Chapter 7: The Skeleton – Structure and Function of the Human Skeletal System

Overview of the Human Skeleton

Introduction

The human skeleton is a complex framework of bones and associated structures that provides support, protection, and movement for the body. It is divided into two major components: the axial skeleton and the appendicular skeleton.

Objectives of Study

Learning Goals

• Identify the major components and functions of the axial and appendicular skeletons.

• Locate and describe the bones of the cranium and face, including cranial sutures.

• Explain the structural and functional characteristics of vertebrae, ribs, sternum, and pelvis.

• Distinguish between male and female skeletons.

• Describe the bones of the limbs, girdles, wrist, hand, ankle, and foot using anatomical terminology.

Axial vs. Appendicular Skeleton

Axial Skeleton

The axial skeleton forms the central axis of the body and consists of 80 bones. It provides support and protection for the brain, spinal cord, and organs in the thorax.

• Components:

  • Skull and associated bones (including auditory ossicles and hyoid bone)

  • Vertebral column

  • Thoracic cage (ribs and sternum)

  • Supplemental cartilages

• Functions:

  • Support and protect vital organs (brain, lungs, heart)

  • Provide attachment points for muscles

  • Form joints for movement and flexibility

Appendicular Skeleton

The appendicular skeleton consists of 126 bones and is responsible for movement and manipulation of objects. It includes the limbs and the girdles that attach them to the axial skeleton.

• Components:

  • Pectoral girdle (scapula and clavicle)

  • Upper limbs (humerus, radius, ulna, carpals, metacarpals, phalanges)

  • Pelvic girdle (innominate bones: ilium, ischium, pubis)

  • Lower limbs (femur, tibia, fibula, tarsals, metatarsals, phalanges)

  • Associated cartilages and ligaments

Key Differences Between Axial and Appendicular Skeletons

Feature	Axial Skeleton	Appendicular Skeleton
Main Function	Support, protection	Movement, manipulation
Number of Bones	80	126
Major Components	Skull, vertebral column, thoracic cage	Limbs, pectoral and pelvic girdles

Examples and Applications

• Axial Skeleton Example: The vertebral column protects the spinal cord and supports the head.

• Appendicular Skeleton Example: The pectoral girdle and upper limb bones allow for a wide range of arm movements necessary for daily activities.

Additional info:

• The axial skeleton is essential for maintaining posture and protecting the central nervous system.

• The appendicular skeleton enables locomotion and interaction with the environment.