What is tibia bone? Writes it's side determination, anatomical position and features?

Tibia Bone

The tibia bone (Latin Shin Bone) is the medial and larger bone of the leg. It  is homologous with the radius of the upper limb.

Reference: 

 https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhASIVPeBORmWMcTw5WcJjr3c6C0evkhcaVFVgfe2BjvAUJ0FqRlvD96xl4-jvgakkC57YGrYEVTiY6qnUFov0kl8y00fcBFUKvQxlhNHKdWDMubePWjJ1RyNIbhSmpbqVSKA2Tx9J2_GMO/s645/3-s2.0-B9780124104600000073-f07-023-9780124104600.jpg

Side Determination

1. The upper end is much larger than the lower end.
2. The medial side of the lower end projects downwards beyond the rest of the bone. The projection is called the medial malleolus.
3. The anterior border of the shaft is most prominent and crest-like. It is sinuously curved and terminates below at the anterior border of the medial malleolus. 

Anatomical Position

•  Tibia bone is held vertically.

Features

 The tibia bone has an:

1. Upper end 
2. Shaft
3. Lower end       

Upper End: 

The upper end of the tibia is markedly expanded from side to side, to form two large condyles which overhang the posterior surface of the shaft .The upper end includes:

1. A middle condyle 
2. A lateral condyle
3. An intercondylar area
4. A tuberosity             

Middle Condyle:   

• Medial condyle is larger than the lateral condyle. It's superior surface articulates with the medial condyle of the femur. 

•  The articular surface is oval and its long axis is anteroposterior. 
•  The central part of the surface is slightly concave and comes into direct contact with the femoral condyle. The peripheral part is flat and is separated from the femoral condyle by the medial meniscus.
• The lateral margin of the articular surface is raised to cover the medial intercondylar tubercle.
• The posterior surface of the medial condyle has a groove. The anterior  and medial surfaces are marked by numerous vascular foramina.

Lateral Condyle: 

• The lateral condyle overhangs the shaft more than the medial condyle .The superior surface of the condyle articulates with the lateral condyle of the femur. The articular surface is nearly circular.
• As in the case of the medial condyle, the central part is slightly concave and comes in direct contact with the femur, but the peripheral part is flat and is separated from the femur by the lateral meniscus. 

•  The articular surface has a raised medial margin which covers the lateral intercondylar tubercle.
• The posteroinferior   aspect of the lateral condyle articulates with the fibula. The fibular facet is flat ,circular and is directed downwards ,backwards and laterally. 
• Superomedial  to the fibular facet ,the posterior surface of the condyle is marked by a groove. The anterior aspect of the condyle bears a flattened impression knows as Gerdy's Tubercle.

Intercondylar Area: 

• Intercondylar area is the roughened area on the superior surface, between the articular surfaces of the two condyles. The area is narrowest in it's middle part.
•  This part is elevated to form the intercondylar eminence which is flanked by the medial and lateral intercondylar tubercles.

Tuberosity of the Tibia:

• Tuberosity of the tibia is a prominence located on the anterior aspect of the upper end of the tibia .It forms the anterior limits of the intercondylar area.
• Inferiorly it is continuous  with the anterior border of the shaft.
• Tuberosity is divided into an upper smooth area and a lower rough area. The epiphyseal line for the upper end of the tibia passes through the junction of these two parts

Reference:

 https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgO_Bo-Ghyaqg9YByQOocshwyBbdktzvzxt6p3k7e-b0dz3RT4SgVFC2n8QPoSpV0YU941S8lLoEvtkC3HMB8_zZOV2dVIOOyHMlNjVifGnZ2q8JWHnzVzOdp8goezWBxKlkVlBPAHWBtp0/s1291/Image00024.jpg 

Shaft

 The shaft of the tibia is prismoid in shape. It has three :

Borders: anterior, medial and interosseous.

Surfaces: lateral , medial and posterior. 

Borders:

• The anterior border  is sharp and S-shaped being convex medially in the upper part and convex laterally in the lower part. It extends from the tibial tuberosity above to the anterior border of the medial malleolus below. It is subcutaneous and forms to shin.
•  The medial border is rounded. It extends from the medial condyle , above , to the posterior border of the medial malleolus, below.
•  The interosseous or lateral border extends from the lateral condyle a little below and in front of the fibular facet, to the anterior border of the fibular notch.

Surfaces:

• The lateral surface lies between the anterior and interosseous borders. In it's upper three-fourth , it is concave and is directed laterally and in its lower one- fourth it is directed forwards.
• The medial surface lies between the anterior and medial borders .It is broad and most of it is subcutaneous.
• The posterior surface lies between the medial and interosseous borders .It  is widest in its upper part .This part is crossed obliquely by a rough ridge called the soleal  line.  The  soleal line begins just behind the fibular facet, runs downwards and medially and terminates by joining the medial border at the junction of its upper and middle thirds.
• Above the soleal line ,the posterior  surface is in the form of a triangular area. The area below the soleal line is elongated . It is divided into medial and lateral parts by a vertical ridge. A nutrient foramen is  situated near the upper end of this ridge. It is directed downwards and transmits the nutrient artery which is a branch of the posterior tibial artery .

Lower End

The lower  end of the tibia is slightly expanded .It has five surfaces. Medially it is prolonged downwards as the medial malleolus.

• The anterior larger surface of the lower end has an upper smooth part and a lower  rough and grooved part.
• The medial surface is subcutaneous and is continuous  with the medial surface of the medial malleolus.

•  The lateral surface of the lower end presents a triangular fibular notch to which the lower end of joint. The upper part of the notch is rough. The lower part is smooth and may be covered with hyaline cartilage.
• The inferior surface  of the lower end is articular . It articulates with the superior  trochlear surface of the talus and thus takes part in forming the ankle joint. Medially the articular surface extends on the medial malleolus.
• Posterior surface is smaller than anterior surface. 
• The medial malleolus is a short but strong process which projects downwards from the medial surface of he lower end of the tibia, it forms subcutaneous prominence on the medial side of the ankle. 

Reference: 

 BD  Chaurasia's Anatomy of Lower Limb.

Chief Editors: 

Krishna Garg, Pragati  Sheel Mittal,  Mrudula 

 Chandrupatla

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About Author: 

Iqra Naeem (PT)

Doctor of Physical Therapy