Musculature of the Hand Flashcards
Name the 4 flexor muscles
- FDS: Flexor digitorum superficialis
- FDP: Flexor digitorum profundus
- FPL: Flexor pollicis longus
- APL: ABductor pollicis longus
Name 5 extensor muscles
- EPB: Extensor pollicis brevis
- EPL: Extensor pollicis longus
- EDC: Extensor digitorum communis
- EIP: Extensor indicis proprius
- EDQ, EDM: Extensor digiti minimi
Name the 4 muscles found in the thenar imminence
- OP: opponens pollicis
- FPB: flexor pollicis brevis
- APB: ABductor pollicis brevis
- ADductor pollicis brevis
Name the 3 muscles of the hypothenar imminence
- ODM: opponens digit minimi
- ABductor digiti minimi
- Flexor digiti minimi
How many lumbricals?
4
How many volar (palmar) interossei?
3
How many dorsal interossei?
4
At the wrist, which tendons go under the flexor retinaculum in the ulnar bursa?
FDS and FDP, the divide into 4 tendons each
What is the purpose of the flexor retinaculum?
tethers down the tendons to avoid bowstringing
What do bursas provide?
synovial fluid for tendon gliding to reduce friction
What enters hand in the radial bursa?
FPL
Which nerve also goes under the flexor retinaculum?
Median n.
The ulnar bursa ends at mid palm, so the flexor tendons enter the fingers after passing through what?
A-1 pulley: Annular Pulley (another structure that tethers down the tendons)
What alternates with the annular pulleys?
cruciate pulleys (x shaped)
What is the purpose of the Cruciate pulleys?
fewer in # and weaker so it gives flexibility to the flexor system
Bowstringing of the fingers are due to congenital absence of what?
pulleys
What is the only flexor of the DIP joint?
FDP (it can also flex the PIP joint)
What tethers down and helps the thumb to avoid bowstringing?
2 annular pulleys and an oblique pulley
What is the only flexor of the PIP of the thumb?
FPL
On the dorsum of the hand is another retinaculum. What is its purpose and what muscles enter the hand under it?
PURPOSE: tethers down tendons;
Muscles: all extrinsic extensors and thumb ABductor
The extrensic extensors go through compartments/canals into the hand. What do these compartments do?
Help with smooth gliding of tendons (they are synovial)
The ABductor pollicis longus ________ motion of opposition by moving thumb metacarpal anterior and lateral.
initiates
Only extensor of the PIP of the thumb.
EPL (synergist with Extensor Pollicis Brevis to extend the MP joint of the thumb)
Which muscle tendon proceeds past the MCP joint then divides into 3 parts.
EDC
Extensor Digitorum Communis expansion mechanism
Name the 3 parts of the EDC expansion mechanism
- central tendon
- lateral bands
- lateral bands joining with retinacular ligaments
What are the 2 kinds of retinacular ligaments?
- transverse
2. oblique
What 3 muscles allows extension of the digits to occur?
- extensor digitorum
- digit II: also Extensor Indicis
- digit V: also Extensor digiti minimi
What 3 injuries can be associated with the Extensor Mechanism?
- mallet finger
- swan neck
- boutonniere deformity
What is the decription of mallet finger?
A. injury to terminal extensor tendon and presents as DIP flexion
B. DIP is pulled into flexion by the FDP and PIP hyperextends due to imbalance
C. presents as PIP flexion, lateral bands slip below asix of PIP joint
A. injury to terminal extensor tendon and presents as DIP flexion
What is Boutonniere Deformity?
A. injury to terminal extensor tendon and presents as DIP flexion
B. DIP is pulled into flexion by the FDP and PIP hyperextends due to imbalance
C. presents as PIP flexion, lateral bands slip below asix of PIP joint
C. presents as PIP flexion, lateral bands slip below asix of PIP joint
What is Swan Neck Deformity?
A. injury to terminal extensor tendon and presents as DIP flexion
B. DIP is pulled into flexion by the FDP and PIP hyperextends due to imbalance
C. presents as PIP flexion, lateral bands slip below asix of PIP joint
B. DIP is pulled into flexion by the FDP and PIP hyperextends due to imbalance
TRUE or FALSE:
If mallet finger is not fixed, it can become a fixed deformity.
TRUE
What can be a result of untreated mallet finger?
Swan Neck
With a Swan Neck Deformity, does the lateral band slip ABOVE or BELOW the axis of flexion?
ABOVE
With which deformity can the DIP be drawn into extension if the lateral bands become contracted?
Boutonniere Deformity
Which intrinsic hand muscles do ABduction?
4 dorsal interossei
Which intrinsic hand muscles do ADDuction?
3 volar interossei
Which interossei contribute to IP extension of digits?
dorsal interossei (with lumbricals, EDC, and retinacular ligament)
Which interossei help lumbricals to do MP flexion?
volar interossei
Which muscles flex MCP joint and extends IP joints?
lumbricals
The “Quad Group” that extends the IP joints consists of what?
- lumbricals
- interossei
- EDC
- OPL
What flexes the MP joint of the thumb?
flexor pollicis brevis (FPB)
What abducts thumbs perpendicular to the palm?
Abductor Pollicis Brevis
What does the Opponens Pollicis muscle do?
opposes thumb metacarpal toward the middle of the palm and rotates it
