Editing Tibia

{{Short description|Leg bone in vertebrates}}
{{About|the human leg bone}}
{{Infobox bone
|  Name              = Tibia

|  Latin             = (os) tibia
|  Image             = Tibia - frontal view.png
|  Caption           = Position of tibia (shown in red)
|  Image2            = Braus 1921 293.png
|  Caption2          = Cross section of the leg showing the different compartments (''latin terminology'')
|  Origins           = 
|  Insertions        = 
|  Articulations     = [[Knee]], [[ankle]], [[superior tibiofibular articulation|superior]] and <br/>[[inferior tibiofibular joint]]
}}

The '''tibia''' ({{IPAc-en|ˈ|t|ɪ|b|i|ə}}; {{plural form}}: '''tibiae''' {{IPAc-en|ˈ|t|ɪ|b|i|i}} or '''tibias'''), also known as the '''shinbone''' or '''shankbone''', is the larger, stronger, and anterior (frontal) of the two [[Leg bones|bone]]s in the [[leg]] below the [[knee]] in [[vertebrates]] (the other being the [[fibula]], behind and to the outside of the tibia); it connects the knee with the [[ankle bones|ankle]]. The tibia is found on the [[anatomical terms of location#Medial|medial]] side of the leg next to the fibula and closer to the [[median plane]]. The tibia is connected to the fibula by the [[interosseous membrane of leg]], forming a type of [[fibrous joint]] called a [[syndesmosis]] with very little movement. The tibia is named for the flute ''[[aulos|tibia]]''. It is the second largest bone in the [[human body]], after the [[femur]]. The leg bones are the strongest [[long bone]]s as they support the rest of the body.

==Structure==
In [[human anatomy]], the tibia is the second largest bone next to the [[femur]]. 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 tibia together with the fibula  make up the front part of the leg, between the knee and the ankle, known as the '''shin'''.

The [[Ossification of tibia|ossification]] 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]] and two [[epiphysis|epiphyses]]. The diaphysis is the midsection of the tibia, also known as the [[Body of tibia|shaft]] or body. While the epiphyses are the two rounded extremities of the bone; an [[Upper extremity of tibia|upper]] (also known as superior or proximal) closest to the [[thigh]] and a [[Lower extremity of tibia|lower]] (also known as inferior or distal) closest to the [[human foot|foot]]. The tibia is most contracted in the lower third and the distal extremity is smaller than the proximal.

===Upper extremity===
====Condyles of tibia====
[[File:Gray257.png|thumb|Upper surface of right tibia. (Anterior is at top.)|alt=|left]]
[[File:Knee diagram.svg|thumb|Knee]]
The proximal or upper extremity of the tibia is expanded in the transverse plane with a [[Medial condyle of tibia|medial]] and [[Lateral condyle of tibia|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 [[Body of tibia|shaft]]. The upper surfaces of the condyles [[Articulations (anatomy)|articulate]] with the femur to form the tibiofemoral joint, the weightbearing part of the knee joint.<ref name=GrayStudent>{{cite book |last1=Drake |first1=Richard L.  |last2=Vogl |first2=A. Wayne |last3=Mitchell|first3=Adam W. M.| year=2010 |title=Gray´s Anatomy for Students |edition=2nd | isbn =978-0-443-06952-9|pages=558–560 |publisher=Churchill Livingstone/Elsevier }}{{page needed|date=May 2015}}</ref>

The medial and lateral condyle are separated by the [[intercondylar area]], where the [[cruciate ligament]]s and the [[Meniscus (liquid)|menisci]] attach. Here the [[medial intercondylar tubercle|medial]] and [[lateral intercondylar tubercle]] forms the [[intercondylar eminence]]. 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 femur|lower extremity of the femur]]. The intercondylar eminence divides the intercondylar area into an [[anterior intercondylar area|anterior]] and [[posterior intercondylar area|posterior part]]. The anterolateral region of the anterior intercondylar area are perforated by numerous small openings for [[nutrient artery|nutrient arteries]].<ref name=GrayStudent/>

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 lateral condyles superior surface is more circular in form and its medial edge extends onto the side of the [[lateral intercondylar tubercle]]. 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 [[Fibula#Head|head of the fibula]].<ref name="GrayStudent" />

Beneath the condyles is the [[tibial tuberosity]] which serves for attachment of the [[patellar ligament]], a continuation of the [[quadriceps femoris muscle]].<ref name="GrayStudent" />

====Facets====
The superior articular surface presents two smooth articular [[facet]]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 [[femur]], while their peripheral portions support the [[Meniscus (anatomy)|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 cruciate ligament|anterior]] and [[posterior cruciate ligament]]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 [[patellar ligament]]; a [[Bursa (anatomy)|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 [[posterior cruciate ligament]] of the [[knee-joint]]. The medial condyle presents posteriorly a deep transverse groove, for the insertion of the tendon of the [[semimembranosus]].

