Generality
The tibia is the even bone, which together with the fibula (with respect to which it is in the medial position) constitutes the skeleton of each leg.
To simplify the study, the anatomists divide it into three portions: the proximal end (or proximal epiphysis), the body (or diaphysis) and the distal end (or distal epiphysis).
The proximal end is the portion closest to the femur and that makes up the knee.
The body is the portion between the proximal epiphysis and the distal epiphysis; has the task of accommodating different muscles of the leg and foot.
Finally, the distal end is relevant for its union with the talus, one of the seven tarsal bones of the foot.
What is Tibia
The tibia is the even bone which, together with the fibula (another even bone), forms the skeleton of each leg .
As bone of the leg, it resides between the femur (thigh bone), above, and the astragalus (foot bone), inferiorly, and develops in the longitudinal direction.
Both between tibia and femur and between tibia and foot, there is an articulation: in the first case, it is the knee joint; in the second case, it is the ankle joint.
Belonging to the category of long bones, the tibia is the second longest bone in the human skeleton, after the femur.
LOCATION COMPARED TO PERON
The tibia develops along the inner side of the fibula. With reference to the sagittal plane, this means that the tibia is medial to the fibula and the fibula is lateral to the tibia.
An explanation of the concepts sagittal plane, lateral and medial is present in the box below.
Important note: meaning of medial and lateral
Medial and lateral are two terms with the opposite meaning. However, to fully understand what they mean, it is necessary to take a step back and review the concept of the sagittal plan.
Figure: the plans with which the anatomists dissect the human body. In the image, in particular, the sagittal plane is highlighted.
The sagittal plane, or median plane of symmetry, is the antero-posterior division of the body, a division from which two equal and symmetrical halves are derived: the right half and the left half. For example, from a sagittal plane of the head derive a half, which includes the right eye, the right ear, the right nasal nostril and so on, and a half, which includes the left eye, the left ear, the left nasal nostril etc.
Returning to the medial-lateral concepts, the word media indicates a relationship of proximity to the sagittal plane; while the word side indicates a relationship of distance from the sagittal plane.
All anatomical organs can be medial or lateral with respect to a reference point. A couple of examples clarify this statement:
First example. If the reference point is the eye, it is lateral to the nasal nostril of the same side, but medial to the ear.
Second example. If the reference point is the second toe, this element is lateral to the first toe (toe), but medial to all the others.
IN THE UPPER ARTS IT CORRESPONDS TO ...
In the upper limb, the bone corresponding to the tibia is radium . Together with the ulna, the radius constitutes the skeleton of the forearm. Like the tibia, radius and ulna are two even bones.
Anatomy
Anatomy experts divide the tibia into three main bone regions (or portions): the proximal end (also called the proximal epiphysis), the body (or diaphysis) and the distal end (also known as the distal epiphysis).
Anatomical meaning of 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).
End? NEXT OF TIBIA
The proximal end of the tibia is the tibial portion located closest to the femur.
Implicated in the knee joint, it is a visibly enlarged area, with two prominent prominences, which are called medial condyle and lateral condyle .
The medial condyle is on the inner side of the leg, while the lateral condyle is on the external side.
The upper surfaces of the two condyles give rise to a characteristic area of the tibia, an area that the anatomists identify with the term tibial plate, due to its resemblance to the dishes usually used in the kitchen.
In the tibial plateau, exactly in the center, two small pyramidal bone processes take place, which act as a point of attachment for the terminal heads of the two cruciate ligaments (anterior and posterior) of the knee and for the two meniscuses (always of the knee) . These two pyramid-shaped bone processes are known as intercondylar diuretic tubercles and together form the so-called intercondylar eminence .
The intercondylar eminence fits perfectly into a concavity, present on the femur and which takes the name of intercondylar fossa . The initial ends of the two cruciate ligaments (anterior and posterior) of the knee originate from the intercondylar fossa.
