Anatomy and Physiology

• Short bones are roughly cube-shaped and are found in the wrists and ankles.
• Bones are classified according to shape into long bones, short bones, flat bones, and irregular bones.
• The components of a long bone include the diaphysis, endosteum, and epiphyses.
• Ligaments differ slightly in that they also contain elastic fibres.
• Tendons and ligaments are similar in structure consisting of bundles/cables of dense connective tissue containing collagen fibres.
• The structure and function of spongy bone versus compact bone can be described.
• There are four types of cells in bone tissue: osteogenic cells, osteoblasts, osteocytes, and osteoclasts.
• The general functions of bone tissue include support, protection, movement, and anchorage of muscles.
• Bone stores minerals such as calcium and phosphorus, which are released when needed.
• All blood cells are formed in the red marrow of certain bones.
• Bones can be classified according to shape into long bones, which have a shaft with two knob-like ends, short bones, which are cube-like, flat bones, which are thin and provide extensive muscle attachment surfaces, and irregular bones, which have varied, complex shapes.
• Sesamoid bones develop within a tendon in areas of tension/friction/stress.
• The macroscopic anatomy of a typical long bone includes the diaphysis, endosteum, epiphyses, articular cartilage, metaphysis, periosteum, and nutrient foramen.
• The histology of bone includes the chemical composition, which is 35% organic components: cells, osteogenic cells, osteoblasts, and osteocytes.
• Endochondral Ossification is a process where bone is formed from a hyaline cartilage model, most bones form in this manner.
• Osteoblast cells produce the extracellular matrix, which includes collagen fibres and other constituents.
• Bone formation, or osteogenesis/ossification, begins in the embryo and continues throughout adulthood.
• Endochondral Ossification involves the development of a cartilage model, growth of the cartilage model, and the formation of a periosteum.
• The Haversian System includes osteocytes, which are bone cells in "lacunae", and concentric lamellae (hard layers) around a central Haversian Canal containing blood vessels and nerves.
• Osteocytes are involved in the day-to-day homeostasis of bone tissue, including repair.
• Calcium levels in the blood are held constant because of the ability of osteoclasts to resorb bone.
• The microscopic structure of compact bone includes bone tissue, cells, matrix, fibres, and the Haversian System or Osteon, which are elongated cylinders cemented together to form the long axis of the bone.
• Osteoclasts are large cells located in the endosteum of bone, where they resorb bone matrix, contribute to bone development, growth, maintenance, and repair.
• Intramembranous Ossification is a process where bone forms on or within a CT membrane, such as in flat bones (skull bones, clavicles).
• The inorganic component of bone is 65% hydroxyapatite, which gives bone hardness/rigidity.
• Osteoclast cells cause resorption of bone tissue in response to hormones.
• The microscopic structure of spongy (cancellous) bone includes poorly organized trabeculae (small needle-like pieces of bone) with lots of open space between them, sometimes with red marrow, and no osteons.
• Intramembranous Ossification involves the development of an ossification centre, calcification, and the formation of trabeculae.
• The appendicular skeleton includes the pectoral (shoulder) girdle, upper limbs, and pelvic (hip) girdle.
• The maxillae are mostly upper jaw bones, while the mandible is the lower jaw bone which is moveable.
• The socket which articulates with the head of femur is called the acetabulum.
• The pectoral (shoulder) girdle connects the upper limbs to the rib cage and includes the anterior clavicles (2) and posterior scapulae (2).
• The thorax consists of ribs, sternum, thoracic vertebrae, and costal cartilage.
• The upper limbs consist of 2 humerus (upper arm bone), 2 radius (forearm bone on same side as thumb), and 2 ulna (forearm bone on same side as pinky), extending from the elbow to the wrist.
• The sternum (breastbone) has a manubrium (upper portion) that articulates with the clavicle, a body in the middle, and a xiphoid process at the lower cartilaginous extension from the body.
• The nasal bones form the bridge of the nose, the vomer is part of the nasal septum, and the inferior nasal conchae are the inferior portions of the lateral nasal wall.
• The general structure of vertebrae includes the body (centrum), vertebral arch, pedicle, lamina, and vertebral foramen.
• The hyoid bone is located in the neck, between the lower jaw and larynx, and is held in place by muscles and ligaments.
• The lacrimal bone is located lateral and posterior to the nasal bones, and the palatine bone is located posterior to the nasal cavity and orbits.
• The facial bones (14) shape the face, attach to various muscles that move the jaw and control facial expressions, and protect and support the entrance of digestive and respiratory systems.