Lower Limbs - Structure, Joints, Ligaments, fractures
Know your Body

Lower Limbs - Going Places

Dr.Surya Rao Poodipeddi profile Authored by Dr.Surya Rao Poodipeddi on 6 Mar 2014 - 14:38.
A profound thought goes - "A man complained he had no shoes, until he saw a man without feet."  Thanks to our lower limbs (legs), they take us places, help explore the world, walk, run, play and keep us in good shape and health.
Dealing with any part of the lower limb of one side would mean the same in respect of the other side as well, except that one lower limb is on the right side and the other on the left side.
Structure of lower limbs:Similar to upper limb terminology, the leg does not comprise the complete lower limb. In medical parlance the portion between the ankle and the knee is called the leg. The whole length from the ankle to the hip is called the lower limb.
The lowest portion of the lower limb is called the foot. From the foot upward are the leg and the thigh. The foot joins the leg at the ankle joint formed with the help of tarsal bones, talus and the heel bone called calcaneum and the lower end of the leg bone called Tibia. The foot consists of an upper portion and a lower portion. The upper portion is called the dorsum of the foot covered by thin skin through which can be seen the veins and tendons meant for the movements of the toes. The Lower portion of the foot is called the plantar surface covered by very thick skin and large amount of pad of fat to protect the structures inside. The extreme back portion of the foot is called the heel mainly consisting of calcaneum or the heel bone surrounded by a rich amount of fat.
The plantar aspect of the foot has an arch called the plantar arch, which transmits the center of gravity evenly for the person to walk. From the tarsal bones emerge five bones fairly long, one each for the toes of the foot called metatarsals. The front end of each metatarsal joins the phalanx of each toe. There are five toes. Starting from the inner end of the foot they are called the great toe, second toe, middle toe, fourth toe and the little toe. Each toe has three phalanxes except the great toe, which has only two phalanxes. Like in hands of upper limbs, the toes have inter- phalangeal joints and the one between the proximal phalanx and the metatarsal is called metatarso-phalangeal joint. These joints enable the toes to move downward and upward and also sideways. The foot has rich blood supply venous drainage and nerve supply.
The ankle joint enables the foot to move backwards and upwards and to some extent sideways and rotatory movements with the help of the tarsal bones and the tibia. The leg has two bones called tibia and fibula. The tibia is very thick and strong and bears the brunt of the body weight. The fibula also called the funny bone is very thin and forms the tibiofibular joints. Behind the leg is a strong and belly like muscle called the soleus. The long tendon of this muscle attaches itself to the foot bone enabling the movements over ankle. If this tendon is torn the foot cannot work. This tendon is called Tendo Achilles named because an archer hit the tendon with an arrow and disabled the person from walking.
The upper end of the tibia and the undersurface of the thighbone form the knee joint with the help of the kneecap called the patella. Between the bones there are two cartilages, semicircular in shape, which prevent the bone ends from rubbing with each other. As age advances, these cartilages get worn out and degenerated leading to a condition called Osteoarthritis. The patella is usually prone to fracture. If this happens the kneecap needs to be repaired through wiring. The back portion of the knee is a hollow called popliteal fossa through which the vessels and nerves from the thigh pass through.
The thigh has one strong bone called the femur. The femur is the strongest and longest bone in the human body measuring about 18 inches. The lower end of the femur joins the upper surface of the tibia to form the knee joint. The upper end of the femur, like the humerus in the arm, has a neck and head. The head fits into a cavity in the pelvic bones called the acetabulam to form the hip joint. The hip joint is a ball and socket joint with wide range of movements over the hip enabling a person to move the lower limb in any direction he wants including circular movements.
The main joints of the lower limb are held together by strong ligaments over which the muscles move to end as tendons to perform the movements needed. The front part of the upper end of the thigh has a fold called the groin through which the great vessels and nerves pass through from the abdomen to the thigh.
The front of the thigh has four strong muscles called quadriceps femoris. The back portion of the upper end of the thigh has the strongest muscles called the glutei, which form the shape of the buttocks along with liberal amount of fatty tissue. Like in case of the upper limbs, there are so many conditions affecting the lower limbs and its structures, that it is beyond the scope of this article to describe all of them.
The main conditions affecting the lower limbs are those related to fractures and dislocations. Though not very common, certain congenital conditions do affect the lower limbs. It is essential for every one young or old to maintain regular movements of each joint, small or big through regular exercises so that they don’t become stiff. This is truer as age advances when stiffness is a common problem encountered.
*Disclaimer: This is not medical advice. The content is for educational purposes only. Please contact your doctor for any health care issues.