Podcast
Questions and Answers
Which of the following bones is not part of the distal carpal row?
Which of the following bones is not part of the distal carpal row?
The triangular fibrocartilage complex (TFCC) helps stabilize the radial side of the wrist.
The triangular fibrocartilage complex (TFCC) helps stabilize the radial side of the wrist.
False
What type of joint is the intercarpal joint?
What type of joint is the intercarpal joint?
Synovial gliding
The wrist joint complex consists of multiple articulations involving the eight carpal bones, metacarpals, and the distal ______.
The wrist joint complex consists of multiple articulations involving the eight carpal bones, metacarpals, and the distal ______.
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Match the following carpal bones with their respective characteristics:
Match the following carpal bones with their respective characteristics:
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What is the function of the triangular fibrocartilage complex (TFCC)?
What is the function of the triangular fibrocartilage complex (TFCC)?
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The wrist has three main joints, including the distal radioulnar joint.
The wrist has three main joints, including the distal radioulnar joint.
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Which axis of motion allows for 35 degrees of ulnar deviation?
Which axis of motion allows for 35 degrees of ulnar deviation?
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What type of joint is the wrist classified as?
What type of joint is the wrist classified as?
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During wrist ulnar deviation, the scaphoid and lunate roll toward the radius.
During wrist ulnar deviation, the scaphoid and lunate roll toward the radius.
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What are the two main types of ligaments in the wrist?
What are the two main types of ligaments in the wrist?
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The scaphoid transmits _____% of force during wrist extension.
The scaphoid transmits _____% of force during wrist extension.
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Which ligament plays an important role in stabilizing the wrist when lifting heavy objects?
Which ligament plays an important role in stabilizing the wrist when lifting heavy objects?
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Match the following wrist ligaments with their functions:
Match the following wrist ligaments with their functions:
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Radial deviators are stronger than ulnar deviators.
Radial deviators are stronger than ulnar deviators.
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During wrist extension, the scaphoid/lunate roll _____ and glide _____ .
During wrist extension, the scaphoid/lunate roll _____ and glide _____ .
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What two movements are involved in wrist circumduction?
What two movements are involved in wrist circumduction?
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Carpal tunnel syndrome is more prevalent in males than females.
Carpal tunnel syndrome is more prevalent in males than females.
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What is the Finkelstein test used to identify?
What is the Finkelstein test used to identify?
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In wrist arthrokinematics, the roll occurs in the same direction, while the glide occurs in the ______ direction.
In wrist arthrokinematics, the roll occurs in the same direction, while the glide occurs in the ______ direction.
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Match the wrist injuries with their descriptions:
Match the wrist injuries with their descriptions:
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Which ligament is often associated with ligamentous sprains in the wrist?
Which ligament is often associated with ligamentous sprains in the wrist?
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The wrist has 3 degrees of freedom in its movements.
The wrist has 3 degrees of freedom in its movements.
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What is the loose packed position of the wrist?
What is the loose packed position of the wrist?
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Study Notes
Biomechanics 2 Course Information
- Course title: Biomechanics 2
- Lecturer: Dr. Amany Gomaa Atiaa
- Affiliation: Lecturer of Burn & Surgery, Faculty of Physical Therapy, Sinai University
- Website: sinaiuniversity.net
Biomechanics of the Wrist Joint
- Components: Wrist complex, ligaments, muscles
- Positions: Loose packed position, close packed position
- Other features: Angles, arthrokinematics
Wrist Complex and Articulations
- Structure: Multiple articulations of eight carpal bones, distal radius, ulnocarpal space structures, metacarpals, and each other.
Bony Structure
- Division: The carpus is divided into proximal and distal rows.
- Distal row: Trapezium, trapezoid, capitate, and hamate (relatively immobile)
- Distal function: Forms carpometacarpal joint.
- Proximal row: Scaphoid, lunate, and triquetrum (more mobile)
- Proximal function: Forms radiocarpal joint with the distal radius.