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

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]]. Just below this a part of the [[extensor digitorum longus]] takes origin and a slip from the tendon of the [[biceps femoris]] is inserted.

===Shaft===
[[File:Gray258.png|thumb|upright=0.6|Bones of the right leg anterior surface]]
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.<ref name=GrayStudent2>{{cite book |last1=Drake |first1=Richard L.  |last2=Vogl |first2=A. Wayne |last3=Mitchell|first3=Adam W. M.| year=2010 |title=Gray´s Anatomy for Students |edition=2nd | isbn =978-0-443-06952-9|pages=584–588 |publisher=Churchill Livingstone/Elsevier }}</ref>

==== Borders ====
The '''anterior crest or border''', the most prominent of the three, commences above at the [[tuberosity of the tibia|tuberosity]], and ends below at the anterior margin of the [[Malleolus#Medial malleolus|medial malleolus]]. 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]] 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&nbsp;cm., and insertion to some fibers of the [[popliteus muscle]]. From its middle third some fibers of the [[soleus muscle|soleus]] 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 muscle|sartorius]], and by the tendons of the [[Gracilis muscle|Gracilis]] and [[Semitendinosus]], all of which are inserted nearly as far forward as the anterior crest; in the rest of its extent it is [[Subcutaneous tissue|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]], [[Extensor hallucis longus]], and [[Extensor digitorum longus]], 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]], serves for the attachment of the fascia covering this muscle, and gives origin to part of the [[Soleus]], [[Flexor digitorum longus]], and [[Tibialis posterior]]. 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 [[Tibialis posterior]]. The remaining part of the posterior surface is smooth and covered by the Tibialis posterior, [[Flexor digitorum longus]], and [[Flexor hallucis longus]]. Immediately below the popliteal line is the nutrient foramen, which is large and directed obliquely downward.

===Lower extremity===
[[File:Tibia - inferior epiphysis (anterior view).jpg|thumb|Lower extremity of right tibia seen from the front]]
[[File:Tibia - inferior epiphysis (posterior view).jpg|thumb|Lower extremity of right tibia seen from the back]]
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 [[Malleolus#Medial malleolus|medial malleolus]]. The lower extremity of the tibia together with the fibula and [[talus bone|talus]] forms the [[Ankle|ankle joint]].

====  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 [[Flexor hallucis longus]].

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 colliculus|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 [[medial malleolus]] for details.

====Fractures====
[[Ankle fracture]]s of the tibia have several classification systems based on location or mechanism:

*[[Medial malleolus]] – [[Herscovici classification]]
*[[Posterior malleolus]] – [[Haruguchi classification]]
*Mechanism – [[Lauge-Hansen classification]]

===Blood supply===
The tibia is supplied with blood from two sources: A [[nutrient artery]], as the main source, and [[periosteum|periosteal]] vessels derived from the [[anterior tibial artery]].<ref>{{cite journal |vauthors=Nelson G, Kelly P, Peterson L, Janes J |title=Blood supply of the human tibia |journal=J Bone Joint Surg Am |volume=42-A |issue= 4|pages=625–36 |year= 1960|doi=10.2106/00004623-196042040-00007 |pmid=13854090}}</ref>

===Joints===
The tibia is a part of four joints; the knee, ankle, [[superior tibiofibular articulation|superior]] and [[inferior tibiofibular articulation|inferior tibiofibular joint]].

In the knee the tibia forms one of the two [[Articulations (anatomy)|articulations]] with the [[femur]], often referred to as the ''tibiofemoral components'' of the knee joint.;<ref name="pmid19594940">{{cite journal |vauthors=Rytter S, Egund N, Jensen LK, Bonde JP |title=Occupational kneeling and radiographic tibiofemoral and patellofemoral osteoarthritis |journal=J Occup Med Toxicol |volume=4 |issue= 1|pages=19 |year=2009 |pmid=19594940 |pmc=2726153 |doi=10.1186/1745-6673-4-19 |doi-access=free }}</ref><ref name="pmid19726621">{{cite journal |vauthors=Gill TJ, Van de Velde SK, Wing DW, Oh LS, Hosseini A, Li G |title=Tibiofemoral and patellofemoral kinematics after reconstruction of an isolated posterior cruciate ligament injury: in vivo analysis during lunge |journal=Am J Sports Med |volume=37 |issue=12 |pages=2377–85 |date=December 2009 |pmid=19726621 |doi=10.1177/0363546509341829 |pmc=3832057}}</ref> it is the weightbearing part of the knee joint.<ref name=GrayStudent2/>
The tibiofibular joints are the articulations between the tibia and fibula which allows very little movement.{{citation needed|date=February 2013}}
The [[proximal tibiofibular joint]] is a small [[plane joint]]. The joint is formed between the undersurface of the [[Lateral condyle of tibia|lateral tibial condyle]] and the [[head of fibula]]. The [[joint capsule]] is reinforced by [[Anterior ligament of the head of the fibula|anterior]] and [[posterior ligament of the head of the fibula]].<ref name=GrayStudent2/>
The [[Inferior tibiofibular joint|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.<ref name=GrayStudent2/>
The part of the ankle joint known as the talocrural joint, is a [[Synovial joint|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.{{citation needed|date=February 2013}}[[Image:Gray260.png|thumb|Plan of ossification of the tibia. From three centers.|alt=|left|262x262px]][[Image:Gray261.png|thumb|Epiphysial lines of tibia and fibula in a young adult. Anterior aspect.|242x242px]]

