The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...

s in the

leg A leg is a weight-bearing and locomotive anatomical structure, usually having a columnar shape. During locomotion, legs function as "extensible struts". The combination of movements at all joints can be modeled as a single, linear element ca ...

below the knee in

vertebrates Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with c ...

(the other being the

fibula The fibula or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. Its upper extremity i ...

, behind and to the outside of the tibia); it connects the knee with the

ankle The ankle, or the talocrural region, or the jumping bone (informal) is the area where the foot and the leg meet. The ankle includes three joints: the ankle joint proper or talocrural joint, the subtalar joint, and the inferior tibiofibular joi ...

. The tibia is found on the medial side of the leg next to the fibula and closer to the

median plane The median plane also called a mid-sagittal plane is used to describe the sagittal plane as it bisects the body vertically through the midline marked by the navel, dividing the body exactly in left and right side. The term parasagittal plane is u ...

. The tibia is connected to the fibula by the

interosseous membrane of leg The interosseous membrane of the leg (middle tibiofibular ligament) extends between the interosseous crests of the tibia and fibula, helps stabilize the Tib-Fib relationship and separates the muscles on the front from those on the back of the leg. ...

, forming a type of fibrous joint called a

syndesmosis In anatomy, fibrous joints are joints connected by fibrous tissue, consisting mainly of collagen. These are fixed joints where bones are united by a layer of white fibrous tissue of varying thickness. In the skull the joints between the bones ar ...

with very little movement. The tibia is named for the flute ''

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

''. It is the second largest bone in the human body, after the

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...

. The leg bones are the strongest long bones as they support the rest of the body.

Structure

In human anatomy, the tibia is the second largest bone next to the

. As in other vertebrates the tibia is one of two bones in the lower leg, the other being the fibula, and is a component of the knee and ankle joints. The

ossification Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in ...

or formation of the bone starts from three centers, one in the shaft and one in each extremity. The tibia is categorized as a long bone and is as such composed of a

diaphysis The diaphysis is the main or midsection (shaft) of a long bone. It is made up of cortical bone and usually contains bone marrow and adipose tissue (fat). It is a middle tubular part composed of compact bone which surrounds a central marrow cavit ...

and two

epiphyses The epiphysis () is the rounded end of a long bone, at its joint with adjacent bone(s). Between the epiphysis and diaphysis (the long midsection of the long bone) lies the metaphysis, including the epiphyseal plate (growth plate). At the jo ...

. The diaphysis is the midsection of the tibia, also known as the shaft or body. While the epiphyses are the two rounded extremities of the bone; an upper (also known as superior or proximal) closest to the

thigh In human anatomy, the thigh is the area between the hip ( pelvis) and the knee. Anatomically, it is part of the lower limb. The single bone in the thigh is called the femur. This bone is very thick and strong (due to the high proportion of ...

and a

lower Lower may refer to: *Lower (surname) *Lower Township, New Jersey *Lower Receiver (firearms) *Lower Wick Gloucestershire, England See also *Nizhny Nizhny (russian: Ни́жний; masculine), Nizhnyaya (; feminine), or Nizhneye (russian: Ни́� ...

(also known as inferior or distal) closest to the foot. The tibia is most contracted in the lower third and the distal extremity is smaller than the proximal.

Upper extremity

Condyles of tibia

The proximal or upper extremity of the tibia is expanded in the transverse plane with a medial and lateral condyle, which are both flattened in the horizontal plane. The medial condyle is the larger of the two and is better supported over the shaft. The upper surfaces of the condyles articulate with the femur to form the tibiofemoral joint, the weightbearing part of the kneejoint. The medial and lateral condyle are separated by the intercondylar area, where the

cruciate ligament Cruciate ligaments (also cruciform ligaments) are pairs of ligaments arranged like a letter X. They occur in several joints of the body, such as the knee joint and the atlanto-axial joint. In a fashion similar to the cords in a toy Jacob's la ...

s and the menisci attach. Here the medial and

lateral intercondylar tubercle The intercondylar area is the separation between the medial and lateral condyle on the upper extremity of the tibia. The anterior and posterior cruciate ligaments and the menisci attach to the intercondylar area. The intercondyloid eminence i ...

forms the

intercondylar eminence The intercondylar area is the separation between the medial and lateral condyle on the upper extremity of the tibia. The anterior and posterior cruciate ligaments and the menisci attach to the intercondylar area. The intercondyloid eminence i ...

