The divisions of the skeletal system for the NASM-CPT exam are the axial skeleton and the appendicular skeleton. If you are preparing for the NASM CPT exam, you need to know what belongs in each division, how many bones each contains, and why the distinction matters for movement.
If you're studying for the NASM Certified Personal Trainer (NASM CPT) exam, this post gives you the exam-ready version of skeletal divisions, bone function, and the major bone types. You will also see the key terms the textbook uses so you can recognize them quickly on test day.
Key Takeaways
- Axial skeleton: The skull, rib cage, and vertebral column form the body’s central skeletal division.
- Appendicular skeleton: The upper and lower extremities plus the shoulder and pelvic girdles make up the limb division.
- Movement roles: Bones provide leverage and support, which helps posture and force distribution.
- Bone types: Long, short, flat, irregular, and sesamoid bones are classified by shape, size, and bone tissue proportion.
- Remodeling: Bone is constantly renewed through resorption and formation.
- Exam focus: The pelvic girdle can be treated as a link between the axial and appendicular systems.
What Are the Two Divisions of the Skeletal System?
The skeletal system has two divisions: the axial skeleton and the appendicular skeleton. The axial skeleton is the central framework of the body, and the appendicular skeleton includes the limbs and the girdles that attach them.
The axial skeleton is made up of the skull, rib cage, and vertebral column. The textbook states that there are approximately 80 bones in the axial skeleton.
The appendicular skeleton is made up of the upper and lower extremities as well as the shoulder and pelvic girdles. The textbook states that the appendicular skeleton encompasses approximately 126 bones.
Axial skeleton: The portion of the skeletal system that consists of the skull, rib cage, and vertebral column.
Appendicular skeleton: The portion of the skeletal system that includes the upper and lower extremities.
Why the pelvic girdle matters
The pelvic girdle is often considered part of either the axial or appendicular system. The textbook identifies it as a link between the two systems. That makes it an exam-relevant detail because it sits at the boundary between trunk and limb function.
How Do Bones Support Movement?
Bones support movement by acting as levers and by providing support for posture. The textbook gives those as the two vital movement functions of bone.
Muscles connect to bones by tendons. Bones form junctions with muscles and connective tissue at joints, and movement occurs at those joints when muscles contract.
That means the skeletal system is not passive. It works with the muscular system to make movement possible. Bones help create the mechanical conditions for that movement, while joints are the sites where motion actually occurs.
Joints: Junctions of bones, muscles, and connective tissue where movement occurs; they are also called articulations.
Leverage and posture on the exam
Bones act as levers when muscles act on them. Bones also provide support, and that support translates into posture. The textbook ties posture directly to the efficient distribution of forces acting on the body.
That connection matters because posture is not just appearance. In this text, posture is a mechanical outcome of skeletal support and force distribution.
How Does Bone Remodeling Work?
Bone is constantly renewed through remodeling. Remodeling is the process of resorption and formation, and it continues throughout life.
During resorption, old bone tissue is broken down and removed by osteoclasts. During bone formation, new bone tissue is laid down by osteoblasts to replace the old.
In childhood through adolescence, new bone is added faster than old bone is removed. For most people, bone formation continues at a faster pace than removal until bone mass peaks, usually by the time individuals reach their thirties.
Remodeling: The process of resorption and formation of bone.
Osteoclasts: Bone cells that remove bone tissue.
Osteoblasts: Cells responsible for bone formation.
Why stress and alignment matter
Remodeling tends to follow the lines of stress placed on the bone. Exercise and habitual posture therefore have a fundamental influence on skeletal health.
The textbook also states that incorrect exercise technique, combined with generally poor alignment, can reinforce the predominant bad posture. For you as a future trainer, that means skeletal adaptation is not random. The stresses you apply help shape what the bone emphasizes over time.
What Are the Five Major Types of Bones?
