Chapter 7 Sec. 2 Bone Structure Waleed Othman Yhesmein Alhassan Ali Sobh Bone Structure Waleed Bones in the skeletal system develop similarly, have closely related functions, and are structured practically the same. Bone Classification Waleed Bones in our body are classified by shape, their are five types. ● ● ● ● ● Long bones - They have expanded ends and long longitudinal axes. Ex:Forearm and Thigh bones Short bones - cube like structure and their lengths and widths are generally the same or close. Ex: Bones found in your wrists and ankles Flat bones - Broad platelike surfaces. Ex: the ribs Irregular bones - Variety of shapes and sizes and are usually connected to multiple bones. Ex: Vertebrae and many facial bones Sesamoid bones (round) - Small and inside of tendons adjacent to joints. Ex:The knee cap Sobh Another example of a long bone is a femur. The femur is located in the thigh and is the longest bone in the body. Parts of a long bone Sobh Epiphysis: the epiphysis forms a joint with another bone and is located at the end of each bone and there are two types. 1. 2. Proximal: Nearest to the center of the body. Distew: Farthest from the center of the body. Parts of a long bone cont. - - Articular cartilage: Hyaline cartilage coats the epiphysis. ● Between the epiphysis is the shaft of the bone which in this case is called diaphysis. Periosteum: A tough vascular fibrous tissue which encloses the bone completely except for the ends. ● Firmly attached to the bone ● Helps form and repair bone tissue Parts of a long bone cont. - The walls of the diaphysis are mainly composed of compact bone. ● Tightly packed; No space The walls of the epiphyses are composed of spongy bone. ● Has thin layers of compact bone ● Both bones are strong and resist bending Parts of a long bone cont. - Compact bone in the diaphysis of a long bone form a tube which has a hollow chamber called the medullary cavity. (pg. 132) ● These areas are lined by cells called endosteum ● Filled with bone marrow (soft connective tissue) Microscopic Structure ● ● ● Yhesmein Bone Cells called osteocytes have small bony chambers called “lacunae” Lacunae forms concentric circles around central canals Osteocytes communicate with nearby cells by a cellular process called canaliculi Microscopic Structure Cont. Yhesmein - Extracellular matrix of bone tissue is composed of collagen/inorganic salts. ● Collagen gives bones their strength and resilience ● Inorganic salts harden the bone making it more resistant to being crushed - Each central canal contains blood vessels/nerve fibers that are surrounded by loose connective tissue ● Blood in the vessels are there for nourishment of the bone cells (that are associated with central canals) Microscopic Structure Cont….. Again - - Yhesmein Central Canals ● Extend longitudinally through bone tissue ● Transverse perforating canals (Volkmann's canals) Perforating Canals ● Contains larger blood vessels/nerve fibers in the central canal ● Communicates with the surface of the bone/medullary cavity
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