Structure and Function of the Skeletal System

• A&P
• Higher Education (non-degree)

ANATOMY AND PHYSIOLOGY FOR SPORTS MASSAGE 

THE STRUCTURE AND FUNCTION OF THE SKELETAL SYSTEM

ANATOMY AND PHYSIOLOGY 

THE STRUCTURE AND FUNCTION OF THE SKELETAL SYSTEM

What are you going to learn?

In this lesson you're going to learn to . . .

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Describe the structure of the skeletal system.

Describe the functions of the skeletal system.

Explain the classification of bone.

Explain the stages of bone growth and repair. 

4

STRUCTURE OF THE SKELETON  

Axial Skeleton

Includes the:

• Cranium
• Spine (vertebrae)
• Sternum
• Ribs

Appendicular Skeleton

Includes the:

• Shoulder girdle
• Upper limbs
• Pelvic girdle
• Lower limbs

The human skeleton is divided into 2 different sections:

STRUCTURE OF THE SKELETON  

Cervical region

7 vertebrae form a flexible framework for the neck and support the head. Top two bones are the Atlas (C1) and Axis (C2).

7

Thoracic region

12 vertebrae that move with the ribs.

12

Lumbar region

 5 largest vertebrae that support most of the body’s weight.

5

Sacral region

5 vertebrae form the back wall of the pelvis (fused to the sacrum)

5

Coccyx region

4 vertebrae also known as the tailbone

4

The axial skeletons vertebral column consists of the following sections: 

Match the axial skeleton components to the descriptions 

This is the highest bone of the skeleton and is made up of 8 bones fused together to protect the brain.

This is a flat bone in the middle of the chest that is shaped like a dagger. It is attached to the clavicle and protects the heart and joins the ribs together.

Adults have 12 pairs of these flat bones which attach at the spine and the chest bone to form a cage around heart and lungs to protect them.

This is 33 separate bones all joined together and join your cranium to your hips. These bones also allow your to perform movements like bending and nodding.

7 vertebrae for the neck and support the head.

5 largest vertebrae.

4 vertebrae also known as the tailbone.

5 vertebrae fused to the sacrum.

12 vertebrae that move with the ribs and allow the largest range of movement. 

Cervical

Coccyx

Thoracic

Ribs

Lumbar

Sacral

Sternum

Cranium

Vertebrae

STRUCTURE OF THE SKELETON  

Appendicular Skeleton 

The shoulder girdle consists of the scapula and clavicle bones. 

Connecting the bones of the upper limbs to the axial skeleton.

These bones also provide attachment for muscles that move the shoulders and upper limbs.

STRUCTURE OF THE SKELETON  

Appendicular Skeleton 

The upper limbs include:

• The humerus (sometimes called the funny bone) that forms the upper arm connecting the shoulder at the top and the forearm at the bottom.

• The radius and ulna form the forearm articulating with the humerus to form the elbow joint. The radius runs inline with the thumb whilst the ulna runs inline with the little finger. 

• The carpals form the wrist joint connecting the end of the radius and ulnar bones of the forearm to the bases of the metacarpals of the hand. 

• In the hand. metacarpals connect to the phalanges the bony core digits of the fingers.

STRUCTURE OF THE SKELETON  

Appendicular Skeleton 

The pelvic girdle consists of three bones:

1. Ilium

2. Ischium

3. Pubis

The pelvic girdle is a ring of bones attached to the vertebral column that connects the bones of the lower limbs to the axial skeleton.

STRUCTURE OF THE SKELETON  

Appendicular Skeleton 

The lower limbs include the bones of the

• Upper leg (femur),
• Lower leg (tibia & fibula), 
• Foot (tarsals, metatarsals & phalanges).

The femur articulates with both the tibia (commonly known as the shin) and fibula.

The knee joint that is protected and enhanced by the patella bone.

STRUCTURE OF THE SKELETON  

Cranium- This is the highest bone of the skeleton and is made up of 8 bones fused together to protect the brain.

Scapula- This bone is also named as the shoulder blade that connects the clavicle to the humerus. It forms the posterior of the shoulder girdle.

RIbs- Adults have 12 pairs of these flat bones which attach at the spine and the sternum to form a cage around heart and lungs to protect them.

Radius- This bone also forms part of the lower arm as it is positioned next to the Ulna and runs in line with the thumb side of the hand.

Clavicle- This bone forms part of the shoulder and attaches the upper arm to the body. It is sometimes called your collar bone.

Mandible- the lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton.

Femur- This is the longest bone in the body and attaches to the pelvis at the top and the knee at the bottom. It is commonly known as the thigh bone.

Fibula- This is the smaller bone of the lower leg, positioned behind the Tibia, it is mainly used for muscles of the lower leg to attach to

Tibia- This is the biggest bone in the lower leg, which joins with the Femur and Patella to form the knee joint, positioned at the front of the Fibula.

Pubis - This bone is one of three bones that fuse to form the hip bone. Together with the ilium and ischium.

Carpals- These bones are bones of the wrist that connect the end of the radius and ulnar bones of the forearm to the bases of the metacarpal bones of the hand.

Metacarpals- These bones are located in the wrist between the carpals and phalanges. 

Phalanges- These bones are found in both the hands and feet and form the bony core of the digits

Sternum- This is a flat bone in the middle of the chest that is shaped like a dagger. It is attached to the clavicle and protects the heart and joins the ribs together.

Patella- This is a small square bone that sits on top of the femur and the Tibia to form the knee joint.

Tarsals- These bones are situated between the lower end of the tibia and the fibula of the lower leg and the metatarsals. 

Metatarsals- These bones are located in the foot between the tarsals and phalanges.  

Phalanges - These bones are found in both the hands and feet and form the bony core of the digits.

Humerus- This is sometimes called your funny bone and it forms the upper arm connecting the shoulder at the top and the forearm at the bottom.

Ulna- This bone forms part of the lower arm and joins the Humerus with the elbow joint and runs in line with the little finger.

Illium- This bone is the uppermost and largest part of the hip bone.

Ishium- This bone is a paired bone of the pelvis that forms the lower and back part of the hip bone. 

Vertebral Coloumn- This is 33 separate bones all joined together and join your cranium to your hips. These bones also allow your to perform movements like bending and nodding.

 

Cranium

Mandible

Humerus

Clavicle

Scapula

Sternum

Ulna

Radius

Patella

Fibula

Tibia

Illium 

Ishium

Ribs

Pubis

Tarsals, metatarsals, phalanges

Carpals, metacarpals, phalanges

FUNCTIONS OF THE SKELETON  

Functions of the skeleton

1. Storage 
2. Production 
3. Shape / Structure 
4. Protection 
5. Movement 

FUNCTIONS OF THE SKELETON  

Functions of the skeleton

1. Storage 
2. Production 
3. Shape / Structure 
4. Protection 
5. Movement 

• Bones provide a massive storage for minerals (calcium) which help the bone to grow and remain healthy. 

FUNCTIONS OF THE SKELETON  

Functions of the skeleton

1. Storage 
2. Production 
3. Shape / Structure 
4. Protection 
5. Movement 

• The centre of the bone is made up of bone marrow.

• The bone marrow continually produces red and white blood cells. 

• Bones provide a massive storage for minerals which help the bone to grow and remain healthy.  

FUNCTIONS OF THE SKELETON  

Functions of the skeleton

1. Storage 
2. Production 
3. Shape / Structure 
4. Protection 
5. Movement 

• Bones and cartilage that make up the skeleton are the only rigid materials in the body.

• The 206 bones of the skeleton provide a framework and points of attachment for many of the soft tissues of the body.

FUNCTIONS OF THE SKELETON  

Functions of the skeleton

1. Storage 
2. Production 
3. Shape / Structure 
4. Protection 
5. Movement 

Some structures protect the vital tissues and functional organs of the body.

Typical examples are:

• Cranium- protects the brain.
• Vertebrae - protects the spinal cord.
• Rib cage - protects the heart and lungs. 

FUNCTIONS OF THE SKELETON  

Functions of the skeleton

1. Storage 
2. Production 
3. Shape / Structure 
4. Protection 
5. Movement 

• Parts of your skeleton provide a surface for your skeletal muscles to attach to, allowing you to move.  
• Bones act as levers during movement and provide solid structures to which muscles are attached.
• The joints allow movement between bones and these movements are directly related to the type of joint and range of motion.

Match up the functions of the skeleton to the images

Storage

Production

Protection

Movement

Structure

CLASSIFICATION OF BONES

All bones are made up from two different types of bone tissue. 

Compact bone- comprises a closely packed network of bone cells and forms the extremely hard exterior of bones. Helping to provide strength and support. 

Cancellous bone- fills the interior or cavity of bones arranged in a latticework that resembles a sponge or a honeycomb. These spaces helps to minimise weight and allow room for blood vessels and bone marrow. 

CLASSIFICATION OF BONES

The human skeleton has a number of functions, such as protection and supporting weight. Different types of bones have differing shapes related to their particular function.

There are five types of bones in the skeleton: flat, long, short, irregular, and sesamoid.

Let’s go through each type and see examples.

CLASSIFICATION OF BONES

Long Bones 

 Long bones are longer than they are wide, their function is to support the weight of the body and facilitate movement. 

Long bones are mostly located in the appendicular skeleton and include bones in the lower limbs (the tibia, fibula, femur, metatarsals, and phalanges) and bones in the upper limbs (the humerus, radius, ulna, metacarpals, and phalanges).

CLASSIFICATION OF BONES

Long Bone Composition

Periosteum- a membrane covering the outer surface of all bones. 

Diaphysis- the bone shaft. 

Epiphysis- the end of a long bone which forms the joint. 

Epiphyseal line- or plates considered growth plates. 

Medullary cavity- where bone marrow is stored. 

Articular cartilage- tough connecvtive tissue helps to protect the ends of bone from wear and tear. 

Epiphysis

Epiphysis

Diaphysis

Periosteum

Red bone marrow

Medullary cavity

Articular cartilage 

Epiphyseal line

CLASSIFICATION OF BONES

Flat Bones 

There are flat bones in the skull, thoracic cage (sternum and ribs), and pelvis (ilium, ischium, and pubis).

 The function of flat bones is to protect internal organs Flat bones are somewhat flattened and can provide protection, like a shield; flat bones can also provide large areas of attachment for muscles.

CLASSIFICATION OF BONES

Short Bones 

 Short bones are about as long as they are wide. Located in the wrist and ankle joints, short bones provide stability and some movement. 

The carpals in the wrist and the tarsals in the ankles are examples of short bones..

CLASSIFICATION OF BONES

Irregular Bones 

 Irregular bones vary in shape and structure and therefore do not fit into any other category. 

They often have a fairly complex shape, which helps protect internal organs. For example, bones of the vertebral column protect the spinal cord. The irregular bones of the pelvis protect organs in the pelvic cavity..

CLASSIFICATION OF BONES

Sesamoid Bones 

Sesamoid bones are bones embedded in tendons. These small, round bones are commonly found in the tendons of the hands, knees, and feet. 

Sesamoid bones function to protect tendons from stress and wear. The patella, commonly referred to as the kneecap, is an example of a sesamoid bone.

Finish the sentence.

Flat Bones...

1. Support Weight and Facilitate Movement
2. Protect Internal Organs
3. Have Complex Shapes
4. Are Cube-shaped.

Finish the sentence.

Short Bones...

1. Support Weight and Facilitate Movement
2. Reinforce Tendons.
3. Are Cube-shaped.
4. Have Complex Shapes.

Finish the sentence.

Long Bones...

1. Protect Internal Organs.
2. Are Cube-shaped.
3. Reinforce Tendons.
4. Support Weight and Facilitate Movement.

Finish the sentence.

Irregular Bones...

1. Reinforce Tendons.
2. Are Cube-shaped.
3. Protect Internal Organs.
4. Have Complex Shapes.

Finish the sentence.

Sesamoid Bones...

1. Reinforce Tendons.
2. Have Complex Shapes.
3. Support Weight and Facilitate Movement.
4. Are Cube-shaped.

STAGES OF BONE GROWTH & REPAIR

Bone Growth

Bone is a very active tissue. Its cells are constantly forming and resorbing bone matrix.

Early in the development of a human fetus, the skeleton is made almost entirely of cartilage. The relatively soft cartilage gradually turns into hard bone.

This is called ossification.

STAGES OF BONE GROWTH & REPAIR

Keys bone growth cells

 

Osteoclasts- A type of cell which resorbs bone to enable bones to be formed correctly. 

Osteoblasts- A bone building cell. 

Osteocytes- A mature bone cell

Ossification

Ossification is a process in which bone tissue is created from cartilage. 

It begins at a primary ossification center in the middle of the bone (during fetal development), and later also occurs at secondary ossification centers at the ends of the bone (after birth). 

The bone can no longer grow in length after the areas of ossification meet and fuse at the time of skeletal maturity.

STAGES OF BONE GROWTH & REPAIR

The steps in which bones of the skeleton form from cartilage are illustrated. The steps are as follows:

1. Cartilage “model” of bone forms. This model continues to grow as ossification takes place.

2. Ossification begins at a primary ossification center in the middle of bone.

3. Ossification then starts to occur at secondary ossification centers at the ends of bone.

4. The medullary cavity forms. This cavity will contain red bone marrow.

5. Areas of ossification meet at epiphyseal plates, osteoblasts are triggered to transform cartilage into osteocytes. Bones strengthen and increase in size. 

6. More cartilage is added to the epiphyseal plate and repeated until adolescence (growth) ceases. 

STAGES OF BONE GROWTH & REPAIR

STAGES OF BONE GROWTH & REPAIR

Bone remodeling serves several functions. It shapes the bones of the skeleton as a child grows, and it repairs tiny flaws in bone that result from everyday movements. Remodeling also makes bones thicker at points where muscles place the most stress on them. In addition, remodeling helps regulate mineral homeostasis, because it either releases mineral from bones into the blood or absorbs mineral from the blood into bones.

STAGES OF BONE GROWTH & REPAIR

Following an injury to the bone

• There is a trigger for osteoblast activity due to damage to the bones periosteum. 
• Osteoblasts migrate to the blood clot formed at the site of injury. 
• Ossification takes place casuing the entire blood clot to become calcified before beginning to turn into bone. 
• The repaired bone is often larger than its original size therefore osteoclasts are released to resorb/ remodel any unnecessary bone back to original shape and size before cells are fully matured (osteocytes). 

What you have learnt

Following this lesson you should now be able to . . .

1

2

3

Describe the structure of the skeletal system.

Describe the functions of the skeletal system.

Explain the classification of bone.

Explain the stages of bone growth and repair. 

4

00:47

The density of bone is modulated by a group of cells called...?

01:58

Osteoblasts in the bone matrix become...?

03:07

After the age of 30, most people experience a loss of bone mass due to a decrease of

1. osteoclasts compared to osteoblasts.
2. osteoblasts compared to osteoclasts.
3. osteocytes compared to osteoclasts,

04:07

What are benefits of staying physically active with increased age?

Well done! Great job, you have now completed this lesson. Next up...The structure and function of joints.