Regions of the Lower Limb
The lower extremities or lower limbs are built for support and propulsion. They are extensions from the trunk specialized to support body weight as well as maintain balance. The lower limbs are conventionally described to include transitional regions between the trunk and the free lower limbs
Therefore, the lower limbs are comprised of the following six regions:
- Buttock or gluteal region
- Thigh or femoral region
- Knee or knee region
- Leg or leg region
- Ankle or talocrural region
- Foot or foot region
The gluteal region lies behind the pelvis, and extends from the iliac crest to the gluteal fold (fold of the buttock), which is the posterior horizontal crease line of the hip joint. Various muscles, nerves, and vessels emerge from the pelvis to enter the lower limb in this region.
The muscles of the region are the:
- three gluteal muscles – gluteus maximus, gluteus medius and gluteus minimus, which is the smallest of all three
- the deeply situated piriformis muscle
- obturator internus muscle
- superior gemellus
- inferior gemellus
- quadratus femoris muscles
The bony and ligamentous features of the region include the back of the sacrum and hip bone, the upper end of the femur, and the sacrotuberous and sacrospinous ligaments. Thus, the gluteal muscles constitute the bulk of this region.
Because of the location of the gluteal region, it is considered a transitional region between the trunk and the free lower limbs.
The thigh or femoral region is the most superior part of the free lower limbs. It lies between the gluteal, abdominal, and perineal regions proximally and the knee region distally. It contains a large percentage of the femur or thigh bone, which forms the bony connection between the hip region and knee region.
The transition between the trunk and the free lower limb is abrupt anteriorly and medially. The boundary between the thigh and abdominal regions is demarcated by the inguinal ligament anteriorly and the ischiopubic branch of the hip bone medially. The junction of these regions is the inguinal region or groin.
Although this region is named according to the bone femur, the bulk of structures it contains are muscles, which are grouped by fasciae and intermuscular septa into compartments.
This region includes:
- the prominences (or condyles) of the distal femur and proximal tibia
- the head of the fibula
- the patella (knee cap, which lies anterior to the distal end of the femur)
- joints between the above bony structures
The posterior part of the region is marked by a fossa. This fossa is a well defined, fat-filled space called the popliteal fossa. The word popliteal is derived from the Latin word “poples”, and this fossa mainly transmit neurovascular structures.
This is the part of the lower limb that lies between the knee and the rounded medial and lateral prominences (medial and lateral malleoli) that flank the ankle joint. It contains the tibia (shin bone) and fibula (Latin word meaning “buckle”) and connects the knee and foot. The calf of the leg is the posterior prominence caused by the triceps surae muscle, from which the calcaneal (Achilles) tendon extends to reach the heel.
This region is marked by the malleoli. It includes the narrow, distal part of the leg. The ankle (talocrural) joint is located between the malleoli.
This is the most distal part of the lower limb containing the tarsus, metatarsus, and phalanges (or toe bones). The superior surface of this region is called the dorsum of the foot and the inferior, ground-contacting surface is the sole or plantar region of the foot. The toes are the digits of the foot, and of these toes the great toe (called the hallux in Latin), like the thumb, has only two phalanges (digital bones). The other four digits have three phalanges each.