Plantar plate
Encyclopedia
In the human foot, the plantar or volar plates (also called plantar or volar ligament
s) are fibrocartilaginous
structures found in the metatarsophalangeal
(MTP) and interphalangeal
(IP) joints. The anatomy and composition of the plantar plates is similar to the palmar plates in the metacarpophalangeal
(MCP) and interphalangeal joints in the hand; the proximal origin is thin but the distal insertion is stout. Due to the weight-bearing nature of the human foot, the plantar plates are exposed to extension forces not present in the human hand.
The plantar plate supports the weight of the body and restricts dorsiflexion, whilst the main collateral ligament
and the accessory collateral ligament (together referred as the Collateral Ligament Complex, CLC), prevent motions in the transverse and sagittal planes.
The major difference between the plantar plates of the MTP and IP joints, is that they blend with the transverse metatarsal ligament
in the MTP joints (not present in the toes). The MTP joint of the first toe differs from those of the other toes in that other muscles act on the joint, and in the presence of two sesamoid bones.
The plantar plate is firm but flexible fibrocartilage with a composition similar to that found in the menisci
of the knee (composed roughly of 75% type-I collagen
), and can thus withstand compressive loads and act as a supportive articular surface. Most of its fibers are oriented longitudinally, in the same direction as the plantar fascia, and the plate can thus sustain substantial tensile loads in this direction.
The plantar plate is attached to the proximal phalanx, to the major longitudinal bands of the plantar fascia
, and to the collateral ligaments. Together with the collateral ligaments, it forms a soft tissue box which is connected to the sides of the metatarsal head. The plate from the substantial distal insertion of the plantar fascia and can withstand tensile loads in line with the fascia itself. The plate can witstand compressive loads from the metatarsal head because of the orientation of the fibers in its fibrocartilage.
The skeleton of the foot rests on a multi-layered ligamentous system of beams and trusses that responds to weight-bearing on irregular surfaces. A transverse system at the MTP joints is formed by the plantar plates and the deep transverse metatarsal ligament. The strong, longitudinal fibres of the deep plantar fascia
are inserted along this transverse system to form a strong longitudinal system. The longitudinal system controls the longitudinal arches of the foot, whilst the transverse system controls the splay of the forefoot. Both systems are centered on the plantar plates and activated weight-bearing pressure on the metatarsal heads.
The tendon of the extensor digitorum longus muscle
extends the MTP joint by using the plantar fibroaponeurotic
structure as a sling. The muscle becomes a deforming force if the MTP joint is held in an extended position over a long time, such as in a high-heeled footwear. The muscle extends at the IP joints when the MTP joint is flexed or in neutral position. Flexion is primarily performed by intrinsic foot muscles; the second toe (the) is unique as it has two dorsal interossei
but no plantar interossei muscles
. The lumbrical muscles
, attached to the medial side of the lesser toes, act as unopposed adductor, but become insufficient plantar flexors with chronic extension.
Ligament
In anatomy, the term ligament is used to denote any of three types of structures. Most commonly, it refers to fibrous tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament.Ligament can also refer to:* Peritoneal...
s) are fibrocartilaginous
Fibrocartilage
White fibrocartilage consists of a mixture of white fibrous tissue and cartilaginous tissue in various proportions. It owes its flexibility and toughness to the former of these constituents, and its elasticity to the latter...
structures found in the metatarsophalangeal
Metatarsophalangeal articulations
The metatarsophalangeal articulations are the joints between the metatarsal bones of the foot and the proximal bones of the toes...
(MTP) and interphalangeal
Interphalangeal articulations of foot
The interphalangeal articulations of the foot are the joints between the phalanges of the toes. They are ginglymoid joints, and each has a plantar and two collateral ligaments...
(IP) joints. The anatomy and composition of the plantar plates is similar to the palmar plates in the metacarpophalangeal
Metacarpophalangeal joint
The metacarpophalangeal joints 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, which presents more of the characters of a ginglymoid joint...
(MCP) and interphalangeal joints in the hand; the proximal origin is thin but the distal insertion is stout. Due to the weight-bearing nature of the human foot, the plantar plates are exposed to extension forces not present in the human hand.
The plantar plate supports the weight of the body and restricts dorsiflexion, whilst the main collateral ligament
Collateral ligaments of metatarsophalangeal articulations
The collateral ligaments of metatarsophalangeal articulations are strong, rounded cords, placed one on either side of each joint, and attached, by one end, to the posterior tubercle on the side of the head of the metatarsal bone, and, by the other, to the contiguous extremity of the phalanx.The...
and the accessory collateral ligament (together referred as the Collateral Ligament Complex, CLC), prevent motions in the transverse and sagittal planes.
