Osteology of the Lower Limb

Study Notes

Osteology of the Lower Limb

The lower limb skeleton (inferior appendicular skeleton) is divided into two components:
- The pelvic girdle (often discussed with the pelvic region)
- The bones of the free lower limb
The pelvic girdle attaches the free lower limb to the axial skeleton
Body weight is transferred from the vertebral column to the pelvic girdle via the sacroiliac joints
From the pelvic girdle, weight is transferred through the hip joints to the femurs
To support bipedal posture, the femurs are angled obliquely (inferomedially) such that the knees are positioned below the trunk, centering the body's weight over the supporting legs and feet
The femur is the longest and heaviest bone in the body
Femur length is approximately one-quarter of a person's height
The femur has a shaft (body) and two ends (superior/proximal and inferior/distal)
The patella is a large sesamoid bone formed within the tendon of the quadriceps femoris muscle after birth
The patella is triangular, located anterior to the femur's midcondylar region, and articulates with the patellar surface of the femur
The patella's anterior surface is convex, with a thick base (superior border) sloping infero-anteriorly; the lateral and medial borders converge inferiorly to form a pointed apex (inferior extremity)
The posterior articular surface is smooth and covered with a thick layer of articular cartilage
The tibia and fibula are the bones of the leg
The tibia articulates with the femur's condyles superiorly and the talus inferiorly, transmitting body weight
The fibula primarily serves as a muscle attachment site, but is also important for ankle joint stability
The tibia is located on the anteromedial side of the leg, roughly parallel to the fibula
The tibia is the second-largest bone in the body
The tibia flares outward at both ends to increase the articulation area and facilitate weight transfer
The tibia shaft is a true vertical structure, unlike the femur's oblique shaft
The fibula is positioned posterolateral to the tibia
The fibula is firmly attached to the tibia via the tibiofibular syndesmosis (including the interosseous membrane)
The fibula has no weight-bearing function
The fibula serves as an attachment site for several muscles
The fibers of the tibiofibular syndesmosis prevent downward pull on the fibula
The bones of the foot include the tarsus, metatarsus, and phalanges
- The tarsus consists of seven bones: talus, calcaneus, cuboid, navicular, and three cuneiforms
- Only the talus articulates with the leg bones
- The metatarsus consists of five metatarsals
- The five metatarsals are numbered from the medial side of the foot
- The tarsometatarsal joints form an oblique line, connecting the medial and lateral midpoints of the shorter lateral borders of the foot
- The metatarsals and phalanges comprise the forefoot; the tarsals, the hindfoot
The 14 phalanges follow this pattern: the great toe (hallux) has two, and the other toes have three each (proximal, middle, and distal)
The first toe's phalanges are short, broad, and strong. The fifth toe's middle and distal phalanges tend to fuse in elderly individuals
Injuries to the lower limb can include:
- Hip bone injuries
- Coxa vara and coxa valga
- Femoral head dislocation
- Femoral fracture
- Tibial fracture
- Fibular fracture
- Bone grafting
- Calcaneal fracture