Lower Limb Skeleton: Lecture 7

• Lecture 7 is on the Skeleton of the Lower Limb I, by C. Mupfiga from the University of the Western Cape

Lower Limb Skeleton

• Consists of 30 bones adapted for weight-bearing and locomotion.
• Includes the pelvic girdle, hip bone, femur, patella, tibia, fibula, tarsals, metatarsals, and the phalanges
• Regions are gluteal, thigh, leg, ankle, and foot
• Adapted for weight-bearing, locomotion, and bipedal posture
• Bones of the pelvic girdle and lower limb are more massive than their homologues of the upper limb

Pelvic Girdle

• Transfers the weight of the upper body to the lower limbs
• The pelvic girdle consists of 2 hip bones, each with 3 fused bones: ilium, ischium, and pubis
• Along with the sacrum and coccyx, they form a bowl-shaped region called the pelvis
• Each hip bone is large, flattened, and irregularly shaped
• The right and left hip bones meet anteriorly, forming the lateral and anterior walls of the pelvic cavity
• The 3 parts (ilium, ischium, and pubis) merge at the acetabulum, forming the hip joint with the femur
• Functions of the pelvic girdle include supporting and protecting abdominal and pelvic organs and the developing foetus
• Attaches lower limbs to the trunk, and transmits weight of upper body from vertebral column to lower limbs
• The pelvis, resembles a basin, a bony ring between the vertebral column and lower limbs
• Divided by the pelvic brim into a false pelvis and true pelvis
• The false pelvis is an expanded portion of the cavity lying above the pelvic brim
• The true pelvis is situated below the pelvic brim and consists of an inlet, outlet, and cavity
• Human pelvic anatomy must allow for both bipedalism and childbirth, which results in a narrower pelvic outlet for humans, potentially causing pain and difficulty during childbirth

Femur

• It is the longest and strongest bone of the skeleton
• In the erect posture, it is slightly inclined medially
• The proximal end consists of the head, neck, greater and lesser trochanter, intertrochanteric crest and line
• The shaft: linea aspera, gluteal tuberosity, popliteal surface
• The distal end consists of medial and lateral condyles, intercondylar fossa, patellar surface

Femoral Fractures

• The neck of the femur is most frequently fractured because it is the narrowest and weakest part of the bone
• Lies at an angle to the line of weight-bearing
• It becomes increasingly vulnerable with age, especially in females, secondary to osteoporosis
• Fractures of the femoral shaft result from direct trauma sustained by the bone resulting from falls

Patella

• A flat triangular bone situated anterior to distal end of femur
• The anterior surface is roughened
• The posterior surface is smooth and oval; has medial and lateral facets which articulate with condyles of femur
• Borders include a superior base border, medial and lateral borders
• The apex is pointed inferiorly
• It is a roughly triangular sesamoid bone embedded in the tendon of the quadriceps femoris muscle
• Largest sesamoid bone
• It protects the tendon against friction and increases mechanical advantage by changing the direction of pull