Forearm Flashcards
Anterior compartment of forearm
3 layers
Superficial intermediate and deep
Superficial layer of anterior compartment of forearm
Flexor carpi ulnaris
Palmaris longus
Flexor carpi radialis
Pronator teres
Flexor carpi ulnaris
Most medial
Origin: medial epicondyle (humeral head) and olecranon (ulnar head)
Insertion: Distal fibre attaches to pisiform bone
Ulnar nerve passes through triangular gap between humeral and ulnar heads of flexor carpi ulnaris
Palmaris longus
Origin: medial epicondyle
Insertion: palmar aponeurosis of hand
Flexor carpi radialis
Origin: medial epicondyle
Insertion: base of metacarpals II and III
Pronator teres
Origin: medial epicondyle
Insertion: roughening on lateral surface of radius
Median nerve passes through ulnar and humeral head of this muscle
Intermediate layer - flexor digitorum superficialis
Two heads
Origin: humero-ulnar head - medial epicondyle
Radial head - anterior oblique line of radius
Median nerve and ulnar artery passes deep to FDS between the two heads
Tendons of ring and middle finger are superficial to index and little finger. Tendons of FDS are anterior to tendons of FDP
Flex PIP, MCP and wrist joint
Deep muscles of anterior compartment
Flexor digitorum profundus
Flexor pollicis longus
Pronator quadratus
Flexor digitorum profundus
Origin: anterior and medial surface of ulna + interosseous membrane
Insertion: distal phalanx
Innervation: lateral half (anterior interosseous - branch of median nerve) medial half (ulnar nerve)
Flexes MCP, DIP and PIP + wrist
In the palm, lumbricals originate from sides of tendons of FDP.
Flexor pollicis longus
Origin: anterior surface of radius
Insertion: palmar surface of base of distal phalanx of thumb
Innervation: Anterior interosseous nerve (median)
Flexes MCP and IP joint of thumb
Pronator quadratus
Origin: linear ridge on distal anterior surface of ulna
Insertion: distal anterior surface of radius
Innervation: anterior interosseous nerve (median)
Pronate forearm
Radial artery
Passes along lateral aspect of forearm:
- Just deep to brachioradialis in proximal half of forearm
- Superficial branch of radial nerve is lateral to it in middle third of forearm
- Tendon of brachioradialis is lateral to it in the distal forearm
Leaves the forearm by passing around lateral side of wrist and penetrates posterolateral aspect of hand between bases of metacarpals I and II.
Branches of radial artery
Radial recurrent artery - elbow joint + muscles on lateral side of forearm
Palmar carpal branch - carpal bones and joints
Superficial palmar branch - passes superficial to thenar muscles at base of thumb to enter hand
Ulnar artery
Larger than radial artery, medial side of forearm
Leaves cubital fossa by passing deep to pronater teres muscle, then passes through forearm between FCU and FDP
Distal forearm - ulnar nerve is medial to ulnar artery, with FCU most medial
Enters hand by passing lateral to pisiform bone and superficial to flexor retinaculum and arches over palm
Branches of ulnar artery
Ulnar recurrent artery for elbow joint
Common interosseous artery - divides into anterior and posterior - for muscles
Dorsal and palmar carpal branches for wrist
Median nerve
Leaves cubital fossa between pronator teres and FDS
Continues down on deep surface of FDS; just proximal to the wrist moves to lateral side of muscle and becomes more superficial, lying between palmaris longus and FCR
Enters hand deep to flexor retinaculum
Branches of median nerve
Anterior interosseous nerve (between two heads of pronator teres) - innervates deep layer
Small palmar branch - passes superficially into hand over flexor retinaculum - skin over base and central palm
Ulnar nerve
Posterior to medial epicondyle and between humeral and ulnar heads of FCU.
In forearm - in between FCU and FDP
Lies lateral to FCU tendon proximal to wrist. Ulnar artery is lateral to ulnar nerve
Along with ulnar artery, passes superficial to flexor retinaculum and immediately lateral to pisiform bone
Branches of ulnar nerve
Muscular branches to FCU and medial half of FDP
Cutaneous branch - palmar branch and larger dorsal branch (passes posteriorly deep to FCU)
Radial nerve
Bifurcates into deep and superficial branch under the margin of brachioradialis at lateral border of cubital fossa
Deep branch of radial nerve
Predominantly motor and passes between two heads of supinator
Superficial branch of radial nerve
Sensory.
Passes down anterolateral aspect of forearm deep to brachioradialis and along with radial artery.
approx 2/3rds down forearm, superficial branch of radial nerve passes laterally and posteriorly around radial side of forearm deep to tendon of brachioradialis
Posterior compartment of forearm
Superficial and deep
Muscles in superficial layer
Brachioradialis (from medial to lateral) Extensor carpi radialis longus Extensor carpi radialis brevis Extensor digitorum Extensor digiti minimi Extensor carpi ulnaris Anconeus
Brachioradialis
origin: proximal part of lateral supraepicondylar ridge of humerus
Insertion: lateral surface of distal end of radius
Accessory flexor of elbow when forearm midpronated
Distally lies over radial nerve and artery
Extensor carpi radialis longus
Origin: Distal part of lateral supraepicondylar ridge of humerus
Insertion: dorsal surface of base of metacarpall II
Extends and abducts wrist
Extensor carpi radialis brevis
Origin: lateral epicondyle of humerus
Insertion: dorsal surface of base metacarpals II and III
Innervation: deep branch of radial nerve
Extends and abducts wrist
Lies deep to ECRL
Extensor digitorum
Origin: lateral epicondyle
Insertion: Middle and distal phalanges
Innervated: posterior interosseous nerve
Extensor digiti minimi
Origin: Lateral epicondyle
Insertion: extensor hood of little finger
Innervation: posterior interosseous nerve
Extensor carpi ulnaris
Origin: Lateral epicondyle
Insertion: medial side of base metacarpal V
Innervation: posterior interosseous nerve
Anconeus
Most medial of superficial extensors
Origin: lateral epicondyle
Insertion: posterolateral surface of olecranon and posterior surface of ulna
Abducts ulna during pronation
Deep layer of posterior compartment
5 muscles Supinator Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus Extensor indicis
Except for supinator, all muscles originate from posterior surface of radius, ulna and interosseous membrane and insert into thumb/finger
APL, EPB and EPL emerge from between ED and ECRB and pass into the thumb
All innervated by deep branch of radial nerve
Supinator
Two heads
Origin: superficial - lateral epicondyle of humerus; deep - supinator crest on postero lateral surface of ulna
Insertion: proximal aspect of radius
Deep branch of radial nerve passes between these 2 heads to enter posterior compartment of forearm
Anatomical snuffbox
Lateral border - APL and EPB
Medial border - EPL
Radial nerve
At lateral wall of cubital fossa, before dividing into superficial or deep branch, innervates brachioradialis and ECRL
Passes between superficial and deep layer of muscle in posterior compartment, and deep to EPL to reach the wrist
