5 Questions
Explain the factors that contribute to the variability of the range of motion (ROM) in the carpal complex.
The ROM of the carpal complex is variable due to differences in carpal kinematics, which could be attributed to ligamentous laxity, the shape of articular surfaces, and the constraining effect of muscles.
What advantages does a 2-joint complex offer over a single joint complex in providing mobility and stability?
A 2-joint complex provides a large ROM with less exposed articular surfaces and a tighter joint capsule, less tendency for structural pinch at extreme ranges, and flattened multijoint surfaces that are more capable of withstanding imposed pressures.
What structures form the wrist and hand complex?
The wrist and hand complex is formed by the radius and radioulnar discs as a part of the triangular fibrocartilage complex (TFCC) proximally, and the scaphoid, lunate, and triquetrum distally.
Describe the characteristics of the distal radius joint surface.
The distal radius has a single continuous biconcave curvature that is long and shallow side to side, and sharper and shorter anteroposteriorly.
What does the proximal joint surface consist of?
The proximal joint surface consists of the lateral.
Study Notes
Wrist and Hand Complex Biomechanics
- The hand consists of 5 digits: 1 thumb and 4 fingers.
- The hand has 8 carpal bones.
- The hand complex has 19 bones and 19 joints distal to the carpal bones.
Joints in the Digits
- Each digit has a carpometacarpal joint (CMC) and a metacarpophalangeal joint (MCP).
- Each finger has 2 interphalangeal joints: one distal (DIP) and one proximal (PIP).
- The thumb has only 1 interphalangeal joint.
Wrist Joint
- The wrist consists of 2 joints: radiocarpal joint and midcarpal joint.
Functions of the Wrist Complex
- The wrist complex controls the length-tension relationship in multiarticular hand muscles.
- The wrist complex allows for fine adjustments of grip.
- Wrist muscles are designed for balance and control, rather than maximizing torque production.
- The wrist complex is biaxial, with motions of flexion/extension (coronal axis) and ulnar deviation/radial deviation (AP axis).
Test your knowledge of the wrist and hand complex biomechanics with this quiz. Learn about the structure, bones, and joints of the hand, including the carpal bones, carpometacarpal joint, and metacarpophalangeal joint.
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