Wrist/Hand Complex Flashcards
What are the two points of consensus in regards to the wrist complex?
- Structure and biomechanics of wrist and hand vary tremendously from person to person
- Even subtle variations can produce differences in the way a given function occurs
What are the bones of the radiocarpal joint, and midcarpal joints?
Radiocarpal - radius with scaphoid, lunate, triquetrum
Midcarpal - schaphoid, lunate, triquetrum with trapezium, trapezoid, capitate, and hamate
What is joint type of wrist joint?
Conyloid
What is the benefit of have a 2 joint system (radiocarpal and midcarpal joints)?
- Permits large ROM with less exposed articular surface and tighter joint capsules
- Less tendency for structural pinch at extremes of motion
- Allows for flatter multi-joint surfaces that are more capable of withstanding imposed pressures
What is the radiocarpal joint structure?
Proximal - concave surface of radius
Distal - convex proximal surfaces of scaphoid and lunate, triquetrum
The small and difficult to isolate wrist ligaments are essential for?
- Maintaining intercarpal alignement
2. Transferring forces within and across carpals
True/False: wrist has only extrinsic ligaments
False: Described as extrinsic (proximal attachment on forearm and attach distally at wrist) and intrinsic (both proximal/distal attachment in wrist complex)
What is the triangular fibrocartilage complex (TFCC)?
- Functions to bind distal ends of ulna and radius while allowing radius to rotate (pronate/supinate) around fixed ulna
1. Reinforces ulnar side of the wrist
2. Transfers compression forces
What is the purpose of the extensor retinaculum?
-Functions to prevent bowstringing with active movement of wrist
What is the purpose of the the palmar carpal ligament?
-Stabilized wrist flexor tendons and prevents excessive bowstringing during flexion
What are factors that contribute to carpal tunnel syndrome?
- Overcrowding
- Excessive mechanical stress (occupation related)
- Fibrotic changes of CT
What structures in general pass through the carpal tunnel?
9 Extrinsic flex tendons and median nerve
Describe the osteo of the radiocarpal and midcarpal joints.
Flex/ext
Radial/ulnar deviation
Describe the arthrokinematics of the radiocarpal and midcarpal joints.
-Convex on concave
Flex - anterior roll/posterior glide
Ext - posterior roll/anterior glide
Radial deviation - lateral roll, medial glide
ulnar deviation - medial roll, lateral glide
What is the open pack position and capsular pattern for the radiocarpal joint?
Open pack = neutral frlex/ext with slight ulnar deviation
Capsular pattern = flexion = extension, slight radial and ulnar deviation
What is the main function of wrist extensors?
- Position and stabilize wrist within activities that require active flexion of digits
- Act to counterbalance wrist flexion torque produced by finger flexor muscles
What degree of extension do you have max grip?
30 - optimizes the length tension relationship of extrinsic finger flexors
How do flexor carpi ulnaris and radialis work synergistically?
To oppose ulnar and radial deviation during active wrist flexion
Peak wrist flexion torque is what degree of wrist flexion?
40
What are the joints of the hand?
CMC, MCP, PIP, DIP
What type of joints are the 5 carpometacarpal joints?
1st = saddle 2nd-5th = plane
Describe the osteo of the 1st CMC joint
1st = flex/ext, abd/add, opposition/reposition
Describe arthro of 1st CMC joint
Abduction/Adduction
-Convex surface of thumb MC moving on concave trapezium
Abduction = anterior roll, posterior glide
Adduction = posterior roll, anterior glide
Describe arthro of 1st CMC joint
Flexion/extension
-Concave surface of MC moving on convex diam or trapezium
Flex = medial roll and glide
Ext = lateral roll and glide
Describe arthro of 1st CMC joint
opposition/reposition
Opposition = abduction/ flex reposition = adduction/ext
Describe the osteo and arthro of the 2nd-5th CMC joint
Osteo = Flex/ext Arthro = undetermined
What is the open pack and capsular pattern for the 1st CMC joint?
Open pack = mid flex/ext and mid abd/add
Capsular pattern = abduction
What is the open pack for the 2nd-5th CMC joint?
Open pack = Mid flex/ext
What are the osteo of the metacarpophalangeal joints?
Flex/ext
abd/add
What are the arthrokinematics of the metacarpophalangeal joints?
-Concave phalanx moving on convex MC head Flex - anterior roll and glide Ext - posterior roll and glide Abd - roll and glide away from 3rd digit Add - roll and glide toward 3rd digit
What are the osteo of the interphalangeal joints?
Flex/ext
What are the arthrokinematics of the interphalangeal joints?
-Concave on convex
Flex = roll anterior, glide anterior
Ext = roll posterior/glide posterior
What are the open pack positions and capsular pattern of the metacarpophalangeal joints?
Open pack = Slight flex
Capsular pattern = flex = ext
hat are the open pack positions and capsular pattern of the interphalangeal joints?
Open pack = slight flex
Capsular pattern = flex = ext
Describe the function of the flexor mechanism.
Flexor pulleys embedded within fibrous digital sheath
-Functions to prevent bowstringing of tendons with contraction of extrinsic finger flexors
Clinical application of flexor mechanism:
Trigger finger - flex finger and when unflex, one gets stuck
Describe the anatomy of the extensor mechanism.
Anatomy - distal to wrist, ext lack digital sheath or pulley system
- tendons become integrated into extensor expansion
- remaining tendon flattens into a central band -> divides into 2 lateral bands before crossing PIP -> reconverge into single terminal tendon
Describe the function of the extensor mechanism.
Function - stabilizes ED tendon, forms sling that assists ED to extend MCP joint and transfers force from lumbricals/interossei to lateral bands to assist with PIP and DIP ext
