TIBIA OF OX
- The tibia is a strong and massive long bone.
- It extends obliquely distally and caudally from the stifle to the hock.
- It articulates proximally with the femur, distally with the tarsus, and laterally with the fibula.
- The bone is twisted in appearance.
- It possesses a body and two extremities.
SHAFT OF TIBIA (BODY)
- The shaft is expanded and prismatic (three sided) at its upper part and narrow and flat at its lower part.
- It presents for description three surfaces (Lateral, Medial, Caudal) and three borders (Cranial, Lateral, Medial).
Lateral surface
- It is faintly concave and gradually spiral down to the front.
- This surface accommodates anterior tibial and complex muscles.
Medial surface
- It is wide above and narrow below.
- Sartorious, Gracilis and Semi-membranosus muscles are attached here.
Caudal surface
- It is rough and traversed by a number of rough lines for the attachment of flexor muscles.
- These are known as popliteal lines.
- There is a smooth triangular area at the upper part and close to the medial aspect for the attachment of popliteus muscle.
Cranial border
- The upper part of the cranial border is very prominent and termed as tibial crest.
- At the distal part of the crest, towards the medial aspect, there is a small prominence for insertion of semitendinosus muscle.
- The distal part of this border is not prominent.
Lateral border
- Lateral border is concave and in life, it forms an interosseous space with the attachment of fibrous cord of the fibula.
Medial border
- The medial border is rounded.
Proximal Extremity
- The proximal extremity is expanded and presents two condyles (lateral and medial) and a Tibial tuberosity.
Condyles
- The condyles are articular prominences.
- Each condyle presents a somewhat saddle-shaped surface for articulation with the corresponding condyle of the femur and meniscus.
- The inter-condyloid eminence or tibial spine (Bifid) is the central prominence, upon the sides of which the articular surfaces are continued.
- Articular surfaces consist of a high medial part and a lower lateral part.
- The peripheral part of the articular surfaces of the condyles are flat.
- On, cranial and caudal to the inter-condyloid eminence are the inter-condyloid fossae, in which the cranial cruciate ligament and the menisci are attached.
- The condyles are separated caudally by the deep popliteal notch, on the medial side of which there is a tubercle for the attachment of the caudal cruciate ligament.
- The lateral condyle has an over hanging lateral margin, distal to which there is a facet for articulation with the fibula.
- The head of the rudimentary fibula is attached to the lateral part of lateral condyle.
Tibial Tuberosity
- The large cranial eminence is the tuberosity of the tibia or Tibial Tuberosity.
- The tuberosity is blunt and situated above the tibial crest.
- A semi-circular smooth notch (sulcus extensorius) or called as sulcus muscularis separates the tibial tuberosity from the lateral condyle.
- This sulcus gives passage to the tendons of extensor muscles.
Distal extremity
- The distal extremity presents two grooves for articulation with the ridges of tibial tarsal bone.
- The lateral border of the lateral groove articulates with lateral malleolus, a small separate piece of bone.
Malleolus
- This malleolus bone has two surfaces and four borders.
- Ventrally it articulates with the fibular tarsal.
- Dorsally it possesses a small spine and articulates with tibia.
- The anterior and posterior borders are convex.
- The medial border of medial groove of the distal end of tibia projects ventrally as it is fused with medial malleollus.
Tibia of Horse
- The bone is larger and longer.
- The sulcus muscularis is wider.
- There is a facet below and lateral to the lateral condyle for the head of fibula.
- Anterior tuberosity is grooved.
- The grooves at the distal end for the ridges of tibial tarsals are oblique.
- Both malleoli bones are fused at the distal end of tibia.
Tibia of dog
- The body forms a double curve
- The proximal part is convex medially, the distal part laterally.
- The proximal third is prismatic, but is compressed laterally and is long cranio-caudally.
- The remainder is almost regularly cylindrical.
- Tibial crest is short but very prominent.
- The nutrient foramen is usually in the proximal third of the lateral border.
- There is a small facet for the fibula on the caudolateral part of the lateral condyle.
- The distal end is quadrangular and relatively small. There is a facet laterally for articulation with the fibula.
Tibia of pig
- The body of the tibia is slightly curved, being convex medially.
- The tuberosity is grooved cranially, and a narrow extensor sulcus separates it from the lateral condyle.
- The facet for the fibula is on the caudal border of the latter and is bounded medially by an eminence.
- The proximal part of the cranial border is very prominent and curves laterally.
- The distal end or cochlea resembles in general that of the ox, but is relatively narrower transversely and thicker from cranial to caudal.
Tibia of fowl
- The bones of the proximal row of tarsus are fused with the distal end of the tibia and hence it is called tibiotarsus.
- Tibial crest is prominent.
- The distal extremity of the tibiotarsus presents prominent condyles for articulation with the tarsometatarsus.
- This is the longest bone in the body.
- The tibiotarsus has a nutrient foramen on its caudal shaft.
- The lateral part of the upper shaft exhibits a ridge for the attachment of the fibula.
- The chicken shows the typical avian condition of having a greatly reduced fibula
FIBULA OF OX
- This bone is highly rudimentary in ox.
- The fibula usually consists of the two extremities only.
- The head is fused with the lateral condyle of the tibia and is continued by a small, blunt-pointed prolongation distally.
- The distal end remains separate and forms the lateral malleolus (sometimes called the os malleolare).
- It is quadrilateral in outline and compressed from side to side.
- The proximal surface articulates with the distal end of the· tibia, and bears a small spine which fits into the groove on that bone
Fibula of horse
- It is an aborted long bone and to some extent better developed in comparison to that of ox.
- The bone presents a head, a body and a pointed distal end.
- It is placed along the lateral border of tibia.
- Proximal end is little large, flat and articulates with the lateral condyle of tibia.
- The distal end extends to the distal third of tibia.
- The interosseous space between tibia and fibula is wide.
Fibula of dog
- The fibula extends the entire length of the region.
- It is slender and somewhat twisted, and is enlarged at either end.
- The proximal part of the body is separated from the tibia by a considerable interosseous space, but the distal part is flattened and closely applied to the tibia.
- The proximal extremity is flattened and articulates with the lateral condyle of the tibia.
- The distal end is somewhat thicker and forms the lateral malleolus.
- It articulates medially with the tibia and the talus. Laterally it bears two tubercles.
Fibula of pig
- The fibula extends the entire length of the region and is separated from the tibia by a wide interosseous space.
- The body is flattened from side to side; the proximal part is wide and deeply grooved laterally; the distal part is narrower and thicker.
- The proximal end is flattened, grooved laterally and articulates medially with the lateral condyle of the tibia.
- The distal end forms the lateral malleolus.
- It is grooved laterally and articulates with the tibia and talus medially, with the calcaneus distally.
Fibula of fowl
- It is a thin rod-shaped long bone remains attached to the lateral part of the proximal end of tibia.
- Distally it is pointed and extends up to the distal third of the tibia and fuses with it.
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