Skeletal system

• Stabilise and support the entire body • Protect the internal tissues and organs • Provide a surface for the attachment of muscles and ligaments -Permit movement of the body by forming joints that are move muscles

Long bones Short bones Flat bones Irregular bones Sesmoid bones

have greater length than the width acts as levers that are pulled by muscles e.g femur,tibia

equal length, width and thickness.only limited movement is required, such as carpal bones in the wrists and tarsal bones in the ankles

bones are thin and are more curved than flat protect the soft tissues and afford extensive areas for muscle attachment e.g cranial bones,scapula an d ribs

have complex shapes that cannot fit neatly into any other category e.g vertebrae,mandible

are small bones and are embedded within certain tendons where there is considerable friction tension and physical stress e.g palms,soles of feet

have a tubular central shaft called diaphysis - that extends outwards at the end and these are called epiphysis

a hollow cylinder surrounding the medullary cavity which is filled with yellow bone marrow. This is mostly fat.

epiphysis is covered in a cartilage where the epiphysis of adjacent bones meet.

is the area where the diaphysis joins the epiphysis

Compact tissues and spongy bone tissues

the harder and outer tissues of bones,It forms the outer layer of all bones and constitutes the bulk of the diaphysis of long bones

Bones consist of numerous longitudinal central canals known as Haversian canals or osteonic canals. These microscopic tubes contain nerve fibers and a small number of capillaries, enabling bones to receive oxygen and nutrients without being overly vascular.

Haversian canals have branches perpendicular to them called perforating canals or Volkmann’s canals. These canals extend the nerves, blood vessels, and lymphatic vessels to the periosteum and inward to the endosteum.

The outer layer of all bones is a dense layer of vascular connective tissue that envelops bones. It plays a crucial role in supplying blood to bone cells and supporting the growth and repair of bones.

is the inner most layer of all bones that lines the centre of compact bone and the medullary cavity

are concentric rings that surround the Haversian canals. These contain little spaces called lacunae where bone cells (osteocytes) are located.

The bone cells in our body connect with each other and with the central canal through small channels known as canaliculi. These canaliculi play a crucial role in supplying necessary nutrients to the bone cells, removing waste materials from them, and facilitating communication between the bone cells.

This layer of bone is known as spongy bone, which is light and porous in nature. It is typically found at the end of long bones, ribs, hip bones, sternum, and vertebrae. The spongy bone that is located in the epiphysis is filled with red bone marrow, whereas the yellow bone marrow is found in the diaphysis. It is important to note that red bone marrow is responsible for creating blood cells.

arranged in needle like threads of bones

This consists of 80 bones of the head and trunk of the body including the , hyoid bone, chest and spine

of 126 bones of the upper and lower extremities.

Occipital Frontal Sphenoid Ethmoid Parietal (pair) Temporal (pair)