Osteology of the Lower Limb

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