Anatomy & Physiology

Anatomy & Physiology Study Guide

Chapter 7: Bone and Osseous Tissue The skeletal system provides the framework for the body and protects it as well. This system is made up of cartilage and bone. All bone derives from skeletal cartilage. There are three types of cartilage: hyaline, elastic, and fibrous. Hyaline cartilage is the most abundant and is found in the larynx, nasal structure, and at the ends of long bones. Elastic cartilage contains elastic fibers and is located in the external ear. Fibrous cartilage, also called fibrocartilage, provides tensile strength and shock absorption. It is found in intervertebral discs. Cartilage becomes bone through a process called ossification. There are a number of different types of bones. Bones are classified according to shape, structure, and surface markings. A bone may be categorized by its general shape or by its internal tissue organization. 7.1 Bone Classification Bone Shape The adult skeleton contains 206 major bones, which can be divided into six broad categories according to their shapes: long, flat, sutural, irregular, short, and sesamoid. • Long bones are relatively long and slender, like bones of the arms and legs. They are also located in the forearms, thighs, palms of the hands, soles of the feet, fingers, and toes. • Flat bones have thin, roughly parallel surfaces. Flat bones form the roof of the skull, the sternum, the ribs, and the scapulae. They protect the vital organs of the brain, heart, lungs, and other underlying soft tissues. Flat bones also offer the surface area for the attachment of skeletal muscles. • Sutural bones , or Wormian bones, are small, flat, irregularly shaped bones between the flat bones of the skull. • Irregular bones have varied shapes with short, flat, notched, or ridged surfaces. The vertebrae, the bony pelvis, and several skull bones are irregular. • Short bones are small and cube-shaped. Some short bones include the carpal bones (wrists) and tarsal bones (ankles). • Sesamoid bones are small, flat, and shaped somewhat like a sesame seed. They develop inside tendons and are most commonly located near joints at the knees, hands, and feet. Bone Markings All bones have unique features, such as elevations or projections, where tendons and ligaments attach, and where adjacent bones articulate. Depressions, grooves, and tunnels in bone indicate sites where blood vessels or nerves lie alongside or penetrate the bone. These features are bone markings.

©2018

Achieve Page 75

of 368