Wrist Joint Flashcards
What is the wrist joint also known as?
The radiocarpal joint
What kind of joint is the wrist joint?
A synovial joint
What does the wrist mark?
The area of transition between the forearm and the hand
What is the wrist joint formed by distally?
The proximal row of the carpal bones (except the pisiform)
What is the wrist joint formed by proximally?
The distal end of the radius, and the articular disc
Is the ulna part of the wrist joint?
No
What prevents the ulna from articulating with the carpal bones?
A fibrocartilaginous ligament, called the articular disc, which lies over the superior surface of the ulna
What do the carpal bones form together?
A convex surface
What shape is the radius and articular disc?
Concave
Where does the wrist joint receive blood from?
Branches of the dorsal and palmar carpal arches
What are the branches of the dorsal and palmar carpal arches derived from?
The ulnar and radial arteries
What is the wrist innervated by?
Medial nerve- anterior interosseous branch
Radial nerve- posterior interosseous branch
Ulnar nerve- deep and dorsal branches
What contributes to the stability of the wrist?
The joint capsule and ligaments
How many layers of the joint capsule of the wrist are there?
Two
What does the fibrous outer layer of the joint capsule of the wrist attach to?
The radius, ulna and proximal row of the carpal bones
What is the internal layer of the joint capsule of the wrist joint composed of?
A synovial membrane
What does the synovial membrane of the wrist joint do?
Secretes synovial fluid which lubricates the joint
What are the ligaments of note in the wrist?
Palmar radiocarpal
Dorsal radiocarpal
Ulnar collateral
Radial collateral
Where is the palmar radiocarpal ligament found?
On the palmar (anterior) side of the hand
Where does the palmar radiocarpal ligament pass?
From the radius to both rows of carpal bones
What is the function of the palmar radiocarpal ligament?
Increase stability
Ensure that the hand follows the forearm during supination
Where is the dorsal radiocarpal ligament found?
On the dorsum (posterior) side of the hand
Where does the dorsal radiocarpal ligament pass?
From the radius to both rows of carpal bones
What is the function of the dorsal radiocarpal ligament?
Contributes to the stability of the wrist
Ensures that the hand follows the forearm during pronation
Where does the ulnar collateral ligament run?
From the ulnar styloid process to the triquetrum and pisiform
What does the ulnar collateral ligament do?
Works in union with other collateral ligament to prevent excessive lateral joint displacement
Where does the radial collateral ligament run?
From the radial styloid process to the scaphoid and trapezium
What does the radial collateral ligament do?
Works in union with the other collateral ligament to prevent excessive lateral joint displacement
What type of synovial joint is the wrist?
A ellipsoid type
What does the joint being an ellipsoid type allow for?
Movement along two axes, meaning that flexion, extension, adduction and abduction can all occur at the wrist joint
What are the movements of the wrist performed by?
Muscles of the forearm
What produces flexion at the wrist?
Mainly the flexor carpi ulnaris and flexor carpi radialis, with assistance from the flexor digitorum superficialis
What produces extension at the wrist?
Mainly by the extensor carpi radialis longus and brevis, and the extensor carpi ulnaris, with assistance from the extensor digitorum
What produces adduction at the wrist?
Extensor carpi ulnaris and flexor carpi ulnaris
What produces abduction at the wrist?
Abductor pollicis longus, flexor carpi radialis, extensor carpi radialis longus and brevis
What happens in the event of the blow to the wrist?
The scaphoid takes most of the force
Who is a fractured scaphoid more common in?
The younger population
How is the scaphoids blood supply unique?
In runs distal to proximal
What can a fracture of the scaphoid disrupt?
The blood supply to the proximal portion
What can failure to revascularise the scaphoid lead to?
Avascular necrosis, and future arthritis
What is the main clinical sign of a scaphoid fracture?
Tenderness in the anatomical snuffbox
How can anterior dislocation of the lunate occur?
Falling on a dorsiflexed wrist
What happens when falling on the dorsiflexed wrist?
The lunate is forced anteriorly, and compresses the carpal tunnel
What is the result of the compression of the carpal tunnel by the lunate?
Causes the symptoms of carpal tunnel syndrome
How does anterior dislocation of the lunate manifest clinically?
Paresthesia in the sensory distribution of the median nerve and weakness of the thenar muscles
What is required when there is anterior dislocation of the lunate?
Immediate clinical attention
Why is immediate clinical attention required when there is an anterior dislocation of the lunate?
The lunate can undergo avascular necrosis
What is the most common pathology involving the wrist?
Colles’ fracture
What is the Colles’ fracture caused by?
Falling onto an outstretched hand
What can happen with radius fractures, with the distal fragment being displaced posteriorly?
The ulnar styloid process can also be damaged, and is avulsed in the majority of cases
What does Colles’ fracture produce?
‘Dinner fork deformity’