Wrist Joint Components
- Distal radioulnar joint: synovial pivot
- Radiocarpal joint: condyloid synovial
- Midcarpal joint: synovial gliding
- Additional parts: ulnocarpal, carpometacarpal (saddle joint), and intercarpal joints
Triangular Fibrocartilage Complex (TFCC)
- Function: Load-bearing structure between the lunate, triquetrum, and ulnar head, stabilizes the ulnar aspect of the wrist.
- Injury risk: Acute or chronic degenerative injury.
- Diagnosis: Gold standard is arthroscopy, sometimes MRI reveals abnormalities.
Radius and Ulna
- Radius angle: Distal end angles 25 degrees toward the ulnar (medial) direction, allowing greater ulnar deviation than radial deviation.
- Radius angle limitation: Bony impingement of carpal (wrist) side against the styloid process of the radius limits radial deviation.
- Ulna angle: Distal articular surface angles 10 degrees in the palmar direction. This tilt influences wrist flexion.
Angles
- Sagittal plane: 10 degrees, range of flexion
- Frontal plane: 25 degrees, range of ulnar deviation.
Radiocarpal Joint
- Proximal component: Biconcave distal end of the radius and articular disc
- Distal component: Biconvex proximal row of carpal (scaphoid, lunate, triquetrum).
- Radiocarpal role of triquetrum: At full ulnar deviation, the medial surface of the triquetrum contacts the articular disc.
- Joint type: Convex on concave; important for mobilization.
- Force distribution: 20% of compression passes through the articular disc, 80% passes through the scaphoid and lunate to the radius.
- Largest contact region: When the wrist is slightly extended (10° ) and slightly deviated in the ulnar direction.
Wrist Joint Positions
- Close packed position: Extension with slight abduction/radial deviation.
- Loose packed position: Neutral wrist with slight abduction/ulnar deviation.
Wrist Ligaments
- Extrinsic ligaments: Attach carpal bones to the radius/metacarpals. Includes volar and dorsal ligaments; palmar radiocarpal, dorsal radiocarpal, radial collateral, ulnar collateral.
- Three important dorsal extrinsic ligaments: dorsal intercarpal, dorsal radiotriquetral, and dorsal radioulnar.
- Intrinsic ligaments: Originate and insert on carpal bones, including scapholunate interosseous, lunotriquetral interosseous, and scaphotrapeziotrapezoid.
Wrist Muscles
- Primary set: Act on the wrist only, tendons attach distally.
- Secondary set: Tendons cross the carpus to attach to the digits (act on the wrist and hand).
- Extensor muscles (primary/secondary): E.g., extensor carpi radialis longus, extensor carpi radialis brevis, extensor carpi ulnaris, extensor digitorum, extensor indicis, extensor digiti minimi, extensor pollicis longus.
- Flexor muscles (primary/secondary): Includes flexor carpi radialis, flexor carpi ulnaris, palmaris longus, flexor digitorum profundus, flexor digitorum superficialis, flexor pollicis longus, abductor pollicis longus, extensor pollicis brevis
Wrist Movements
- Flexion: Anterior movement of the wrist or hand
- Extension: Posterior movement of the wrist or hand
- Radial deviation: Abduction of the hand
- Ulnar deviation: Adduction of the hand
Wrist Kinematics and Kinetics
- Osteokinematics: Wrist has two degrees of freedom (flexion/extension and ulnar/radial deviation)
- Circumduction: Combination of the aforementioned movements.
- Axis of rotation: Passes through the head of the capitate.
- Kinetics of Force Transmission: In extension, scaphoid transmits 51% of force, lunate transmits 49%. In neutral, it is 53% and 47%, and in flexion 55% and 45% respectively.
Wrist and Hand Injuries
- Ligamentous sprain: Scapholunate ligament injury, TFCC injury
- Fracture of distal radius
- Fractures of scaphoid and lunate.
- De Quervain's tenosynovitis (thickening of tendon sheaths/pain)
- Carpal tunnel syndrome (median nerve compression)
Contacting the Lecturer
- Email: [email protected]
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Description
Test your knowledge on the anatomy and function of the wrist joint complex with this engaging quiz. Explore questions on carpal bones, ligaments, and the mechanics of wrist movement. Perfect for students studying anatomy or physical therapy.
