Human Skeleton

 HUMAN SKELETON

 

The human skeleton is divided into two main groups or categories.
They are called:

• the axial skeleton
  and
• the appendicular skeleton

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.

 

Axial Skeleton

This is a continuation of the information about the axial and appendicular skeleton, which is often required knowledge for first-level courses in human anatomy.
The axial skeleton is the part of the human skeleton that includes the skull, vertebral column and thorax.
The axial skeleton is shown shaded greenish-yellow in the diagram of the axial skeleton on the right.
(The bones shaded pink form the appendicular skeleton.)

List of the bones of the
Axial Skeleton:

• Skull Bones
  incl. 8x Cranial Bones
  • Ethmoid bone (x1)
  • Frontal bone (x1)
  • Occipital bone (x1)
  • Parietal bones (x2)
  • Sphenoid bone (x1)
  • Temporal bones (x2)
    
    
• Skull Bones
  incl. 14x Facial Bones
  • Inferior Nasal Conchae (x2)
  • Lacrimal Bones (x2)
  • Mandible (x1)
  • Maxillae (x2)
  • Nasal Bones (x2)
  • Palatine Bones (x2)
  • Vomer (x1)
  • Zygomatic Bones (x2)
• Hyoid bone (x1)
• Auditory ossicles bones (x6)
• Vertebral Column
  (x26 bones, total)
• Bones of the Thorax:
  • Sternum bone (x1)
  • 7 pairs True Ribs
    (x14 bones)
  • 3 pairs False Ribs
    (x6 bones)
  • 2 pairs Floating Ribs
    (x4 bones)

How many bones in the
Axial Skeleton ?

The number of each named bone in the axial skeleton is indicated in red in brackets after the name of the bone/s in the list above.
Adding together all of these numbers gives a total of 80 (named) bones in the human axial skeleton.

Question: So, there are 80 bones in the axial skeleton, right ?
Answer: Strictly, it is better to say that there are 80 named bones in the axial skeleton. That is the minimum number of bones in every normal, complete, human axial skeleton. However, there may be additional (un-named) bones in some axial skeletons, e.g. sutural bones - within the sutural joints between the cranial bones, or possibly even sesamoid bones.
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Appendicular Skeleton

This is a continuation of the information about the axial and appendicular skeleton, which is often required knowledge for first-level courses in human anatomy.

The appendicular skeleton is the part of the human skeleton that includes the arms and hands, legs and feet, the shoulder girdle and the pelvic girdle.

The appendicular skeleton is shown shaded pink in the diagram of the appendicular skeleton on the right.
(The bones shaded greenish-yellow form the axial skeleton.)

List of the bones of the
Appendicular Skeleton:

• Shoulder Girdles
  also called the "pectoral girdles"
  
  • Clavicle bones (x2)
  • Scapulae (x2)
• Arms (arm bones)
  also called "upper limbs"
  
  • Humerus bones (x2)
  • Ulna bones (x2)
  • Radius bones (x2)
  • Carpal bones (x16)
    
    • Scaphoid (x2)
    • Lunate (x2)
    • Triquetrum (x2)
    • Pisiform (x2)
    • Trapezium (x2)
    • Trapezoid (x2)
    • Capitate (x2)
    • Hamate (x2)
  • Metacarpal bones (x10)
  • Phalanges (x28)
• Hip Girdle
  also called the "pelvic girdle"
  
  • Hip bones (x2)
    incl. ilium, ischium & pubis
• Legs
  also called "lower limbs"
  
  • Femur bones (x2)
  • Fibula bones (x2)
  • Tibia bones (x2)
  • Patella bones (x2)
  • Tarsal bones (x14)
    
    • Calcaneus (x2)
    • Talus (x2)
    • Cuboid (x2)
    • Navicular (x2)
    • First Cuneiform (x2)
    • 2nd Cuneiform (x2)
    • 3rd Cuneiform (x2)
  • Metatarsal bones (x10)
  • Phalanges (x28)

Notice that there is an even number of each named bone in the appendicular skeleton. This is because the appendicular skeleton is symmetrical. For example, there are 2 humerus bones in each human appendicular skeleton - one humerus bone in each of the two upper-arms. Similarly, there are two navicular bones in every appendicular skeleton, one in each of the two ankles.

How many bones in the Appendicular Skeleton ?

The number of each named bone in the appendicular skeleton is indicated in red in brackets after the name of the bone/s in the list above.

Adding together all of these numbers gives a total of 126 (named) bones in the human appendicular skeleton.