. Together with the medial and lateral condyle the intercondylar region forms the tibial plateau, which both articulates with and is anchored to the lower extremity of the femur. The intercondylar eminence divides the intercondylar area into an anterior and posterior part. The anterolateral region of the anterior intercondylar area are perforated by numerous small openings for nutrient arteries. The articular surfaces of both condyles are concave, particularly centrally. The flatter outer margins are in contact with the menisci. The medial condyles superior surface is oval in form and extends laterally onto the side of

medial intercondylar tubercle The intercondylar area is the separation between the medial and lateral condyle on the upper extremity of the tibia. The anterior and posterior cruciate ligaments and the menisci attach to the intercondylar area. The intercondyloid eminence i ...

. The lateral condyles superior surface is more circular in form and its medial edge extends onto the side of the

. The posterior surface of the medial condyle bears a horizontal groove for part of the attachment of the semimembranosus muscle, whereas the lateral condyle has a circular facet for articulation with the head of the fibula. Beneath the condyles is the tibial tuberosity which serves for attachment of the

patellar ligament The patellar tendon is the distal portion of the common tendon of the quadriceps femoris, which is continued from the patella to the tibial tuberosity. It is also sometimes called the patellar ligament as it forms a bone to bone connection when ...

, a continuation of the

quadriceps femoris muscle The quadriceps femoris muscle (, also called the quadriceps extensor, quadriceps or quads) is a large muscle group that includes the four prevailing muscles on the front of the thigh. It is the sole extensor muscle of the knee, forming a large ...

Facets

The superior articular surface presents two smooth articular

facet Facets () are flat faces on geometric shapes. The organization of naturally occurring facets was key to early developments in crystallography, since they reflect the underlying symmetry of the crystal structure. Gemstones commonly have facets cut ...

s. * The medial facet, oval in shape, is slightly concave from side to side, and from before backward. * The lateral, nearly circular, is concave from side to side, but slightly convex from before backward, especially at its posterior part, where it is prolonged on to the posterior surface for a short distance. The central portions of these facets articulate with the condyles of the

, while their peripheral portions support the menisci of the knee joint, which here intervene between the two bones.

Intercondyloid eminence

Between the articular facets in the intercondylar area, but nearer the posterior than the anterior aspect of the bone, is the intercondyloid eminence (''spine of tibia''), surmounted on either side by a prominent tubercle, on to the sides of which the articular facets are prolonged; in front of and behind the intercondyloid eminence are rough depressions for the attachment of the anterior and

posterior cruciate ligament The posterior cruciate ligament (PCL) is a ligament in each knee of humans and various other animals. It works as a counterpart to the anterior cruciate ligament (ACL). It connects the posterior intercondylar area of the tibia to the medial cond ...

s and the menisci.

Surfaces

The ''anterior surfaces'' of the condyles are continuous with one another, forming a large somewhat flattened area; this area is triangular, broad above, and perforated by large vascular foramina; narrow below where it ends in a large oblong elevation, the tuberosity of the tibia, which gives attachment to the

; a bursa intervenes between the deep surface of the ligament and the part of the bone immediately above the tuberosity. ''Posteriorly,'' the condyles are separated from each other by a shallow depression, the posterior intercondyloid fossa, which gives attachment to part of the

of the

knee-joint In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia (tibiofemoral joint), and one between the femur and patella (patellofemoral joint). It is the largest joint in the h ...

. The medial condyle presents posteriorly a deep transverse groove, for the insertion of the tendon of the

semimembranosus The semimembranosus muscle () is the most medial of the three hamstring muscles in the thigh. It is so named because it has a flat tendon of origin. It lies posteromedially in the thigh, deep to the semitendinosus muscle. It extends the hip j ...

. Its ''medial surface'' is convex, rough, and prominent; it gives attachment to the

medial collateral ligament The medial collateral ligament (MCL), or tibial collateral ligament (TCL), is one of the four major ligaments of the knee. It is on the medial (inner) side of the knee joint in humans and other primates. Its primary function is to resist outwar ...

. The lateral condyle presents posteriorly a flat articular facet, nearly circular in form, directed downward, backward, and lateralward, for articulation with the head of the fibula. Its ''lateral surface'' is convex, rough, and prominent in front: on it is an eminence, situated on a level with the upper border of the tuberosity and at the junction of its anterior and lateral surfaces, for the attachment of the

iliotibial band The iliotibial tract or iliotibial band (ITB; also known as Maissiat's band or the IT band) is a longitudinal fibrous reinforcement of the fascia lata. The action of the muscles associated with the ITB (tensor fasciae latae and some fibers of glu ...

. Just below this a part of the

extensor digitorum longus 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-quarters of the anterior surface of the body of t ...

takes origin and a slip from the tendon of the biceps femoris is inserted.

