Forearm Flashcards
What compartments is the forearm divided into?
Anterior and posterior compartment
What splits the forearm into the anterior and posterior compartments and joins the radius and the ulna?
interosseus membrane
What does the anterior compartment of the forearm contain?
flexor muscles
What are the muscles of the anterior forearm innervated by?
median and ulnar nerves
What does the posterior compartment of the forearm contain?
extensor muscles
What are the muscles of the posterior forearm innervated by?
radial nerve
What is the role of the forearm movement?
assist the shoulder in the application of force and in controlling the placement of the hand in space
The anterior compartment actions are what?
flexion and pronation
What posterior compartment actions are what?
extension and supination
What is the fibrous tissue with an oblique orientation from the radius to the ulna?
Interosseus membrane
What maintains the interosseus space between the radius and ulna through forearm rotation and actively transfers forces from the radius to the ulna?
interosseus membrane
What helps the interosseus membrane hold the radius and ulna together, particularly when upward thrusts are transmitted through the wrist (during a fall on the hand)
pronator quadratus
What keeps the radius and ulna together?
interosseus membrane and pronator quadratus
What are the common attachments (origins) of the anterior compartment of the forearm?
medial epicondyle of the humerus (superficial and intermediate; only 5 muscles)
What is the common innervation of the anterior forearm compartment?
median nerve with some contribution from the ulnar nerve
What muscle(s) in the forearm are innervated by the ulnar nerve?
1/2 flexor carpi ulnaris
flexor digitorum profundus
What is the common action of the anterior compartment of the forearm?
flexion
What the the 3 groups that the anterior forearm compartment divided into?
- superficial
- intermediate
- deep
What do the 5 superficial and intermediate muscles cross that the 3 deep muscles do not?
elbow joint
What muscles are included in the superficial layer of the anterior forearm compartment?
- pronator teres
- flexor carpi radialis
- palmaris longus
- flexor carpi ulnaris
The 4 superficial anterior forearm muscles are all attached proximally by a _______________ to the medial epicondyle of the humerus, the ____________
common flexor tendon
common flexor origin
What is the origin of the pronator teres, flexor carpi radialis, and palmaris longus?
medial epicondyle of the humerus
What is the origin of the flexor carpi ulnaris?
humeral head- medial epicondyle
ulnar head- olecranon and posterior border of ulna
What does the pronator teres insert onto?
middle lateral surface of the radius
What does the flexor carpi radialis insert onto?
Base of the metacarpals 2 and 3
What does the palmaris longus muscle insert onto?
distal 1/2 of flexor retinaculum and palmar aponeurosis
What does the flexor carpi ulnaris insert onto?
pisiform bone, hook of hamate, and base of metacarpal 5
What is the pronator teres, flexor carpi radialis, and palmaris longus muscles innervated by?
median nerve
What is the flexor carpi ulnaris muscle innervated by?
ulnar nerve
What are the actions of the pronator teres muscle?
forearm pronation and flexion
What are the actions of the flexor carpi radialis muscle?
flexes hand at wrist and assists in wrist abduction
What are the actions of the palmaris longus muscle?
flexes hand and tenses palmar fascia
What are the actions of the flexor carpi ulnaris muscle?
flexes hand at wrist and assists in wrist adduction
What is the blood supply of the pronator teres muscle?
anterior ulnar recurrent artery
What is the blood supply of the flexor carpi radialis muscle?
radial artery
What is the blood supply of the palmaris longus and flexor carpi ulnaris muscles ?
posterior ulnar recurrent artery
What is the only muscle included in the intermediate layer of the anterior forearm compartment?
flexor digitorum superficialis
What is the origin of the flexor digitorum superficialis muscle?
humeral head: medial epicondyle
ulnar head: coronoid process
radial head: anterior border of radius
What does the flexor digitorum superficialis muscle insert onto?
bodies of the middle phalanges of digits 2-5
What is the innervation of the flexor digitorum superficialis muscle?
median nerve
What are the actions of the flexor digitorum superficialis muscle?
flexes middle and proximal phalanges of digits 2-5
assists in hand flexion
What is the blood supply of the flexor digitorum superficialis?
ulnar and radial arteries
What are the 3 muscles included in the deep layer of the anterior forearm compartment?
flexor digitorum profundus
flexor pollicis longus
pronator quadratus
What nerve travels right on top of the flexor digitorum profundus muscle?
median nerve
What is the origin of the flexor digitorum profundus muscle?
proximal 3 quarters of medial and anterior surfaces of ulna and interosseus membrane
What is the origin of the flexor pollicis longus muscle?
anterior surface of radius and interosseus membrane
What is the origin of the pronator quadratus muscle?
distal quarter of the anterior surface of ulna
What does the flexor digitorum profundus insert onto?
bases of distal phalanges 2-5
What does the flexor pollicis longus muscle insert onto?
base of distal phalanx of thumb
What does the pronator quadratus muscle insert onto?
distal quarter of anterior surface of radius
What is the innervation of the flexor carpi profundus muscle?
digits 2 and 3: median nerve
digits 4 and 5: ulnar nerve
What is the innervation of the flexor pollicis longus muscle?
anterior interosseus nerve from median nerve
What are the actions of the flexor digitorum profundus muscle?
-flexes wrist joint and carpometacarpal (CMC) joints
-flexes distal interphalangeal (DIP) joints of digits 2-5
-assists with wrist flexion
What are the actions of the flexor pollicis longus muscle?
-flexes wrist joint and CMC joints
-flexes metacarpophalangeal (MCP) and interphalangeal joints of thumb
What are the actions of the pronator quadratus muscle?
pronates forearm
What muscle flexes the fingers in slow action?
Flexor digitorum profundus
What muscle reinforces the slow action of finger flexion when speed and flexion against resistance are required?
flexor digitorum superficialis
What are the long flexors of the digits?
flexor digitorum superficialis
flexor digitorum profundus
When the wrist is flexed, the contraction of the digits into the flexed position is ______. why?
weaker; the FDS and FDP are operating over a shortened distance between attachments
When the wrist is extended, the contraction of the digits into the flexed position is ______. Why?
stronger (strong grip); the FDS and FDP has a longer operating distance when the wrist is extended
What muscle is in the posterior compartment of the forearm but is the exception to the rule that the forearm flexor muscles are innervated by the median n.?
brachioradialis
What muscle is a relatively weak elbow flexor but is strongest when the forearm is in mid-pronated position?
brachioradialis
What muscle is important in arm wrestling?
brachioradialis
What are the common attachments (origins) of the posterior forearm muscles?
lateral epicondyle of the humerus
What is the common innervation of the posterior forearm muscles?
radial nerve
What is the common action of the posterior forearm muscles?
extension