Exam2 Flashcards
Describe the difference between course lines and papillary ridges in the hand.
Course Lines: Flexion folds or skin joints, located where skin ADHERES to the deeper FASCIA, permits the hand to close without the skin bunching up into folds
Papillary Ridges: at volar pulps of digits & over thenar/hypothenar eminences, provide friction to increase the efficacy of the hand during grip, also rich with sensory nerve endings, commonly known example are fingerprints
Skin at the [volar/dorsal] side of hand is thick, inelastic, rich in sensory receptors, and supplied with sweat glands. Skin is [loosely/firmly] attached to connective tissue, called the __ which prevents slippage while grasping.
VOLAR. FIRMLY attached to CT, PALMAR APONEUROSIS
With hand flexion, we see a convergence toward the ___. This facilitates___ [movement direction of the fingers with the thumb and results in a grip that is tighter on the [radial/ulnar] side. When can this go wrong?
Converges on the SCAPHOID TUBEROSITY. Facilitates OPPOSITION of fingers with the thumb –> grip that is tighter on ULNAR side. With a fx malunion, you may get crossing over of fingers during grip, which is NOT normal.
Describe the 3 skeletal arches.
1) Proximal transverse (through distal row of carpals)
2) Distal transverse (through metacarpal heads)
3) Longitudinal (Through length of digits and carpus; perpindicular to other 2 arches!)
The ulna [does/does not] directly articulate with the carpals. Explain.
Ulna DOES NOT articulate with carpals, but instead articulates with TRIANGULAR FIBROCARTILAGE COMPLEX (TFCC)
The wrist consists of (#) compound joints. Name them!
2 compound joints (meaning they have 3 or more articulating surfaces.
(1) Radiocarpal joint
(2) Midcarpal joint
The TFCC stands for __. It is an extension of the ___ and is made up of ___. It consists of ___ and ___ which provide the primary support for what joint?
The TFCC stands for TRIANGULAR FIBROCARTILAGE COMPLEX. It is an extension of the DISTAL RADIUS and is made up of CONNECTIVE TISSUE STRUCTURES. It consists of RADIOULNAR ARTICULAR DISC and LIGAMENTS which provide the primary support for the RADIOULNAR JOINT
When you apply a LONGITUDINAL compressive force to the neutral wrist, what is the force distribution across bones?
TFCC gets ~20% of load
Scaphoid and lunate get ~80% total
What’s the purpose of the pisiform? What does it articulate with?
Pisiform = sesamoid bone that articulates with the TRIQUETRUM
- It is enveloped by the FCU and functions to increase the moment arm of the FCU
In the radiocarpal joint, the radius articulates with what carpal bones? The ulna?
Radius articulates with the scaphoid and lunate. Ulna does NOT articulate directly with any carpels, but instead articulates with the TFCC.
The wrist is tilted [volarly/dorsally] ___ degrees. The length of the radius is ___mm greater than the ulna, leading to a ___ inclination. Put both in layman’s terms.
1) 11* volar tilt
2) Radius is 12mm longer than ulna –> 23* radial inclination, aka toward ulnar deviation.
This means that the wrist is capable of MORE FLEXION than extension and MORE ULNAR DEV than radial deviation
What is a FOOSH?
Slang term for “Fall on outstretched hand”
What is Colles’ Fx?
Most common skeletal fx, complete fx of distal radius with DORSAL displacement of the DISTAL fragment (so proximal radius displaces in VOLAR direction). Frequently results from a FOOSH. Ulna not necessarily involved
Reduction of a Collies’ Fx results in a loss of the volar angulation of the radius. This reduces what motion?
Collies Fx results in loss of VOLAR angulation, thus reducing FLEXION (and can actually gain more extension than at baseline!)
What is it called when there is a change in the relationship of the ulna to the radius (think length)?
ULNAR VARIANCE
Positive ulnar variance can potentially impinge the __.
Positive ulnar variance = longer ulna compared to distal radius, and potentially impinges on TFCC
A negative ulnar variance can cause ___ and___
Negative ulnar variance can cause ABNORMAL FORCE DISTRIBUTION and DEGENERATION AT RADIOCARPAL JOINT
___ is associated with negative ulnar variance.
Kienbock’s Disease = avascular necrosis of the LUNATE is associated with negative ulnar variance.
What carpels articulate with which metacarpals?
1st metacarpal: Trapezium 2nd Metacarpal: Trapezium, Trapezoid, Capitate 3rd metacarpal: Capitate 4th metacarpal: Capitate, Hammate 5th Metacarpal: Hammate
The ulnar a and n travel around what bony structure? Injuries here can lead to avascularity and neural problems
Hook of hammate
Which row of carpals allows more movement?
PROXIMAL: interosseous joints in that row are small and allow motion between mutually articulating bones in flex/ext plane.
What ligament attaches the scaphoid and lunate? What can happen if this ligament ruptures?
Scapholunate ligament
DISI: Dorsal intercollated scaphoid instability…scaphoid sneaks forward into flexion, Lunate follows triquetrum into extension, and capitate sneaks down into proximal carpel row!
What muscles are primary digit flexors with SECONDARY actions at the wrist?
FDS, FDP, FPL
Primary wrist flexors
FCR, FCU, PL
The work capacity of the wrist [flexors/extensors] is 2x greater than the [flexors/extensors]
Work capacity of wrist FLEXORS is 2x greater per cross sectional unit than extensors
Which wrist flexors do NOT travel under the flexor retinaculum?
Pollicus longus, Flexor carpi ulnaris
The palmaris longus is found unilaterally or bilaterally in __% of the population. The rest of the people are [SOL/Fine]
PL found in 86% of population. Rest of people are sad, but they have no apparent strength of functional deficit at the wrist
Primary wrist extensors
ECRL, ECRB, ECU
[All/some/none] of the wrist extensors pass under the extensor retinaculum
ALL 9 wrist extensors pass under extensor retinaculum
