L40. Joints of the Wrist and Hands Flashcards

1
Q

How are the carpals arranged?

A

In two rows the proximal row (towards forearm) and the distal row (towards the fingers)

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2
Q

What are the carpals of the proximal row?

A

From lateral to medial:

Scaphoid, Lunate, Triquetrium, Pisiform

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3
Q

What are the carpals of the distal row?

A

From lateral to medial:

Trapezium, Trapezoid, Capitate, Hammate

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4
Q

The hand is subdivided into three regions, what are these?

A
Short bones (carpals of the wrist)
Metacarpals (long bones of the hand - palm)
Phalanges
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5
Q

How are the phalanges subdivided?

A

All (except the first metacarpal phalange) is divided into three: proximal, middle and distal (the thumb only has 2 subdivisions)

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6
Q

What bone forms the floor of the anatomical snuff box?

A

The scaphoid

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7
Q

The pisiform bone is an example of a sesamoid bone. What does this mean?

A

It lies completely within a tendon

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8
Q

The metacarpal of the thumb is at a right angle to the other metacarpals. What does this signify?

A

This has an impact on the movement of the thumb in relation to the rest of the hand (the thumb has relative increased range of movement)

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9
Q

Metacarpals are examples of long bones however they differ in their development to typical long bones. How is this so?

A

They only ossify at one end

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10
Q

Why is there are large (boney) gap between the head of the ulnar and the triquetrium?

A

Because the ulna is not in any way involved in the wrist joint. There is a cartilaginous disc there

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11
Q

The two wrist creases form important landmarks in terms of underlying boney anatomy. What do they form?

A

Distal wrist crease: the proximal attachement of the flexor retinaculum (ligament) that extends to the palm of the hand

Proximal wrist crease: where the wrist joint itself is

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12
Q

Do the carpal bones ossify before or after birth?

A

Only after birth and progressively so. The captitate is the first one to ossify and then progressively in a counterclockwise direction ossify (hammate, triquetrium, lunate etc)
The pisiform is the last to ossify

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13
Q

The pisiform sits up and projects anteriorly than the rest of the carpal. What is a major significance of this?

A

A muscle lies on top of it and this raised bone allows higher efficiency of the muscle in flexor action

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14
Q

The flexor retinaculum ligament overlies and attaches to certain parts of the carpal bones forming a tunnel. Where does it attach to?

A

Pisiform
Hook of the hammate
Scaphoid tubercle
Trapezium tubercle

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15
Q

What runs through the tunnel made by the carpal bones and the flexor retinaculum ligament?

A

a key structure of vessels tendons and nerves enter the hand through it.

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16
Q

What are the two major joints of the wrist complex?

What type of joint is each one?

A
Radiocarpal joint (wrist joint proper) between the radius and the scaphoid+lunate
= synovial ellipsoid joint (also called condylar) = circumduction movement

Intercarpal (midcarpal) joint between the proximal and distal carpal rows
= plane synovial joints

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17
Q

Is there a joint cavity in the wrist?

A

There is no single joint cavity. The bones simply articulate with each other

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18
Q

What kind of movements occur at the wrist complex joints?

A

Biaxial movement:
Flexion and extension
AND
Radial and ulnar deviation (adduction and abduction)

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19
Q

The radiocarpal (wrist joint) has articular surfaces that are concave in 2 different directions. What does this mean for its movement?

A

There is no pure rotation of the joint

there is CIRCUMDUCTION which means a combination of all movements

20
Q

With the movements of the wrist, flexion is greater than extension. Why is this so?

A

Because posteriorly, the radius descends further than in the anterior plane. Thus there is more potential of movement in the anterior part of the wrist which is the flexor movement.

21
Q

Which movement in the wrist is larger, ulnar deviation (adduction) or radial deviation (abduction)?

A

Ulnar deviation is much greater than radial deviation because the radial styloid process blocks complete movement of the wrist in the radial direction.

22
Q

Are the intercarpal joints functional or anatomic?

A

The are functional

23
Q

The amalgum of spaces of the intercapal joints are linked by what?

A

Interosseus ligaments

24
Q

How are the movements related (ie. which is greater) in the intercarpal joints to that of the wrist?

A

movement is generally much, much smaller overall

Movement trends are opposite to the wrist.
Thus intercarpal:
extension>flexion
radial > ulnar

25
Q

Both the radiocarpal and the intercarpal joints contain synovial membrane and hyaline cartilage. What does this mean?

A

They are synovial joints

26
Q

The joints are reinforced by ligaments. What are the 2 major functions of these ligaments?

