third metatarsal bone
{{Short description|Long bone in the foot}}
{{Infobox bone
| Name = Third metatarsal bone
| Latin = os metatarsale III
| Image = Gray286.png
| Caption = The third metatarsal. (Left.)
| Image2 = Ospied-en.svg
| Caption2 = Bones of the right foot. Dorsal surface. Third metatarsal bone is the yellow bone third from the left
| Articulations =
}}
The third metatarsal bone is a long bone in the foot. It is the second longest metatarsal, the longest being the second metatarsal. The third metatarsal is analogous to the third metacarpal bone in the hand{{cite book |last=Bojsen-Møller |first=Finn |last2=Simonsen |first2=Erik B. |last3=Tranum-Jensen |first3=Jørgen| year=2001 |title=Bevægeapparatets anatomi |edition=12th |language=Danish |trans-title=Anatomy of the Locomotive Apparatus | isbn =978-87-628-0307-7|pages=246 }}
Like the four other metatarsal bones, it can be divided into three part: base, body and head. The base is the part closest to the ankle and the head is closest to the toes. The narrowed part in the middle is referred to as the body of the bone. The bone is somewhat flattened, giving it two surfaces: the plantar (towards the sole of the foot) and the dorsal side (the area facing upwards while standing). These surfaces are rough for the attachment of ligaments. The bone is curved longitudinally, so as to be concave below, and slightly convex above.
The base or posterior extremity is wedge-shaped.
The third metatarsal bone articulates proximally, by means of a triangular smooth surface, with the third cuneiform; medially, by two facets, with the second metatarsal; and laterally, by a single facet, with the fourth metatarsal. This last facet is situated at the dorsal angle of the base.
The head or anterior extremity articulates with the third proximal phalanx.
Muscle attachments
| align=right | |
| File:Gray268.png | File:Gray269.png |
The second and third dorsal interossei muscles attaches to the third metatarsal bone. The second dorsal interossei from the medial side of the bone and the third dorsal interossei from the lateral side. The function of the muscle is to spread the toes.{{cite book |last=Bojsen-Møller |first=Finn |last2=Simonsen |first2=Erik B. |last3=Tranum-Jensen |first3=Jørgen| year=2001 |title=Bevægeapparatets anatomi |edition=12th |language=Danish |trans-title=Anatomy of the Locomotive Apparatus | isbn =978-87-628-0307-7|pages=300–301 }}
The first Plantar interossei muscle originates from the medial side of the base and shaft of the third metatarsal. The function of the muscle is to move the third toe medially and move the toes together.
The horizontal head of the adductor hallucis also originates from the lateral side of the metacarpophalangeal joint and from the deep transverse metatarsal ligament, a narrow band which runs across and connects together the heads of all the metatarsal bones.
| class="sortable wikitable"
! Muscle | Direction | Attachment{{cite book |last=Bojsen-Møller |first=Finn |last2=Simonsen |first2=Erik B. |last3=Tranum-Jensen |first3=Jørgen| year=2001 |title=Bevægeapparatets anatomi |edition=12th |language=Danish |trans-title=Anatomy of the Locomotive Apparatus | isbn =978-87-628-0307-7|pages=364–367 }} |
| Dorsal interossei II | Origin | Medial side of the shaft |
| Dorsal interossei III | Origin | Lateral side of the shaft |
| Plantar interossei I | Origin | Medial side of the base and shaft |
| Horizontal head of adductor hallucis | Origin | Deep transverse metatarsal ligament and the metacarpophalangeal joint |
Additional images
File:Footx.jpg|X-ray of foot, showing phalangeal fracture
File:Gray290.png|Skeleton of foot. Medial aspect.
File:Gray360.png|Oblique section of left intertarsal and tarsometatarsal articulations, showing the synovial cavities.
File:Foot bones - tarsus, metatarsus.jpg|Foot bones - tarsus, metatarsus
File:Foot bones - metatarsus and phalanges.jpg|Foot bones - metatarsus and phalanges
File:Metatarsus.jpg|Metatarsus
References
{{Gray's}}
{{reflist}}
{{Commons category|Third metatarsal bone}}
{{Bones of lower extremity}}
Category:Bones of the lower limb
{{Portal bar|Anatomy}}