligament arches over the concavity located on the palmar side of the wrist?
transverse carpal ligament
What four bony attachments does the transverse carpal ligament attach to?
Pisiform and hook of hamate on ulnar side
Tubercles of scaphoid and trapezium on radial side
This transverse carpal ligament is the attachment site for what?
for many muscles located within hand and the palmaris longus (wrist flexor muscle)
The transverse carpal ligament and the concavity made by the carpal bones forms what structure?
The carpal tunnel
What passes through the carpal tunnel?
median nerve and tendons of extrinsic flexor muscles of digits
What are the 2 bones compressed between the distal forearm and distal row of carpals?
Scaphoid and Lunate
Because the scaphoid and lunate are compressed between the distal forearm and distal row of carpals what type of injuries are they prone to?
compression-related injuries
The scaphoid accounts for __ - __ % of all carpal fractures. Why?
60 - 70 % because it is in direct path of force transmission
Where does the scaphoid receive its blood supply?
from radial artery and branches of anterior interosseous artery
Where do people with a fractured scaphoid typically show tenderness?
Within the anatomic “snuffbox” of wrist
Where do most scaphoid fractures occur?
near or along scaphoid’s “waist,” midway b/w bone’s two poles
Describe why there may be complication of an untreated scaphoid fracture
Because most blood vessels enter the scaphoid distally, if a fracture occurs proximal to the waist avascular necrosis of the proximal pole
Does a fracture of the proximal pole of the scaphoid require surgery?
YES
How long must a fracture of the proximal pole of the scaphoid be immobilized?
at least 12 weeks
Does a fracture of the distal pole of the scaphoid require surgery?
NO
How long must a fracture of the distal pole of the scaphoid be immobilized?
5 to 6 weeks
What are associated injuries involved with a scaphoid fracture?
fracture and/or dislocation of lunate and fracture of trapezium and distal radius
What is Kienböck’s Disease characterized by?
AVN of the lunate of unknown cause
A complete collapse of the lunate is found in what type of worker?
This tends to occur more often in those involved in manual labor such as pneumatic drill operators
Describe management of mild, moderate and advanced cases of Kienböck’s disease
- In mild forms treatment may involve immobilization by casting or splinting
- In moderate cases the length of ulna or radius may be surgically altered as a means to reduce contact stress on lunate
- In advanced cases, treatments may include partial fusion of selected carpal bones, lunate excision, or proximal row carpectomy
What are the 2 PRIMARY articulation within the wrist?
radiocarpal and midcarpal joints
What type of joint is found between adjacent carpal bones?
intercarpal joints
Intercarpal joints contribute to wrist motion through what types of motions
small gliding and rotary motions that are essential for normal wrist motion
The proximal components of radiocarpal joint are con___ surfaces of radius and adjacent articular disc.
concave
What is the articular disc of the radiocarpal joint aka?
triangular fibrocartilage
Distal components of radiocarpal joint are con___ proximal surfaces of scaphoid and lunate.
convex
What 3 carpal bones are part of the radiocarpal joint?
- scaphoid
- lunate
- Triquetrum (b/c at full ulnar deviation its medial surface contacts articular disc)
Approximately __% of total compression force that crosses radiocarpal joint passes through articular disc
20
Approximately __% of total compression force that crosses radiocarpal joint passes directly through scaphoid and lunate to radius
80
When do contact areas at the radiocarpal joint tend to be greatest?
When the wrist is partially extended and ulnarly deviated
In what wrist position is grip strength maximized?
Partially extended and ulnarly deviated
The midcarpal joint is an articulation between what 2 surfaces?
proximal and distal rows of carpal bones
Midcarpal joint divided descriptively into ___ and ____ joint compartments
medial and lateral
Which midcarpal compartment is larger?
Medial
What forms the medial compartment?
convex head of capitate and apex of hamate, fitting into concave recess formed by distal surfaces of scaphoid, lunate, and triquetrum
What forms the lateral compartment?
slightly convex distal pole of scaphoid with slightly concave proximal surfaces of trapezium and trapezoid
Is there more movement at the lateral or medial compartment?
medial
