144 - Muscles of the Forearm Flashcards
Number of muscles of the forearm
Eight
Muscles of the anterior compartment of the forearm (superficial) 1 2 3 4 5
1) Pronator teres
2) Flexor carpi radialis
3) Palmaris longus
4) Flexor digitorum superficialis
5) Flexor carpi ulnaris
Names of forearm flexors that have more than one origin
1
2
3
1) Pronator teres
2) Flexor digitorum superficialis
3) Flexor carpi ulnaris
Insertions of flexor digitorum superficialis
1
2
1) Proximal ulna, CFO, oblique line of the anterior aspect of the radius
2) Tendons run across wrist, carpometacarpal joints, inserts into middle phalanx
Flexor carpi radialis and ulnaris
Flexors that run on the ulnar or radial sides, join to the wrist.
Attach to base of metacarpals.
NO action on fingers
Meaning of ‘carpi’
To the wrist
Where does flexor carpi radialis insert?
Base of the 2nd and 3rd metacarpals (radial two fingers).
Where does flexor carpi ulnaris insert?
Inserts into thepisiform bone.
Pisiform has a ligament that attaches to the base of the 5th metacarpal
(so FCU functionally attaches to 5th metacarpal)
Palmaris longus insertion
Doesn’t insert into any bone.
Vestigial. Absent in ~15% of people
Three deep muscles of anterior forearm
1) Flexor pollicis longus
2) Flexor digitorum profundis
3) Pronator quadratus
Arrangement of insertions of flexor digitorum superficialis and profundis
As FDS splits to insert into base of each middle phalanx, FDP travels between split tendons.
Only tendon crossing distal interphalangeal joint
Flexor digitorum profundis
Deep thumb flexor
Flexor pollicis longus
Where does flexor pollicis longus originate?
Distal shaft of the radis
Where does flexor pollicis longus insert?
Base of distal phalanx (of thumb).
What makes the roof of the carpal tunnel?
Flexor retinaculum
Forearm flexors that don’t really travel through carpal tunnel
Flexor carpi radialis (there is a split in flexor retinaculum that FCR travels through).
Flexor carpi ulnaris (attaches to pisiform, which has a ligament attaching to 5th metacarpal)
Carpal tunnel syndrome
If there is swelling of tendons in carpal tunnel, there is little give in flexor retinaculum, and median nerve can be compressed
Muscles of the posterior forearm
1 - 9
1) Bracioradialis
2) Extensor carpi radialis longus
3) Externsor carpi radialis brevis
4) Extensor digitorum
5) Extensor digitorum minimi
6) Extensor carpi ulnaris
7) Abductor pollicis longus
8) Extensor pollicis brevis
9) Extensor pollicis longus
Common extensor origin
Lateral epicondyle.
A lateral epicondylar ridge (lateral supracondylar ridge) is a part of the humerus leading to the lateral epicondyle.
Where do the radialis forearm extensors originate?
Brachioradialis and extensor carpi radialis longus attach to lateral supracondylar ridge.
Extensor carpi radialis brevis attaches to lateral epicondyle.
Where do the radialis forearm extensors run?
Down lateral compartment of posterior forearm
Path of brachioradialis
Attaches to radius, just above radial styloid.
Doesn’t cross wrist.
Role of brachioradialis
Elbow flexion
Path of flexor carpi radialis longus and brevis
ECRL and ECRB attach to base of 2nd and 3rd metacarpals.
Extensor equivalents of flexor carpi radialis
Effect of contracting both extensor carpi radialis longus and brevis and flexor carpi radialis
Radial deviation (these muscles cancel out respective flexion and extension of wrist)
Most posterior muscles of the posterior forearm
1
2
3
1) Extensor digitorum
2) Extensor digitorum minimi
3) Extensor carpi ulnaris
Relationship between extensor digitorum and extensor digitorum minimi
Share common origin.
Extensor digitorum minimi splits form extensor digitorum to attach to little finger
Where do Extensor digitorum, Extensor digitorum minimi
and Extensor carpi ulnaris originate?
Common extensor origin
Muscles forming the medial border of anterior forearm
Extensor carpi ulnaris and flexor carpi ulnaris
Extensor carpi ulnaris role
Attaches to base of 5th metacarpal.
Equivalent of flexor carpi ulnaris.
Extends wrist.
Role of extensor digitorum and ED minimi
Attach to fingers, extend fingers.
Three thumb muscles of posterior forearm
Abductor pollicis longus
Extensor pollicis brevis
Extensor pollicis longus
Structure to which three deep posterior forearm muscles attach
Thumb
Path of extensor pollicis longus
Runs towards the posterior hand until the dorsal tubercle at the back of the radius, then runs towards thumb.
Where does extensor pollicis longus attach?
Base of the distal phalanx of the thumb
Deep posterior forearm muscles not affecting the thumb
1) Aconeus
2) Supinator
3) Extensor indicis
Role of extensor indicis
Extra extensor of index finger
Groups of posterior forearm muscles
Four groups of three
Forearm supinator muscles
Biceps brachii and supinator
Extensor tendons at the wrist
Travel underneath extensor retinaculum
Role of extensor digitorum
Forms an ‘extensor hood’ over the back of the fingers.
Forms three tendinous slits.
Middle slit inserts into middle phalanx.
Two outer slits insert into distal phalanx.
Sort of equivalent to flexor carpi ulnaris and radialis splitting.
