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
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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
Metaphysis
Medullary
Diaphysis
Cavity
Metaphysis
Epiphysis
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• 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
Cd
Skull
Ribs
Stermun
Axial Skeleton of cattle
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Skull
• Forms basis for head
• Made of - cranial bones
- Facial bones
• Protects brain
• Support sense organs
• Digestive & respiratory system starts
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Skull of cattle
Cranial bones
Diploe
Facial Bones
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Bored again???
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Vertebral column
• Made of unpaired irregular bones
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Divided into:
•
Cervical vertebrae (C)
•
Thoracic vertebrae (T)
•
Lumbar vertebrae (L)
•
Sacral vertebrae (S)
•
Coccygeal vertebrae (Cd)
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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
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Still bored???
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Pectoral limb
Scapula
Humerus
Ulna
Radius
Carpus
Metacarpus
Digits
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Pelvic Limb
Pelvis
Femur
Tibia & fibula
Tarsus
Metatarsus
digits
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Avian skeleton
Digits
skull
Radius & Ulna
Neck
Humerus
Femur
Pelvic bone
Sternum
ribs
Tibia
Metacarpus
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Skeleton of goat
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Skeleton of pig
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