Lecture on Lower Appendicular Skeleton

Overview

• Focus on the pelvic girdle and legs.
• Components: Pelvic girdle (O coxa, sacral bone) and legs (femur, tibia, fibula).

Pelvic Girdle

• Structure:

  • Composed of two O coxa and the sacral bone.
  • Right and left O coxa unite with the sacral bone at the sacroiliac joint.
  • Mickey Mouse method to determine orientation (ears up, acetabulum forward, pubic symphysis in the middle).

• Bones of the Pelvic Girdle:

  • Ilium:
    • Iliac crest: The top edge of the ilium, felt when hands on hips.
    • Sacroiliac joint: Roughened area where ilium joins sacrum.
    • Greater and lesser sciatic notches: Allow passage of nerves and blood vessels.
  • Ischium:
    • Ischial tuberosity: The "butt bone" felt when sitting.
  • Pubis:
    • Pubic symphysis: Cartilage joint between pubic bones, softens during childbirth.
    • Pubic arch: Wider in females for childbirth.

Acetabulum

• A cup-like structure where the femur head fits, forming the ball and socket joint.
• Critical for leg movement flexibility.

Femur

• Proximal End:

  • Head: Features a fovea capitis for blood vessels and nerves.
  • Neck: Supports the head.
  • Greater and lesser trochanters: Muscle attachment sites.

• Distal End:

  • Medial and lateral condyles: Articulate with the tibia.
  • Medial and lateral epicondyles: Above condyles for muscle attachments.

Tibia and Fibula

• Tibia:

  • Major weight-bearing bone.
  • Articulates with the femur at its condyles.

• Fibula:

  • Articulates posteriorly with the tibia.
  • Smaller, non-weight bearing.

Conclusion

• Understand the structure and articulation of the pelvic girdle and leg bones.
• Differences in male and female pelvis due to hormonal effects on bone formation.