Hand questions Flashcards
- Describe the arches of the hand including the keystones for each.
- Transverse Proximal Arch is made of the distal carpals and the keystone is the capitate.
- Transverse Distal Arch is made of the MCP joints. The keystones are the 2nd and 3rd MCP.
- Longitudinal Arch is made of the 2nd and 3rd ray. The keystones are the 2nd and 3rd MCP.
- Describe the voluntary degrees of freedom of the 1st CMC and the MCP, PIP, DIP joints of the fingers.
1st CMC: 2 MCP: 2 PIP:1 DIP:1
- Describe the convex/concave behavior of the 1st CMC and the MCP, PIP, DIP joints of the fingers.
- 1st CMC: Saddle joint; Abduction is vex/cave. Flex/ext if cave/vex
- MCP: Cave/vex
- PIP: Cave/vex
- DIP: Cave/vex
- Describe the attachment points of the ligaments if the 1st CMC.
see image
- Describe the Zig Zag deformity.
can happen in any finger, but one relatively common deformity involves CMC joint flexion and adduction, MCP joint hyperextension, and IP joint flexion
In class notes:
Ruptured UCL and AOL at 1st CMC
dislocation of the 1st CMC
Adductor pollicis goes into spasm (and probably some other muscles too)
Hyperextension of MCP occurs in an attemot maintain function. uses extensor pollicis longus and brevis.
This increases the internal moment arm of EPL and EPB which eventually breaks the palmar plate.
Passive tension in FPL causes flexion at the IP joint.
- Describe the attachment sites of the collateral ligaments of the MCP joints of the fingers.
Radial and Ulnar collateral ligamanets have proximal attachment on the posterior tubercle of the metacarpal head.
- Cord Fibers attach distally to palmar aspect of the proximal end of the phalanx
- Accessory Fibers attach distally to palmar plate
Palmar plate
proximal end attaches to the metacarpal bone
distal end of each plate attaches to the base of each proximal phalanx
- Describe the palmar dislocation of the MCP joints of the fingers.
Basically bowstringing force at A1 (which attaches to the palmar plate) pulley breaks collateral ligamants of the MCP. Proximal phalanx dislocates palmarly. See image.’
- For the fingers, List MCP, PIP, DIP flexors/extensors
MCP Flexors
FDS, FDP, I and L
MCP extensors
ED, EI, EDM
PIP Flexors
FDS, FDP
PIP Extensors
EI, ED, EDM I and Ls
DIP Flexors
FDP
DIP Extensors
I and Ls
Little finger (NOT COMPLETE)
MCP flex
FDM ADM FDSFDP I L
PIP Flex
FDP, FDP,
DIP FLex
FDP
- List MCP flexors/extensors of the thumb.
MCP Flexors
FPL, FPB, APB Add P
MCP Extensors
EPL, EPB,
IP Flex
- FPL
IP ext
- EPL, a little of addPL/abdPL not sure which one.
List flexor/extensors of the IP joint of the thumb.
IP Flex
FPL
IP ext
EPL, a little of addPL/abdPL not sure which one.
- List abductors/adductors of the CMC joint ofthe thumb.
Abduction:
- AbPL, APB, FPB
- Adduction:
- Discuss the location, attachment and function of the flexor pulleys.
A1 attches to proximal palmar plate
fuck it
- Define Tenodesis
Actively extending the wrist and observing the passive flexion of the fingers and thumb
- Demonstrate an extrinsic plus hand; and intrinsic plus hand.
see image
As described in Figure 8-48, simultaneous contraction of the intrinsic muscles of the fingers (lumbricals and interossei) produces a combined MCP joint flexion and IP joint extension. This position of the hand is referred to as the intrinsic-plus position.
In contrast, simultaneous contraction of the extrinsic muscles of the fingers (extensor digitorum, flexor digitorum superficialis, and flexor digitorum profundus) produces MCP joint hyperextension and IP joint flexion: the extrinsic-plus position. A very important kinesiologic principle of the hand is that most functional or complex digital movements require a synergistic blending of these two opposite actions. This point is reinforced in the next sections.
15a. Describe the extensor mechanism
15b. Describe the Flexor mechanism
1
- Describe the mechanism of a swan neck deformity.
Caused by the rupture of the palmar plate.
hyperextension of the PIP joint with flexion at the DIP joint caused by weakened palmar plates at the PIP joint, the tension within the intrinsic muscles may eventually collapse the PIP joints into hyperextension (Figure 8-60, A). The hyperextended position of the PIP joint causes the lateral bands of the extensor mechanism to bowstring dorsally, away from the joint’s axis of rotation
- Describe the mechanism of a Boutonniere deformity.
Central band is torn near PIP
flexion of the PIP joint and hyperextension of the DIP joint
The interphalangeal joints collapse essentially in a reciprocal pattern to that described for the swan-neck deformity. The primary cause of the boutonniere deformity is abnormal displacement of the bands of the extensor mechanism at the PIP joint and rupture of the central band, usually the result of chronic synovitis. The lateral bands slip toward the palmar side of the axis of rotation at the PIP joint (see Figure 8-60, B). Consequently, forces transferred across the slipped lateral bands (either from active or passive sources) cause flexion at the PIP joint instead of normal extension. Essentially, the PIP joint loses all sources of extension.
- Describe the mechanism of a Ulnar drift of the MCP joints of the fingers.
Notes from class
Radial tranverse fibers (sagittal bands) rupture because were have ulnar directed forces caused by FDS, FDP and ED.
RA seems to only affect the radial collateral ligament of the MCP.
excessive ulnar deviation and ulnar translation (slide) of the proximal phalanx.
relentless, ulnar-directed forces applied against the proximal phalanges of the radial fingers. These forces are produced by contact from hand-held objects and large “pinching” forces generated by the flexor muscles of the thumb. Figure 8-59, A shows these ulnar-directed forces pushing the index finger in an ulnar direction. The subsequent ulnar deviation of the MCP joint increases the ulnar deflection—or bend—in the extensor digitorum (ED) tendon as its crosses the dorsal side of the joint. The deflection creates a potentially destabilizing bowstringing force on the tendon.
- What structure limits the hyperextension of the MCP joints?
Palmar plates!
- The collateral ligamanets of the MCPs are tight in what position?
flexion
- When casting the hand, where are the MCP IP joints placed in terms of flexion and extension?
70 degrees MCP flex and 15 pip amd dip flex for broken metacarpal.
For Neuro:
The position of function incorporates the following: wrist, 20 to 30 degrees of extension with slight ulnar deviation; fingers, 35 to 45 degrees of metacarpophalangeal (MCP) joint flexion and 15 to 30 degrees of proximal interphalangeal (PIP) and distal interphalangeal (DIP) joint flexion; and thumb, 35 to 45 degrees of carpometacarpal (CMC) joint abduction. These positions may vary based on the patient’s underlying physical or medical condition.
How does RA cause a zig zag deformity of the hand?
Internal moment arm of ECRB and ECRL is increased causing ulnar shift of the carpals, radial deviation of the metacarpals and ulnar deviation o fthe phalanges.