Shaft

The shaft or body of the tibia is triangular in cross-section and forms three borders: an anterior, medial, and lateral or interosseous border. These three borders form three surfaces: the medial, lateral, and posterior. The forward flat part of the tibia is called the fibia, often confused with the fibula.

Borders

The anterior crest or border, the most prominent of the three, commences above at the tuberosity, and ends below at the anterior margin of the

medial malleolus A malleolus is the bony prominence on each side of the human ankle. Each leg is supported by two bones, the tibia on the inner side (medial) of the leg and the fibula on the outer side (lateral) of the leg. The medial malleolus is the promine ...

. It is sinuous and prominent in the upper two-thirds of its extent, but smooth and rounded below; it gives attachment to the

deep fascia Deep fascia (or investing fascia) is a fascia, a layer of dense connective tissue that can surround individual muscles and groups of muscles to separate into fascial compartments. This fibrous connective tissue interpenetrates and surrounds the ...

of the leg. The medial border is smooth and rounded above and below, but more prominent in the center. It begins at the back part of the medial condyle, and ends at the posterior border of the medial malleolus; its upper part gives attachment to the tibial collateral ligament of the knee-joint to the extent of about 5 cm., and insertion to some fibers of the popliteus muscle. From its middle third some fibers of the

soleus In humans and some other mammals, the soleus is a powerful muscle in the back part of the lower leg (the calf). It runs from just below the knee to the heel, and is involved in standing and walking. It is closely connected to the gastrocnemius mu ...

and flexor digitorum longus muscles take origin. The interosseous crest or lateral border is thin and prominent, especially its central part, and gives attachment to the interosseous membrane; it commences above in front of the fibular articular facet, and bifurcates below, to form the boundaries of a triangular rough surface, for the attachment of the interosseous ligament connecting the tibia and fibula.

Surfaces

The medial surface is smooth, convex, and broader above than below; its upper third, directed forward and medialward, is covered by the aponeurosis derived from the tendon of the sartorius, and by the tendons of the Gracilis and

Semitendinosus The semitendinosus () is a long superficial muscle in the back of the thigh. It is so named because it has a very long tendon of insertion. It lies posteromedially in the thigh, superficial to the semimembranosus. Structure The semitendinosus, r ...

, all of which are inserted nearly as far forward as the anterior crest; in the rest of its extent it is subcutaneous. The lateral surface is narrower than the medial; its upper two-thirds present a shallow groove for the origin of the Tibialis anterior; its lower third is smooth, convex, curves gradually forward to the anterior aspect of the bone, and is covered by the tendons of the

Tibialis anterior The tibialis anterior muscle is a muscle in humans that originates along the upper two-thirds of the lateral (outside) surface of the tibia and inserts into the medial cuneiform and first metatarsal bones of the foot. It acts to dorsiflex and inve ...

Extensor hallucis longus The extensor hallucis longus muscle is a thin skeletal muscle, situated between the tibialis anterior and the extensor digitorum longus. It extends the big toe and dorsiflects the foot. It also assists with foot eversion and inversion. Struct ...

, and

Extensor digitorum longus 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-quarters of the anterior surface of the body of t ...

, arranged in this order from the medial side. The posterior surface presents, at its upper part, a prominent ridge, the popliteal line, which extends obliquely downward from the back part of the articular facet for the fibula to the medial border, at the junction of its upper and middle thirds; it marks the lower limit of the insertion of the

Popliteus The popliteus muscle in the leg is used for unlocking the knees when walking, by laterally rotating the femur on the tibia during the closed chain portion of the gait cycle (one with the foot in contact with the ground). In open chain movements ...

, serves for the attachment of the fascia covering this muscle, and gives origin to part of the

Soleus In humans and some other mammals, the soleus is a powerful muscle in the back part of the lower leg (the calf). It runs from just below the knee to the heel, and is involved in standing and walking. It is closely connected to the gastrocnemius mu ...

Flexor digitorum longus The flexor digitorum longus muscle is situated on the tibial side of the leg. At its origin it is thin and pointed, but it gradually increases in size as it descends. It serves to flex the second, third, fourth, and fifth toes. Structure The fl ...

, and

Tibialis posterior The tibialis posterior muscle is the most central of all the leg muscles, and is located in the deep posterior compartment of the leg. It is the key stabilizing muscle of the lower leg. Structure The tibialis posterior muscle originates on the ...

