The Human Skeleton: Structure and Function (Axial Skeleton Focus)

The Skeleton: Overview

Composition and General Structure

The human skeleton is a structural framework composed of bones, cartilages, and ligaments. It provides support, protection, and facilitates movement.

• Bones: Rigid organs forming the majority of the skeleton.

• Cartilage: Flexible tissue found in isolated areas, such as joints.

• Ligaments: Connect bones and reinforce joints.

• The skeleton accounts for approximately 20% of total body mass.

The skeleton is divided into two main regions:

• Axial skeleton

• Appendicular skeleton

Axial Skeleton

Main Regions and Functions

The axial skeleton consists of 80 bones and is divided into three major regions:

• Skull

• Vertebral column

• Thoracic cage

Functions of the axial skeleton:

• Forms the axis of the body

• Supports the head, neck, and trunk

• Protects the brain, spinal cord, and thoracic organs

The Skull

Structure and Divisions

The skull is a superior, complex bony structure that protects the brain and forms the face. It consists of two main sets of bones:

• Cranial bones (cranium): Enclose and protect the brain.

• Facial bones: Form the structure of the face.

The skull also contains cavities for special sense organs (sight, taste, smell).

• Sutures: Immovable joints that firmly lock cranial bones together (except for the mandible).

Skull Geography

The skull can be described from different anatomical perspectives:

• Anterior aspect: Formed by facial bones.

• Vault and base: The skull is divided into a vault (calvaria) and a base (cranial floor).

Key Terms

• Vault: The dome-like upper portion of the skull.

• Base: The bottom part of the skull, containing cranial fossae.

Major Cranial Sutures

Sutures are important anatomical landmarks:

• Lambdoid suture: Separates the parietal bones from the occipital bone.

• Other major sutures: Coronal, sagittal, and squamous (not shown in these slides but essential for study).

Functions of the Skull

• Protection of the brain

• Support for facial structures

• Houses sensory organs

Summary Table: Axial Skeleton Regions and Functions

Region	Main Components	Primary Functions
Skull	Cranial and facial bones	Protects brain, forms face, houses sensory organs
Vertebral column	Vertebrae, intervertebral discs	Supports trunk, protects spinal cord
Thoracic cage	Ribs, sternum, thoracic vertebrae	Protects thoracic organs, supports upper limbs

Additional info:

• The appendicular skeleton (not covered in these slides) includes the limbs and girdles.

• Understanding the structure and function of the axial skeleton is foundational for studying movement, protection, and support in human anatomy.