Pelvic and Lower Limb Anatomy

Overview

This lecture covers the anatomy of the pelvic girdle and lower limb, including bone names, features, articulations, and differences between male and female pelves.

Pelvic Girdle and Pelvis Structure

• The pelvic girdle forms a complete ring and connects the lower limbs to the axial skeleton.
• The pelvis consists of two ilium, two ischium, and two pubis bones, along with the sacrum.
• The sacrum is part of the axial skeleton, not the pelvis.
• The pelvic girdle supports and protects organs, balances the trunk, and provides muscle attachment areas.
• The acetabulum is formed by ilium, ischium, and pubis, serving as the socket for the femur.
• The obturator foramen reduces pelvic weight and allows passage for nerves and vessels.

Anatomical Landmarks of Pelvic Bones

• Iliac crest: superior border of ilium, palpable.
• Anterior superior iliac spine (ASIS): muscle attachment, "hip bones" you can feel.
• Sacroiliac joint: articulation between sacrum and ilium.
• Ischial tuberosity: "sits bones," muscle attachment.
• Pubic symphysis: immovable fibrocartilage joint between pubic bones.
• Pubic tubercle: attachment for inguinal ligament.
• Pubic crest: muscle attachment.
• Greater and lesser sciatic notches: form boundaries for important foramina.

False and True Pelvis

• The pelvic brim separates the false (greater) pelvis (superior) from the true (lesser) pelvis (inferior).
• False pelvis includes lower abdomen organs; true pelvis contains pelvic cavity organs.
• The pelvic outlet is bounded by ischial tuberosities and coccyx.
• The pelvic axis curves through the true pelvis (important in childbirth).

Sex Differences in the Pelvis

• Female pelvis: lighter, wider, shallower; pelvic inlet oval; greater sciatic notch and pubic arch angle wider.
• Male pelvis: heavier, narrower, deeper; pelvic inlet heart-shaped.

Lower Limb Regions and Bones

• Thigh: hip to knee (femur); leg: knee to ankle (tibia and fibula).
• Femur: head fits in acetabulum; neck permits range of motion.
• Greater and lesser trochanters: muscle attachment sites.
• Medial/lateral epicondyles and condyles: knee joint and ligament attachment.
• Patella: largest sesamoid bone, within quadriceps tendon, increases leverage.

Leg Bones and Joints

• Tibia: medial, weight-bearing, shin bone; articulates with femur and talus.
• Fibula: lateral, non-weight-bearing, stabilizes ankle.
• Interosseous membrane connects tibia and fibula for muscle attachment.
• Medial malleolus (tibia) and lateral malleolus (fibula): ankle stabilization.

Ankle and Foot Bones

• Ankle joint: involves tibia, fibula, and talus (a tarsal bone).
• Seven tarsals: talus, calcaneus, navicular, medial/intermediate/lateral cuneiforms, cuboid.
• Mnemonic: "Tall Centers Never Take Shots From Corners."
• Metatarsals: numbered 1–5, big toe is 1.
• Phalanges: toes have proximal, middle, distal; big toe (hallux) has only proximal and distal.

Key Terms & Definitions

• Pelvic girdle — ring-like bony structure attaching lower limbs to axial skeleton.
• Acetabulum — socket in pelvis for femoral head.
• Obturator foramen — large pelvic opening for nerves/vessels.
• False pelvis — portion above pelvic brim.
• True pelvis — portion below pelvic brim.
• Malleolus — bony prominence at ankle.
• Sesamoid bone — bone embedded in tendon, e.g., patella.

Action Items / Next Steps

• Review diagrams of pelvic and lower limb bones.
• Memorize major bone features and their functions.
• Practice labeling diagrams for exam preparation.