Chapter 7: Bones of the Axial Skeleton – Human Anatomy Study Notes

Overview of the Human Skeleton

Introduction to the Skeletal System

The human skeleton is a complex framework that provides structure, protection, and movement for the body. It consists of bones, cartilage, joints (articulations), and ligaments. The adult human skeleton is composed of 206 named bones, which are grouped into two major divisions: the axial skeleton and the appendicular skeleton.

• Axial skeleton (80 bones): Includes the skull, vertebral column, and thoracic cage.

• Appendicular skeleton (126 bones): Comprises the upper and lower limbs (covered in Chapter 8).

Functions of the Skeleton

• Support: Provides a rigid framework for the body.

• Protection: Shields vital organs (e.g., brain, heart, lungs).

• Movement: Acts as levers for muscles to produce movement.

• Mineral Storage: Stores calcium and phosphorus.

• Blood Cell Formation: Houses bone marrow for hematopoiesis.

The Axial Skeleton

Components of the Axial Skeleton

The axial skeleton forms the central axis of the body and consists of three main regions:

• Skull

• Vertebral column

• Thoracic cage

These structures protect the brain, spinal cord, and thoracic organs, and provide attachment points for muscles.

The Skull

General Structure and Function

The skull is the body's most complex bony structure, formed by two sets of bones: cranial and facial bones.

• Cranial bones:

  • Enclose and protect the brain.

  • Provide attachment sites for some muscles of the head and neck.

• Facial bones:

  • Form the framework of the face.

  • Create cavities for sense organs of sight, taste, and smell.

  • Provide openings for the passage of air and food.

  • Hold the teeth in place.

  • Anchor muscles of facial expression.

Divisions of the Skull

• Cranium: Houses the brain and forms the cranial cavity.

• Facial skeleton: Forms the structure of the face and supports sensory organs.

Key Terms

• Articulations (Joints): Points where two or more bones meet, allowing for movement and flexibility.

• Foramina: Openings in bones that allow the passage of nerves and blood vessels.

Examples and Applications

• Example: The foramen magnum in the occipital bone allows the spinal cord to connect with the brain.

• Application: Understanding the structure of the skull is essential for fields such as neurology, dentistry, and forensic science.

Additional info: The axial skeleton provides the main support for the body and is crucial for protecting the central nervous system and thoracic organs. The appendicular skeleton, while not covered in detail here, is essential for movement and manipulation of the environment.