Parts of the Lower Extremity of the Body

Understanding the Anatomy of the Lower Extremity

Reading Time: 3 minutes

The lower extremity refers to the region of the body extending from the hips to the feet. It consists of several important structures, including the hip, knee, and ankle joints, as well as the bones of the thigh, leg, and foot.

Many people colloquially refer to the entire lower extremity as the “leg.” However, anatomically speaking, the leg specifically refers to the area between the knee and the ankle. To be precise, the proper term for the whole region from the hips down to the feet is the lower extremity.

Key Parts of the Lower Extremity

• Thigh: This is the section between the hip and the knee.

• Leg: The area between the knee and ankle.

In comparison, the upper extremity consists of the following:

• Arm: The area from the shoulder to the elbow.

• Forearm: The area from the elbow to the wrist.

Blood Circulation in the Lower Extremity

Blood is supplied to the lower extremity via the femoral artery. The return blood flow occurs through the superficial saphenous veins and deep veins such as the femoral, popliteal, anterior tibial, posterior tibial, and fibular veins. A critical medical condition linked to the veins is deep vein thrombosis, which occurs when clots form in these veins, posing significant health risks.

Nerves of the Lower Limb

The lower limb is controlled by nerves that branch from the lumbosacral plexus. The sciatic nerve, which originates in the pelvis, travels down the back of the leg and branches into the peroneal and tibial nerves, controlling the legs and feet. Injuries to the peroneal nerve can lead to foot drop, a condition that affects the ability to lift the foot. Additionally, spinal nerve compression can cause pain that radiates along the sciatic nerve, a condition known as sciatica.

Bones and Joints of the Lower Extremity

The lower extremity is connected to the pelvic bones through the hip joint. The femur, or thigh bone, extends down to the knee, where it articulates with the patella. The bones of the leg include the larger tibia (shin bone) and the smaller fibula. These bones connect to the foot through the ankle joint, which meets the tarsal bones. Key tarsal bones include the talus, calcaneus (heel bone), cuboid, navicular, and cuneiform bones. These bones interact with the metatarsal bones of the foot and the phalanges of the toes, forming the structure of the foot.

Fractures and joint injuries in the lower extremity are common, with knee and hip replacements often performed in cases of severe osteoarthritis.

Muscles of the Lower Extremity

The muscles in the lower extremity are among the strongest and longest in the body, designed to support movement such as walking and standing. These muscles control the thigh, leg, and foot. Key muscle groups include:

• Hip Muscles: Gluteus maximus, gluteus medius, iliopsoas, adductors, sartorius, and gracilis.

• Thigh Muscles: Quadriceps in the front and hamstrings in the back.

• Calf Muscles: Gastrocnemius and soleus.

The Achilles tendon is the largest tendon in the body, connecting the calf muscles to the heel bone.

Key Takeaways

• The lower extremity includes the hip, thigh, knee, leg, ankle, and foot.

• Understanding the anatomy of the lower extremity is essential for healthcare professionals and individuals alike.

• Common issues like deep vein thrombosis and sciatic nerve compression can cause significant discomfort or health risks.