Forearm

Supinator and extensors are on the ___ side of the forearm

Posterior

Functional Groups of the Forearm

Pronators Supinators Flexors of wrist Extensors of wrist Extensors of fingers Flexors of fingers

Deep layer of anterior compartment: muscles

Three muscles that lie deep to the flexor digitorum superficialis: flexor digitorum profundus flexor pollicis longus pronator quadratus

Ulnar Nerve

Ulnar nerve courses posterior to elbow joint, enters forearm between two heads of flexor carpi ulnaris. innervates flexor carpi ulnaris and ulnar half of flexor digitorum profundus. gives rise to muscular branches and tow cutaneous branches from medial side of palm (palmar branch) and from skin on posteromedial back of hand (dorsal branch)

Deep layer of posterior compartment of forearm muscles innervation

supinator, one muscle to index finger, three muscles to thumb. superior to inferior, medial to lateral supinator abductor pollicis longus extensor pollicis longus extensor indicis extensor pollicis brevis posterior interosseous nerve

Superficial layer of anterior compartment: origin, muscles

Arise from medial epicondyle by fused common flexor tendon Lateral to medial: Pronator teres Flexor carpi radialis Palmaris longus Flexor carpi ulnaris

Pronators and flexors are on the ___ side of the forearm

Anterior

Posterior compartment Action? Layers, innervation

(extensors & 1 supinator) Superficial Deep

At the elbow, the Radial Nerve divides into the ____ and _____ branch. what type of nerves are these (Sensory or motor)? _____ enters the supinator and emerges from _____ as the ______ nerve.

**at elbow, radial nerve divides into superficial and deep branch. Superficial = sensory Deep = motor Deep branch enters the supinator, emerges from inferior border as posterior interosseous nerve.

Flexordigitorum profundus (deep) layer/ compartment origin insertion innervation action

Deep layer of anterior compartment origin: ulna, interosseous membrane insertion:distal phalanges of 2-5 innervation: lateral by median nerve, medial by ulnar nerve action: flexion of distal interphalangeal & metacarpophalangeal joints of 2-5, wrist flexion

Flexor pollicis longus layer/ compartment origin insertion innervation action

Deep layer of anterior compartment pollex (L): Thumb origin: radius, interosseous membrane insertion: distal phalanx of thumb innervation: median nerve action: flexes interphalangeal and metacarpophalangeal joint of thumb.

Pronator quadratus

Deep layer of anterior compartment origin: ulna insertion: fibers pass laterally to insert into radius innervation: median nerve action: pull distal end of radius over ulna.

Flexor digitorum superficialis layer/ compartment origin insertion innervation action

Intermediate (Superficial) layer of anterior compartment of forearm common flexor tendon, radius, and ulna (coronoid process) insertion: four tendons into middle phalanges of fingers 2-5 innervation: median nerve action: flexion of wrist, metacarpophalangeal and proximal interphalangeal joints of index, middle, ring, little fingers -median nerve and ulnar nerve course on it's deep surface. it's between & deep to superficial layer muscles

Forearm Nerves

Median Nerve Ulnar Nerve Radial Nerve

Anterior (Flexor) Compartment layers & innervation

Superficial Intermediate Deep **flexor carpi ulnaris & ulnar (medial) half of flexor digitorum profundus innervated by the ulnar nerve. All others innervated by the median nerve.

Flexor carpi radialis layer/ compartment origin insertion innervation action

Superficial layer of anterior compartment. Origin: common tendon Insertion: base 2nd/3rd metacarpal Innervation: median nerve Action: flexion and abduction of wrist

Flexor carpi ulnaris layer/ compartment origin insertion innervation action

Superficial layer of anterior compartment. Origin: two heads (humeral, ulnar) Insertion: pisiform, continues via pisohamate and pisometacarpal ligaments Innervation: ulnar nerve (passes between two heads) Action: flexion and adduction of wrist

Palmaris longus layer/ compartment origin insertion innervation action

Superficial layer of anterior compartment. Origin:comon tendon Insertion: palmar aponeurosis Innervation: median nerve Action: accessory flexor of wrist. Opposes shearing of skin of palm. ~absent in 15% people

Pronator Teres layer/ compartment origin insertion innervation action

Superficial layer of anterior compartment. origin: two heads (humeral, ulnar) insertion: mid shaft of radius Innervation: median nerve (between two heads of pronator teres)

Anatomical Snuff Box what is it? what lies at the floor of it?

Triangular area seen as depression between tendons of extensor pollicis brevis and extensor pollicis longus when thumb is abducted scaphoid bone, radial artery at floor of this area

Superficial layer of deep compartment of forearm arise from? Muscles included?

arise from lateral epicondyle and supracondylar ridge, form common extensor tendon. Brachioradialis Extensor carpi radialis longus Extensor carpi radialis brevis Extensor digitorum Extensor digiti minimi Extensor carpi ulnaris Anconeus

Blood supply of forearm

brachial artery divides into radial and ulnar arteries at the cubital fossa (at the neck of radius) radial artery courses deep to brachioradialis gives muscular branches to proximal portion of forearm distally, the radial artery is lateral to the brachioradialis tendon at wrist courses through the anatomical snuff box, branches to thumb and index finger, forms deep palmar arch. Radial artery branches in forearm: radial recurrent small palmar carpal branch superficial palmar branch

Superficial layer of posterior muscles of forearm (both compartments, lateral to medial and superior to inferior)

brachioradialis extensor carpi radialis longus extensor carpi radialis brevis abductor pollicis longus extensor pollicis brevis extensor digitorum extensor digiti minimi anconeus extensor carpi ulnaris Flexor carpi ulnaris

