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Flashcards in Hand: Bones and muscles Deck (18):

What are some evolutionary adaptations of the human hand?

- Power grip: Use palm and fingers to manipulate objects
- Precision grip: Put thumb and finger in opposition

- Thumb is rotated in relation to fingers
- Prehensile fingers but not toes
- Thumb is relatively long in humans in comparison to other primates
- Can carry out many fine muscular movements


What are the carpal bones?

These are the most proximal bones of the hand. There are 8 bones arranged into two rows, bridged by the flexor retinaculum.

Bones (Prox-dist/Lat-med):
- Scaphoid (Some)
- Lunate (Lovers)
- Triquetrum (Try)
- Pisiform (Positions)
- Trapezoid ( They)
- Capitate (Can't)
- Hamate (Handle)


What fractures are the carpal bones subject to?

The scaphoid is most vulnerable to dislocation/fracture - blood supply to proximal half of the carpals is compromised.

The hook of hamate is also susceptible to fracture - ulnar canal syndrome or handlebar neuropathy


Describe the metacarpal bones.

Each is made up of a base, body and a head.
Numbered from I-V (thumb to pinky).
Articulate with carpal bones
Fracture usually occurs at I or V metacarpal


Describe the phalanges.

Each finger is made up of a proximal, middle and distal phalanx, except thumb, which is made of a proximal and distal phalanx.
Each is made of a base, body and head


What are the fascial compartments of the hand?

1. Hypothenar fascia
2. Thenar fascia
3. Central fascia
4. Adductor fascia
5. Interosseous fascia

At the wrist is the flexor retinaculum
There is a fibrous septum between each compartment
If there is infection/sepsis, it is compartmentalised to one fascial compartment


Palmar aponeurosis

A tightening of the fascia of the palmar surface, which allows the palm to be divided into compartments. Mostly found in the central part of the palmar surface.
Most superficial: Palmaris brevis and palmar aponeurosis.

Contracture of palmar fascia - thickening and shrinking of palmar fascia, typically affecting ring and little finger - hand of benediction


What is the flexor retinaculum?

Also known as the transverse carpal ligament
Connects the two bones on the medial side to the two bones on the lateral side.
Forms fibro-osseus roof of the carpal tunnel


What is the carpal tunnel?

Roof: Flexor retinaculum
Floor: Carpal bones
Proximal end identified by distal wrist crease
Contains flexor tendons, synovial sheaths and median nerve
Tendons run smoothly through the region, facilitated by synovial fluid form the synovial sheaths.


What structures pass superficial to the flexor retinaculum?

- PL tenon
- Ulnar artery and nerve
- Superficial branch of radial artery
- Palmar cutaneous branch of median nerve

- FCU tendon lies medial to FR


What structures pass deep to the flexor retinaculum?

- FDS (x4 tendons)
- FDP (x4 tendons)
- Median nerve - recurrent thenar branch and lateral and medial branch
- FCR (within roof of carpal tunnel)
- Synovial sheaths


What is the extensor retinaculum?

- Radius laterally
- Triquetrum, pisiform, FCU tendon medially

- Six tunnels
- Nine tendons: 11 in total, 2 don't go all the way through - Brachiradialis and supinator
- Synovial sheaths

1. APL + EPB
3. EPL
4. ED + EI
5. EDM
6. ECU


Describe the anatomical snuffbox.

- Anteriorly: Tendons of APL and EPB
- Posteriorly: Tendon of EPL

Roof: Skin, subcutaneous tissue, cephalic vein, superficial branch of radial nerve

Floor: Scaphoid and trapezium

Contains the radial artery.


Which intrinsic muscle of the hand are present in layer 1?

Thenar muscles:
- Abductor pollicis brevis (AbdPB)
- Flexor pollicis brevis (FPB)

Hypothenar muscles:
- Abductor digiti minimi (AbdDM)
- Flexor digiti minimi (FDM)

Arise from edges of flexor retinaculum
Insert into base of proximal phalanx


Which intrinsic muscles of the hand are present in layer 2?

Lumbricals (x4)
Arise from FDP tendons
Pass to lateral sid eof digit
Insert dorsally into extensor expansion of digits 1-4
Flex at IP joints but not MCP joints (remains straight)


Which intrinsic muscles of the hand are present in layer 3?

Thenar muscles:
- Opponens pollicis (OP)
- Adductor polliis (AddP) - fan shaped muscle in 1st web space

Hypothenar muscles:
- Opponens digiti minimi (ODM) - arrise from edges of flexor retinaculum and instert along borders of MC


Which intrinsic muscles of the hand are present in layer 4?

- 3 palmar (adduct; pAd)
- 4 dorsal (abduct; dAb)
- Arise from metacarpals
- Pass to lateral side of digit
- Insert into extensor retinaculum (digits 1-4)


Nerve supply of intrinsic muscles of the hand

Median nerve:
- Recurrent branch: AbdPB, FPB, OP
- Lateral branch: 1st and 2nd lumbrical

Ulnar nerve:
- Deep branch: AbdDM, FDM, ODM, AddP, 3rd and 4th lumbrical.