Advanced Anatomy & Physiology: The long bones
Advanced Anatomy &
Physiology
E-learning Course
The long bones
© Copyright 2011 Future Fit Training Limited Rev 05
Advanced Anatomy & Physiology: The long bones
Step 1 – Introduction
This lesson will enable you to:

Revise the structure of the long bones

Identify the different parts of a long bone

Explain their functions
Step 2 – The function of bones
Before we look in detail at a long bone, let’s take a few moments to remind
ourselves of the general function of bones.
When most of us consider the function of bones, the first one that springs to mind
is probably their role in supporting the body. Besides giving us structure, the bones
also provide the framework to which our muscles attach.
Step 3 – The function of bones
When our muscles contract they pull on the bones, creating movement.
Bones such as the ribs, pelvis and skull provide examples of the skeleton’s role in
the protection of vital organs.
A considerable amount of activity takes place within a bone. It is here that blood
cell formation takes place, as well as the storage of excess minerals, such as
phosphorus and calcium, to help maintain correct levels in the blood.
Step 4 – Structure of a long bone
Like other types of bone, long bones can be considered to be organs, as they are
made up of several different types of tissue, and have their own blood supply.
They are made up of two types of bone tissue: compact bone and spongy bone.
Compact or cortical bone is dense, strong material that forms the external layer
of all bones and makes up the bulk of the shaft of long bones. It provides
protection and support and resists the stresses produced by weight and
movement.
© Copyright 2011 Future Fit Training Limited Rev 05
Advanced Anatomy & Physiology: The long bones
Spongy bone tissue makes up most of the bone tissue of short, flat and irregular
bones and forms the ends of the long bones. It is light, which reduces the weight
of the bones, and it supports and protects the red bone marrow. This is the site of
blood cell production.
© Copyright 2011 Future Fit Training Limited Rev 05
Advanced Anatomy & Physiology: The long bones
Step 5 – Structure of a long bone
Now let’s have a look at the other parts of an adult long bone.
The epiphyses of a long bone are its proximal and distal end sections. These ends
meet, or articulate, with other bones to create a joint.
Articular cartilage surrounds these articulating ends of bone, providing a smooth
surface for movement in a synovial joint. It also protects long bones from wear at
the points where they connect with other bones and helps to absorb shock during
movement.
If we move down the bone a little we can see the area in mature bone where the
diaphysis joins the epiphysis. This is referred to as the metaphysis. In a growing
bone, the metaphysis contains the epiphyseal growth plate, a layer of hyaline
cartilage that allows the bone to grow in length. Once the bone has stopped
growing, the cartilage in the epiphyseal or growth plate is replaced by bone and is
referred to as the epiphyseal line.
We’ve now worked our way down to the main shaft of a long bone, which is
referred to as the diaphysis. It is cylindrical in shape and makes up the main
portion of a long bone.
Surrounding the compact bone of the main shaft is the periosteum. This is a tough,
fibrous membrane that protects the bone, serves as an attachment point for
muscles, and contains blood vessels that nourish the underlying bone. It’s the
action of the bone cells within the periosteum that results in bone formation and
bone repair after a breakage.
Within the diaphysis is the medullary cavity. This is the hollow cavity that contains
yellow bone marrow, which is mainly fat and serves as an energy reserve.
And finally, there in the spongy bone we see the red bone marrow, which
produces red blood cells, white blood cells and platelets.
Step 6 – Activity
Name the different sections of the long bone below.
© Copyright 2011 Future Fit Training Limited Rev 05
Advanced Anatomy & Physiology: The long bones
Step 7 – Activity
Refer to the table below to view the bone parts and their correct descriptions.
Bone part
Proximal epiphysis
Articular cartilage
Periosteum
Compact (cortical) bone
Cancellous (spongy) bone
Diaphysis
Yellow bone marrow
Medullary cavity
Distal epiphysis
Description
The end of the bone closest to the
body
Surrounds the articulating ends of a
bone
Contains blood vessels that nourish
the underlying bone
Dense, strong bone material that
forms the outer layer
A strong, but lightweight, lattice work
of plates called trabeculae
It’s here that the longitudinal bone
growth occurs
Serves as an energy reserve
Contains the bone marrow
The end of the bone furthest from
the body
Feedback: Remember, the bones may have more functions.
Step 8 – Summary
Now that you have completed this lesson you will have a better understanding of
the following:
Bones give us structure, provide the framework to which muscles attach, facilitate
movement, protect vital organs and are the site of blood cell formation.
Compact and cortical bone is dense, strong material that forms the external layer
of all bones and makes up the bulk of the shaft of long bones. It provides
protection and support and resists the stresses provided by weight and movement.
© Copyright 2011 Future Fit Training Limited Rev 05
Advanced Anatomy & Physiology: The long bones
Cancellous or spongy bone makes up most of the bone tissue of short, flat and
irregular bones and forms the ends of the long bones. It is formed by an irregular
latticework of thin columns of bone known as trabeculae, making it lightweight. It
also supports and protects the red bone marrow.
The epiphyses of a long bone are its proximal and distal end sections.
The diaphysis is the main shaft of the bone.
Articular cartilage surrounds the ends of bones protecting them from wear and
absorbing shock during movement.
The metaphyses are the areas in mature bone where the diaphysis joins the
epiphyses. In a growing bone, they contain the epiphyseal growth plate, which is a
layer of hyaline cartilage that allows the bone to grow in length.
The epiphyseal line is formed once bone has stopped growing and the cartilage in
the epiphyseal growth plate is replaced by bone.
The periosteum is a tough fibrous membrane that protects the compact bone of
the main shaft and serves as a point of attachment for muscles, as well as
containing blood vessels that nourish underlying bone.
The medullary cavity is a hollow cavity that lies within the diaphysis. It contains the
yellow bone marrow, which is mainly fat and serves as an energy reserve.
© Copyright 2011 Future Fit Training Limited Rev 05