OCP C1 B Anatomy and Physiology > Skeletal System > Skeletal System
What You'll Learn
After you finish this lesson, you will be able to:
The skeletal system refers to the bones that form the framework of the body. An adult human has 206 bones. The skeletal system performs these functions:
Types of Bones
Bones vary in shape and size depending on where they are found in the body. Bones are classified by shape.
Which type of bones has a broad shape to cover and protect organs or to provide a surface for large areas of muscle?
Which type of bones forms the arms and legs?
The outer part of the bone is made of compact bone tissue, which does not bend easily. It is covered by the periosteum, which is a tough, fibrous tissue. This tissue contains blood vessels, lymph vessels, and osteoblasts for bone growth, repair, and nutrition.
Inside the compact bone is spongy bone. The medullary canal is a cavity in the center of the shaft where marrow is stored. It is lined by theendosteum to keep the cavity intact.
Parts of Long Bones
The longest part of a long bone is called the diaphysis, or shaft.
Each end of the shaft is called an epiphysis. A thin layer of articular cartilage covers the epiphysis to absorb shock where two bones meet to form a joint.
Present in long bones, marrow is important in making blood cells.
What is another name for the shaft (longest part) of a long bone?
What part of long bones stores bone marrow?
Bone marrow is important in making red blood cells.
Sections of the Skeletal System
The skeletal system is divided into two sections, axial and appendicular.
Which section of the skeleton forms the main trunk of the body?
Which section of the skeleton includes the arm and leg bones?
Axial Skeleton: Skull
The skull consists of the cranium and facial bones.
The cranium surrounds and protects the brain. The cranial bones join at points called sutures. At birth, there are two openings in the cranium called fontanels, or "soft spots." They give space for the skull to enlarge as the brain grows, and they usually close by 18-24 months of age. The 8 cranial bones include the following:
The mandible is the only movable bone in the face. It contains the sockets for the lower teeth. The maxilliary bones contain the sockets for the upper teeth.
Axial Skeleton: Skull (continued)
Facial bones are also part of the skull. Facial bones guard and support the eyes, nose, mouth, and ears. Sinuses are air spaces in and around these bones. These spaces allow the voice to resonate to sound stronger. The 14 facial bones include the following:
Which of these skull bones surround and protect the brain?
What is the name of the bone for the lower jaw?
Axial Skeleton: Spinal Column
The spinal column consists of 26 bones called vertebrae. It is also known as the vertebral column. It encloses and protects the spinal cordand supports the head and trunk. Discs of cartilage tissue separate the vertebrae to cushion the bones and allow movement.
The spinal column includes these vertebrae:
The spinal column consists of 26 bones called _______.
What is the name for the bones of the chest?
What is the name for the bones of the lower back?
The sternum includes 3 parts:
Axial Skeleton: Thorax
The thorax is also known as the chest cavity. It helps to protect the heart and lungs.
There are 12 pairs of ribs, or costae:
They attach only to other ribs or have no attachment.
Why are some costae called "false ribs?"
What is the name of the breastbone?
The clavicles help brace the shoulders and prevent a person from having too much forward motion. The scapulas provide a place for the arms to be attached, and together with muscles they assist with arm movement.
Appendicular Skeleton: Shoulder Girdle
The shoulder girdle is also known as the pectoral girdle. It includes 4 bones:
Appendicular Skeleton: Arms and Hands
The bones of each arm include the following:
The bones of each hand include the following:
What is the name of the collarbones?
What is the name of the upper arm bone?
What is the name of the wrist bones?
The pelvic girdle supports the trunk of the body, in particular the lower soft abdominal organs. It also provides a place for the legs to be attached.
Appendicular Skeleton: Pelvic Girdle
The pelvic girdle includes 2 os coxae, or hip bones. They attach to the sacrum in addition to connecting to each other at a joint called thesymphysis pubis. Each os coxae consists of these 3 fused sections:
Appendicular Skeleton: Legs and Feet
The bones of each leg include the following:
The bones of each foot include the following:
How many sections are fused to make up each of the os coxae, or hip bones?
What is the name of the upper leg bone, in the thigh?
What is the name of the shin bone?
What is the name of the bones for both the toes and fingers?
Joints are areas where two or more bones connect. Bands of connective tissue called ligaments help hold bones together at joints. Joints are classified by movement.
An area where two or more bones connect is called a _______.
In this lesson, you learned that: