Above right: Axial and Appendicular Skeleton diagram
Axial and Appendicular Skeleton
The human skeleton is divided into two main groups or categories of bones.
They are called:
The classification of the human skeleton into the axial skeleton and the appendicular skeleton may seem somewhat arbitrary - especially if, as is usual, you have to learn about all of the bones in both groups i.e. all the human skeleton for your course.
As with many aspects of studying anatomy & physiology, it is important to be familiar with medical terminology. The appendicular and axial skeleton is part of the basic terminology required when learning about anatomy.
The axial and appendicular skeleton is shown in the diagram on the right. The axial skeleton is shown in a bright yellow/green colour and the appendicular skeleton is shown in pink (or pale purple, depending on your display and settings). As shown in the diagram of the axial and appendicular skeleton:
The Axial Skeleton consists of the:
- Skull (cranial bones and facial bones)
- Hyoid bone - not shown opposite
- Auditory ossicles - not shown opposite
- Vertebral column
(also called the 'spine' or 'backbone')
- Sternum bone
- Ribs (which, together with the sternum, form the 'thorax')
The Appendicular Skeleton consists of the:
- Shoulder girdles, which include the scapulae (shoulder blades) and a clavicle on each side of the bone (also known as 'collar bones')
- Upper Limbs = Arms (incl. wrists and hands). See arm bones and hand bones.
- Pelvic (hip) girdle, which includes the hip bones (= 'coxal bones') called the ilium, ischium and pubis
- Lower Limbs = Legs (incl. ankles and feet).
It is easy to remember how the axial skeleton and appendicular skeleton are classified by learning and remembering the meaning of the word appendage (or appendages in the plural).
In general biology the word 'appendage' refers to a natural body part that protrudes from the centre of an animal's body. Examples of appendages include the limbs of vertebrates (animals that have backbones e.g. humans). So in the case of the human body arms and legs are appendages.
The human appendicular skeleton consists mainly of the four appendages of the human body - plus, of course, the shoulder girdle and the pelvic girdle by which the limbs are inter-connected with the rest of the human body.
In order to demonstrate thorough knowledge of the human skeleton together with understanding of the difference between the axial and appendicular skeleton students may be asked to list or label all of the (named) bones in each of the appendicular and axial skeletons. You may be able to do so just from the diagram above. If not see the individual pages about the axial skeleton and the appendicular skeleton for complete lists in each case.
See also the page about how many bones in the human body ? Related pages include the structure and functions of bones, cranial and facial bones, bones of the feet and hands, bone markings and skeletal disorders.