Osteology & Arthrology: Pelvic Girdle & Lower Limb

Introduction

This study guide covers the anatomy and physiology of the pelvic girdle and lower limb, focusing on the bones (osteology) and joints (arthrology) of this region. It is designed to help students understand the structure, function, and terminology associated with the lower appendicular skeleton, including the hip, knee, ankle, and foot.

Contents

• Basics – Lower Appendicular Skeleton

• Pelvic Girdle (osteology & arthrology)

• Coxal Joint = Hip Joint (arthrology)

• Femur & Patella (osteology)

• Knee Joint (arthrology)

• Leg & Foot (osteology & arthrology)

Basics – Lower Appendicular Skeleton

Overview

The appendicular skeleton consists of the bones of the limbs and their girdles, which attach them to the axial skeleton. The lower appendicular skeleton includes the pelvic girdle and the bones of the lower limb.

• Appendages: Limbs or extremities attached to the trunk.

• Girdle: A bony or cartilaginous structure that supports the limbs (e.g., pelvic girdle for lower limb).

Regions of the Lower Limb

• Pelvic Girdle: Formed by the two hip bones (os coxae).

• Thigh: Contains the femur.

• Leg: Contains the tibia and fibula.

• Foot: Includes tarsals, metatarsals, and phalanges.

Pelvic Girdle (Osteology & Arthrology)

Structure and Function

The pelvic girdle is composed of two hip bones (os coxae), which articulate with the sacrum posteriorly and with each other anteriorly at the pubic symphysis. It provides support for the lower limbs and protection for pelvic organs.

• Os coxae: Each hip bone is formed by the fusion of three bones: ilium, ischium, and pubis.

• Functions: Supports body weight, provides attachment for muscles, and protects pelvic viscera.

Key Joints of the Pelvic Girdle

• Sacroiliac Joint: Synovial (plane) and fibrous (amphiarthrosis) joint between sacrum and ilium.

• Pubic Symphysis: Cartilaginous (symphysis) joint uniting the two pubic bones.

Coxal Joint (Hip Joint) – Arthrology

Structure

The hip joint is a synovial ball-and-socket joint formed by the articulation of the head of the femur with the acetabulum of the pelvis.

• Type: Synovial, ball-and-socket; allows multiaxial movement.

• Ligaments: Iliofemoral, pubofemoral, and ischiofemoral ligaments stabilize the joint.

• Function: Supports body weight in both static (standing) and dynamic (walking, running) postures.

Key Features

• Acetabulum: Deep socket in the pelvis that receives the femoral head.

• Ligament of the head of femur: Contains a small artery supplying the femoral head.

Femur & Patella (Osteology)

Femur

• Largest bone in the body.

• Key features: Head, neck, greater and lesser trochanters, shaft, medial and lateral condyles.

Patella

• Sesamoid bone: Develops within the tendon of the quadriceps femoris muscle.

• Function: Protects the knee joint and improves leverage of the thigh muscles.

Knee Joint (Arthrology)

Structure

The knee is a complex joint composed of two main articulations: the tibiofemoral joint and the patellofemoral joint.

• Tibiofemoral Joint: Synovial, hinge-like (bicondylar) joint between femur and tibia.

• Patellofemoral Joint: Synovial, plane joint between patella and femur.

Key Ligaments

• Medial (Tibial) Collateral Ligament (MCL): Connects femur to tibia.

• Lateral (Fibular) Collateral Ligament (LCL): Connects femur to fibula.

• Anterior Cruciate Ligament (ACL): Connects femur to tibia, prevents anterior displacement of tibia.

• Posterior Cruciate Ligament (PCL): Connects femur to tibia, prevents posterior displacement of tibia.

Fibrocartilage Components

• Medial and Lateral Menisci: Crescent-shaped fibrocartilaginous pads that improve joint congruency and absorb shock.

Movements

• Flexion and Extension: Primary movements at the knee.

• Rotation: Possible when the knee is flexed (hence, 'modified hinge' or 'bicondylar' joint).

Leg & Foot (Osteology & Arthrology)

Bones of the Leg

• Tibia: Main weight-bearing bone of the leg.

• Fibula: Slender bone lateral to the tibia; provides muscle attachment and stability to the ankle.

Bones of the Foot

• Tarsals (7): Talus, calcaneus, navicular, cuboid, and three cuneiforms (medial, intermediate, lateral).

• Metatarsals (5): Numbered I-V from medial to lateral.

• Phalanges (14): Proximal, middle, and distal for each toe except the hallux (big toe), which has two.

Key Joints of the Leg & Foot

• Proximal Tibiofibular Joint: Synovial, plane joint.

• Distal Tibiofibular Joint: Fibrous, syndesmosis joint.

• Talocrural (Ankle) Joint: Synovial, hinge joint between tibia, fibula, and talus.

• Intertarsal Joints: Synovial, plane joints between tarsal bones.

• Tarsometatarsal Joints: Synovial, plane joints between tarsals and metatarsals.

• Metatarsophalangeal Joints: Synovial, condyloid joints between metatarsals and phalanges.

• Interphalangeal Joints: Synovial, hinge joints between phalanges.

Arches of the Foot

• Medial Longitudinal Arch

• Lateral Longitudinal Arch

• Transverse Arch

• Functions: Shock absorption, energy storage, and protection of nerves and blood vessels.

Ligaments Supporting the Arches

• Spring (Plantar Calcaneonavicular) Ligament

• Long Plantar Ligament

• Plantar Aponeurosis

• Short Plantar (Plantar Calcaneocuboid) Ligament

Etymology: Useful Word Roots for Key Terms

Learning Objectives

• Identify and name the bones of the pelvic girdle and lower limb.

• Describe the main features and functions of these bones.

• Classify and describe the major joints of the hip, knee, ankle, and foot.

• Understand the terminology and etymology of key anatomical terms.

Example: Classification of Major Joints in the Lower Limb

Key Movements of the Lower Limb

• Hip: Flexion, extension, abduction, adduction, rotation, circumduction

• Knee: Flexion, extension, slight rotation when flexed

• Ankle: Dorsiflexion (extension), plantar flexion (flexion)

• Toes: Flexion, extension, abduction, adduction

Summary Table: Seven Tarsal Bones

Additional info:

• Some etymological roots and detailed joint classifications were inferred from standard anatomical terminology.

• Tables were reconstructed for clarity and completeness based on typical anatomy curricula.