Generality
A metatarsal, or metatarsal bone, is one of the 5 long bones, which, in each foot, are placed between the tarsal bones and the proximal phalanges of each finger.
In a generic metatarsal three main portions can be distinguished, which are: the body, the base and the head.
Metatarsal bones in green. Image from the site en.wikipedia.org
The body is the central, prismoid bone portion that extends between the base and the head; the base is the proximal end, bordering and articulating with a tarsus bone; finally, the head is the distal end, connected and articulated with the proximal phalanx of a toe.
The traditional name of the 5 metatarsals involves the use of the first 5 Roman numerals. From this it follows that: the metatarsal bone is the metatarsal bone that precedes the phalanges of the big toe, the metatarsal II is the metatarsal bone that anticipates the phalanges of the first toe, the metatarsal III is the metatarsal bone placed before of the phalanges of the third finger, the IV metatarsal is the metatarsal bone that precedes the phalanges of the fourth finger and, finally, the V metatarsal is the metatarsal bone that is placed anteriorly to the phalanges of the fifth finger.
Metatarsals are a very important place for the insertion of muscles and ligaments of the foot, due to its functionality.
Like any bone in the human skeleton, metatarsals can also be broken.
What is a metatarsal?
A metatarsal, or metatarsal bone, is one of the 5 long bones, which, in each foot, are positioned between the bones of the tarsus (or tarsal bones ) and the proximal phalanges (or first phalanges ) of each finger.
In a human foot, the metatarsals are 5 of the 26 total bones (7 tarsal bones, 5 metatarsal bones and 14 phalanges).
Review of the meaning of the terms proximal and distal
Proximal and distal are two terms with opposite meaning.
Proximal means "closer to the center of the body" or "closer to the point of origin". Referring to the femur, for example, it indicates the portion of this bone closest to the trunk.
Distal, on the other hand, means "farther from the center of the body" or "farther from the point of origin. Referred (always to the femur), for example, it indicates the portion of this bone furthest from the trunk (and closer to the knee joint).
Anatomy
In each metatarsal, three bone portions are distinguishable, called: body, base and head .
The body of a metatarsal is its central bony portion, included between the so-called base and the so-called head. Prismatic in shape, it is slightly convex on the dorsal side and slightly concave on the palmar side; tends to thin in the direction of the phalanges.
The base of a metatarsal is its proximal end, preceding the body and clearly the head and bordering one or more tarsal bones. It has the shape of a wedge and, both on the palm side and on the dorsal side, has a rough surface, which serves to anchor important ligaments of the foot.
Finally, the head of a metatarsal is its distal end, following the body and head and in close contact with the first phalanx of a specific finger (eg: the metatarsal head is bordered by the first phalanx of the big toe). Anteriorly, it has an oblong articular surface; on the sides, it is flattened and has a small depression and a tubercle, on which other important ligaments of the foot are inserted; inferiorly (plantar surface), it has a typical groove.
By convention, the 5 metatarsals are indicated with the first 5 Roman numerals, ie I (first), II (second), III, IV and V. The metatarsal marked with the number I ( I metatarsus ) is the metatarsal bone that precedes the proximal phalanx of the big toe ; the metatarsal indicated with the number II ( II metatarsal ) is the metatarsal bone preceding the proximal phalanx of the first toe; the metatarsus marked with the number III ( metatarsal III ) is the metatarsal bone preceding the first phalanx of the second finger ; the metatarsal identified with the number IV ( IV metatarsal ) is the metatarsal bone preceding the proximal phalanx of the fourth finger ; finally, the metatarsal indicated with the number V ( V metatarsal ) is the metatarsal bone that precedes the first phalanx of the fifth finger .
Also by convection, the metatarsal considered to be the most medial is the metatarsus (that of the big toe), while the metatarsus considered more lateral is the V metatarsus (that of the fifth finger).
WHAT BONAL TARSES DO THE MATCH CONFIRM?
The tarsus of the foot comprises 7 bones, which are: the astragalus, the calcaneus, the navicular, the cuboid, the lateral cuneiform, the intermediate cuneiform and the medial cuneiform.
Of these newly mentioned bone elements, they confine only the last 4 to the metatarsals, namely: the cuboid bone, the lateral cuneiform, the intermediate cuneiform and the medial cuneiform.
The ratio of metatarsus to tarsal bones is as follows:
- The metatarsus is bordered by the medial cuneiform bone and only partially touches the intermediate cuneiform bone;
- The metatarsal II adheres, mainly, to the intermediate cuneiform bone and, secondarily, to the remaining cuneiform bones;
- The metatarsal III adheres to the lateral cuneiform bone;
- The IV and V metatarsus border on the cuboid bone.
The particular arrangement of the three cuneiforms and the cuboid, compared to the metatarsals, leads to the constitution of the so-called transverse arch of the foot .
ARTICULATIONS: SUMMARY AND NAME
Each metatarsal participates in 3-4 joints : a joint with a tarsus bone, one or two joints with one or two adjacent metatarsals and, finally, a joint with the first phalanx of a finger.
