Skeletal system
The organ system of the body which provides support and help in the movement
Functions of the skeletal system :
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Keeps the body in the shape
Protects the vital organs of the body
Provides the site of attachment to the bones
Helps in the movement
Helps in the locomotion
Components of the skeletal system
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Bones
Joints
Cartilage
Muscles
Joints
-Junctions between the two bones is called a joint
Types of the joints on the basis od the movement
Immovable joints
Slightly movable joints
Freely movable joints
Immovable joints
Freely movable joints
It further comprises of
1)Hinge joint
Allows movement only in one direction e.g elbow joint, knee joint
2)Ball and socket joint
It allows movement in all direction e.g elbow joint , shoulder joint
3)Slightly movable joints
Allows a slight movement e.g vertebrae
Cartilage
➢ These are flexible connective tissues with no blood supply
➢ Chondrocytes are mature cartilage cells
There are three types of the cartilages
1. Hyaline cartilage
2. Fibrous cartilage
3. Elastic cartilage
Ligaments
They are fibrous connective tissues which join one bine to another
Tendons
These are connective tissues which join the bones aith the muscles and vicer virsa
Bones
There are three types of the cells
1.Osteoblasts
Bone forming cells
2.Osteocytes
Mature bine cells
3.Osteoclasts
Bone dissolving cells
-Study of the bones is called osteology
Division of the human skeleton
➢ The 206 bones in the adult human skeleton
➢ It comprise of the axial and appendicular skeleton
Axial skeleton
➢ Axial skeleton consists of the 80 bones in the head and trunk of body
➢ It is composed of five parts.
Skull contains 22 bones out of which:
I.
cranial bones (enclosing the brain)
8
II.
facial bones
14
III.
middle ear ossicles
6 (3 in each ear).
IV.
There is also a hyoid bone in neck.
V.
Vertebral column
26 bones (vertebrae).
The chest is made of a:
VI.
chest bone called sternum
1 bone
VII.
ribs
12 pairs( last two pairs are floating bones )
Appendicular skeleton
It is composed of 126 bones.
I.
Pectoral (shoulder) girdle
II.
Arms
III.
Both hands
IV.
Pelvic girdle (hips)
V.
Legs
VI.
Both feet
4 bones.
6 bones.
54 bones.
2 bones.
6 bones.
54 bones.
Muscles
Special tissues which are involved in the movement and locomotion
Types of the muscles
There are three types of the muscles
1. Skeletal muscles
2. Cardiac muscle
3. Smooth muscles
I.Smooth muscles
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They are present in the visceral organs
They are involuntary in action
These are controlled by the autonomic nervous system
The muscles are also neurogenic
They have no striation in their appearance
II.Cardiac muscles
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These muscles are present only in the heart
They are involuntary in action
These muscles are myogenic
They are fatigue less muscles
III. Skeletal muscles
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These muscles are attached to the bones
They have striations
They are voluntary muscles
These muscles are neurogenic