Superficial/intermediate layer of anterior forearm muscles (lateral to medial and superior to inferior)

brachioradialis pronator teres flexor carpi radialis palmaris longus flexor digitorum superficialis (deep to carpi radialis, palmaris longus) flexor carpi ulnaris

Interosseous Membrane: where & function?

connects lateral ulna to medial radius. connects radius to ulna without restricting supination/pronation place for attachment of anterior/ posterior compartment of forearm transmits forces from radius to ulna (wrist to humerus)

Extensor pollicis longus compartment/ layer origin insertion innervation action

deep layer of posterior compartment of forearm origin: arises from interosseous membrane and ulna insertion: tendon curves around dorsal tubercle of radius, terminates in base of distal phalanx of thumb innervation: posterior interosseous nerve action: extends interphalangeal joint of thumb, extends carpometacarpal and metacarpophalangeal joints of thumb

Extensor pollicis brevis compartment/ layer origin insertion innervation action

deep layer of posterior compartment of forearm origin: interosseous membrane and radius insertion: base of proximal phalanx (finger bone) of thumb innervation: posterior interosseous nerve action: extends carpometacarpal and metacarpophalangeal joints of thumb

Extensor indicis compartment/ layer origin insertion innervation action

deep layer of posterior compartment of forearm origin: posterior ulna insertion: tendon joins extensor hood of index finger innervation: posterior interosseous nerve action: extends index finger

Abducter pollicis longus compartment/ layer origin insertion innervation action

deep layer of posterior compartment of forearm origin: radius and ulna, interosseous membrane inserts: base of 1st metacarpal innervation: posterior interosseous nerve action: abducts carpometaphalangeal joint of thumb, accessory extensor of thumb

Supinator compartment/ layer origin insertion innervation action

deep layer of posterior compartment of forearm origin: two heads humeral head from lateral epicondyle deep/ulnar head from supinator crest of ulna insert: -two heads wrap around posterior/ lateral head of radius --> insert at lateral surface of the radius innervation: posterior interosseous nerve

Movements of forearm, wrist, hand summary flexion/extension of forearm occurs at ___ joint pronation/supination of forearm occurs as _______ wrist movements movements of digits

flexion/extension of forearm occurs at the elbow joint pronation/supination of forearm occurs as distal part of radius swings over ulna wrist: flexion, extension, abduct, adduct, circumduction digits: flexion, extension, abduction, adduction. Thumb/ little finger have opposition.

Median nerve in forearm

median nerve enters forearm between two heads of pronator teres. innervates anterior compartment of forearm (except flexor carpi ulnaris and ulnar half of digitorum profundus) median nerve branches : anterior interosseous nerve (to deep layer of anterior compartment) small palmar branch to skin of base of central palm

Ulnar artery

larger than radial artery passes down medial side of forearm common interosseous artery divides into anterior/ posterior membrane, supplying deep muscles. Main ulnar trunk courses distally between flexor digitorum superficialis and flexor digitorim profundus, giving muscular branches. In hand, ulnar artery terminates by forming superficial palmar arch.

Aconeus compartment/ layer origin insertion innervation action

most medial of superficial extensors origin: lateral epidonyle of humerus insertion: posterolateral surface of ulna innervation: radial nerve action: abducts ulna during pronation, accessory extensor of forearm

Radial Nerve

radial nerve courses anterior to elbow joint deep to brachialis innervates brachioradialis, extensor carpi radialis longus then divides into superficial (cutaneous) and deep branches. superficial radial nerve innervates skin on posterolateral surface of the hand deep branch innervates supinator, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi and extesnor carpi ulnaris deep radial nerve courses deep to supinator deep radial nerve emerges from supinator, changes to posterior interosseous nerve posterior interosseous nerve innervates abductor pollicis longus, extensor pollicis longus, extensor pollici brevis, and extensor indicis muscles.

Intermediate layer of anterior compartment

sometimes with superficial layer Flexor digitorum superficialis

Extensor carpi radialis brevis compartment/ layer origin insertion innervation action

superficial layer of posterior compartment of forearm origin: common extensor tendon insertion: base 2nd/3rd metacarpal innervation: deep branch of radial nerve action: extends and abducts wrist

Extensor digitorum compartment/ layer origin insertion innervation action

superficial layer of posterior compartment of forearm origin: common extensor tendon insertion: extensor expansion (extensor hood, aponeurosis of hand) innervation: posterior interosseous nerve (extension of deep radial) action: extends wrist and fingers 2-5

Extensor carpi ulnaris compartment/ layer origin insertion innervation action

superficial layer of posterior compartment of forearm origin: common extensor tendon and ulna insertion: base of 5th metacarpal innervation: posterior interosseous nerve action: extends and adducts wrist

extensor digiti minimi compartment/ layer origin insertion innervation action

superficial layer of posterior compartment of forearm origin: common with extensor digitorum insertion: own tendon inserts onto extensor hood of 5th digit innervation: posterior interosseous nerve action: extends little finger

Extensor carpi radialis longus compartment/ layer origin insertion innervation action

superficial layer of posterior compartment of forearm origin: supracondylar ridge insertion: base 2nd metacarpal innervation: radial nerve action:extends and abducts wrist

Brachioradialis compartment/ layer origin insertion innervation action

superficial layer of posterior compartment of forearm origin: supracondylar ridge of humerus insertion: distal end of radius innervation: radial nerve action: accessory flexor of elbow joint

Elbow joint anastomosis

ulnar artery sends two branches back to arm to anastomose with arm vessels anterior ulnar recurrent anastomoses with inferior ulnar collateral artery posterior interosseus artery sends recurrent interosseus brnach to anastomose with middle collateral artery radial artery sends radial recurrent branch back to anastomose with radial collateral artery