. The triangular area, above this line, gives insertion to the Popliteus. The middle third of the posterior surface is divided by a vertical ridge into two parts; the ridge begins at the popliteal line and is well-marked above, but indistinct below; the medial and broader portion gives origin to the Flexor digitorum longus, the lateral and narrower to part of the

. The remaining part of the posterior surface is smooth and covered by the Tibialis posterior,

, and

Flexor hallucis longus The flexor hallucis longus muscle (FHL) is one of the three deep muscles of the posterior compartment of the leg that attaches to the plantar surface of the distal phalanx of the great toe. The other deep muscles are the flexor digitorum longus an ...

. Immediately below the popliteal line is the nutrient foramen, which is large and directed obliquely downward.

Lower extremity

Tibia - inferior epiphysis (anterior view)

Tibia - inferior epiphysis (posterior view)

The distal end of the tibia is much smaller than the proximal end and presents five surfaces; it is prolonged downward on its medial side as a strong pyramidal process, the

. The lower extremity of the tibia together with the fibula and talus forms the

ankle joint The ankle, or the talocrural region, or the jumping bone (informal) is the area where the foot and the leg meet. The ankle includes three joints: the ankle joint proper or talocrural joint, the subtalar joint, and the inferior tibiofibular joi ...

Surfaces

The inferior articular surface is quadrilateral, and smooth for articulation with the talus. It is concave from before backward, broader in front than behind, and traversed from before backward by a slight elevation, separating two depressions. It is continuous with that on the medial malleolus. The anterior surface of the lower extremity is smooth and rounded above, and covered by the tendons of the Extensor muscles; its lower margin presents a rough transverse depression for the attachment of the articular capsule of the ankle-joint. The posterior surface is traversed by a shallow groove directed obliquely downward and medialward, continuous with a similar groove on the posterior surface of the talus and serving for the passage of the tendon of the

. The lateral surface presents a triangular rough depression for the attachment of the inferior interosseous ligament connecting it with the fibula; the lower part of this depression is smooth, covered with cartilage in the fresh state, and articulates with the fibula. The surface is bounded by two prominent borders (the anterior and posterior colliculi), continuous above with the interosseous crest; they afford attachment to the anterior and posterior ligaments of the lateral malleolus. The medial surface -- see

for details.

Fractures

Ankle fracture An ankle fracture is a break of one or more of the bones that make up the ankle joint. Symptoms may include pain, swelling, bruising, and an inability to walk on the injured leg. Complications may include an associated high ankle sprain, compartme ...

s of the tibia have several classification systems based on location or mechanism: *

Medial malleolus A malleolus is the bony prominence on each side of the human ankle. Each leg is supported by two bones, the tibia on the inner side (medial) of the leg and the fibula on the outer side (lateral) of the leg. The medial malleolus is the promine ...

- Herscovici classification *

Posterior malleolus The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); i ...

Haruguchi classification The Haraguchi classification is a system of categorizing posterior malleolus fractures. Classification References

{{reflist Ankle fracture classifications Injuries of ankle and foot ...

*Mechanism -

Lauge-Hansen classification The Lauge-Hansen classification is a system of categorizing ankle fractures based on the foot position and the force applied. __TOC__ Classification See also * Danis–Weber classification The Danis–Weber classification (often known just as t ...

Blood supply

The tibia is supplied with blood from two sources: A

nutrient artery The nutrient artery (arteria nutricia, or medullary), usually accompanied by one or two veins, enters the bone through the nutrient foramen, runs obliquely through the cortex, sends branches upward and downward to the bone marrow, which ramify in ...

, as the main source, and periosteal vessels derived from the

anterior tibial artery The anterior tibial artery is an artery of the leg. It carries blood to the anterior compartment of the leg and dorsal surface of the foot, from the popliteal artery. Structure Course The anterior tibial artery is a branch of the poplitea ...

Joints

The tibia is a part of four joints; the knee, ankle, superior and

inferior tibiofibular joint The distal tibiofibular joint (tibiofibular syndesmosis) is formed by the rough, convex surface of the medial side of the distal end of the fibula, and a rough concave surface on the lateral side of the tibia. Below, to the extent of about 4& ...

. In the knee the tibia forms one of the two articulations with the

, often referred to as the ''tibiofemoral components'' of the knee joint.; it is the weightbearing part of the knee joint. The tibiofibular joints are the articulations between the tibia and fibula which allows very little movement. The proximal tibiofibular joint is a small plane joint. The joint is formed between the undersurface of the lateral tibial condyle and the head of fibula. The

joint capsule In anatomy, a joint capsule or articular capsule is an envelope surrounding a synovial joint.anterior and

posterior ligament of the head of the fibula The posterior ligament of the head of the fibula is a part of the knee. It is a single thick and broad band, which passes obliquely upward from the back of the head of the fibula The fibula or calf bone is a leg bone on the lateral side of t ...

