The third metatarsal bone is a

long bone The long bones are those that are longer than they are wide. They are one of five types of bones: long, Short bone, short, Flat bone, flat, Irregular bone, irregular and Sesamoid bone, sesamoid. Long bones, especially the femur and tibia, are subj ...

in the foot. It is the second longest

metatarsal The metatarsal bones, or metatarsus, are a group of five long bones in the foot, located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the med ...

. The longest being the

second metatarsal The second metatarsal bone is a long bone in the foot. It is the longest of the metatarsal bones, being prolonged backward and held firmly into the recess formed by the three cuneiform bones. The second metatarsal forms joints with the second pr ...

. The third metatarsal is analogous to the

third metacarpal bone The third metacarpal bone (metacarpal bone of the middle finger) is a little smaller than the second. The dorsal aspect of its base presents on its radial side a pyramidal eminence, the styloid process, which extends upward behind the capitate; ...

in the hand As the four other metatarsals bones it can be divided into three parts; 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 flatten giving it two surfaces; the plantar (towards the

sole of the foot The sole is the bottom of the foot. In humans the sole of the foot is anatomically referred to as the plantar aspect. Structure The glabrous skin on the sole of the foot lacks the hair and pigmentation found elsewhere on the body, and it has ...

) and the dorsal side (the area facing upwards while standing). These surfaces are rough for the attachment of

ligament A ligament is the fibrous connective tissue that connects bones to other bones. It is also known as ''articular ligament'', ''articular larua'', ''fibrous ligament'', or ''true ligament''. Other ligaments in the body include the: * Peritoneal li ...

s. The bone is curved longitudinally, so as to be concave below, slightly convex above. The base or posterior extremity is

wedge A wedge is a triangular shaped tool, and is a portable inclined plane, and one of the six simple machines. It can be used to separate two objects or portions of an object, lift up an object, or hold an object in place. It functions by converti ...

-shaped. The third metatarsal bone articulates proximally, by means of a triangular smooth surface, with the third cuneiform; medially, by two facets, with the

; and laterally, by a single facet, with the

fourth metatarsal The fourth metatarsal bone is a long bone in the foot. It is smaller in size than the third metatarsal bone and is the third longest (and smallest) of the five metatarsal bones. The fourth metatarsal is analogous to the fourth metacarpal bone in t ...

. This last facet is situated at the dorsal angle of the base. The head or anterior extremity articulates with the third

proximal phalanx The phalanges (singular: ''phalanx'' ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones. ...

Muscle attachments

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. 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 The Adductor hallucis (Adductor obliquus hallucis) arises by two heads—oblique and transverse and is responsible for adducting the big toe. It has two heads, both are innervated by the lateral plantar nerve. Structure Oblique head The ''oblique ...

also originates from the lateral side of the metacarpophalangeal joint and from the deep

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 (glenoid) ligaments of the metatarsophalangeal articulations. Its plantar ...

, a narrow band which runs across and connects together the heads of all the metatarsal bones.

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

Bones of the lower limb Bones of the foot 3 {{Portal bar, Anatomy