dr. sreekanth thota department of anatomy upper limb forearm

Dr. SREEKANTH THOTA

DEPARTMENT OF ANATOMY

UPPER LIMB

FOREARM

FOREARMFOREARMThe forearm is the

part of the upper limb that extends between the elbow joint and the wrist joint.

As in the arm, the forearm is divided into anterior and posterior compartments

Compartments of forearmCompartments of forearmMuscles in the anterior

compartment of the forearm flex the wrist and digits and pronate the hand.

Muscles in the posterior compartment extend the wrist and digits and supinate the hand.

ANTERIOR COMPARTMENT ANTERIOR COMPARTMENT OF THE FOREARMOF THE FOREARM

Muscles in the anterior (flexor) compartment of the forearm occur in three layers:

1. Superficial2. Intermediate3.DeepAll muscles in the anterior compartment of

the forearm are innervated by the median nerve, except for the flexor carpi ulnaris muscle and the medial half of the flexor digitorum profundus muscle, which are innervated by the ulnar nerve.

Superficial layerSuperficial layer Four muscles in the superficial layer-1.flexor carpi ulnaris2.palmaris longus3.flexor carpi radialis4. pronator teres-All four muscles have a common origin

from the medial epicondyle of the humerus, and, except for pronator teres, extend distally from the forearm into the hand

Intermediate layerIntermediate layerFlexor digitorum superficialis

Deep layerDeep layer1.flexor digitorum profundus2.flexor pollicis longus3.pronator quadratus

Anterior ForearmAnterior ForearmPronator

TeresPronates and flexes forearm at the elbow

Flexor Carpi

Radialis

Flexes and abducts hand(at the wrist)

PalmarusLongus

Flexes hand at the wrist and tightens palmar aponeurosis

FlexorCarpi

Ulnaris

Flexes and adducts hand at the wrist

Flexor Digitorum Superficialis Flexes middle phalanges at the proximal interphalangeal joints of medial four digits; acting more strongly, it also flexes proximal phalanges at metacarpophalangeal joints and hand[wrist]

Flexor Digitorum Profundus Flexes distal phalanges at distal interphalangeal joints of medial four digits; assist with flexion of hand

Flexor pollicis Longus Flexes 1st digit (thumb)

Pronator Quadratus Pronates forearm; deep fibers bind radius and ulna together

Arteries of the anterior Arteries of the anterior compartment of the forearm.compartment of the forearm.At the apex of the

cubital fossa, Brachial artery divides into its two major branches, the radial and ulnar arteries.

Radial artery Radial artery In the distal

forearm, the radial artery can be located using the flexor carpi radialis muscle as a landmark.

Radial artery lies immediately lateral to the large tendon of the flexor carpi radialis muscle.

Radial pulseRadial pulseThe radial

pulse can be felt by gently palpating the radial artery against the underlying muscle and bone.

Nerves Nerves Nerves in the

anterior compartment of the forearm are the median and ulnar nerves, and the superficial branch of the radial nerve.

Median nerve Median nerve The median nerve innervates the

muscles in the anterior compartment of the forearm except for the flexor carpi ulnaris and the medial part of the flexor digitorum profundus (ring and little fingers).

It leaves the forearm and enters the palm of the hand by passing through the carpal tunnel deep to the flexor retinaculum.

Branches of median nerveBranches of median nerve

1. Anterior interosseous nerve: innervates the muscles in the deep layer

2. A small palmar branch originates from the median nerve in the distal forearm immediately proximal to the flexor retinaculum.

Innervates the skin over the base and central palm.

This palmar branch is spared in carpal tunnel syndrome because it passes into the hand superficial to the flexor retinaculum of the wrist.

Cutaneous branches of Cutaneous branches of median and ulnar nervemedian and ulnar nerve

Ulnar nerve Ulnar nerve In the forearm, the ulnar nerve

innervates only the flexor carpi ulnaris muscle and the medial part (ring and little fingers) of the flexor digitorum profundus muscle.

