WEEK 3: HUMAN ANATOMY - Pelvic and Lower Limb Anatomy 3d

Overview

This lecture covers the anatomy of the pelvic girdle and lower limbs, detailing the structure, function, and distinguishing features of the bones from the pelvis to the foot.

Pelvic Girdle Structure & Function

• The pelvic girdle forms a complete ring made of seven bones (including the sacrum).
• The pelvis itself consists of six bones: two ilia, two ischia, and two pubic bones.
• The pelvic girdle attaches the lower limbs to the body, transmits forces to the axial skeleton, and supports/protects organs.
• Unlike the shoulder girdle, the pelvic girdle offers greater stability and protection.

Features of the Pelvis

• Iliac crest: top of the ilium, palpable, muscle attachment site.
• Anterior superior iliac spine (ASIS): front point of iliac crest, muscle attachment.
• Sacroiliac joint: articulation between sacrum and ilia.
• Ischial tuberosity: "sits bones," muscle attachment.
• Pubic symphysis: fibrocartilage joint, little movement.
• Pubic tubercle and crest: ligament and muscle attachment points.
• Acetabulum: socket for femur head, formed by all three pelvic bones.
• Obturator foramen: large hole for nerves/blood vessels, reduces bone weight.

Distinct Pelvic Regions & Sex Differences

• The pelvic brim divides the pelvis into the false (superior) and true (inferior) pelvis.
• The false pelvis supports abdominal organs; the true pelvis contains pelvic organs.
• Female pelvis: wider, lighter, larger pelvic inlet/outlet, >90° pubic arch, shorter/wider sacrum.
• Male pelvis: narrower, heavier, smaller inlet/outlet, <90° pubic arch, longer/narrower sacrum.

Bones of the Lower Limb

• The thigh (hip to knee) contains the femur; the leg (knee to ankle) contains tibia and fibula.
• Femur features: head (articulates with acetabulum), neck, greater/lesser trochanters (muscle attachment), linea aspera (posterior ridge), condyles/epicondyles (knee joint).
• Patella: sesamoid bone embedded in quadriceps tendon, increases leverage at the knee.

Leg (Knee to Ankle)

• Tibia (medial, weight-bearing): medial/lateral condyles (articulate with femur), tibial tuberosity (attachment), medial malleolus (ankle bump).
• Fibula (lateral, non-weight-bearing): head, lateral malleolus (ankle bump), stabilizes ankle.
• Interosseous membrane connects tibia and fibula, providing muscle attachment/stability.

Ankle and Foot

• Ankle formed by tibia, fibula, and talus (a tarsal bone).
• Three ankle joints: tibio-talar, fibulo-talar, inferior tibiofibular.
• Seven tarsals: talus, calcaneus, navicular, cuboid, medial/intermediate/lateral cuneiforms.
• Metatarsals (numbered I-V from big toe to little toe) articulate with cuneiforms/cuboid.
• Phalanges: numbered I-V; big toe (hallux) has two, others have three each.

Key Terms & Definitions

• Pelvic Girdle — ring of bones connecting the lower limbs to the axial skeleton.
• Acetabulum — hip socket, receives the head of the femur.
• Obturator Foramen — large hole in pelvis for nerves/blood vessels.
• ASIS (Anterior Superior Iliac Spine) — prominent bump on the ilium.
• Ischial Tuberosity — sit bone, supports weight when sitting.
• Patella — kneecap, largest sesamoid bone.
• Talus — tarsal bone forming the lower part of the ankle joint.
• Tibia — shin bone, main weight-bearing bone of the leg.
• Fibula — slender bone lateral to tibia, stabilizes the ankle.

Action Items / Next Steps

• Review diagrams of pelvis, femur, tibia, fibula, and foot bones.
• Memorize features and attachments for major bones.
• Learn differences between male and female pelvis for exams.
• Practice naming phalanges and metatarsals using correct anatomical terminology.