Full Title: The Tibia
Author: Dave Wilde
Date of Publication: January 1, 2017
Research Paper Text:
The tibia is a long, strong bone that lies on the medial part of the crus (or true leg), and consists of a shaft and two extremities. The tibia articulates proximally with the femur, distally with the tarsus, and on the lateral side both proximally and distally with the companion bone of the crus, the fibula.
The shaft of the tibia is large, triangular, and three sided, proximally becoming smaller and flatter in the middle section. The shaft of the tibia widens and becomes nearly cylindrical at the distal extremity.
The body of the tibia (corpus tibiae), is three sided throughout its proximal half, while the distal half is essentially quadrilateral or cylindrical.
There are three surfaces and borders recognized in the proximal half of the tibia.
The surfaces are medial, lateral, and caudal. The medial surface is broad and rough proximally and narrowing distally. The lateral surface is a smooth, spiral curve. It is wide and concave in its proximal portion, narrow and convex centrally, and wider and flatted distally. The caudal surface is flattened and divided into two parts by the popliteal line. Near the popliteal line is a nutrient foramen.
The three borders of the tibia are cranial, medial, and lateral. The cranial border bears a crest to the proximal end.
Extremities of the tibia are proximal and distal. The proximal extremity is large and triangular, bearing two condyles, medial and lateral, and a tuberosity. The medial condyle is larger and of a slight saddle shape. It is separated from the lateral codyle by the popliteal notch and the tibial spine. The lateral condyle has an overhanging margin below which is a facet for articulation of the fibula. The tuberosity is located on the proximal end of the crest.
The distal end of the tibia is quadrilateral and smaller than the proximal, but slightly more massive than the adjacent part of the body. It has an articular surface and two malleoli. The malleoli are bony promiences on the outer margin of the articular grooves. The medial malleolus is smaller than the lateral, which is the distal extremity of the fibula. The articular surface consists of two grooves, separated by a ridge. The two grooves face obliquely forward and laterally. The medial groove is narrower and deeper than the lateral groove.
There are several ligament connections to the tibia. From a medial view, the tibial tuberosity connects to the cranial edge asa n extention of the patellar ligament. The medial collateral ligament attaches to the side (from the femur).
Muscular attachments lie on the cranial, lateral, and caudal surfaces of the tibia, whereas the medial surface is essential muscle-free. Flexor and extensor groups are not separated on the crus as they are on the antebrachium. Cranally and laterally are found extensors of the digital joints and flexors of the tarsus; caudally lie flexors of the digital joints and extendors of the tarsus. These functional muscle groups are mixed on the crus because the tarsal joint is set at an angle opposite of that of the digital joints.
Muscles that are attached to the cranial aspect of the tibia are bicep femoris, quadricep femoris, sartoius, gracilis, cranial tibial, peroneus longus, lateral digital extensor, and semitendinosus.
Muscles that attach to the caudal aspect are the semimembranosus, popliteus, flexor digitorum longus, flexor hallucis longus, and the caudal tibial.
Medial aspect muscles attachments are the semimembranosus, quadriceps, Sartorius, gracilis, popliteus, and semitendinosus.
The general area of the tibia also is the sight of many acupressure points. Six of the thirteen meridian run through the hind legs, including the stomach, spleen, bladder, kidney, gall bladder, and liver meridians. Within those meridians in the proximity of the tibia are thirteen acupressure points; five of them accumulation points, eleven command points, five connection points, three influential points, two master points, two sedation points, two source points, and three tonification points.
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