Bone concept

  1. Skull :- it is protective covering of head. It has 4 parts :-

Cranium and face : hyoid bone and ear osicles.



It is large sound, hollow part of skill. Its cavity is called cranial cavity. It is also called brain box. As it covers & protects the brain.

It is lower part of skull lies lower to cranium. It has 14 bones.



It has 8 bones :-

Frontal       1

Parietal       2

Occipital     1

Temporal   2

Spheroid    1

Ethmoid     1  

It has 14 bones :-

2 nasals , maxillae, 2  palatines , 2 cheek bone, 2 lachrymals, 2 inferior nasal, 1 vomer, 1 mandible.   

Hyoid bone

Ear ossicles

It is U shaped bone that lies at the base of tongue, also called tongue bone.

There are 3 bones:-

Malleus, incur and stapes. Help in hearing.

Functions of skull:-

  1. It protects brain.
  2. Protects sense organs : ears, eyes, tongue, nose.
  1. Vertebral column ( backbone or spine ):-

It is curved, vertical mod of 70 cm length. It has 33 movable rings called vertebral. Between these vertebral, cartilaginous discs lies called intervertebral discs.

These vertebrae are subdivided into 5 parts :-

  1. Cervical -------7                                 = 7          lies in neck.
  2. Thoracic ------12                                                = 12        lies in chest.
  3. Lumber--------5                                 = 5          lies in abdomen.
  4. Sacral ---------5 fused to form a single vertebral lies in tail =1
  5. Caudal -------4 fused to form a single vertebral   =1


Note :- sacral when fused to form a single vertebrae, called sacrum.

Atlas and axis vertebrae :-

First vertebrae of vertebral column is called atlas, it is also called yes bone.

It is responsible for forward and backward movement of head.

Second vertebrae of vertebral column is called Axis, it is also called no-bone.

It is responsible for side way movement of head.

Functions of vertebral  column :-

  1. It protects (supports) the head above.
  2. It strengthens the neck.
  3. It also supports the ribs.
  4. Provide flexibility to back.
  5. It covers & protects the spinal cord.
  1. Ribs :-

Ribs are curved bars, that are attached to thoracic vertebrae at backside and are attached to sternum at front side. They occur in 12 pairs.

They are of 3 types :-

True ribs

False ribs

Floating ribs

  1. They are 7 fairs.
  2. Their sterna part is attached and vertebral part is attached to vertebrae.
  1. They are 3 pairs.
  2. Their vertebral part is attached to vertebrae but sternal part is attached to sternum through true ribs. 
  1. They are 2 pairs.
  2. Their sternal part is free (do not attached anywhere).

Functions of Ribs :-

  1. They protect heart, lungs & large blood vessels.
  2. Lower 2 pairs (floating ribs ) protects the kidneys.
  1. Sternum (breast bone):-

It is long, narrow, flat bone lies in front wall of chest (thoracic cavity). True ribs are attached to it on front side.

Functions :-

  1. It also protects thoracic cavity.
  2. It plays a role in respiratory mechanism also.
  1. Girdles :-

They give articulation to limb bone.

They are two :- pectoral and pelvic.

Pectoral girdle (shoulder)

Pelvic girdle (hip)

They lies in upper of thorax on sides.

They have 2 bones : scapula and clavicle .

Scapula is triangular shaped bone also called shoulder blade. And clavicle is F shaped bone lies horizontally, also called collar bone.

Functions :-

  1. Pectoral girdle provide articulation to arms bones.
  2. Also provide attachment to arm muscles.

Total bone 4 in both pectoral girdles.

They lies in lower part of trunk (back). Each pelvic girdle has 3 bones : ileum, ischium, and pubis. All there fused to form a single hip bone also called obturator foramen. These 2 hip bones and sacrum (vertebrae) together form a bowel, called pelvic. Female pelvic is broader for childbirth then male pelvis.

Functions :-

  1. Pelvic girdle provide articulation to leg bones.
  2. Also provide attachment to leg muscles.
  3. It transfers the weight of body to leg.

Total bones 2 in both pelvic girdles.     

  1. Limb bones :-

Limb bones provide support to arms (upper limbs) and legs (lower limbs). The bones of legs are stronger than those of arms.

  1. Arms (upper limb) : total 60 bones.

Each arm has 30 bones.


In upper arm



In lower arm


In lower arm










  1. Legs (lower limb ): total 60 bones.

Each arm has 30 bones.


In upper arm



In knee



In lower arm



In lower arm





Function of arms bones

Function of legs bones

Bones of arms provide strength to the arms.

Bones of leg provide strength to legs and also balance the weight of body.



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11    PMT    Biology    Locomotion and Movement    Bone concept