The major difference between the plantar plates of the MTP and IP joints, is that they blend with the transverse metatarsal ligament
Transverse metatarsal ligament
The transverse metatarsal ligament is a narrow band which runs across and connects together the heads of all the metatarsal bones; it is blended anteriorly with the plantar ligaments of the metatarsophalangeal articulations....
in the MTP joints (not present in the toes). The MTP joint of the first toe differs from those of the other toes in that other muscles act on the joint, and in the presence of two sesamoid bones.
The plantar plate is firm but flexible fibrocartilage with a composition similar to that found in the menisci
Meniscus (anatomy)
In anatomy, a meniscus is a crescent-shaped fibrocartilaginous structure that, in contrast to articular disks, only partly divides a joint cavity. In humans it is present in the knee, acromioclavicular, sternoclavicular, and temporomandibular joints; in other organisms they may be present in other...
of the knee (composed roughly of 75% type-I collagen
Type-I collagen
Type-I collagen is the most abundant collagen of the human body.It is present in scar tissue, the end product when tissue heals by repair.It is found in tendons, the endomysium of myofibrils and the organic part of bone.- See also :* Collagen...
), and can thus withstand compressive loads and act as a supportive articular surface. Most of its fibers are oriented longitudinally, in the same direction as the plantar fascia, and the plate can thus sustain substantial tensile loads in this direction.
Metatarsophalangeal joints
At the metatarsophalangeal joint the plantar plate plays an important role in the foot's weight-bearing function.The plantar plate is attached to the proximal phalanx, to the major longitudinal bands of the plantar fascia
Plantar fascia
The plantar fascia is the thick connective tissue which supports the arch on the bottom of the foot. It runs from the tuberosity of the calcaneus forward to the heads of the metatarsal bones .The often painful condition plantar fasciitis is an inflammatory condition of the plantar...
, and to the collateral ligaments. Together with the collateral ligaments, it forms a soft tissue box which is connected to the sides of the metatarsal head. The plate from the substantial distal insertion of the plantar fascia and can withstand tensile loads in line with the fascia itself. The plate can witstand compressive loads from the metatarsal head because of the orientation of the fibers in its fibrocartilage.
The skeleton of the foot rests on a multi-layered ligamentous system of beams and trusses that responds to weight-bearing on irregular surfaces. A transverse system at the MTP joints is formed by the plantar plates and the deep transverse metatarsal ligament. The strong, longitudinal fibres of the deep plantar fascia
Plantar fascia
The plantar fascia is the thick connective tissue which supports the arch on the bottom of the foot. It runs from the tuberosity of the calcaneus forward to the heads of the metatarsal bones .The often painful condition plantar fasciitis is an inflammatory condition of the plantar...
are inserted along this transverse system to form a strong longitudinal system. The longitudinal system controls the longitudinal arches of the foot, whilst the transverse system controls the splay of the forefoot. Both systems are centered on the plantar plates and activated weight-bearing pressure on the metatarsal heads.
The tendon of the extensor digitorum longus muscle
Extensor digitorum longus muscle
The Extensor digitorum longus is a pennate muscle, situated at the lateral part of the front of the leg.-Origin and insertion:It arises from the lateral condyle of the tibia; from the upper three-fourths of the anterior surface of the body of the fibula; from the upper part of the interosseous...
extends the MTP joint by using the plantar fibroaponeurotic
Aponeurosis
Aponeuroses are layers of flat broad tendons. They have a shiny, whitish-silvery color, are histologically similar to tendons, and are very sparingly supplied with blood vessels and nerves. When dissected, aponeuroses are papery, and peel off by sections...
structure as a sling. The muscle becomes a deforming force if the MTP joint is held in an extended position over a long time, such as in a high-heeled footwear. The muscle extends at the IP joints when the MTP joint is flexed or in neutral position. Flexion is primarily performed by intrinsic foot muscles; the second toe (the) is unique as it has two dorsal interossei
Dorsal interossei of the foot
In human anatomy, the dorsal interossei of the foot are four muscles situated between the metatarsal bones.- Origin :The four interossei muscles are bipenniform muscles each originating by two heads from the proximal half of the of the sides of adjacent metatarsal bones.- Insertion :The two heads...
but no plantar interossei muscles
Plantar interossei muscles
The plantar interossei, three in number, lie beneath rather than between the metatarsal bones, and each is connected with but one metatarsal bone....
. The lumbrical muscles
Lumbrical muscle (foot)
The lumbricals are four small skeletal muscles, accessory to the tendons of the flexor digitorum longus and numbered from the medial side of the foot; they arise from these tendons, as far back as their angles of division, each springing from two tendons, except the first.The muscles end in...
, attached to the medial side of the lesser toes, act as unopposed adductor, but become insufficient plantar flexors with chronic extension.