Tibia – Bone Land Marks, Anatomy, Muscle Attachment

The tibia also is known as the shinbone or shank bone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia), and it connects the knee with the ankle bones. The tibia is found on the medial side of the leg next to the fibula and closer to the median plane or center-line. The tibia is connected to the fibula by the interosseous membrane of the leg, forming a type of fibrous joint called a syndesmosis with very little movement. The tibia is named for the flute tibia. It is the second-largest bone in the human body next to the femur. The leg bones are the strongest long bones as they support the rest of the body.

Upper End

The proximal or upper extremity of the tibia is expanded in the transverse plane with a medial and 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 shaft. The upper surfaces of the condyles articulate with the femur to form the tibiofemoral joint, the weight-bearing part of the knee joint

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 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.

Borders

The anterior crest or border, the most prominent of the three, commences above at the tuberosity and ends below at the anterior margin of the 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 cm., and insertion to some fibers of the popliteus muscle; from its middle third some fibers of the 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.

Lower extremity

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 medial malleolus. The lower extremity of the tibia together with the fibula and talus forms the 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 and posterior colliculi), continuous above with the interosseous crest; they afford attachment to the anterior and posterior ligaments of the lateral malleolus.

Muscles

Muscles demonstrating origin/insertion footprints on the tibia include [rx][rx][rx][rx][rx][rx]

• Tensor fasciae latae inserts on the lateral (Gerdy) tubercle of the tibia.
• Quadriceps femoris inserts anteriorly on the tibial tuberosity.
• Sartorius, gracilis, and semitendinosus insert anteromedially on the pes anserinus.
• Horizontal head of semimembranosus muscle inserts on the medial condyle.
• Popliteus inserts on the sole line of the posterior tibia.
• Tibialis anterior originates at the upper two-thirds of the lateral tibia.
• Extensor digitorum longus originates at the lateral condyle of the tibia.
• Soleus and flexor digitorum longus originates at the posterior aspect of the tibia on the sole line.

Muscles associated with the fibula

• The biceps femoris tendon inserts on the fibular head.
• The fibularis longus and fibularis brevis tendons insert on the lateral fibula.
• The extensor digitorum longus and extensor hallucis longus tendons insert on the medial fibula.
• The fibularis tertius (FT) is a small muscle in the anterior compartment of the leg that inserts on the anterior surface of the distal fibula.[rx]

Muscles Inserting on the Tibia

• Tensor fasciae latae inserts on the lateral tubercle of the tibia, which is known as the Gerdy tubercle
• Quadriceps femoris inserts anteriorly on the tibial tuberosity
• Sartorius, gracilis, and semitendinosus insert anteromedially on the pes anserinus
• Horizontal head of semimembranosus muscle inserts on the medial condyle
• Popliteus inserts on the soleal line of the posterior tibia

Muscles Originating at the Tibia

• Tibialis anterior originates at the upper two-thirds of the lateral tibia
• Extensor digitorum longus originates at the lateral condyle of the tibia
• Soleus and flexor digitorum longus originate at the posterior aspect of the tibia on the soleal line

References

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