A
  1. Stabilise the joints

2. All of them transmit vessels to the bones

27
Q

What are the major ligaments that support the joints?

A
  1. Palmar ligaments: ANTERIOR
    - ventral radiocarpal palmar ligament attaching from the radius then travelling obliquely distally and medially towards the metacarpals
    - ventral ulnocarpal palmar ligmant similarily attaching to the ulna and travelling obliquely
  2. Dorsal ligaments: POSTERIOR
    - dorsal radiocarpal
    - dorsal ulnocarpal (much smaller and less significant)
28
Q

Which of the ligmanets is stronger?
Palmar or dorsal?
Ulnar or radial?

A

Palmer are stronger than dorsal

AND

Radio are stronger than ulnar (because they prevent the carpal bones from sliding medially into the gap)

29
Q

Where do the main flexor and extensor tendons (off muscles in the forearm) extend to?

A

They attach to proximal aspects of the metacarpals

NOTHING ATTACHES TO THE CARPAL BONES (except the pisiform)

30
Q

Describe how contraction of the flexor and extensor tendons reinforces the joints?

A

Contraction pulls the metacarpals distally towards the carpals leading to compressive forces that stabilise the joints

31
Q

What percent of all fractures and dislocations of the body occur at the wrist?

A

About 6%

32
Q

What is the most commonly fractured bone in the upper limb? How does this occur?

A

The distal radius (and the clavicle), especially in the elderly
= called Colles Fracture

Forces on the hand transmit especially from the capitate carpal up to the scaphoid (and lunate) and to the distal radius.

33
Q

What is the most frequently fractured carpal bone? How does this occur?

A

The scaphoid

Forces on the hand act on the capitate (large and strong) which transmits forces that fracture the scaphoid bone

34
Q

Which is the most commonly subluxed bone of the hand? Why is this so?

A

The lunate bone is most commonly subluxed because it lies adjacent to the ‘gap’ between the ulnar and the wrist.

This is particularly common secondary to ligament, radio-scaphoid-lunate injury

35
Q

There is a specialised ligament in the wrist, what is it called and what is the function?

A

The radio-scapho-lunate ligament from the radius over the scaphoid and onto the lunate to stabilise the lunate and prevent it from subluxation

36
Q

What are the two common fractures of the metacarpals?

A

At the base of the first metacarpal = bennet’s fracture

At the neck of the 5th metacarpal = boxer’s fracture

37
Q

What are the different movements of the thumb?

A

Extension, Flexion, Abduction, Adduction, Circumduction and Opposition

38
Q

What bones make up the major carpometacarpal joint of the thumb and what kind of joint is this?

A

Trapezoid and first metacarpal

Saddle joint

39
Q

What is the pathology of a scaphoid fracture?

A

The scaphoid bone has numerous vascular foraminae between the two articular surfaces. These allow for vessels to pass through.

In about 30-35% of the population, the location of the foraminae are only distally (hence supply goes to distal and then back to proximal).

Fracture occurs through the waist where these vessels lie and if it occurs in these people, interruption of proximal blood supply occurs leading to avascular necrosis.

40
Q

What kind of joints are the carpometacarpal joints?

A

All are synovial

41
Q

The four carpometacarpal joints (exception is the thumb saddle joint) are linked, what by and what does this mean?

A

By a deep transverser metacarpal ligament

Means that joints II-III are immobile between the joints and that there is force transmission

42
Q

Carpometacarpal joints IV and V are slightly more mobile that the others. How so

A

IV and V are hinge joints allowing for flexion and extension and V is also able to abduct further.

43
Q

What kind of joint are the metacarpophalangeal joints?

A

Condyloid joints
Convex head of the metacarpal joins with the concave base of phalax.

Also hinge joints

44
Q

What is the volar plate?

A

A fibrocartilaginous plate that expands the surface of articulation between the metacarpals and the phalages (this is also present in the interphalangeal joints).

45
Q

How are the metacarpophalangeal joints stabilised?

A

They all have collateral ligaments attached to them

46
Q

What is easier, flexed abduction/adduction or extended abduction/adduction of the fingers. Why is this so?

A

It is easier to be extended and abduct and adduct because of the tension of the ligaments.

Thus it is better to immobilise in flexion (tensed/tightened ligament)

47
Q

What are the two different types of injury to the interphalangeal joints? What happens in compensation?

A

Palmar (hyper extension): swan’s neck with compensatory flexion of the tip

Dorsal (flexion): boutonniere with compensatory hyperextension of the tip