BONE & MUSCLES Dr. LUBNA NAZLI ASST. PROF. ANATOMY RAK MHSU Dt: 13/ 10/08

2 Objectives Features of bone Cells of bone Functions Classification of bone: Compact bone and Spongy bone Muscle Types of muscles.

3 Features of bone Widely separated cells surrounded by large amounts of matrix containing collagen fibers and mineral salts (mainly calcium and phosphorus).

4 Functions of bone support - for muscles, organs, and soft tissues leverage and movement - the synovial joints protection - for critical organs calcium phosphate storage - mineral balance hemopoiesis - formation of blood cells

5 Bone cells Osteoblasts - bone forming cells - produce matrix Osteocytes - mature bone cells Osteoclasts – phagocytic cells.

6 Osteoblasts osteoblasts - these are the "bone forming cells" which secrete the collagen and ground substance that constitutes unmineralized bone (osteoid), and is responsible for calcification of the matrix.

7 Osteocytes are mature bone cells. Each osteocyte occupies a space, the lacuna, and is surrounded by matrix. Osteocytes extend processes through canaliculi to connect to neighboring cells.

8 Osteoclasts Osteoclasts are large multinucleated cells whose function is to resorb (reabsorb) bone. Osteoclasts dissolve the matrix and osteoid with acids and hydrolytic enzymes. Osteoclasts are phagocytic and are derived from monocytes.

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10 Osteons or Haversian system Osteons, or Haversian systems, are the units of structure in mature bone. They are tightly arranged running generally parallel to the long axis of the bone. At the center of each is an Haversian canal which carries blood vessels and nerves.

11 Canaliculi (small canals) connect the Haversian canals with lacunae containing the osteocytes. Osteocytes extend processes into the canaliculi and receive nutrients and get rid of wastes through the canaliculi. The lacunae and canaliculi form lamellae or layers of two types: concentric lamellae form circular rings around each Haversian canal, and interstitial lamellae, fill in the spaces between existing osteons.

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15 Volkmann’s canals – channels lying at right angles to the central canal, connecting blood and nerve supply of the periosteum to that of the Haversian canal

16 Bone or osseous tissue is found in two different forms: compact bone cancellous or spongy bone

17 Compact Bone Compact bone is a very dense tissue forming the outer layer of all bones and the thickened shafts or diaphyses of long bones. In a microscopic view, compact bone always contains numerous osteons or Haversian Systems. Each consists of a central canal through which blood vessels and nerves pass. Surrounding this canal are multiple concentric lamellae or layers of bone. Haversian systems are only found in compact bone.

18 Cancellous (Spongy) Bone One of the most obvious features of cancellous or spongy bone is the absence of Haversian Systems or Osteons. During bone formation, the first bone to form is always cancellous. Where compact bone is needed, cancellous bone forms first and later is remodeled into the denser, compact type.

19 Bones of the skeleton contain a combination of both types of bone tissue organization.

20 MUSCLE TISSUE Made of elongated cells Found in muscles, heart and glands that contract Functions to produce movement.

21 There are three structurally and functionally distinct types of muscles. smooth muscle (involuntary, unstriated) skeletal muscle (voluntary, striated) cardiac muscle. (involuntary, striated)

22 Smooth Muscle Smooth muscle consists of spindle shaped cells of variable size. Smooth muscle cells contain one centrally placed nucleus. The innervation of smooth muscle is provided by the autonomic nervous system. Smooth muscle makes up the visceral or involuntary muscle. Eg: walls of hollow organs.

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24 Skeletal Muscle Skeletal muscle consists of very long tubular cells (also called muscle fibres). Skeletal muscle fibres contain many peripherally placed nuclei. Skeletal muscle fibres show cross-striations. It is therefore also called striated muscle. Skeletal muscle is innervated by the somatic nervous system. Skeletal muscle makes up the voluntary muscle. Eg: muscles that move the skeleton

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27 Cardiac Muscle Cardiac muscle consists of muscle cells with one centrally placed nucleus. Cardiac muscle is innervated by the autonomic nervous system. Cardiac muscle exhibits cross-striations. Cells branch & joined by intercalated discs. Cardiac muscle is for these reasons also called involuntary striated muscle. Eg: walls of the heart

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