The metacarpophalangeal joints (MCP) are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow cavities on the proximal ends of the first phalanges, with the exception of that of the thumb

Thumb

The thumb is the first digit of the hand. When a person is standing in the medical anatomical position , the thumb is the lateral-most digit...

, which presents more of the characters of a ginglymoid joint. Arthritis of the MCP is a distinguishing feature of Rheumatoid Arthritis

Rheumatoid arthritis

Rheumatoid arthritis is a chronic, systemic inflammatory disorder that may affect many tissues and organs, but principally attacks synovial joints. The process produces an inflammatory response of the synovium secondary to hyperplasia of synovial cells, excess synovial fluid, and the development...

, as opposed to the distal interphalangeal joint

Distal interphalangeal joint

Distal interphalangeal joint can refer to:* Interphalangeal articulations of hand* Interphalangeal articulations of foot...

 in osteoarthritis

Osteoarthritis

Osteoarthritis also known as degenerative arthritis or degenerative joint disease, is a group of mechanical abnormalities involving degradation of joints, including articular cartilage and subchondral bone. Symptoms may include joint pain, tenderness, stiffness, locking, and sometimes an effusion...

.

Ligaments

Each joint has:

• palmar ligaments of metacarpophalangeal articulations
• collateral ligaments of metacarpophalangeal articulations

Dorsal surfaces

The dorsal surfaces of these joints are covered by the expansions of the Extensor tendons, together with some loose areolar tissue which connects the deep surfaces of the tendons to the bones.

Movements

The movements which occur in these joints are flexion

Flexion

In anatomy, flexion is a position that is made possible by the joint angle decreasing. The skeletal and muscular systems work together to move the joint into a "flexed" position. For example the elbow is flexed when the hand is brought closer to the shoulder...

, extension

Extension (kinesiology)

In kinesiology, extension is a movement of a joint that results in increased angle between two bones or body surfaces at a joint. Extension usually results in straightening of the bones or body surfaces involved. For example, extension is produced by extending the flexed elbow. Straightening of...

, adduction

Adduction

Adduction is a movement which brings a part of the anatomy closer to the middle sagittal plane of the body. It is opposed to abduction.-Upper limb:* of arm at shoulder ** Subscapularis** Teres major** Pectoralis major** Infraspinatus...

, abduction

Abduction (kinesiology)

Abduction, in functional anatomy, is a movement which draws a limb away from the median plane of the body. It is thus opposed to adduction.-Upper limb:* of arm at shoulder ** Supraspinatus** Deltoid* of hand at wrist...

, and circumduction

Circumduction (anatomy)

In anatomy, circumduction means to move a limb in a circular manner.Circumduction is defined as the movement pattern which is a combination of flexion, extension, adduction and abduction. It occurs at synovial joints where a circle can be described by the body part...

; the movements of abduction and adduction are very limited, and cannot be performed while the fingers form a fist.
The muscles of flexion and extension are as follows:

Location

Flexion

Extension >- | fingers

Flexor digitorum superficialis Flexor digitorum superficialis muscle Flexor digitorum superficialis is an extrinsic flexor muscle of the fingers at the proximal interphalangeal joints....  and profundus, lumbricales Lumbricals of the hand The lumbricals are intrinsic muscles of the hand that flex the metacarpophalangeal joints and extend the interphalangeal joints.-Structure:There are four of these small, worm-like muscles on each hand. These muscles are unusual in that they do not attach to bone... , and interossei Interossei Interossei refer to muscles between certain bones. There are many interossei in a human body. Specific interossei include:-On the hands:* Dorsal interossei muscles of the hand* Palmar interossei muscles-On the feet:... , assisted in the case of the little finger Little finger The little finger, often called the pinky in American English, pinkie in Scottish English , or small finger in medicine, is the most ulnar and usually smallest finger of the human hand, opposite the thumb, next to the ring finger.-Muscles:There are four muscles that...  by the flexor digiti minimi brevis Flexor digiti minimi brevis (hand) For the muscle of the foot, see Flexor digiti quinti brevis muscle The flexor digiti minimi brevis is a muscle in the hand that flexes the little finger...

extensor indicis proprius Extensor indicis proprius -External links: - "Extensor Region of Forearm and Dorsum of Hand: Deep Muscles of Extensor Region"... , and extensor digiti minimi muscle Extensor digiti minimi muscle The extensor minimi digiti is a slender muscle of the forearm, placed on the ulnar side of the Extensor digitorum communis, with which it is generally connected.... >- | thumb

flexores pollicis longus Flexor pollicis longus muscle The flexor pollicis longus is a muscle in the forearm and hand that flexes the thumb...  and brevis Flexor pollicis brevis muscle The flexor pollicis brevis is a muscle in the hand that flexes the thumb. It is one of three thenar muscles. It has both a superficial part and a deep part.-Origin and insertion:...

extensores pollicis longus Extensor pollicis longus muscle In human anatomy, the extensor pollicis longus is a skeletal muscle located dorsally on the forearm. It is much larger than the extensor pollicis brevis, the origin of which it partly covers, and acts to stretch the thumb together with this muscle....  and brevis Extensor pollicis brevis muscle In human anatomy, the extensor pollicis brevis is a skeletal muscle on the dorsal side of the forearm. It lies on the medial side of, and is closely connected with, the abductor pollicis longus.-Origin and insertion:...

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