Wrist Joint & Superior & Inferior Radio-Ulnar Joints
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WRIST JOINT & SUPERIOR & INFERIOR RADIO-ULNAR JOINTS
OBJECTIVES
TO KNOW THE TYPE OF JOINTS. TO DISCUSS THE PARTS OF JOINT. LIST THE BONES INVOLVED IN THE FORMATION OF JOINTS. DISCUSS OTHER RADIOULNAR ARTICULATIONS. DISCUSS THE MOVEMENTS OCCURING ON THESE JOINTS. NAME THE MUSCLES ACTING ON ELBOW JOINT. DISCRIBE NERVES AND VESSELS SUPPLYING THESE JOINTS. DISCUSS CLINICAL PROBLEMS RELATED TO THESE JOINTS. Wrist Joint Formed by distal end of radius articulating with scaphoid & lunate, and triangular disc articulating with lunate & triquetrum.
Capsule: • Encloses the joint • Attached: • above to distal ends of radius and ulna • Below to proximal row of carpal bones.
Movements: flexion, extension, abduction, adduction, circumduction.
Relations Anterior: long flexor tendons with their synovial sheaths, and median nerve.
Posterior: extensor tendons of wrist and fingers with their synovial sheaths.
Laterally: radial artery.
Medially: posterior cutaneous branch of ulnar nerve. Ligaments of Wrist Joint
Lateral ligament / Radial collateral ligament (RCL):
• origin- styloid process of the radius • insertion- scaphoid & trapezium
Medial ligament/ Ulnar collateral ligament (UCL): • origin- ulnar styloid process • insertion- triquetrum dorsally & pisiform palmarly
Anterior ligament/ Palmar (volar) radiocarpal ligament • most important ligament for controlling motion and wrist stability • origin- anterior surface of distal radius • insertion- courses obliquely and medially to split into the radiocapitate ligament, the radiotriquetrum ligament, and the radioscaphoid ligament.
Posterior ligaments/ Dorsal radiocarpal ligament: • origin- posterior surface of the distal radius & styloid process • insertion- lunate & triquetrum Nerve supply
Anterior interosseous nerve (branch of median nerve)
Posterior interosseous nerve (deep terminal branch of radial nerve). Blood supply
Anterior and posterior carpal arches RADIOULNAR JOINT Trochoid or pivot-type joint.
Radial head rotates around at proximal ulna.
Distal radius rotates around distal ulna.
Annular ligament maintains radial head in its joint.
Joint between shafts of radius& ulna held tightly together between proximal & distal articulations by an interosseus membrane (syndesmosis).
Substantial rotary motion between the bones. RADIOULNAR PRONATION
Agonists • Pronator teres • Pronator quadratus • Brachioradialis
RADIOULNAR SUPINATION Agonists – Biceps brachii – Supinator muscle – Brachioradialis
E.g. Tightening a screw
MOVEMENTS
Pronation • internal rotary movement of radius on ulna that results in hand moving from palm-up to palm-down position. Supination • external rotary movement of radius on ulna that results in hand moving from palm-down to palm-up position.
Supinate 80 to 90 degrees from neutral. Pronate 70 to 90 degrees from neutral
Most upper extremity movements involve the elbow & radioulnar joints. Usually grouped together due to close anatomical relationship. Elbow joint movements may be clearly distinguished from those of the radio- ulnar joints. Radioulnar joint movements may be distinguished from those of the wrist. The complex action of turning the forearm over (pronation or supination) happens at the articulation between the radius and the ulna. In the anatomical position (with the forearm supine), the radius and ulna lie parallel to each other. During pronation, the ulna remains fixed, and the radius rolls around it at both the wrist and the elbow joints. In the prone position, the radius and ulna appear crossed.
Synergy between glenohumeral, elbow & radioulnar joint muscles
Glenohumeral & elbow muscles contract to stabilize or assist in movement at radioulnar joints through its ROM.
Tightening a screw with a screwdriver involves radioulnar supination, i.e. externally rotate & flex glenohumeral & elbow joints, respectively.
Loosening a tight screw with pronation, i.e. internally rotate & extend the elbow & glenohumeral joints, respectively.
Depend on both agonists and antagonists in surrounding joints to assist in an appropriate amount of stabilization & assistance with the required task.
Clinical Correlates • Fracture & Dislocation.
• Ganglion (back of the wrist is a common site), cystic swelling resulting from the degeneration of synovial sheath).
• Arthritis causes damage to the bone surfaces and cartilage where the three bones rub together. These damaged surfaces eventually become painful.