Chapter 7: The Skeleton – Study Guide & Key Learning Objectives

Chapter 7: The Skeleton

Overview

This chapter focuses on the structure and function of the human skeleton, including the identification of major bones, anatomical landmarks, and the significance of skeletal features. Understanding these concepts is essential for comprehending human movement, protection of organs, and overall body support.

Functions of the Skeletal System

• Support: The skeleton provides a structural framework for the body, supporting soft tissues and giving shape to the organism.

• Protection: Bones protect vital organs (e.g., the skull protects the brain, the rib cage protects the heart and lungs).

• Movement: Bones act as levers and points of attachment for muscles, facilitating movement.

• Mineral Storage: Bones store minerals such as calcium and phosphorus, which can be released into the bloodstream as needed.

• Blood Cell Production: Hematopoiesis occurs in the red marrow of certain bones, producing red and white blood cells and platelets.

Major Bones of the Human Body

• Axial Skeleton: Includes the skull, vertebral column, and thoracic cage.

• Appendicular Skeleton: Includes the bones of the limbs and girdles (pectoral and pelvic girdles).

• 206 Bones: The adult human skeleton typically consists of 206 named bones.

Example: The femur is the longest bone in the body, located in the thigh, while the humerus is the long bone of the upper arm.

Important Bony Landmarks

• Landmarks: Specific features on bones, such as processes, tubercles, condyles, and foramina, serve as attachment points for muscles, ligaments, and tendons, or as passageways for nerves and blood vessels.

• Examples:

  • Greater trochanter of the femur – muscle attachment site

  • Acetabulum of the pelvis – articulates with the femoral head

  • Foramen magnum of the occipital bone – passage for the spinal cord

Differences Between the Male and Female Pelvis

• General Structure: The female pelvis is broader, lighter, and shallower to accommodate childbirth, while the male pelvis is more robust, narrower, and deeper.

• Pelvic Inlet: Wider and more oval in females; heart-shaped in males.

• Subpubic Angle: Greater in females (usually >80°) than in males (usually

  • Sacrum: Shorter and less curved in females.

Example: The adaptations in the female pelvis facilitate the passage of a newborn during delivery.

Unique Features of the Skull

• Cranial Bones: Protect the brain and provide attachment sites for head and neck muscles.

• Facial Bones: Form the structure of the face, house the special sense organs, and provide openings for air and food passage.

• Sutures: Immovable joints connecting the bones of the skull.

• Sinuses: Air-filled cavities that reduce skull weight and enhance voice resonance.

Example: The mandible is the only movable bone of the skull, allowing for mastication (chewing).

Important Holes in the Human Skull

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

• Examples:

  • Foramen magnum – passage for the spinal cord

  • Optic canal – passage for the optic nerve

  • Jugular foramen – passage for the jugular vein and cranial nerves

Normal and Abnormal Spinal Curvatures

• Normal Curvatures: The vertebral column has four normal curvatures: cervical, thoracic, lumbar, and sacral. These curves help absorb shock and maintain balance.

• Abnormal Curvatures:

  • Scoliosis: Lateral curvature of the spine.

  • Kyphosis: Exaggerated thoracic curvature (hunchback).

  • Lordosis: Exaggerated lumbar curvature (swayback).

Curvature	Normal/Abnormal	Description
Cervical	Normal	Concave posteriorly; develops as infant lifts head
Thoracic	Normal	Convex posteriorly; present at birth
Lumbar	Normal	Concave posteriorly; develops as child begins to walk
Sacral	Normal	Convex posteriorly; present at birth
Scoliosis	Abnormal	Lateral curvature, often in thoracic region
Kyphosis	Abnormal	Excessive thoracic curvature
Lordosis	Abnormal	Excessive lumbar curvature

Additional info: Understanding the normal and abnormal curvatures of the spine is important for diagnosing and treating postural and developmental disorders.