. The distal tibiofibular joint (tibiofibular syndesmosis) is formed by the rough, convex surface of the medial side of the distal end of the fibula, and a rough concave surface on the lateral side of the tibia. The part of the ankle joint known as the talocrural joint, is a synovial hinge joint that connects the distal ends of the tibia and fibula in the lower limb with the proximal end of the talus. The articulation between the tibia and the talus bears more weight than between the smaller fibula and the talus.

Development

The tibia is

ossified Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in t ...

from three centers: a primary center for the

(shaft) and a secondary center for each

epiphysis The epiphysis () is the rounded end of a long bone, at its joint with adjacent bone(s). Between the epiphysis and diaphysis (the long midsection of the long bone) lies the metaphysis, including the epiphyseal plate (growth plate). At the jo ...

(extremity). Ossification begins in the center of the body, about the seventh week of fetal life, and gradually extends toward the extremities. The center for the upper epiphysis appears before or shortly after birth at close to 34 weeks gestation; it is flattened in form, and has a thin tongue-shaped process in front, which forms the tuberosity; that for the lower epiphysis appears in the second year. The lower epiphysis fuses with the tibial shaft at about the eighteenth, and the upper one fuses about the twentieth year. Two additional centers occasionally exist, one for the tongue-shaped process of the upper epiphysis, which forms the tuberosity, and one for the

Function

Muscle attachments

Strength

The tibia has been modeled as taking an axial force during walking that is up to 4.7 bodyweight. Its

bending moment In solid mechanics, a bending moment is the reaction induced in a structural element when an external force or moment is applied to the element, causing the element to bend. The most common or simplest structural element subjected to bending mo ...

in the sagittal plane in the late stance phase is up to 71.6 bodyweight times millimetre.

Clinical significance

Fracture

Fractures of the tibia can be divided into those that only involve the tibia; bumper fracture, Segond fracture, Gosselin fracture, toddler's fracture, and those including both the tibia and

; trimalleolar fracture, bimalleolar fracture, Pott's fracture.

Society and culture

Judaism Judaism ( he, ''Yahăḏūṯ'') is an Abrahamic, monotheistic, and ethnic religion comprising the collective religious, cultural, and legal tradition and civilization of the Jewish people. It has its roots as an organized religion in t ...

, the tibia, or shankbone, of a goat is used in the Passover Seder plate.

Other animals

The structure of the tibia in most other

tetrapods Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids (reptiles, including dinosaurs and therefore birds) and synapsids ( pelycosaurs, extinct therapsi ...

is essentially similar to that in humans. The tuberosity of the tibia, a crest to which the

attaches in mammals, is instead the point for the tendon of the

quadriceps The quadriceps femoris muscle (, also called the quadriceps extensor, quadriceps or quads) is a large muscle group that includes the four prevailing muscles on the front of the thigh. It is the sole extensor muscle of the knee, forming a large ...

muscle in reptiles, birds, and amphibians, which have no

patella The patella, also known as the kneecap, is a flat, rounded triangular bone which articulates with the femur (thigh bone) and covers and protects the anterior articular surface of the knee joint. The patella is found in many tetrapods, such as ...

Additional images

File:Right tibia - close up - animation.gif, Shape of right tibia File:Human tibia.stl, 3D image File:Braus 1921 292.png, Longitudinal section of tibia showing interior File:Gray345.png, Right knee-joint. Anterior view. File:Gray347.png, Right knee joint from the front, showing interior ligaments File:Gray348.png, Left knee joint from behind, showing interior ligaments File:Gray356.png, Left talocrural joint File:Gray357.png, Coronal section through right talocrural and talocalcaneal joints File:Slide3Bubu.JPG, Dorsum of Foot. Ankle joint. Deep dissection File:Slide2bubu.JPG, Dorsum of Foot. Ankle joint. Deep dissection File:Slide2tat.JPG, Ankle joint. Deep dissection. Anterior view File:Gray258.png, Bones of the right leg. Anterior surface File:Gray259.png, Bones of the right leg. Posterior surface File:Slide2coco.JPG, Dorsum of Foot. Ankle joint. Deep dissection. File:Slide4CEC3.JPG, Ankle joint. Deep dissection. File:Slide5CEC4.JPG, Ankle joint. Deep dissection. File:Slide7CEC6.JPG, Ankle joint. Deep dissection. File:Slide8CEC7.JPG, Ankle joint. Deep dissection. File:Tibia Anatomy by Jason Christian.webm, Tibia Anatomy

References

{{Authority control Bones of the lower limb Long bones