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The joints of the hand form a highly flexible and coordinated system enabling precise movements required for grip and manipulation.
These include:
Intercarpal joints – between carpal bones.
Midcarpal joint – between proximal and distal carpal rows.
Carpometacarpal (CMC) joints – between carpus and metacarpals.
Intermetacarpal joints – between adjacent metacarpals.
First carpometacarpal joint – unique, highly mobile saddle joint of the thumb.
Plane synovial joints.
Adjacent carpal bones of proximal and distal rows articulate through small, flat facets.
Midcarpal joint lies between the two carpal rows — functionally the most mobile part of the wrist complex.
Intermetacarpal joints are small synovial articulations between bases of 2nd–5th metacarpals.
| Ligament | Description / Function |
|---|---|
| Dorsal & palmar intercarpal ligaments | Unite adjacent carpal bones, strengthen joint capsule. |
| Interosseous ligaments | Bind bones within each carpal row, restrict separation. |
| Dorsal & palmar carpometacarpal ligaments | Connect distal carpal row to metacarpal bases. |
| Intermetacarpal ligaments | Between bases of 2nd–5th metacarpals; stabilize arches of hand. |
Most intercarpal, midcarpal, and CMC (2nd–5th) joints communicate with one another, forming a common synovial cavity.
1st CMC joint (thumb) and pisiform joint are separate.
Small gliding and rotational movements between carpal bones allow:
Flexion/extension and abduction/adduction at wrist.
Midcarpal joint contributes greatly to the total wrist range of motion.
Saddle-type synovial joint — unique and highly mobile.
Trapezium: Concavoconvex.
Base of 1st metacarpal: Reciprocal concavoconvex surface.
Both are covered with fibrocartilage and oriented at right angles to each other → enabling multiaxial movement.
| Ligament | Function |
|---|---|
| Capsular ligament | Loose but strong; surrounds joint. |
| Anterior & posterior oblique ligaments | Reinforce capsule; prevent displacement. |
| Intermetacarpal ligament | Connects base of 1st metacarpal to 2nd metacarpal; stabilizes thumb. |
| Movement | Axis / Plane | Muscles Responsible |
|---|---|---|
| Flexion | Across palm (frontal plane) | Flexor pollicis longus & brevis |
| Extension | Away from palm | Extensor pollicis longus & brevis |
| Abduction | Perpendicular to palm (sagittal plane) | Abductor pollicis longus & brevis |
| Adduction | Toward palm | Adductor pollicis |
| Opposition | Combined flexion, abduction, medial rotation | Opponens pollicis (assisted by FPL, APB) |
| Reposition | Reverse of opposition | EPL, EPB, APL |
Enables opposition of thumb to fingers, forming the anatomical basis of precision grip — a hallmark of human hand function.
Flexion–extension: Transverse axis through trapezium.
Abduction–adduction: Sagittal axis perpendicular to plane of palm.
Opposition–reposition: Composite movement involving rotation around both axes.
Anterior interosseous branch of median nerve.
Dorsal interosseous branch of radial nerve.
Radial artery (through its superficial palmar and dorsal carpal branches).
Make dorsal and palmar incisions to expose the carpal region.
Remove extensor retinaculum and dorsal tendons to reveal dorsal intercarpal ligaments.
Open the capsule of midcarpal joint to show articulation between scaphoid–lunate–triquetral and trapezium–capitate–hamate.
Identify interosseous ligaments joining adjacent carpal bones.
Trace distal articulations to carpometacarpal joints — note the separate thumb joint capsule.
Demonstrate movement of thumb base on trapezium (flexion, extension, opposition, and rotation).
Observe the pisiform–triquetral joint (plane synovial, distinct capsule).
Common in postmenopausal women and manual workers.
Pain at thumb base during grip or pinching.
Radiographs show joint space narrowing and osteophyte formation.
May require arthroplasty or fusion in severe cases.
Rupture of ulnar collateral ligament of 1st CMC joint due to forced abduction (fall while holding ski pole).
Leads to joint instability and pain at thumb base.
Treated with immobilization or surgical repair.
May occur after trauma or forced hyperextension.
Thumb appears displaced dorsally; opposition impaired.
Generalized hypermobility can cause recurrent thumb base instability → weakness of grip.
Ligament injury between scaphoid–lunate or lunate–triquetral → abnormal alignment, pain on wrist motion.
Early involvement of intercarpal and CMC joints, especially ulnar side → swelling, pain, “ulnar deviation” of fingers.
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