Skeletal System

The skeletal system is the system of bones with a wide network that holds and supports the body.

Bones

They are Very hard and tough part of the body. The outer part of the bone is made of hard, dense bone tissue Hardness is due to calcium phosphate and other minerals. The inner portion is spongy bone tissue with blood supply. The middle part is called bone marrow the red blood cells and the white blood cells are formed in the bone marrow.

Functions of Bones
1) It forms specific frame of the body.
2) Gives protection to the vital organs.
3) Gives support to the muscles.
4) Helps in respiration.
5) Helps in hearing.
6) Formation of R.B.C. in marrow.
7) Lifting the weight and doing movements.

Types of Bones

Our body is made up of different type of bones based on their shapes and sizes.
1) Long bones- e.g.. Humerus, Hip.
2) Short bones-metacarpal, phalanges.
3) Flat bones-e. g. Head, Pelvic bones.
4) Irregular bones –e.g.. Vertebrae, ribs.
5) Sesamoid- e.g.. Patella
6) Pneumatic bones –e.g.. Skull.

Types of bones according to their function.

The skeletal system is categoriesd in two major skeletal systems:
1) Axial skeleton- it consist of Skull Vertebrae.
2) Appendicular skeleton- it consists of Extremities Pelvic girdle. Pectoral girdle.

Skull
It is divided into Cranium and Face.
1) Cranium- has 8 flat, tough bones.
Frontal, Occipital , Sphenoid ,Ethmoid ,2 parietal ,2 temporal. Joined to each other by sutures.
2) Face- has many bones as Maxillary-2, Zygomatic-2, Palatine-2, Nasal-2, Lachrymal-2, Vomer [Nasal septum]-2, Nasal cartilage, Mandible.

Vertebral column:
Formed by 33 vertebrae.
Cervical-7
Thoracic-12
Lumbar-5
Sacrum-5
Coccyx-4
These vertebrae are present in the spine in the form of Specific curves.
Each vertebrae is inlined with aCushion like structure called the Intervertabral discs that protects the vertebrae and provide lubrication for the movement.

Strucure of a vertebrae:

Each vertebra contains- Body – Neural arch – Processes. [Transverse and Spinal]

Thoracic cage:
Is formed by –sternum, Ribs and Vertebrae.
Sternum-Palpable.
It contains three parts-Manubrium, Body, Xyphoid process.
Ribs- we have 12 pairs of ribs.
It contains –Bony part and cartilaginous part.
First 10 ribs are attached to the sternum.
Remaining 2 are floating.

Bones related to upper limb:
1)Scapula.-2
2)Clavicle.-2
3)Humerus-2
4)Radius-2
5)ulna-2
6)Wrist-8 irregular ,small bones-16 carpel bones
7)Metacarpels.-10
8)Phalenges.-28
The metacpels carpels and phalanges form the complete hand.
Total-64.

Bones related to Lower limb:

1)Pelvic Girdle-Ilium-2,Ischium-2,Pubic -2,Sacrum-1, Coccyx-4 Femur-2-,Pattella-2,Tibia-2,fibula-2,Tarsal-14 Metatarsal-10 Phalanges-28 The tarsals, metatarsals and the phalanges forms the bone of the foot.

Cartilage:

It’s a soft elastic flexible tissue present in the Nose, Ear, Larynx, Trachea, Bronchi,joints.

TENDONS :

They are the fibrous structures that connect muscle to a bone. This connective tissue joins the muscles to the bones as cord like fibres with different shapes at the point of their attachment.

LIGAMENTS :

They are the connective tissue that bind bones and bones together. They are attached between two bones making the binding between two bones stronger for better supportive movement.

Joints

They Combining point of 2 or more bones. They function for the movements and helps in bearing weight.

Types-
1)Immovable-
2)Movable.
3)slightly movable.

Immovable joint: They are those joints where two or more bones meet but they cannot move.
1)Sutures-eg.-skull.

2)Peg and socket joint-Maxillary bone and teeth.
Mandible and teeth.

3)Primary cartilaginous joint-in growing age.
Eg .Upper or lower end and shaft of the bone.
Bones of child is more flexible than adult.

Slightly movable joint- They are those joints which show slight movement.
1)secondary cartilaginous joint-
articulating part of the bone is covered by
hyaline or fibrous cartilage.
Eg-Intervertebral ,
Pubic symphysis.

2)Fibrous joint-both bones are joined by inter-ossious ligament.
Lower end of tibia and femur.

Moveable joints
1)Ball and socket.-shoulder,hip
2)Hinge-Elbow , knee ,
3)Saddle-Wrist(Metacarpel and trapezium.)
4)Pivot-Atlantoaxial joint.
5)Gliding-One can glide .
Eg-Wrist,costovertebral.

The skeletal system with the muscles and nerves work for the following movements in the body such as Flexion, extension,Adduction,Abduction, Pronation and Supination.