Going into more detail:
- The joints that join the metatarsals to the tarsal bones are called tarso-metatarsal joints . The tarsal-metatarsal joints are the protagonists of the bases of the metatarsals and the tarsal bones bordering on the latter, namely the three cuneiforms and the cuboid;
- The joints that bind the metatarsals together are called intermetatarsal joints . The extreme metatarsals, ie I and V, take part in only one intermetatarsal articulation, since there is only one metatarsal adjacent to them; on the contrary, the central metatarsus, that is, the II, III and IV, are the protagonists of two intermetatarsal articulations each, because adjacent to them there is a metatarsus per side;
- The joints that connect the metatarsals to the phalanges of the toes are called metatarsophalangeal joints . The metatarsal-phalangeal joints stabilize the heads of the various metatarsals at the so-called bases of the first phalanges of the fingers.
LIGAMENTS
A ligament is a formation of fibrous connective tissue, which connects two bones or two parts of the same bone.
The ligaments that relate to the metatarsals are:
- The tarsal-metatarsal ligaments, which run between the tarsal bones and the metatarsals and support the tarsal-metatarsal joints;
- The intermetatarsal ligaments, which have origin and term only in the metatarsals and support the intermetatarsal joints. There are 3 sub-types of intermetatarsal ligaments: the palmar, the dorsal and the interosseous;
- The metatarsal-phalangeal ligaments, which originate from the metatarsals and end on the phalanges of the toes and are responsible for strengthening the metatarsal-phalangeal joints.
MUSCLES
On the metatarsals, the terminal ends of some important leg muscles and the originals of some important foot muscles are inserted.
Among the muscles of the leg that end their path with the insertion on the metatarsals, they fall:
- The tibialis anterior muscle . With its terminal head, it is inserted on the base of the V metatarsus;
- The anterior peroneal muscle (or peroneal third muscle ). It ends its course on the dorsal side of the base of the V metatarsus;
- The long peroneal muscle . It concludes its course on a characteristic tuberosity of the base of the metatarsus;
- The short peroneal muscle . With the terminal extremity, it finds insertion on a characteristic tuberosity present on the base of the V metatarsus.
As for the muscles of the foot that originate at the level of the metatarsals, these muscular elements are:
- Hallux adductor . It is a particular muscle, with two heads of origin, called oblique head and transverse head. The oblique head resides on the base of the metatarsal III, while the transverse head is found in correspondence of the metatarso-falangei ligaments, which have relations with the third, fourth and fifth toe;
- The short flexor of the fifth toe . Its original head is located at the base of the V metatarsus;
- The 3 interosseous plantar muscles of the foot . One is born on the medial side of the third metatarsal, another on the medial side of the fourth metatarsal and another on the medial side of the 5th metatarsal.
- The 4 interosseous back muscles of the foot . Provided each with a double origin, they reside between metatarsal and metatarsal. For each of them, the two heads of origin concern the proximal portions of the two metatarsals, which include them. For example, the interosseous dorsal muscle located between the I and II metatarsus has an origin on the proximal portion of the metatarsal I and on the proximal portion of the II metatarsal.
Functions
Metatarsals are bones of fundamental importance, as they contribute to the supporting function, carried out by the skeleton of the lower limbs, and are the seat of muscles and joints essential to the correct motor function of the foot.
clinic
Metatarsals can be subject to fractures, just like all other bones in the human body.
They are also known to develop a painful condition called metatarsalgia .
metatarsalgia
Metatarsalgia is the medical term that refers to a painful, inflammatory nature, located at the forefoot level, exactly in correspondence of the metatarsal bones.
To trigger the appearance of metatarsalgia is, usually, a set of factors, which, if taken individually, would hardly cause the same pain symptoms (which they cause concomitantly with each other).
In addition to pain, which is the main clinical manifestation of metatarsalgia, the latter can cause: tingling and numbness in the toes and a sensation on the sole of the foot comparable to when you have pebbles in your shoes.
In general, the diagnosis of metatarsalgia is based on an accurate physical examination and a careful analysis of the patient's clinical history.
Based on the results of diagnostic research, doctors establish the most appropriate therapy, a therapy that is usually conservative (that is, rest, application of ice, painkillers when needed, change of shoes, etc.).
The use of surgery for metatarsalgia is a very remote possibility, put into practice only in the presence of very serious clinical cases.
FRACTURE OF A METATARSUS
Metatarsal fractures are injuries that can result from:
- A direct and very violent blow on the back foot . This is the case, for example, of a heavy object falling on the foot.
Metatarsal fractures due to violent shocks are the most common.
- A stress factor that affects the foot in general or a part of it in particular . This type of fracture is called metatarsal stress fracture and mainly affects the metatarsals of the 2nd, 3rd and 4th finger. It is very common among good athletes and is generally a microfracture .
- Excessive foot inversion movement . With a violent and very marked inversion of the foot, the short peroneal muscle could "pull" the metatarsal of the 5th finger and cause its rupture.
The typical clinical manifestations of a metatarsal fracture are: fractured foot pain and lameness.
For a certain diagnosis, X-ray examination of the foot is essential.
The treatment of metatarsal fractures varies according to the site of the injury and the extent of the rupture (compound fracture or displaced fracture). In fact, in certain cases, rest and immobilization of the lower limb could suffice; in others, on the other hand, it may be necessary to have surgery to weld the fractured metatarsus.
