Bones of the Wrist Joint
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Transcript of Bones of the Wrist Joint
BONES OF THE
WRIST JOINT
The wrist
area b/w the hand and forearm.Made up of a group of short bones known
as the carpus or wrist bonesConsists of eight carpal bones which form
2 rows 4 proximal carpal bones 4 distal carpal bones
The proximal carpal bones (PCB) are :Scaphoid bone Lunate boneTriquetrumPisiform bone
The distal carpal bones (DCB) are :TrapeziumTrapezoid boneCapitate boneHamate bone
THE PROXIMAL CARPAL BONES
Scaphoid bone
Boat –shaped
PCB on the lateral border of the wrist
The carpal bone closest to the styloid process of
the radius
Has a prominent tubercle on its lateral palmar
surface directed anteriorly
Lunate bone
Comma-shaped
Articulates with the radius like the
scaphoid bone
Medial to the scaphoid bone
Triquetrum
Small 3-sided shaped boneMedial to lunate boneArticulates with the articular disc separating
the ulnar head from the wrist
Pisiform bone
Small, pea-shapedArticulates with ant. surface of triquetrum
THE DISTAL CARPAL BONES
Trapezium
Irregular 4-sided bone
Lateral bone of the distal row
Has a distinct tubercle on its palmar surface
that projects ant
Proximal surface articulates with scaphoid bone
Articulates with metacarpal of thumb
Trapezoid bone
4-sided wedge shaped
Lies medial to the trapezium
Like the trapezium it has aproximal
articulation with the scaphoid
Capitate bone
Largest carpal bone Sits b/w trapezoid bone and the hamate bone Articulates with the base of metacarpal III
Hamate bone
Has a hook on its palmar surface that projects ant.
Medial distal carpal bone
To remember…Sam- Scaphoid PCB FROM
Likes - Lunate LATERAL TO
To – Triquetrum MEDIAL
Push - Pisiform
The - Trapezium
Toy – Trapezoid DCB FROM
Car – Capitate LATERAL TO
Hard- Hamate MEDIAL
ARTICULAR SURFACES
Carpals have numerous articular surfaces
1. They articulate with each other
2. DCB articulate with metacarpals of the digits
3. The expansive proximal surfaces of the scaphoid and lunate articulate with the radius to form the most of the wrist joint
THE WRIST JOINT
Synovial joint (ellipsoid joint) b/w distal end
of the radius and the articular disc
overlying the distal end of the ulna, the
scaphoid, lunate & triquetrum
The articular surfaces of the carpals form
an oval shape with a convex contour
with the corresponding concave surface
of the radius and articular disc
The capsule of the wrist joint is reinforced by palmar
radiocarpal, palmar ulnocarpal, and dorsal
radiocarpal ligaments. In addition, radial and ulnar
collateral ligaments of the wrist joint span the
distance between the styloid processes of the radius
and ulna and the adjacent carpal bones. These
ligaments reinforce the medial and lateral sides of
the wrist joint and support them during flexion and
extension.
CARPAL JOINTS
The synovial joints between the carpal bones share
a common articular cavity. The joint capsule of the
joints is reinforced by numerous ligaments.
Although movement at the carpal joints
(intercarpal joints) is limited, they do contribute to
the positioning of the hand in abduction, adduction,
flexion, and, particularly, extension.
Movements of the wrist joint
The wrist joint allows movement around two axes
abduction and adduction
flexion and extension
NOTE: Because the radial styloid process extends
further distally than does the ulnar styloid process, the
hand can be adducted to a greater degree than it can
be abducted.
REFERENCES
Gray’s Anatomy for students; Drake et al ; Elsevier; 2005
Principles of anatomy and physiology; Tortora Gerard; 3rd edition; New York. John Wiley, 2003
Fundamentals of Anatomy and Physiology; Martini F; USA; Benjamin Cummings; 2004
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