The Skeletal System

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Skeletal system…

• Is made up of hard tissues like bone and cartilages. • Gives form and shape to animal body • The skeleton of a living animal is made up living structures of bones. • The bones have blood vessels, lymphatic vessels and nerves. • They are subject to disease, repair themselves and adjust to changes during stress.

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Functions of Bones

1.Protection:

of some vital organs from the external damages -important function CNS is protected by the skull and vertebral column; the heart and lungs by rib cage; and pelvis protects the internal parts of urogenital system.

2.Rigidity and form to the body:

animals without a skeleton of some type have little or no regular form. Gives a basis for the external structure and appearance of most animals.

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3.Act as lever:

in the vertebrates, locomotion, defense, offense, grasping, and other activities .Almost without exception, these levers are made of bone and are integral parts of skeleton.

4.Storage of minerals:

-dynamic storage area for minerals, particularly calcium and phosphorous.

5.Site for blood formation:

blood formation is not strictly a function of bone proper, but of the marrow found within the marrow cavity of long bones and within the spongy substance of all young bones.

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Classification of bones

Any bone may be classified into one of the following groups:

I. Long bones:

• relatively cylindrical in shape with two extremities called epiphyses.

• Metaphysis between each epiphysis and the diaphysis.

• A long bone grows in length only at the epiphyseal cartilage which is located within the metaphysis.

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Long bone Epiphysis Diaphysi s Epiphysis Metaphysis Medullary Cavi ty Metaphysi s Anato/Skelsyst/pj 6

• Examples of long bones -

pectoral limb

, humerus, radius, ulna, metacarpals, phalanges;

pelvic limb

, femur, fibula, tibia, metatarsals and phalanges.

2. Short bones

• Somewhat cuboid in shape i.e approximately equal in all dimensions.

• No marrow cavity.

• Found in complex joints such as the carpus (knee) and tarsus (hock).

• Example of short bones: Patella.

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• Function: - for variety of movement - absorption of shock

3.Flat bones

• relatively thin and expanded in two dimensions.

• Consist of two plats of compact substance, lamina externa and lamina interna, • Separated by diploe.

• Example -frontal base of skull, scapula and pelvic bones • Functions: - protects vital organs such as brain, the heart and lungs.

• - many provide large areas for muscle attachment.

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4. Sesamoid bones:

they are developed along the course of tendons. Example: Patella (knee cap) is the largest sesamoid in the body.

Functions: -reduces friction or change the course of tendons.

- may change the angle of the pull of muscles and this give a greater mechanical advantage.

5. Pneumatic bones:

they contain air spaces or sinuses that communicate with the exterior. Example: long bones of bird, frontal bones and maxillary bones of the skull.

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6. Irregular bones:

are unpaired bones located on the median plane and include the vertebrae and some of the unpaired bones of the skull.

Functions: - protection, support and muscle attachment.

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Bored????

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TWO PARTS OF SKELETAL SYSTEM

For better understanding the skeletal system can be divided into two part: 1. Axial skeleton 2. Appendicular skeleton.

1.AXIAL SKELETON

is made up of skull, and vertebral column sternum and ribs. The table below indicates the bones of the axial skeleton by regions.

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C T L S Skull Stermun Axial Skeleton of cattle Ribs Cd Anato/Skelsyst/pj 14

Skull

• Forms basis for head • Made of - cranial bones - Facial bones • Protects brain • Support sense organs • Digestive & respiratory system starts Anato/Skelsyst/pj 15

Skull of cattle Cranial bones Facial Bones Diploe Anato/Skelsyst/pj 16

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Bored again???

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Vertebral column

• Made of unpaired irregular bones Anato/Skelsyst/pj 20

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• • • • •

Divided into:

Cervical vertebrae (C) Thoracic vertebrae (T) Lumbar vertebrae (L) Sacral vertebrae (S) Coccygeal vertebrae (Cd) Anato/Skelsyst/pj 22

Vertebral formula

Cow: C7 T13 L6 S5 cd18-20

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Sternum

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Ribs

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2.APPENDICULAR SKELETON:

Is made of 1.

Pectoral limb or fore limb 2.

Pelvic limb or hind limb Anato/Skelsyst/pj 26

Still bored???

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Pectoral limb Scapula Humerus Radius Metacarpus Anato/Skelsyst/pj Ulna Digits Carpus 28

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Pelvic Limb Pelvis Femur Tarsus digits Anato/Skelsyst/pj Tibia & fibula Metatarsus 30

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Avian skeleton Radius & Ulna Humerus Pelvic bone Tibia Metacarpus Anato/Skelsyst/pj Digits Neck skull Femur Sternum ribs 32

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Skeleton of goat Anato/Skelsyst/pj 35

Skeleton of pig Anato/Skelsyst/pj 36