RADIUS BONE - Jinnah Sindh Medical University



RADIUS BONE & BONES OF HAND

LEARNING OBJECTIVES

Students should able to

Recognize the bones of forearm &hand

Determine side of bones.

Identify the features of bones.

Identify the muscles attached to bones.

Identify clinical significance of bones.

RADIUS BONE

Lateral bone of forearm

Three Parts

Upper end

Head

Neck

Tuberosity

Shaft

Lower end

DETERMINATION OF SIDE

Upper end rounded & bears the head.

Lower end more wider than the upper end

Lateral surface of shaft is convex & its anterior surface is concave in lower part

Styloid process projects from lateral surface of the lower end

HEAD

Disc-shaped, overhangs the neck on all sides

Medially it articulates with radial notch of ulna.

Upper surface articulates with capitulum-- form elbow joint

It is covered with hyaline cartilage.

Medial surface articulates with radial notch of ulna to form superior radio-ulnar joint

Attachment

Annular ligament to the articular cicumference of head

NECK

Constricted part below head

Surrounded by lower part of annular ligament

Attachments:

Supinator is inserted into the lateral anterior &posterior aspects of neck

TUBEROSITY

Lies below the medial part of the neck.

Attachments:

Biceps brachii is inserted into rough posterior part.

Smooth anterior part is related to bursa.

SHAFT

Narrow above, broader below

Three borders.

Interosseous(medial)

Anterior

Posterior

Three surfaces

Anterior

Posterior

Lateral

BORDERS

INTEROSSEOUS (MEDIAL) BORDER

Sharp except at its upper part

Begins from posterio-inferior part of radial tuberosity

Lower end form posterior boundary of small triangular area above ulnar notch of radius

Attachment on interosseous border

Pronator quadratus is inserted

Gives attachment to interosseous membrane in lower 3\4

ANTERIOR BORDER

Begins just below antero-lateral part of radial tuberosity

Upper & lower parts are sharp

Attachments on anterior border

Origin of Flexor digitorum superficialis from upper & lower parts

Extensor retinaculum is attached to lower edge

POSTERIOR BORDER

Begins from posterio-inferior part of tuberosity

End in dorsal tubercle at back of lower end

Prominent in middle part

SURFACES

ANTERIOR SURFACE

Lies between anterior and interosseous border

Presents nutrient foramen directed up ward

Attachments on anterior surface

Origin to flexor pollicis longus from upper 2\3

Insertion to pronator quadratus in lower 1\4

POSTERIOR SURFACE

Lies between interosseous & posterior borders

Origin of Abductor pollicis longus from upper part

Origin of Extensor pollicis brevis from lower part

LATERAL SURFACE

Lies between anterior&posterior borders

Rough ridge in middle part gives insertion to pronator teres

Insertion to supinator into V Shape area at upper part

Brachioradialis is inserted just above styloid process

LOWER END

Expanded &rectangular

Has five surfaces

Lateral surface

Medial surface

Anterior surface

Posterior surface

Inferior surfaces

LATERAL SURFACE

Present styloid process

Radial collateral ligament of wrist joint is attached at tip of styloid process

Brachiodialis is inserted into lower part of lateral surface

Two grooves lateral to styloid process for tendons of Abductor pollicis longus &Extensor pollicis brevis

MEDIAL SURFACE

Bears ulnar notch for articulation with head of ulna

Articular disc of inferiorradio-ulnar joint is attached to ridge at lower part.

ANTERIOR SURFACE

In form of thick prominent ridge

Radial artery is palpated as radial pulse

Pronator quadratus is inserted into the lower part of anterior surface

POSTERIOR SURFACE

Irregular

Present dorsal tubercle(of lister)

Four grooves for extensor tendons

INFERIOR SURFACE

Bears triangular area for Scaphoid bone

Medially, quadrangular area for Lunate

Takes part in forming wrist joint

CLINICAL ANATOMY

Fractures of radius

Fracture of head

Can occur from fall on outstretched hand

Fracture of neck of radius

Occur in young children

FRACTURES OF SHAFT OF RADIUS

May or may not occur with ulna

Displacement of fractured fragment depends on pull of muscle

Supinator and biceps supinate the proximal fragment

Pronator quadratus pronates the distal fragment

Brachioradialis and extensor carpi radialis and brevis shortens the fore arm

COMBINE FRACTURES OF RADIUS AND ULNA

Shaft of ulna fractured by a force from behind

Bowing forward of ulnar shaft with anterior dislocation of radial head

Rupture of annular ligament

COMBINE FRACTURES OF RADIUS AND ULNA

Proximal third of radius is fractured

Distal end of ulna is dislocated at distal radio ulnar joint

FRACTURES OF DISTAL END

Colles’ fracture

Fall on outstretched hand

Distal fragment is displaced posteriorly and superiorly

The fore arm and wrist resembles the shape of dinner fork

Dinnerfork deformity

Reverse colles’s fracture

Distal fragment displaced anteriorly

Fall on back of hand

BONES OF HAND

Eight carpal bones

Five metacarpal bones

Fourteen phalanges

CARPAL BONES

Eight carpal bones

Arranged in two rows

Proximal row

Medial to lateral

Scaphoid

Lunate

Triquetral

Pisiform

Distal row

Trapezium

Trapezoid

Capitate

Hamate

CHARACTERISTICS OF EACH BONE

Each bone has six surfaces.

Scaphoid is boat –shaped

tubercle on its lateral side

Lunate is half moon shaped or crescentic

Triquetral is pyramidal shape

has oval facet on distal part of palmar surface

Pisiform is pea shaped

only one oval facet on proximal part of dorsal surface

Trapezium is quadrangular in shape

crest & groove anteriorly

Trapezoid resemble shoe of baby

Capitate is largest with rounded head

Hamate is wedge –shaped with hook near base

ATTACHMENTS

Most important structure related with carpal bones --------- FLEXOR RETINACULUM

Attachment:

Lateral

scaphoid

anterior border of lower end

Medial

Pisiform

Hamitate

CLINICAL ANATOMY

Fracture of scaphoid

Most common fractured bone among carpal bone

Non union & avascularity common problem

Tenderness & swelling in anatomical snuff box

Dislocation of lunate

Most common dislocated bone of carpal bone

May compress median nerve in front of wrist

Carpal tunnel syndrome

CARPAL TUNNEL SYNDROME

Carpal tunnel:

osseofibrous space formed by anterior concave surface of carpus and flexor retinaculum

Passage of long flexor tendon and median nerve

CARPAL TUNNEL SYNDROME

Syndrome is caused by compression of median nerve due to reduced size of canal

Pain and paraesthesia of lateral one and half finger

Weakness of thenar muscle

METACARPAL BONES

Short long bones

Numbered from lateral to medial side

1st metacarpal Shorter & thicker articulates with trapezium.

Other metacarpal bones

Expanded bases articulate with distal row of carpal bones & with each other

Middle metacarpal show styloid process

Heads has boldly rounded articular facets

Form concavity for palm

Heads form knuckles of fist

PHALANGES

14 in number

Parts

Base

Shaft

Head

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