Hand bones Flashcards
What do the bones of the hand provide?
Support and flexibility to the soft tissues
What can the bones of the hand be divided into?
Carpal bones
Metacarpals
Phalanges
What are the most proximal bones of the hand?
Carpal bones
What are the carpal bones?
A set of 8 irregularly shaped bones
Where are the carpal bones located?
In the wrist area
How many metacarpals are there?
5- one related to each digit
What are the phalanges?
The bones of the fingers
How many phalanges does each finger have?
3, apart from the thumb, which has two
How are the carpal bones organised?
Into two rows, proximal and distal
What are the carpal bones in the proximal row (lateral to medial)?
Scaphoid
Lunate
Triquetrum
Pisiform
What kind of bone is the pisiform?
A sesamoid bone
What is the pisiform formed with?
The tendon of the flexor carpi ulnaris
What are the carpal bones of the distal row (lateral to medial)?
Trapesium
Trapezoid
Capitate
Hamate
What does the hamate have?
A projection on its palmar surface, called the hook of hamate
What articulates with the radius proximally?
The scaphoid and lunate
What do the carpal bones in the distal row articulate with?
The metacarpals
What are the carpal bones most commonly fractured?
The scaphoid and lunate
What is the usual mechanism of injury for fracture of scaphoid and lunate?
FOOSH (falling on outstretched hand)
What is the classical clinical feature of a scaphoid fracture?
Pain and tenderness in the anatomical snuffbox
What needs to happen to a scaphoid fracture?
It needs to be reduced quickly
Why does a scaphoid fracture need to be reduced quickly?
As the blood supply to the proximal part of the bone can be cut off, causing it to undergo avascular necrosis
What are patients with a missed scaphoid fracture likely to develop?
Arthritis later in life
When does a lunate fracture occur?
When there is hyperextension at the wrist
What is a lunate fracture associated with?
Damage to the median nerve
What do the metacarpal bones articulate with?
Proximally, with carpals
Distally, with proximal phalanges
What are the metacarpal bones?
Metacarpal I- thumb Metacarpal II- index finger Metacarpal III- middle finger Metacarpal IV- ring finger Metacarpal V- little finger
What does each metacarpal consist of?
A base, shaft, and a head
What is true of the medial and lateral surfaces of the metacarpals?
They are concave
Why are the medial and lateral surfaces of the metacarpals concave?
Allowing attachment of the interoessei muscles
What are the common fractures of the metacarpals?
Boxer’s fracture
Bennett’s fracture
What is the Boxer’s fracture?
A fracture of the 5th metacarpal neck
What is the Boxer’s fracture usually caused by?
A clenched fist striking a hard object
What happens in the Boxer’s fracture?
The distal part of the fracture is displaced posteriorly, producing a shortening of the affected finger
What is a Bennett’s fracture?
A fracture of the first metacarpal base, extending into the carpometacarpal joint
What is Bennett’s fracture caused by?
Hyperabduction of the thumb
