JOINTS OF FOREARM

MAJ RISHI POKHREL

NAIHS

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• Carpel tunnel syndrome?

• Radioulnar joints

• Proximal

• Distal

• Intermediate

• Wrist Joint

Joint

• Introduction

• Articulating surfaces

• Ligaments

• Synovial membrane

• Special feature e.g. disc, meniscus

• Blood supply & innervation

• Movements & muscles

• Applied

Proximal Radioulnar Joint

• Type: Uniaxial pivot joint.

• Articulating surfaces

– Circumference of the radial head

– Fibro-osseous ring formed by

ulnar radial notch & annular

ligament

Ligaments

• Fibrous capsule

– continuous

with that of

elbow joint &

attached to

the annular

ligament

Ligaments

• Annular ligament

– Strong band, 4/5th of ring

– Encircles the radial head, holding it against radial notch of the

ulna.

– Attached to anterior margin of the notch and rough ridge at or

behind the posterior margin of the notch

Ligaments

• Quadrate ligament

– thin, fibrous

– stretches between neck of the radius & upper part

of the supinator fossa of the ulna

– covers the synovial membrane on the distal

surface of the joint

– maintains constant tension throughout pronation

and supination.

Synovial membrane

• continuous with that of elbow

joint

• Covers proximal radio-ulnar joint

& elbow joint as 1 synovial cavity

• Prevented from herniation

between anterior & posterior free

edges of the annular ligament by

the quadrate ligament

Vascular supply

Periarticular anastomosis around elbow joint

Innervation

• Small branches from

– Musculocutaneous

– Median

– Radial

– Ulnar

• Hilton’s law

Factors maintaining stability

• Prime stabilizing factor - annular ligament

• Encircles the radial head and holds it against the radial notch of the ulna

Applied anatomy

• Pulled elbow

• Subluxation of the radial head through annular ligament arising from a sudden jerk

• common injury in young children

• annular ligament has vertical sides in children compared with more funnel-shaped sides in adults

• Reduction by forcefully supinating and flexing elbow which snaps the ligament back into place.

Distal Radioulnar Joint• Uniaxial pivot joint

• Articulating surfaces

– convex distal head of ulna & concave ulnar notch of the radius

– connected by an articular disc.

Ligaments

• Fibrous capsule

– Thicker anteriorly and posteriorly

– Proximal part of the capsule is lax.

• Articular disc

– Fibrocartilaginous

– Binds distal ends of ulna &

radius

– Thick periphery, centre thin

or sometimes perforated.

– Triangular in shape

– Apex attached to depression

between styloid process and

distal articular surface of ulna

– Base attached to prominent

edge between ulnar notch

and carpal articular surface of

the radius

Synovial membrane• Projects proximally between radius & ulna - ‘recessus

sacciformis’ in front of distal part of the interosseous

membrane

• Does not communicate with wrist joint

• Blood supply

– palmar and dorsal br of the ant interosseous A with post interosseous & ulnar A

• Innervation

– Branches of ant & post interosseous N

Intermediate Radioulnar Joint

• Interosseous membrane

• Type: Syndesmosis type of

Fibrous joint

Movements

• Pronation

– Pronator quadratus

– pronator teres

• Supination

– Supinator

– Biceps brachii

Wrist / Radiocarpal jt

• Type: synovial, biaxial,

ellipsoid

• Articulating surfaces:

– distal end of radius &

triangular fibrocartilage

– scaphoid, lunate and

triquetral

Ligaments• Fibrous capsule

• Palmar radiocarpal & ulnocarpal

• Dorsal radiocarpal

• Radial and ulnar collateral ligaments

• Synovial membrane: lines the fibrous capsule

• Vascular supply

– Ant interosseous A

– Ant & post carpal br of radial and ulnar arteries

– Palmar & dorsal metacarpal A

– Recurrent rami of the deep palmar arch.

• Innervation

– Ant & post interosseous

– median, ulnar & radial N.

Movements & muscles

Range of movements

• flexion (85°),

• extension (85°),

• adduction or ulnar deviation (45°),

• abduction or radial deviation (15°)

• circumduction

Muscles• Flexion

– FCR, FCU, Palmaris longus

– assisted by FDS, FDP, FPL

• Extension

– ECRL, ECRB, ECU,

– assisted by ED, EDM, EI and EPL

• Adduction

– FCU, ECU

• Abduction

– FCR, ECRL, ECRB,

– abductor pollicis longus and extensor pollicis brevis