Skeletal system

 

COMPONENTS OF HUMAN SKELETON:

Human skeleton is made of three basic components:-

  • Bones,
  • Associated cartilages
  • joints

 

BONES:

Osteology:- study of bones called osteology.

Bones are hard,tough and rigid form of connective tissue. in humane it is the weight bearing organ.  it is responsible for all strength of human skeleton.

Human skeleton made of 126 bones in human. It includes  the bones of the upper and lower limb.

In late fetal age- 306

At birth-270

After birth-206

 

Cartilages:

Cartilage is also a form of connective tissue. but cartilage is not as tough and rigid as bone. Mineralization factor is the main difference in the cartilage and bone. In Bones-highly mineralized with calcium salts

 

Joints:

Joints are most important part of human skeleton. because they make the human skeleton mobile. A joint occurs between “two or more bones”, “bone and cartilage” and “cartilage and cartilage”.

 

There are two main forms of skeleton.

  • Exo Skeleton
  • Endo Skeleton

 

EXOSKELETON:-  this is the developed from epidermis.

Ex.- hair, nails, claws etc.

ENDOSKELETON:-  endoskeleton is present inside of the human body.  This is developed from mesodermal.

 

HUMAN SKELETON

System of bone called skeletan system, it associated with cartilages and joints of human. Together these structures form the human skeleton. Skeleton can be defined as the hard framework of human body around which the wall body is built.

 

Endo skeleton is divided into two part.

Axial skeleton

Appendicular skeleton

 

AXIAL SKELETON

In human 80 bone present in axial skeleton.

The axial skeleton consists of bone of – skull

vertebral column

Ribs

Sternum.

 

Skull:

Skull consist of 29 bones.

All skull bones are immovable.

Cranium:- cranium formed of 8 bones.

 

1 Frontal bone

It is the anterior or front part of the top of cranium it forms the forehead and some upper parts (roofs) of eye sockets.

Pariental-2

Temporal-2

Occipital-1

Sphenoid-1

Ethmoid-1

All these bones of the skull are joined together by suture.

Coronal  suture:- between the frontal and pariental bone

Lambdoidal suture:- between parietal and occipital

 

 

Vertebral Column:-  it made of 33 vertebrae or 26 bone.

Cervical, thoracic, lumbar, secrum and coccyx.

Formula- CT12  L5  S5  C4

24 movable or true vertebrae and (5) +(4) = 9 fused or false vertebrae (immovable).

False vertebrae- sacrum and coccyx.

Vertebral column has 4 curvature which are known as cervical, thoracic, lumbar and pelvic curvature.

 

Ribs:-  in human body 12 ribs on each side. Each rib is a flat bone connected dorsally to the vertebral column and ventrally to the sternum. In ribs two articular surfaces are present.

True ribs:  First 7 ribs which are connected to sternum are called true ribs

False ribs: other 5 ribs which are not connect to sternum. They are false ribs. Out of these the cartilage of the 8th 9th and 10th ribs are joined to the next higher cartilage, 8th 9th 10th are called vertebrochondral ribs.

 

Sternum:-

It is 15 cm long flat bone. It is divided into three segments-

  • manubrium
  • Body
  • Xiphoid process.

 

                               APPENDICULAR SKELETON

 

It is the skeleton of appendages of human body. It consists of Skeleton of upper limb and lower limb , Shoulder girdle, Pelvic girdle.

 

  • Skeleton of Upper limb:-

Bone of fore limb

 

Total number of the bones in each fore limb-30

Arm bone:              humerus-1

Fore arm:               radius and ulna-2

Wrist bone:-          carpals-8

Palm:                     metacarpals-5

Digits:                   phalanges-14

 

  • Skeleton of Lower limb:

Total number of bones in each limb : 30

Thigh bone:-               femur-1

Knee bone:-                patella -1

Shank region:-             tibia and fibula 2

Ankle region:-             tarsals : 7

Sole :-                         metatarsals 5

Digits :-                       phalanges 14

 

  • (Shoulder Girdle):

Pectoral girdle: each pectoral girdle consist of two bones, scapula and clavicale.

Scapula has 3 process which provide attachment to muscles- spinous process

Acromion process

Coracoids process

Clavical (collar bone):  it is thin, cylindrical and weakest bone.

It have two end

Medial end- articulates with the clavicular notch of manubrium.

Lateral end- bears a facet which articulate with acromion process of scapula.

 

  • Hip bone (Pelvic Girdle):

Also known as innominate or coxal bone. Each hipbone is made by fusion of three bones

Superior- ilium

Anteroinferior- pubis

Postero inferiorly- ischium

Pubis and ischium are separated by a large opening (obturator foramen). At the point of fusion of above bones is a cavity called acetabulum to which thigh bone articulate

 

TYPES OF BONE ON THE BASIS OF DEVELOPMENT:

 

  1. Membranous bones,
  2. Cartilaginous bones,
  3. Membro-cartilaginous bones

 

TYPES OF BONE ON THE BASIS OF REGION:

 

  1. Bones of axial skeleton,
  2. Bones of appendicular skeleton

 

TYPES OF BONE ON THE BASIS OF STRUCTURE:

According to Macroscopic approach;

  1. Compact bone,
  2. spongy bone

 

According to microscopic approach:

  1. Fibrous bone
  2. Lamellar bone.

 

 

             IMPORTANCE OF SKELETON SYSTEM

 

 

 

DISORDERS OF BONES:-

 

Arthritis:- it is caused by the inflammation of the joints. This is of several types, Ex- rheumatoid arthritis, osteoarthritis and gouty arthritis.

 

  • Rheumatoid arthritis- it is primary symptom of inflammation of synovial membrane. If it is left untreated, then the membrane thickens and synovial fluid increases then exerting pressure that causes pain.

 

  • Osteoarthritis- it is a degenerative joint disease characterized by the degeneration of the articular cartilage and proliferation of the new bones. It mostly afflicted joints are of knee, spine and hand.

 

  • gouty arthritis or gout:- it is caused either due to excessive formation of uric acid, or inability to excrete it. It gets deposited in joints as monosodium salt.

 

2 . osteoporosis-  osteoporosis is  age related disorder characterized by bone mass and increased changes of fractures. Decreased level of estrogen is common cause.

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