The interphalangeal joints of the hand are the
hinge joints between the
phalanges of the
finger
A finger is a limb of the body and a type of digit, an organ of manipulation and sensation found in the hands of most of the Tetrapods, so also with humans and other primates. Most land vertebrates have five fingers ( Pentadactyly). Chambers ...
s that provide flexion towards the
palm of the hand.
There are two sets in each finger (except in the thumb, which has only one joint):
* "proximal interphalangeal joints" (PIJ or PIP), those between the first (also called proximal) and second (intermediate)
phalanges
* "distal interphalangeal joints" (DIJ or DIP), those between the second (intermediate) and third (distal) phalanges
Anatomically, the proximal and distal interphalangeal joints are very similar. There are some minor differences in how the
palmar plate
In the human hand, palmar or volar plates (also referred to as palmar or volar ligaments) are found in the metacarpophalangeal (MCP) and interphalangeal (IP) joints, where they reinforce the joint capsules, enhance joint stability, and limit hy ...
s are attached proximally and in the segmentation of the flexor tendon sheath, but the major differences are the smaller dimension and reduced mobility of the distal joint.
Joint structure
![Slide1tyty](https://upload.wikimedia.org/wikipedia/commons/4/41/Slide1tyty.JPG)
The PIP joint exhibits great lateral stability. Its transverse diameter is greater than its antero-posterior diameter and its thick collateral ligaments are tight in all positions during flexion, contrary to those in the
metacarpophalangeal joint
The metacarpophalangeal joints (MCP) are situated between the metacarpal bones and the proximal phalanges of the fingers. These joints are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow ca ...
.
Dorsal structures
The capsule, extensor tendon, and skin are very thin and lax dorsally, allowing for both phalanx bones to flex more than 100° until the base of the middle phalanx makes contact with the condylar notch of the proximal phalanx.
At the level of the PIP joint the extensor mechanism splits into three bands. The central slip attaches to the dorsal tubercle of the middle phalanx near the PIP joint. The pair of lateral bands, to which contribute the extensor tendons, continue past the PIP joint dorsally to the joint axis. These three bands are united by a transverse
retinacular ligament, which runs from the palmar border of the lateral band to the flexor sheath at the level of the joint and which prevents dorsal displacement of that lateral band. On the palmar side of the joint axis of motion, lies the oblique retinacular ligament
f Landsmeerwhich stretches from the flexor sheath over the proximal phalanx to the terminal extensor tendon. In extension, the oblique ligament prevents passive DIP flexion and PIP hyperextension as it tightens and pulls the terminal extensor tendon proximally.
Palmar structures
In contrast, on the palmar side, a thick ligament prevents
hyperextension
Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...
. The distal part of the palmar ligament, called the
palmar plate
In the human hand, palmar or volar plates (also referred to as palmar or volar ligaments) are found in the metacarpophalangeal (MCP) and interphalangeal (IP) joints, where they reinforce the joint capsules, enhance joint stability, and limit hy ...
, is thick and has a fibrocartilaginous structure. The presence of
chondroitin
A chondroitin is a chondrin derivative.
Types include:
* Chondroitin sulfate
* Dermatan sulfate
Chondroitin as a supplement is now commonly used (often in combination with glucosamine) in treating the joint disease of osteoarthritis. In contrast ...
and
keratan sulfate in the dorsal and palmar plates is important in resisting compression forces against the condyles of the proximal phalanx. Together these structures protect the tendons passing in front and behind the joint. These tendons can sustain traction forces thanks to their collagen fibers.
Palmar ligament
![Gray337](https://upload.wikimedia.org/wikipedia/commons/5/53/Gray337.png)
The
palmar ligament is thinner and more flexible in its central-proximal part. On both sides it is reinforced by the so-called check rein ligaments. The accessory collateral ligaments (ACL) originate at the proximal phalanx and are inserted distally at the base of the middle phalanx below the collateral ligaments.
The accessory ligament and the proximal margin of the palmar plate are flexible and fold back upon themselves during flexion. The flexor tendon sheaths are firmly attached to the proximal and middle phalanges by annular pulleys A2 and A4, while the A3 pulley and the proximal fibres of the C1 ligament attach the sheaths to the mobile volar ligament at the PIP joint. During flexion this arrangement produces a space at the neck of the proximal phalanx which is filled by the folding palmar plate.
The palmar plate is supported by a ligament on either side of the joint called the collateral ligaments, which prevent deviation of the joint from side to side. The ligaments can partially or fully tear and can avulse with a small fracture fragment when the finger is forced backwards into hyperextension. This is called a "palmar plate, or volar plate injury".
The palmar plate forms a semi-rigid floor and the collateral ligaments the walls in a mobile box which moves together with the distal part of the joint and provides stability to the joint during its entire range of motion. Because the palmar plate adheres to the
flexor digitorum superficialis near the distal attachment of the muscle, it also increases the moment of flexor action. In the PIP joint, extension is more limited because of the two so called
check-rein ligaments, which attach the palmar plate to the proximal phalanx.
Movements
The only movements permitted in the interphalangeal joints are
flexion
Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...
and
extension.
* Flexion is more extensive, about 100°, in the PIP joints and slightly more restricted, about 80°, in the DIP joints.
* Extension is limited by the volar and collateral ligaments.
The muscles generating these movements are:
The relative length of the digit varies during motion of the IP joints. The length of the palmar aspect decreases during flexion while the dorsal aspect increases by about 24 mm. The useful range of motion of the PIP joint is 30–70°, increasing from the index finger to the little finger. During maximum flexion the base of the middle phalanx is firmly pressed into the retrocondylar recess of the proximal phalanx, which provides maximum stability to the joint. The stability of the PIP joint is dependent of the tendons passing around it.
Clinical significance
Rheumatoid arthritis
Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are invol ...
generally spares the distal interphalangeal joints. Therefore, arthritis of the distal interphalangeal joints strongly suggests the presence of
osteoarthritis
Osteoarthritis (OA) is a type of degenerative joint disease that results from breakdown of joint cartilage and underlying bone which affects 1 in 7 adults in the United States. It is believed to be the fourth leading cause of disability in the w ...
or
psoriatic arthritis
Psoriatic arthritis is a long-term inflammatory arthritis that occurs in people affected by the autoimmune disease psoriasis. The classic feature of psoriatic arthritis is swelling of entire fingers and toes with a sausage-like appearance. Th ...
.
[ Last updated: Jan 22, 2016.]
See also
*
Interphalangeal joints of foot
The interphalangeal joints of the foot are between the phalanx bones of the toes in the feet.
Since the great toe only has two phalanx bones (proximal and distal phalanges), it only has one interphalangeal joint, which is often abbreviated as the ...
*
Metacarpophalangeal joints
The metacarpophalangeal joints (MCP) are situated between the metacarpal bones and the proximal phalanges of the fingers. These joints are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow ca ...
References
External links
Diagram at depuy.comVolar Plate Injury - Hand Therapy
Further reading
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{{DEFAULTSORT:Interphalangeal Articulations Of Hand
Joints
Hand