ANA Upper Limb 5 Hand, Carpal tunnel and wrist Flashcards
(77 cards)
There are three groups of bones in the hand:
- the eight carpal bones are the bones of the wrist;
- the five metacarpals (I to V) are the bones of the metacarpus.
- the phalanges are the bones of the digits-the thumb has only two, the rest of the digits have three.
what forms much of the bony framework of the palm?
The carpal bones and metacarpals of the index, middle, ring, and little fingers (metacarpals II to V) tend to function as a unit and form much of the bony framework of the palm.
The function of the metacarpal bone of the thumb
The metacarpal bone of the thumb functions independently and has increased flexibility at the carpometacarpal joint to provide opposition of the thumb to the fingers.
Bones in the proximal row
the boat-shaped scaphoid;
the lunate, which has a ‘crescent shape’;
the three-sided triquetrum bone;
the pea-shaped pisiform
Location type and location of the pisiform bone
The pisiform is a sesamoid bone in the tendon of flexor carpi ulnaris and articulates with the anterior surface of the triquetrum.
Describe the scaphoid bone
The scaphoid has a prominent tubercle on its lateral palmar surface that is directed anteriorly.
Bones in the distal row
- the irregular four-sided trapezium bone;
- the four-sided trapezoid;
- the capitate, which has a head;
- the hamate, which has a hook.
Describe the articulation of the phalanges
The base of each proximal phalanx articulates with the head of the related metacarpal bone.
The head of each distal phalanx is non-articular and flattened into a crescent-shaped palmar tuberosity, which lies under the palmar pad at the end of the digit.
Describe the structure of a phalanx
the thumb has two-a proximal and a distal phalanx;
the rest of the digits have three-a proximal, a middle, and a distal phalanx.
Each phalanx has a base, a shaft (body), and distally, a head.
What is the wrist joint?
The wrist joint is a condyloid synovial joint between the distal end of the radius and the articular disc overlying the distal end of the ulna, and the scaphoid, lunate, and triquetrum.
Describe the articulation of the wrist joint
Together, the articular surfaces of the carpals form an oval shape with a convex contour, which articulates with the corresponding concave surface of the radius and articular disc.
Movements around the wrist joint
abduction, adduction, flexion, and extension.
Why can the hand can be adducted to a greater degree than it can be abducted?
Because the radial styloid process extends further distally than does the ulnar styloid process
Ligaments of the wrist and their function
- palmar radiocarpal
- palmar ulnocarpal
- 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.
Function of the carpal joints in movement
limited but contribute to the positioning of the hand in abduction, adduction, flexion, and, particularly, extension.
What are the carpal joints?
Is a synovial joint between the carpal bones which share a common articular cavity.
What joint imparts a wide range of mobility to the thumb?
The saddle joint, between metacarpal I and the trapezium, imparts a wide range of mobility to the thumb that is not a feature of the rest of the digits.
Movements at the carpometacarpal joint
flexion, extension, abduction, adduction, rotation, and circumduction.
Describe the degree of movement between metacarpals II to V?
The carpometacarpal joints between metacarpals II to V and the carpal bones are much less mobile than the carpometacarpal joint of the thumb, allowing only limited gliding movements.
Movement of the joints increases medially so metacarpal V slides to the greatest degree.
What are metacarpophalangeal joints?
The joints between the distal heads of the metacarpals and the proximal phalanges of the digits are condylar joint of synovial joint, which allow flexion, extension, abduction, adduction, circumduction, and limited rotation.
Ligaments of the metacarpophalangeal joints
The capsule of each joint is reinforced by the palmar ligament and by medial and lateral collateral ligaments.
In addition to the above ligaments, there is the deep transverse metacarpal ligaments.
The three deep transverse metacarpal ligaments are thick bands of connective tissue connecting the palmar ligaments of the metacarpophalangeal joints of the fingers to each other.
They are important because, by linking the heads of the metacarpal bones together, they restrict the movement of these bones relative to each other.
As a result, they help form a unified skeletal framework for the palm of the hand.
What are the INTERPHALANGEAL JOINTS OF HAND?
The interphalangeal joints of the hand are hinge joints that allow mainly flexion and extension.
They are reinforced by medial and lateral collateral ligaments and palmar ligaments.
Describe the carpal injury of a fracture across the waist of the scaphoid bone.
It is uncommon to see other injuries.
In approximately 10% of individuals, the scaphoid bone has a sole blood supply from the radial artery, which enters through the distal portion of the bone to supply the proximal portion.
When a fracture occurs across the waist of the scaphoid, the proximal portion therefore undergoes avascular necrosis.
It is impossible to predict which patients have this blood supply.
What is Avascular necrosis?
Avascular necrosis is the death of bone tissue due to a lack of blood supply. Also called osteonecrosis, it can lead to tiny breaks in the bone and cause the bone to collapse. The process usually takes months to years