Branches in forearm:1.Palmar branch originates in the

middle of the forearm and passes into the hand to supply skin on the medial side of the palm

Radial nerve Radial nerve The radial nerve bifurcates

into deep and superficial branches under the margin of the brachioradialis muscle in the lateral border of the cubital fossa.

The deep branch is predominantly motor and passes between the two heads of the supinator muscle to access and supply muscles in the posterior compartment of the forearm.

The superficial branch of the radial nerve is sensory.

POSTERIOR POSTERIOR COMPARTMENT OF THE COMPARTMENT OF THE FOREARMFOREARM

POSTERIOR COMPARTMENT POSTERIOR COMPARTMENT OF THE FOREARMOF THE FOREARM

Muscles in the posterior compartment of the forearm occur in two layers:

1.Superficial 2.Deep layerThe muscles are associated with: 1.Movement of the wrist joint2.Extension of the fingers and thumb3.Supination. All muscles in the posterior

compartment of the forearm are innervated by the radial nerve.

Superficial layerSuperficial layerSeven muscles1.Brachioradialis2.Extensor carpi radialis longus3.Extensor carpi radialis brevis4.Extensor digitorum5.Extensor digiti minimi6.Extensor carpi ulnaris 7.Anconeus

Posterior view

BrachioradialisBrachioradialisActionFlexes

forearm

Extensor carpi radialis longus Extensor carpi radialis longus and brevisand brevis

Action

Extends and abducts hand at wrist joint

Extensor digitorumExtensor digitorumActionExtends the

medial four digits at metacarpo –phalangeal, IP joint and extends hand at wrist

Extensor digiti minimiExtensor digiti minimiActionExtends the 5th

digit at the metacarpal-phalangeal and interphalangeal joints

Extensor carpi ulnarisExtensor carpi ulnaris

ActionExtends and

adducts hand at the wrist

AnconeusAnconeusActionaccessory

extensor of the elbow joint

Tennis elbow(Tennis elbow(Lateral Lateral epicondylitis)epicondylitis)

It occurs at the common extensor tendon that originates from the lateral epicondyle.

The acute pain that a person might feel occurs as one fully extends the arm.

Deep layerDeep layer

Five muscles 1-Supinator 2-Abductor pollicis longus 3-Extensor pollicis brevis 4-Extensor pollicis longus 5-Extensor indicis

SupinatorSupinatorActionSupinates

forearm

Abductor pollicis longusAbductor pollicis longusActionAbducts thumb

Extensor pollicis longus and brevisExtensor pollicis longus and brevis

Action1. Extensor Pollicis

LongusExtends distal phalanx

of thumb2. Extensor Pollicis

BrevisExtends proximal

phalanx of thumb

Extensor indicisExtensor indicisActionExtends index

finger

ANATOMICAL SNUFFBOXANATOMICAL SNUFFBOX

ANATOMICAL SNUFFBOXANATOMICAL SNUFFBOX

• BoundriesMedially

◦-Extensor pollicis longus tendon

Laterally◦Abductor pollicis longus

tendon◦Extensor pollicis brevis

tendon• Clinical importance

◦1- Scaphoid bone◦2- Radial pulsation

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Radial nerve Radial nerve The nerve of the posterior compartment

of the forearm is the radial nerve .In the lateral wall of the cubital fossa,

and before dividing into superficial and deep branches, the radial nerve innervates the brachioradialis and extensor carpi radialis longus muscles.

Posterior interosseous nerve supplies the remaining muscles in the posterior compartment.

Posterior interosseous Posterior interosseous nervenerve

Radial Nerve Injury in the Radial Nerve Injury in the ForearmForearm

Injury to the deep branch of the radial nerve may occur when wounds of the forearm are deep (penetrating). Severance of the deep branch of the radial nerve results in an inability to extend the thumb and the metacarpophalangeal (MP) joints of the other digits.

Testing the radial nerveTesting the radial nerveIntegrity of the

deep radial nerve may be tested by asking the person to extend the MP joints while the examiner provides resistance