The skeletal system has five major bone types: long, short, flat, irregular, and sesamoid. The classification depends on shape, size, and the proportion of bone tissue.
| Bone Type | Characteristic | Example |
|---|---|---|
| Long | Long, cylindrical shaft with irregular or widened ends | Humerus, femur |
| Short | Similar in length and width, somewhat cubical | Carpals of hand, tarsals of feet |
| Flat | Thin, protective | Scapulae, patella |
| Irregular | Unique shape and function | Vertebrae |
| Sesamoid | Small, often round bones in a joint capsule or where a tendon passes over a joint | Patella |
Long bones: Bones with a long cylindrical shaft and widened ends that are shaped to help distribute force efficiently.
Long bones are built for strength and shock absorption
Long bones are shaped like beams and have a slight curvature that helps with efficient force distribution. They are composed predominantly of compact bone tissue for strength and stiffness, but they also contain considerable amounts of spongy bone tissue for shock absorption.
The textbook lists the upper-body long bones as the clavicle, humerus, radius, ulna, metacarpals, and phalanges. In the lower body, it lists the femur, tibia, fibula, metatarsals, and phalanges.
How Many Bones and Joints Are in the Skeletal System?
The textbook states that there are 206 bones in the skeletal system. Of those, approximately 177 are used in voluntary movement.
It also states that the bones in the human body form more than 300 joints. That is a useful exam fact because it ties the skeletal system directly to movement potential.
| Structure | Textbook value | Why it matters |
|---|---|---|
| Skeletal system bones | 206 | Total bony framework |
| Bones used in voluntary movement | Approximately 177 | Movement-related subset |
| Joints formed by bones | More than 300 | Sites of motion |
That distribution reinforces a basic test-day idea. The skeleton is both structural and functional. It supports the body, and it also provides the framework for movement.
How Should You Study Skeletal Divisions for NASM CPT?
You should study skeletal divisions by pairing structure with function. Start with the two divisions, then memorize the major parts of each, then connect each part to movement.
- Memorize the axial list. Learn the skull, rib cage, and vertebral column.
- Memorize the appendicular list. Learn the upper and lower extremities plus the shoulder and pelvic girdles.
- Anchor the pelvic girdle. Remember that it can be viewed as a bridge between systems.
- Connect bones to movement. Review leverage, support, posture, and joints.
- Review bone types with examples. Match each category to one or two textbook examples.
That sequence works because the textbook organizes the information from division to function to classification. If you study in the same order, recall becomes cleaner on exam day.
Frequently Asked Questions
What are the two divisions of the skeletal system?
The two divisions are the axial skeleton and the appendicular skeleton. The axial skeleton includes the skull, rib cage, and vertebral column. The appendicular skeleton includes the upper and lower extremities plus the shoulder and pelvic girdles.
What bones are in the axial skeleton?
The axial skeleton is made up of the skull, rib cage, and vertebral column. The textbook states that it contains approximately 80 bones. That number is worth remembering because it is a common exam-style detail.
What bones are in the appendicular skeleton?
The appendicular skeleton includes the upper and lower extremities as well as the shoulder and pelvic girdles. The textbook states that it encompasses approximately 126 bones. The pelvic girdle is described as a link between the axial and appendicular systems.
Why is the skeletal system important for movement?
The skeletal system is important for movement because bones act as levers and provide support. Joints are the sites where movement occurs when muscles contract. The text also links support to posture and efficient force distribution.
What are the five types of bones?
The five major types are long, short, flat, irregular, and sesamoid bones. The textbook classifies them by shape, size, and proportion of bone tissue. Long bones like the femur and humerus are the main examples used in the chapter.
Conclusion
The divisions of the skeletal system are simple to name, but exam success depends on knowing the textbook details around them. You should be able to identify the axial and appendicular skeleton, explain how bones support movement, and classify the five bone types. You also need the remodeling terms and the key bone counts. That combination gives you a clean, test-ready framework.
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