Tibia

The tibia is a long bone between the knee and ankle. The lower leg has two bones: the tibia is the thick, weight-bearing bone on the inner side, while the Fibula is the slender bone running alongside it on the outer side. Weight passes down from the Femur to the tibia, which transfers it to the ankle and foot. It is the second-longest bone in the body after the thighbone, serving as a central supporting axis whenever you stand, walk, or run.

Following the bone from top to bottom, its structure looks like this.

• Upper end — The broad medial and lateral condyles meet the femur to form the knee. A small prominence rises between the two condyles, where the cruciate ligaments attach.
• Upper front — The Patellar tendon attaches to the Tibial tuberosity, a prominent area below the kneecap. Force from the muscles at the front of the thigh is transmitted here to straighten the knee.
• Shaft — This is a pillar-like structure with a roughly triangular cross-section. Its front edge lies directly beneath the skin with no muscle covering it, so you can feel the bone itself when you run a finger down it.
• Lower end — The medial malleolus projects inward and is the rounded prominence you can feel on the inner side of the ankle. The lower joint surface meets an ankle bone called the talus, forming the upper framework of the Ankle.

The native Korean name for the tibia means “shinbone.” The tibia is the bone in the region commonly called the “shin,” so when someone says they bumped their shin, they usually mean they struck the front edge of the tibia. However, “shin” refers to a region that includes not only the bone but also the muscles, tendons, skin, and nerves in front of and behind it, whereas “shinbone” refers to the single bone within that region. Keeping this distinction in mind makes the anatomy easier to understand when looking into pulling sensations or pain in the Shin.

At its upper end, the tibia forms the Tibiofemoral joint, where the Meniscus helps distribute impact between the bones. The upper inner side has an attachment site for the Pes anserinus, where muscles from the inner and back of the thigh converge, while the upper outer side has an attachment site for the Iliotibial band along the outside of the thigh. Nerves, including the Tibial nerve, and blood vessels pass through several layers around the bone.

• It is a bone that easily takes a direct hit. Because its front edge lies just beneath the skin, hitting it against the edge of a desk or a threshold can cause pain that seems to reverberate through the bone. This is because there is very little muscle or soft tissue covering the front.
• The muscles in front and behind work together when you run or walk for a long time. The tibialis anterior, which lifts the ankle, attaches along the front outer side of the bone, while muscles that lower the ankle and support the arch of the foot attach along the back inner side. A pulling sensation along the inner shin after a sudden increase in exercise is also related to these attachment sites. You can read more about this in Shin tightness.
• During growth, there are growth plates at the ends of the bone. During adolescence, the tibia grows in length at its upper and lower ends, and these plates close once you have reached your full height. Osgood-Schlatter disease, which causes a painful bump at the front just below the knee, is also related to changes around this growth plate region.

• Increase exercise gradually. Rather than suddenly making a large increase in running distance or the number of jumps, building up in stages over a week or two gives your shins time to adapt.
• Try cushioned shoes and softer surfaces. Running for a long time on a hard surface sends impact directly up into the bone.
• Loosen up your calf muscles, too. Tight muscles at the back of the lower leg can easily increase strain around the shin. Gentle stretching and massage after exercise can help.
• Use guards to protect your shins. In sports such as soccer, where blows to the shin are common, shin guards cover the bone’s front edge.

If throbbing continues even at rest, one particular spot over the bone is especially painful when pressed, or it is difficult to bear weight when walking, stop exercising and check your condition. The same applies if there is visible deformity or severe swelling after a blow. If you do a lot of running or jumping, it is also useful to know about Tibial stress fracture, in which small amounts of fatigue accumulate in the bone.