Then changing position, on the front surface of the proximal end, just below the apex of the two condyles, there is a relief, perceptible to the touch, identified with the name of tibial tuberosity . The tibial tuberosity is the insertion point for the terminal head of the patellar tendon (or patellar ligament ). The patellar tendon is a formation of fibrous tissue, which continues the tendons of the quadriceps muscle and connects the knee patella to the tibia.
More or less at the same level as the tibial tuberosity, but in a medial position, another prominence develops, called goose paw . The goose leg welcomes the terminal heads of three muscles: sartorius, gracile and semitendinosus.
- Medial condyle. Its back surface has a horizontal groove, which houses the terminal head of the semimembranosus muscle of the thigh.
- Lateral condyle. In a postero-lateral position, it has a circular area, called a facet, which serves to hook the head of the fibula and form a joint with it. The head of the fibula represents the proximal apex of the second bone that constitutes the skeleton of the leg.
BODY OF THE TIBIA
The so-called body the central section of the tibia, comprised between the proximal end (superiorly) and the distal end (inferiorly).
In cross section, the body of the tibia is triangular in shape and has three surfaces: a medial, a lateral and a posterior. The lateral (or interosseous) surface and the posterior surface are particularly relevant from the anatomical point of view, since:
- On the lateral surface, the so-called interosseous membrane takes place, which binds together the tibia and the fibula.
- The posterior surface has a bone crest, with an infero-medial course (that is, it runs downwards and towards the inside of the leg), from which originates the soleus muscle of the calf. The anatomists call this bone crest with the name of the soleus line .
Compared to the proximal end (and, as will be seen, also with respect to the distal end), the body has a decidedly lower width.
What is the soleus muscle?
Together with the gastrocnemius, the soleus muscle forms the so-called triceps of the sura (NB: the gastrocnemius comprises the two twin muscles of the calf). The sura triceps is the main muscular element of the posterior compartment of the leg.
DISTAL END OF TIBIA
The distal end of the tibia is the tibial portion located closest to the foot.
Like the opposite end, it is a visibly enlarged area with characteristics that allow it to articulate with the tarsal bones of the foot and form the ankle.
The most important anatomical components of the distal end of the tibia are:
- The lower margin, which, together with the lower margin of the fibula, makes up the region known as mortar . The mortar is, in fact, a bone cavity, into which the talo (or astragalus) of the foot is inserted. The talo is one of the 7 bones that make up the tarsus of the foot.
- The medial malleolus (or tibial malleolus ). It is a bone process that develops in the inferior-medial direction, therefore on the inner part of the leg, downwards. Its main function is to guarantee stability to the ankle joint.
To support the action of the medial malleolus, it is another very similar bone process, localized on the fibula, which takes the name of lateral malleolus (or peroneal malleolus).
- A groove in the posterior seat, through which the tendons of the posterior tibial muscle flow.
- The fibular incisura . It is a small shower recess that houses and hooks the distal end of the fibula. Resides in a lateral position.
JOINTS OF THE TIBIA
In summary, the tibia joints are four in all:
- The knee joint.
- The ankle joint, which experts also call the talocrural articulation or tibio-tarsal joint.
- The superior tibio-fibular articulation (or proximal tibio-fibular ). It is the joint that joins the lateral condyle of the tibia to the head of the fibula. To ensure stability to this joint element, are the so-called anterior and posterior ligaments of the head of the fibula (or superior tibio-fibular ligaments).
- The inferior tibio-fibular articulation (or distal tibio-fibular joint ). It is the joint that connects the fibular incisiveness of the tibia with the distal end of the fibula. To reinforce the relationship between these two compartments are the anterior inferior tibio-fibular ligament and the posterior inferior tibio-fibular ligament.
BLOOD SPRAYING
Internally, long bones, such as the tibia (but also the femur, fibula etc.), have a very specific network of arteries and veins, which serves to guarantee them the right supply of oxygen and nutrients.
The arterial vessels of the tibia are the so-called nutritive artery, which penetrates the bone through the nutritive canal (or nutritive hole), and the so-called periosteum arteries, which derive from the anterior tibial artery.
