The extensor tendons and expansions, long tendons of the thumb, actions of IO and lumbricals, Joints of the carpus (dave's notes) Flashcards
Describe the characteristic insertion of the extensor tendons
The tendon crosses the MCP joint partly forming the capsule, then splits into three slips; central inserts into the middle phalanx, lateral slips are augmented by the interosseous and lumbricals to be inserted into the terminal phalanx
What are the long tendons of the thumb?
Flexor: only one, FPL
Extensor surface EPB and EPL are inserted separately
What does a power grip depend on?
What can weaken this grip?
The long flexors of the fingers with opposition of the thumb giving a tight grip.
Increasing flexion at the wrist weakens this grip.
What does a precision grip depend on?
Requires wrist stability, with opposition of the fingers and thumb important aspects
What is the action of the interossei and lumbricals?
PAD DAB
When acting together they flex the digits
What is another role of the lumbricals
The lubricals are attached to the extensor expansions and have a proprioceptive role. Their exact role and function is still somewhat undecided.
Describe the joints of the carpus
An s-shaped joint exists between the two rows of carpal bones extending proximally and distally. This is a continuous synovial space.
What also exists between the distal fowl of carpal bones?
A carpometacarpal space exists between the distal row of carpal bones. These often communicate with each other.
What is a separate synovial cavity between the trapezium and first MC bone?
The 1st CMC joint
Describe the MCP joints type, action
Synovial
Flex, extend, abduct, adduct.
With the joints lying in an arc -> extended fingers fan out and flexed fingers crowd in.
Describe the interphalangeal joints. What limits extension here?
Pure hinge joints, with extension limited due to the palmar ligaments and obliquity of the collateral ligaments.
