TIBIA BONE Learning objectives:

TIBIA BONE Learning objectives: At the end of the lecture, the student should be able to describe:  The division of tibia bone in 3 parts  The surfa...
Author: John Peters
0 downloads 0 Views 701KB Size
TIBIA BONE Learning objectives: At the end of the lecture, the student should be able to describe:  The division of tibia bone in 3 parts  The surfaces and borders of tibia  The attachments of muscles on the tibia bone  The ossification of tibia and its primary and secondary ossification centers

Lecture outline: Tibia:  Prismoid in form, expanded above, where it enters into the knee-joint, contracted in the lower third, and again enlarged but to a lesser extent below.  In the male, its direction is vertical, and parallel with the bone of the opposite side , in the female it has a slightly oblique direction downward and lateralwards, to compensate for the greater obliquity of the femur.  It has a body and two extremities/ ends (upper & lower).

The upper extremity:  The upper extremity is large  Expanded into two eminences, the medial and lateral condyles.  The superior articular surface presents two smooth articular facets .

The medial facet :  oval in shape  slightly concave from side to side, and from before backward .

The lateral facet :  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 menisci of the knee-joint.

Intercondyloid eminence (spine of tibia):

 Located between the articular facets  It is surmounted on either side by a prominent tubercle, on to the sides of which the articular facets are prolonged  In front of and behind are rough depressions for the attachment of the anterior and posterior cruciate ligaments and the menisci.

Anterior surfaces of condyles:

 Continuous with one another  Forms a large flattened triangular area which is broad above, and perforated by large vascular foramina; narrow below where it ends in tuberosity of the tibia

Tuberosity of the tibia :  A large oblong elevation.  Gives attachment to the ligamentum patellae  A bursa intervenes between the deep surface of the ligament and the part of the bone immediately above the tuberosity.

Posterior surfaces of condyles:  Posteriorly , condyles are separated from each other by a shallow depression, the posterior intercondyloid fossa.  This fossa gives attachment to part of the posterior cruciate ligament of the knee-joint.  The medial condyle has a deep transverse groove posteriorly for the insertion of the tendon of the Semimembranosus.  Its medial surface is convex, rough, and prominent and gives attachment to the tibial collateral ligament.

The lateral condyle :  Posteriorly, it has a flat articular facet, circular in form which is directed downward, backward, and lateralward for articulation with the head of the fibula.  Lateral surface is convex, rough, and prominent in front  Has got 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.

Body of tibia: Has three borders and three surfaces.

Borders : Anterior Medial Interosseous

The anterior crest or border :  The most prominent of the three  Commences above at the tuberosity  Ends below at the anterior margin of the medial malleolus.  Is sinuous and prominent in the upper two-thirds of its extent, but smooth and rounded below  Gives attachment to the deep fascia of the leg.

Surfaces: Lateral

Medial Posterior

Lateral surface:

 Narrower than the medial one  Upper two-thirds present a shallow groove for the origin of the Tibialis anterior  Lower third is smooth, convex, curves gradually forward to the anterior aspect of the bone  Is covered by the tendons of the Tibialis anterior, Extensor hallucis longus, and Extensor digitorum longus from medial to lateral side

Posterior surface:

 Has a prominent ridge in its upper part, the popliteal line,  This line 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

Attachments:  Marks the lower limit of the insertion of the Popliteus  Serves for the attachment of the fascia covering this muscle  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.

The lower extremity  The lower extremity, much smaller than the upper, presents five surfaces  It is prolonged downward on its medial side as a strong process, the medial malleolus.

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.

 Is continuous with that on the medial malleolus.

The anterior articular surface  Is smooth and rounded above  Covered by the tendons of the Extensor muscles  Lower margin presents a rough transverse depression for the attachment of the articular capsule of the anklejoint.

The posterior articular surface  Is traversed by a shallow groove directed obliquely downward and medialward,  It is 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 articular 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, continuous above with the interosseous crest  They afford attachment to the anterior and posterior ligaments of the lateral malleolus.

The Medial articular surface  Is prolonged downward to form a strong pyramidal process, flattened from without inward—the medial malleolus.  The medial surface of this process is convex and subcutaneous  Its lateral or articular surface is smooth and slightly concave, and articulates with the talus  Its anterior border is rough, for the attachment of the anterior fibers of the deltoid ligament of the ankle-joint  Its posterior border presents a broad groove, the malleolar sulcus, directed obliquely downward and medialward, and occasionally double  This sulcus lodges the tendons of the Tibialis posterior and Flexor digitorum longus.  The summit of the medial malleolus is marked by a rough depression behind, for the attachment of the deltoid ligament.

Muscular attachments on tibia

Ossification of tibia

 The tibia is ossified from three centers one for the body and one for either 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; it is flattened in form, and has a thin tongue-shaped process in front, which forms the tuberosity;  The center for the lower epiphysis appears in the second year.  The lower epiphysis joins the body at about the eighteenth, and the upper one joins 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.

Fractures of tibia bone The Gosselin fracture is a V-shaped fracture of the distal tibia which extends into the ankle joint and fractures the tibia into anterior and posterior fragments

A Bumper fracture is a fracture of the lateral tibial plateau caused by a forced valgus applied to the knee. This causes the lateral part of the distal femur and the lateral tibial plateau to come into contact, compressing the tibial plateau and causing the tibia to fracture. Pott's fracture also known as Pott’s syndrome and Dupuytren fracture, The injury is caused by a combined abduction external rotation from an eversion force. This action pulls on the extremely strong medial (deltoid) ligament, often tearing off the medial malleolus. The combined fracture of the medial malleolus, lateral malleolus, and the posterior margin of the distal end of the tibia is known

**************************^^^^^^^^^^^^^^^^^^^^^^^^^**********************