===Development===
The tibia is [[ossified]] from three [[ossification center|centers]]: a [[ossification center#primary center|primary center]] for the [[diaphysis]] (shaft) and a secondary center for each [[epiphysis]] (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 [[medial malleolus]].

{{Clear}}

==Function==

===Muscle attachments===
{| class="sortable wikitable" 
| '''Muscle''' || '''Direction''' || '''Attachment'''<ref name=Bojsen364-367>{{cite book |last1=Bojsen-Møller |first1=Finn  |last2=Simonsen |first2=Erik B. |last3=Tranum-Jensen |first3=Jørgen| year=2001 |title=Bevægeapparatets anatomi |edition=12th |language=da |trans-title=Anatomy of the Locomotive Apparatus | isbn =978-87-628-0307-7|pages=364–367 |publisher=Munksgaard Danmark }}</ref>   
|- 
 | [[Tensor fasciae latae muscle]]   ||  Insertion  ||  [[Gerdy's tubercle]]
 |- 
 | [[Quadriceps femoris muscle]]   ||  Insertion  ||  [[Tuberosity of the tibia]]
 |- 
 | [[Sartorius muscle]]   ||  Insertion  ||  [[Pes anserinus (leg)|Pes anserinus]]
 |- 
 | [[Gracilis muscle]]   ||  Insertion  ||  [[Pes anserinus (leg)|Pes anserinus]]
 |- 
 | [[Semitendinosus muscle]]   ||  Insertion  ||  [[Pes anserinus (leg)|Pes anserinus]]
 |- 
 | Horizontal head of the [[semimembranosus muscle]]   ||  Insertion  ||  [[Medial condyle of tibia|Medial condyle]]
 |- 
 | [[Popliteus muscle]]   ||  Insertion  || Posterior side of the tibia over the [[soleal line]]
 |- 
 | [[Tibialis anterior muscle]]   ||  Origin  || Lateral side of the tibia
 |- 
 | [[Extensor digitorum longus muscle]]   ||  Origin  ||  [[Lateral condyle of tibia|Lateral condyle]]
 |- 
 | [[Soleus muscle]]   ||  Origin  ||  Posterior side of the tibia under the [[soleal line]]
 |- 
 | [[Flexor digitorum longus muscle]]   ||  Origin  ||  Posterior side of the tibia under the [[soleal line]]
 |- 
 |}

===Strength===
The tibia has been modeled as taking an axial force during walking that is up to 4.7 bodyweight. Its [[bending moment]] in the sagittal plane in the late stance phase is up to 71.6 bodyweight times millimetre.<ref>{{cite journal | last1 = Wehner | first1 = T | last2 = Claes | first2 = L | last3 = Simon | first3 = U | year = 2009 | title = Internal loads in the human tibia during gait | journal = Clin Biomech | volume = 24 | issue = 3| pages = 299–302 | doi = 10.1016/j.clinbiomech.2008.12.007 | pmid = 19185959 }}</ref>

==Clinical significance==

===Fracture===
[[Bone fracture|Fracture]]s [[Crus fracture|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 [[fibula]]; [[trimalleolar fracture]], [[bimalleolar fracture]], [[Pott's fracture]].

==Society and culture==
In [[Judaism]], the tibia, or shankbone, of a goat or sheep is used in the [[Passover Seder plate]].

==Other animals==
The structure of the tibia in most other [[tetrapods]] is essentially similar to that in humans. The tuberosity of the tibia, a crest to which the [[patellar ligament]] attaches in mammals, is instead the point for the tendon of the [[quadriceps]] muscle in reptiles, birds, and amphibians, which have no [[patella]].<ref name=VB>{{cite book |author=Romer, Alfred Sherwood|author2=Parsons, Thomas S.|year=1977 |title=The Vertebrate Body |publisher=Holt-Saunders International |location= Philadelphia, PA|page= 205|isbn= 0-03-910284-X}}</ref>

==Additional images==
<gallery>
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
</gallery>

== See also ==
{{Anatomy-terms}}
*[[Shin splints]]
*[[Squatting facets]]

==References==
{{Gray's}}
{{Reflist}}

{{Bones of lower extremity}}
{{Subject bar|Anatomy|display=Tibia|wikt=tibia|auto=1}}
{{Authority control}}

[[Category:Tibia| ]]
[[Category:Bones of the lower limb]]
[[Category:Long bones]]