Dorsal carpal major ligaments

Obliquely oriented

Horizontal

Stabilizes the radiocarpal joint and aids scaphoid stability during movement

In flexion/extension of wrist, the _____ exhibits the greatest motion while ______ shows the least

Active extensuon begins at the distal carpal row, gliding over fixed proximal bones

Sccapholunate ligament positions the scaphoid and lunate together

Proximal surfaces moving as a unit on the radius and triangular fibrocartilage, with taut ligaments

As the wrist moves from full extension to flexion, the scaphoid’s role varies while ligaments maintain the proximal carpal row’s integrity. Increasd dorsal contact during extension suggests complex interactions between the concave proximal carpal surface and hand motion

Radial deviation

Ulnar deviation

Full radial deviation maximized stability

Full extension restricts further deviation, while the greatest ROM occurs in a neutral wrist position

ROM is greatest in

Maximum stability occurs in

Full flexion results in

Transitipn from full extension to full flexion

Radial deviation

Ulnar deviation

Injury to ligaments: Damage to scaphoid and lunate ligaments disrupts stabilization. Hamate collapses into flexion on the distal radius

lunate assumes an extebded posture; scaphoid subluxates

Increased contact pressures can lead to degenerative changes at the radioscaphlod joint

May progress to scapholunate advanced collapse (SLAC wrist)

Occurs when lunate-triquetrum ligament is disrupted

Both lunate and scaphoid flex, while triquetrum and distal carpal row extend

More prone to degeneration

Optimal grip strength

Wrist flexors’ work capacity is over twice that of wrist extensors. Radial deviators have slightly higher work capacity than ulnar deviators

Wrist flexion RC and midcarpal degrees

Wrist extension RC and midcarpal degrees

How many bones and joints in hand complex

CMC articulations

Plane joints, almost immobile

More flexible

Saddle joint

Key for thumb opposition and grip

Supports grip and provides sensory feedback

Formed by carpal bones; contribute to palm’s concavity

Formed by the metacarpal bones

Runs length of fingers

Key muscles of CMC jt

MCP joint type

MCP key structures

Fibrocartilage enhancing joint stability, limits hyperextension, supports longitudinal arch

Tightens in flexion

Tightens in hyperextension

IP joint type

1st CMC joint type

1st CMC joint articulation

PIP Normal flexion ROM

DIP Normal flexion ROM

Finger flexion and extension

Finger abduction and adduction

MCP articulation

IP joint articulation

IP joint degrees of freedom

Essential for grip

Flexes PIP jts and assists MCP flexion

Flexes MCP, PIP, and DIP jts

Encloses FDP and FDS tendons, reducing friction

Encases flexor pollicis longus tendon

Minimize friction, ensure smooth tendon gliding

Tendon trapped under annular pulley; locking finger in flexed position

Solution is to passive extend to “unlock” the finger

Nodules form on flexor tendons due to repetitive trauma

Synovial membrane folds supplying blood to FDS and FDP tendons

Ensure tendon functionality despite limited direct vascularization

MCP hyperextension with IP flexion

Caused by EDC contracyion, unopposed by intrinsic muscles

Order of independent extension

Connect EDC tendons for passive extension of adjacent fingers

Ruptured lateral band

Ruptured central slip

Prevents direct tendon to tendon contact and lessens the friction and allows smooth motion

How many anatomical bands

How many cruciform pulleys?

Mechanical locking of the finger flexor tendons

Carpal tunnel

Extensor tunnel lateral to medial

Grasping or holding objects using the hand, with the thumb often playing a key role

Fine placement of an object between fingers and thumb

Involves the entire hand for forceful grasping

Fine manipulation using fibgers and thumb without palm movement

Types of power grips

Move objects using proximal hand joints

Wrapping fingers around an object

Greater finger spread

Fingers without thumb

Holding thin objects between adjacent fingers

Types of precision handling

Opposing pads of thumb and index finger

Tips of thumb and finger contact, requiring full joint flexion

Thumb pad presses against the side of a finger

Fine control via reciprocal muscle activation

Held in neutral or slighr extension to balance forces from finger flexors

Wrist extension can flex fingers passively in paralyzed individuals