Bones provide the body with structure and support. In this chapter you will learn about the bones of the body, their structure, and how the joints of the body work. The skeletal system is composed of 206 bones as well as joints and related connective tissues. The skeleton has two major divisions—the axial skeleton and the appendicular skeleton. The axial skeleton contains 80 bones. It includes the bones of the skull, vertebral column, and rib cage. It functions to support the head, neck, and trunk and protects the brain, spinal cord, and the organs in the thorax. The hyoid bone, which anchors the tongue, is also included in the axial skeleton. The other 126 bones of the body belong to the appendicular skeleton and include the bones of the arms, the legs, the pectoral girdle, and the pelvic girdle. The pectoral girdle attaches the arms to the axial skeleton, and the pelvic girdle attaches the legs to the axial skeleton.
Outline
Bone Structure
Functions of Bones
Bone Growth
Bony Structures
The Skull
The Spinal Column
The Rib Cage
Bones of the Shoulders, Arms, and Hands
Bones of the Hips, Legs, and Feet
Joints
Learning Outcomes
After completing Chapter 25, you will be able to:
25.1 Describe the parts of a long bone.
25.2 List the substances that make up bone tissue.
25.3 List the functions of bones.
25.4 Identify bones by their classifications.
25.5 Describe how long bones grow.
25.6 List and describe the skeletal structures and one location of each structure.
25.7 List the bones of the skull, spinal column, rib cage, shoulders, arms, hands, hips, legs, and feet. Describe the location of each bone.
25.8 Define fontanels and explain their importance.
25.9 Describe the three major types of joints and give examples of each.
25.10 Describe the structure of a synovial joint.
25.11 Describe the causes, signs and symptoms, and treatments of various diseases and disorders of the skeletal system.
Summary
The bones of the skeletal system are divided into two major divisions: the axial and the appendicular skeletons. Bone growth takes place through a process known as ossification and the “soft spots” within an infant's skull to allow for molding of the skull during birth and growth in infancy are called fontanels. In addition to bones, the skeletal system consists of cartilage, tendons, and ligaments. The skeletal system provides support for the body, protects internal organs, serves as attachments for muscles to pro-duce movement, stores minerals such as calcium, and produces new blood cells in a process called hematopoiesis. Bones are joined to other bones by three different types of joints, which allow various amounts of movement. Bones are used as landmarks for procedures such as injections, EKGs, and x-rays. It is important for medical assistants to have knowledge of the skeletal system when it is healthy as well as during illness in order to effectively perform their duties that relate to this body system.
