The metatarsophalangeal joints are of the condyloid kind, formed by the reception of the rounded heads of the metatarsal bones in shallow cavities on the bases of the proximal phalanges.
The ligaments are the plantar and collateral.
The plantar (accessory plantar) ligaments are thick, dense, fibrous structures. They are placed on the plantar surfaces of the joints in the intervals between the collateral ligaments, to which they are connected; they are loosely united to the metatarsal bones, but are firmly fixed to the bases of the proximal phalanges. Their margins are continuous with the deep transverse ligaments of the sole, and their plantar surfaces are grooved for the flexor tendons, the fibrous sheaths of which are connected to the sides of the grooves; the deep surfaces of the ligaments form parts of the articular facets for the heads of the metatarsal bones.
The deep transverse ligaments of the sole (ligamenta capitulorum transversa) consist of four short, wide, flattened bands which connect the plantar ligaments of adjoining metatarsophalangeal joints to one another. Their dorsal aspects are related to the interosseous muscles and their plantar aspects to the lumbricals and the digital vessels and nerves. They correspond closely to the deep transverse ligaments of the palm, but, in addition, they are connected to the plantar ligament of the first metatarsophalangeal joint.
The collateral ligaments are two strong, rounded cords, placed on the sides of the joints; each is attached by one end to the dorsal tubercle on the side of the head of the metatarsal bone, and by the other to the corresponding side of the base of the phalanx.
The extensor tendons supply the place of dorsal ligaments.
Movements.-The movements permitted in the metatarsophalangeal articulations are flexion, extension, adduction, abduction and circumduction.
Muscles producing the movements:
- Flexion – Flexores digitorum longus, brevis et accessorius (Quadratus plantae), Lumbricales, Interossei dorsales et plantares, Flexores hallucis longus et brevis, Flexor digiti minimi brevis.
- Extension – Extensores digitorum longus et brevis, Extensor hallucis longus.
- Adduction – Interossei plantares, Adductor hallucis, long flexors of toes.
- Abduction – Interossei dorsales, Abductor hallucis, Abductor digiti minimi.
THE JOINTS OF THE DIGITS
The digital or interphalangeal articulations are hinge-joints, and each has a plantar and two collateral ligaments. The arrangement of these ligaments is similar to that in the metatarsophalangeal articulations. The extensor tendons supply the places of dorsal ligaments.
Movements.-The only movements permitted in the joints of the digits are flexion and extension; these movements are freer between the proximal and middle phalanges than between the middle and distal. The amount of flexion is very considerable, but extension is limited by the plantar ligaments.
Muscles producing the movements
- Flexion.-Flexores digitorum longus, brevis et accessorius (Quadratus plantae), Flexor hallucis longus.
- Extension.-Lumbricales, Interossei dorsales et plantares, Extensor hallucis longus.
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