出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/05/28 01:23:08」(JST)
| Toes | |
|---|---|
|
Toes on the foot. The innermost toe (bottom-left in image), which is normally called the big toe, is the hallux.
|
|
|
Bones of the foot (the toe bones are the ones in green, blue and orange)
|
|
| Details | |
| Latin | Digiti pedis |
| Identifiers | |
| TA | A01.1.00.046 |
| FMA | 25046 |
| Anatomical terminology | |
Toes are the digits of the foot of a tetrapod. Animal species such as cats that walk on their toes are described as being digitigrade. Humans, and other animals that walk on the soles of their feet, are described as being plantigrade; unguligrade animals are those that walk on hooves at the tips of their toes.
The toe refers to a part of the human foot, with five toes present on each human foot. Each toe consists of three phalanx bones, the proximal, middle, and distal, with the exception of the big toe (Latin: Hallux). The hallux only contains two phalanx bones, the proximal and distal. The phalanx bones of the toe join to the metatarsal bones of the foot at the interphalangeal joints.[1]:557 Outside the hallux bones is skin, and present on all five toes is a toenail.
The toes are, from medial to lateral:
Toe movement is generally flexion and extension via muscular tendons that attach to the toes on the anterior and superior surfaces of the phalanx bones.[1]:573
With the exception of the hallux, toe movement is generally governed by action of the flexor digitorum brevis and extensor digitorum brevis muscles. These attach to the sides of the bones,[1]:572–5 making it impossible to move individual toes independently. Muscles between the toes on their top and bottom also help to bring abduct and adduct the toes.[1]:579 The hallux and little toe have unique muscles:
The toes receive blood from the digital branches of the plantar metatarsal arteries and drain blood into the dorsal venous arch of the foot.[1]:580–581
Sensation to the skin of the toes is provided by five nerves. The superficial fibular nerve supplies sensation to the top of the toes, except between the hallux and second toe, which is supplied by the deep fibular nerve, and the outer surface of the fifth toe, supplied by the sural nerve. Sensation to the bottom of the toes is supplied by the medial plantar nerve, which supplies sensation to the great toe and inner three-and-a-half toes, and the lateral plantar nerve, which supplies sensation to the little toe and half of the sensation of the fourth toe.[1]:583
In humans, the hallux is usually longer than the second toe. There is an inherited trait in humans, where the dominant gene causes a longer second toe ("Morton's toe" or "Greek foot") while the homozygous recessive genotype presents with the more common trait: a longer hallux.[2] People with the rare genetic disease fibrodysplasia ossificans progressiva characteristically have a short hallux which appears to turn inward, or medially, in relation to the foot.
The hallux may not be the longest toe on the foot of some individuals. The name stems from the Latin for the same, similar to the pollex, which refers to the thumb, the corresponding digit of the hand. The fifth toe is the outermost usually the smallest toe of the foot.
Humans usually have five toes on each foot. When more than five toes are present, this is known as polydactyly. Other variants may include syndactyly or amputation.
Forefoot shape, including toe shape, exhibits significant variation among people; these differences can be measured and have been statistically correlated with ethnicity.[3] Such deviations may affect comfort and fit for various shoe types. Research conducted by Freedman for the U.S. Army indicated that larger feet may still have smaller arches, toe length, and toe-breadth.[4]
The human foot consists of multiple bones and soft tissues which support the weight of the upright human. Specifically, the toes assist the human while walking,[5] providing balance, weight-bearing, and thrust during the gait.
A sprain or strain to the small interphalangeal joints of the toe is commonly called a stubbed toe. A sprain or strain where the toe joins to the foot is called turf toe.
Long-term use of improperly sized shoes can cause misalignment of toes, as well as other orthopedic problems.
Morton's neuroma commonly results in pain and numbness between the third and fourth toes of the sufferer, due to it affecting the nerve between the third and fourth metatarsal bones.[6]
The big toe is also the most common locus of ingrown nails and gout attacks.
Deformities of the foot include hammer toe, trigger toe, and claw toe. Hammer toe can be described as an abnormal contraction or “buckling” of a toe. This is done by a partial or complete dislocation of one of the joints, which form the toes. Since the toes are deformed further, these may press against a shoe and cause pain. Deformities of the foot can also be caused by rheumatoid arthritis and diabetes mellitus. Deformities may predispose to ulcers and pain, especially when shoe-wearing.
A common problem involving the big toe is the formation of bunions. These are structural deformities of the bones and the joint between the foot and big toe, and may be painful.[7] Similar deformity involving the fifth toe is described as tailor's bunion or bunionette.
A favourable option for the reconstruction of missing adjacent fingers[8]/multiple digit amputations, i.e. such as a metacarpal hand reconstruction, is to have a combined second and third toe transplantation.[9] Third and fourth toe transplantation are also good.[10]
The Old English term for toe is ta (plural tan). This is a contraction of tahe, and derives from Proto-Germanic taihwo (cognates: Old Norse ta, Old Frisian tane, Middle Dutch te, Dutch teen (perhaps originally a plural), Old High German zecha, German Zehe). Perhaps originally meaning "fingers" as well (many Proto-Indo-European language (PIE) languages still use one word to mean both fingers and toes), and thus from PIE root deik — "to show".[11]
In classical Latin hallex,[12][13] allex,[12][14] hallus [12] and allus,[12] with genitive (h)allicis and (h)alli, are used to refer to the big toe. The form hallux (genitive, hallucis) currently in use is however a blend word of the aforementioned forms.[12][15] Compare pollex, the equivalent term for the thumb.
In birds with anisodactyl or heterodactyl feet, the hallux is opposed or directed backwards and allows for grasping and perching.
While the thumb is often mentioned as one of the signature characteristics in humans, this manual digit remains partially primitive and is actually present in all primates. In humans, the most derived digital feature is the hallux.[16]
| Wikimedia Commons has media related to Toes. |
|coauthors= (help)
|
||||||||||||||||||||||||||||
全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.
| リンク元 | 「母趾」 |
| 関連記事 | 「great」「toed」「toe」「to」 |