Forearm and Wrist Flashcards
What joint is the wrist?
The radiocarpal joint
What forms the radiocarpal joint?
Articulation between the distal radius and 2 of the carpal bones: scaphoid and lunate N.B. the ulna is NOT involved
What type of joint is the wrist?
Synovial joint
What ligaments strengthen the wrist joint? Where do they strengthen it?
Radiocarpal ligaments strengthen the joint anteriorly and posteriorly
Where does the radius sit in relation to the ulna?
Radius is thumb side Ulna sits medial side (closest to body)
What does the radius and the ulna both articulate with proximally?
The humerus (= elbow)
Where do the radius and ulna articulate with each other? What movement is this responsible for?
At the proximal and distal radioulnar joints Pronation and supination
What membrane connects the radius and ulna?
A strong interosseous membrane (IOM)
The IOM has holes/apertures in it. What does this allow?
Allows the passage of vessels
Diagram of bones of the forearm
What is the radial styloid/styloid process?
Bony projection at distal end of radius
What muscle inserts on the ulna tuberosity?
Brachialis
What muscle inserts on the radial tuberosity?
Biceps
What is the ‘carpus’?
The wrist
How many bones make up the carpus?
8 small bones arranged in 2 rows
What are the names of the 8 bones of the carpus?
- Lunate
- Triquetral
- Pisiform
- Hamate (hook)
- Capitate
- Trapezoid
- Trapezium (thumb)
- Scaphoid
What are the bones in the wrist and hand separated into?
Heading from wrist towards fingertips:
- Carpals
- Metacarpals
- Proximal phalanges
- Intermediate phalanges
- Distal phalanges
How do the bones of the thumb differ?
Only have 2 phalanges: proximal and distal (no intermediate)
How many phalanges are found in the 4 fingers?
3; proximal, intermediate, distal
What joints are found in the hand?
- Carpometacarpal (CMCJ)
- Metacarpophalangeal (MCPJ)
- Interphalangeal joint (IPJ) of the thumb
- Proximal interphalangeal (PIPJ)
- Distal interphalangeal (DIPJ)
What joint is found between the carpals and the metacarpals?
The carpometacarpal joint (CMCJ)
What joint is found between the metacarpals and the proximal phalanges?
The metacarpophalangeal (MCPJ)
What joint is found between the proximal phalanges and the intermediate phalanges?
Proximal interphalangeal joint (PIPJ) –> only found in the 4 fingers
What joint is found between the intermediate phalanges and the distal phalanges?
The distal interphalangeal joint (DIPJ)
What joint is found between the proximal phalanges and the distal phalanges in the thumb?
Interphalangeal joint (IPJ) of the thumb
What joint is only found in the 4 fingers?
Proximal interphalangeal joint (PIPJ)
What joint is only found in the thumb?
The interphalangeal joint (IPJ) of the thumb
What can the forearm muscles move?
Contains muscles that move the wrist, elbow, proximal radioulnar joint, thumb and fingers
What are the 2 muscle compartments in the forearm?
Anterior and posterior
How do muscles in the anterior compartment of the forearm move the wrist?
Flex the wrist (and digits)
How do muscles in the posterior compartment of the forearm move the wrist?
Extend (straighten) the wrist (and digits)
What are the movements at the wrist joint?
Flexion, extension, abduction, adduction
Combine all 4 = circumduction
Movements of the fingers?
Abduction, adduction, flexion, extension
What are the 2 joints where flexion/extension of the fingers can happen?
MCP, PIP and DIP
What are the movements of the thumb?
Abduction, adduction, extension, flexion, opposition, reposition
Look at difference between abduction and extension !! –> extension moves thumb away in same plane as hand, abduction move thumb away from hand
How many layers of muscles of the anterior forearm are there?
3 layers –> superfical, middle, deep
What are most of the muscles of the anterior forearm innervated by?
Most by the median nerve (C5-T1), a couple by the ulnar nerve (C8-T1)
Where do the muscles of the anterior forearm insert?
Insert on metacarpals or bones of the digits
Where do most of the muscles of the anterior forearm originate from?
The medial epicondyle of the humerus –> the ‘common flexor origin’
How many muscles of the anterior forearm pronate the forearm?
2 muscles pronate the forearm
Is the origin or insertion of the anterior forearm tendons key for clinical practice?
Insertion points
How many muscles make up the superficial layer of the anterior forearm? What are their names?
4: 1 pronator, 3 wrist flexors
Pronator –> pronator teres
3 wrist flexors:
- Flexor carpi radialis
- Flexor carpi ulnaris
- Palmaris longus
What does the flexor carpi radialis flex? What side is it found on?
Flexor of the wrist, radial side (shown in orange)
What does the pronator teres help to pronate?
Helps to pronate the proximal radio-ulnar joint –> does NOT act on wrist
What does the flexor carpi ulnaris flex? What side is it on?
Flexor of the wrist, ulnar side
Where does the flexor carpi radialis originate/insert?
Originates from the medial epicondyle, attaches to the base of metacarpals II and III.
Where does the flexor carpi ulnaris originate/insert?
Originates from the medial epicondyle with the other superficial flexors. It also has a long origin from the ulna. It passes into the wrist and attaches to the pisiform carpal bone / proximal part of 5th metacarpal
Action of the pronator teres?
Pronation of the forearm.
What are the muscles of the superficial layer of the anterior forearm innervated by?
All supplied by the median nerve EXCEPT the flexor carpi ulnaris which is supplied by the ulnar nerve
I.e.:
- Pronator teres –> median
- Flexor carpi radialis –> median
- Flexor carpi ulnaris –> ulnar
- Palmaris longus –> median
Action of the palmaris longus?
Flexion of wrist