The venous vessels, on the other hand, are the nutritive vein, which also exploits the passage through the nourishing canal, and the periosteal veins, which are branching of the anterior tibial vein.
Figure: The nutritious vessels and the nourishing hole in the long bones.
OBSIFICATION OF THE TIBIA
Three ossification centers contribute to the formation of the tibia: one centered on the body, one on the proximal end and one on the distal end.
Beginning with the ossification process is the center on the body of the tibia; to follow and in succession, the center of the proximal end and the center of the distal end enter into action.
Going into more detail:
- The ossification center of the body is activated around the 7th week of fetal life. Its activity causes the bone to develop towards the body and the ends.
- The ossification center of the proximal end is set in motion shortly before or immediately after birth. The bone portion it gives rise to meets the bony portion of the ossification center of the body at about the twentieth year of life.
- The ossification center of the distal end begins its activity at about the 2nd year of life. The resulting bone portion meets the bony portion of the body around the eighth year of life.
Functions
The tibia covers at least two fundamental functions.
The first important function is to support the weight of the upper part of the body, without overloading the foot: for this purpose, the enlarged extremities of the tibia play a fundamental role, acting almost like bearings; if in their place there were as large surfaces as the body of the tibia, they would be subjected to a force such as to cause them to break more easily.
The second important function is to allow locomotion : the tibia is home to essential muscles for walking, running and jumping and contributes to the formation of the ankle.
The ankle is the joint that guarantees the movements of dorsiflexion and plantarflexion of the foot, that is, respectively, the ability to lift the foot upwards and the ability to point the foot downwards.
| List of the 11 muscle elements that originate and end at the tibia. | ||
Muscle | Head end or initial leader | Contact site on the tibia |
| Tensor muscle of the fascia lata | Head end | Gerdy's tubercle (it is a lateral prominence of the proximal end of the tibia) |
| Quadriceps femoris muscle (rectus femoris, broad intermedia, medial vastus and lateral vastus) | Head end | Tuberosity of the tibia |
| Sartorius muscle | Head end | Goose paw |
| Gracilis muscle | Head end | Goose paw |
| Semitendinosus muscle | Head end | Goose paw |
| Semi-membranous muscle (horizontal head) | Head end | Medial condyle |
| Popliteus muscle | Head end | Just above the sun line |
| Anterior tibial muscle | Initial leader | Lateral margin of the tibia |
| Extensor muscle along the fingers | Initial leader | Lateral condyle |
| Soleus muscle | Initial leader | Soleus line |
| Long flexor muscle of the fingers | Initial leader | Soleus line |
Diseases of the Tibia
If it undergoes severe trauma, the tibia can fracture, like all other bones in the human body.
Tibial fractures are particularly common among the middle-aged and old age population and among those who practice contact sports, such as football, rugby, American football, etc.
There are various types of tibia fractures, including:
- Fracture of the proximal end . Frequently, doctors refer to this condition as " tibial plateau fracture ", referring to the fact that the rupture zone is often the upper surface of the two tibial condyles. It is a fairly common type of fracture, since the region of the tibial plateau is very fragile. Generally, it results from traumatic events, such as road accidents, and is associated with knee injuries (remember that the anterior and posterior cruciate ligaments are inserted on the tibial plateau).
- Fracture of the tibial malleolus (or medial malleolus). Usually due to a marked eversion movement of the foot, this injury is very often associated with the fracture of the peroneal malleolus (or lateral malleolus). The double rupture of the malleoli is called the bimalleolar fracture or Pott fracture .
- The tibia and fibula fracture . It is a condition with long healing times, which requires a period of immobilization and sometimes even an ad hoc surgery.
The double fracture of the tibia and fibula concerns above all the subjects who practice contact sports and the people involved in serious road accidents.
According to an interesting medical statistic, 75-85% of fibular fractures are also accompanied by fractures of the tibia.
Figure: radiological image of a fracture of the tibia.
