25 - Hand Flashcards
What do I need to know?
- Bones in hand, how they articulate, movements allowed at each joint
- Muscles and tendons in palm
- Movements of thumb and fingers and muscles
Bones of the palm?
MCs
Why and how is the 1st MCJ an exception?
- is very mobile
- is a SADDLE joint (reciprocal concave and convex between trapezium and 1st MC)
- permits as much movement as nearly ball in socket (flex/ext, abd/add, little rotation)
The metacarpo-phalangeal joints (knuckles) are … joints and permit ……..
Condyloid joints and permit flexion/extension, abduction/adduction and some rotation
The interphalangeal joints are … joints and permit …
Pure hinge joints and permit only flexion/extension
Triaxial Joint?
Diaxial Joint?
Hinge Joint/uniaxial?
Moves in 3 planes (ball in socket) > femur
Moves in 2 planes > finger joints/MCP joints
Moves in 1 plane > elbow
How does the 1st MCP joint differ from the others?
LESS movement
- only allows flexion/extension as is designed more like IP joint
MCP joints?
- condyloid joint
- 1 curved condyle articulates with corresponding condyle
- allows flex/ext and abd/add
IP joints?
- hinge joints (flex/ext) due to 2 condyles and 2 points of contact
What prevents abduction/adduction at IP joints?
Collateral ligaments (and 2 condyles)
What are the important ligaments of the finger?
There are 3
- Palmar Ligament
- Collateral ligaments
- Deep Transverse Metacarpal ligaments
Collateral ligaments?
Sides of the MCP and IP joint capsules are thickened and are the main strengthening components of the joints
Palmar Ligaments?
Soft felt-like channels on the anterior of the joints. They form the FLOOR of the interosseous tunnels which house the long flexor tendons
What forms the floor of the fibrosseous tunnels and what do they do?
Palmar ligaments of anterior joints (MCP and IP). House the long flexor tendons
Deep Transverse Metacarpal Ligaments?
Span the LATERAL 4 MCP joints to stop oversplaying of the hand/palm. Attach to the sides of the palmar ligaments
Fibrosseous Tunnels?
Flexor tendons are wrapped in fibrous digital sheaths which attach to the palmar ligaments and bones to prevent bowstringing at the fingers
> beneath this they are wrapped in a bursa/synovial sheath which are slack enough to lubricate the tendons
What tendons are in the common synovial sheath?
FDS and FDP
What synovial sheath/bursa is in communication with the common synovial sheath around most of the flexor tendons at the carpal tunnel?
The little finger synovial sheath is. This means infection can be spread to the tendons at the carpal tunnel which can cause swelling - nerves and soft structures get compressed and damaged (Carpal Tunnel Syndrome)
What flexor tendon has its own synovial sheath?
FPL
Purpose of the intrinsic muscles of the hand?
To position the hand for power muscles to get a grip
The interossei muscles pass on the … side of the …
Dorsal side of the transverse metacarpal ligaments
What muscles abduct the fingers and how many are there?
DIMAB
Dorsal Interossei
4 (little and thumb don’t have)
What muscles adduct the fingers and how many are there?
POMAD 4 (thumb is considered deep head of Flexor Pollicis Brevis as flexes doesn't adduct at 1st MCP joint)
Dorsal Interossei?
> Insert Into the Midline and ABduct (DIMAB)
> bipennate (2 origins at the base of neighbouring MCs)
Flexion of IP joints occurs by FDS and FDP but no forearm muscles inserts into PROXIMAL phalynx. Then how do the MCP joints flex?
- partially by FDS and FDP during max shortening (tight fist)
- fine control achieved by interossei and lumbricals with insertions into the DDEH
> these muscles are complex and can flex the MCP joints while extending IP joints (pinch grip/thread a needle)
Adductor Pollicis?
- has own adductor as opposes fingers
O: Metacarpals and carpals of MIDDLE finger
I: Base of proximal phalynx
> ulnar nerve
> strongest intrinsic muscle
> radial artery runs behind the base of the thumb and re-enters the hand between the 2 heads of the 1st dorsal interossei and 2 heads of adductor pollicis and then forms an arched arterial supply
Does the little finger have its own adductor?
NO - it has its own abductor but not adductor. It has a palmer interossei. The THUMB has its own adductor
Where does the radial artery run?
Runs behind base of thumb
Re-enters through 2 heads of 1st dorsal interossei and 2 heads of adductor pollicis
