Skeletal System Anatomy (2013 PDF)

THE SKELETAL SYSTEM © 2013 Pearson Education, Inc.  Learning objectives: Examine the functions of the skeletal system. Classify the divisions of the skeletal system. Identify major bones of the body. Explore different bone shapes. Analyze projections and depr...

THE SKELETAL SYSTEM © 2013 Pearson Education, Inc.  Learning objectives: Examine the functions of the skeletal system. Classify the divisions of the skeletal system. Identify major bones of the body. Explore different bone shapes. Analyze projections and depressions. Investigate the composition of bones. © 2013 Pearson Education, Inc.  Five Functions of the Skeletal System 1. Support Provided for the entire body by the entire skeletal system. Bones provide attachments for soft tissues and organs. 2. Storage Provided by the bones for calcium salts for body fluids. Lipids are stored in yellow marrow for energy reserves. © 2013 Pearson Education, Inc.  Five Functions of the Skeletal System 3. Blood cell production Occurs in the red marrow and results in increases in red blood cells, white blood cells, and platelets. 4. Protection Provided to soft tissues and organs by surrounding them with the skeleton. 5. Movement In part a function of the skeletal system because the bones function as levers. © 2013 Pearson Education, Inc.  Divisions of the Skeletal System Axial skeleton includes: The skull and associated bones The thoracic cage with the ribs and sternum The vertebral column Appendicular skeleton includes: The pectoral girdle and the upper limbs The pelvic girdle and the lower limbs © 2013 Pearson Education, Inc.  Figure 1. The Axial and Appendicular Divisions of the Skeleton. AXIAL SKELETON 80 APPENDICULAR SKELETON 126 Cranium 8 Skull Face 14 Clavicle 2 Skull and Pectoral 4 associated 29 Auditory 6 girdle bones Scapula 2 ossicles Associated Hyoid Hyoid 1 bones Sternum 1 Humerus 2 Thoracic 25 cage Radius 2 Ribs 24 Ulna 2 Upper 60 limbs Carpal bones 16 Metacarpal bones 10 Phalanges (proximal, 28 middle, distal) Hip bone Pelvic 2 2 (coxal bone) girdle Vertebrae 24 Femur 2 Vertebral 26 Sacrum 1 column Patella 2 Coccyx 1 Tibia 2 Fibula 2 Lower 60 limbs Tarsal bones 14 Metatarsal bones 10 Phalanges 28 © 2013 Pearson Education, Inc.  Skull Clavicle Scapula Humerus Ribs Vertebrae Radius Ulna Hip bone Sacrum Carpal Coccyx bones Metacarpal bones Phalanges Femur Patella Tibia Fibula Tarsal bones Metatarsal bones Phalanges Anterior view Posterior view © 2013 Pearson Education, Inc. Figure 2. Major Bones of the Body  Four General Shapes of Bones 1. Long bones are longer than they are wide. 3. Flat bones are broad. Long Bones Flat Bones Parietal bone Humerus Short Bones Irregular Bones Carpal bones Vertebra 2. Short bones 4. Irregular bones are about as wide as Figure 3. Shapes of Bones. are complex in shape. they are long. © 2013 Pearson Education, Inc.  Bone Features Are landmark features on the surfaces of bones Include projections Where tendons and ligaments attach Where bones articulate Include depressions, grooves, and openings Where blood vessels and nerves pass through the bone © 2013 Pearson Education, Inc.  Table 1. An Introduction to Bone Markings © 2013 Pearson Education, Inc.  Figure 4. Bone Markings and Landmarks © 2013 Pearson Education, Inc.  Composition of Bone Tissue Bones or osseous tissue Are a supporting connective tissue; cells are called osteocytes. Matrix made of extracellular protein fibers and a ground substance. Bone consists of organic and inorganic matter. 35% of the bone weight is composed of the organic matter (cells & collagenous fibers). 65% of the bone weight is composed of inorganic matter (hydroxyapatite) © 2013 Pearson Education, Inc.  Effects of Changing the Bone Matrix Figure 5. Effects of changing bone matrix. (a) Normal bone; (b) Demineralized bone; (c) When collagen is denatured in a bone. © 2013 Pearson Education, Inc.  Structure of a Long Bone The diaphysis, or central shaft Has a marrow cavity in the center filled with bone marrow (soft fatty tissue) The epiphyses are the wider portions at each end Covered with articular cartilage Each articulates with an adjacent bone at a joint Figure 6. Regions of the bone © 2013 Pearson Education, Inc. http://www.bbc.co.uk/staticarchive/cc264e98fcc01ddc9c8e41e6a50eb3c2c3e4d782.gif  Structure of a Long Bone Spongy bone, also called cancellous bone Made up of thin rods or plates of bones that run in the same direction called trabeculae. Marrow cavity is the innermost section of bone. Types: Red marrow and Yellow Marrow Figure 6. Regions of the bone © 2013 Pearson Education, Inc.  Structure of a Long Bone Compact bone Is densely packed; forms the diaphysis Periosteum Is the outer covering of bone Endosteum Lines the marrow cavity and spongy bone Figure 7. Structure of a Long Bone © 2013 Pearson Education, Inc.  Figure 8. Periosteum and Endosteum of a Bone © 2013 Pearson Education, Inc. Histology of Bone Figure 9. The Microscopic Structure of a Typical Bone. Bone cells are called osteocytes Located in pockets called lacunae Found between sheets of matrix called lamellae Canaliculi are small channels that run through the matrix and connect the lacunae and blood vessels.  Histology of Compact Bone Has a repeating functional unit called the osteon, or Haversian system Osteon is made of concentric circles of lamella Surrounding a central canal that has blood vessels in it Perforating canals allow for blood vessels in the central canals to be linked to other vessels. © 2013 Pearson Education, Inc.  Figure 10. The Microscopic Structure of a Typical Bone. Spongy bone Cellular layer Marrow cavity of periosteum Fibrous layer Compact bone of periosteum Small vein Capillary Lamellae Canaliculi Lamellae Osteons Endosteum Central canal Vein Artery Osteon Lacunae Osteon LM x 343 In this thin section through compact Central Perforating Trabeculae bone, the intact matrix making up the canal canal of spongy bone lamellae appears white, and the central This diagrammatic view depicts the canal, luacunae, and canaliculi appear parallel osteons of compact bone and black due to the presence of bone dust. the trabecular network of spongy bone. © 2013 Pearson Education, Inc.  Characteristics of Compact Bone Covers all bone surfaces except for the articular surfaces Can tolerate a lot of stress applied to either end of a long bone Cannot tolerate moderate stress applied to the side of the shaft © 2013 Pearson Education, Inc.  Histology of Spongy Bone Has no osteons The lamellae form rods called trabeculae Found in the epiphyses Where the stress is handled by the joints Much lighter than compact Figure 11. Structure of a Typical Bone. bone © 2013 Pearson Education, Inc.  Types of Bone Cells Osteocytes Mature cells that maintain bone structure by recycling calcium salts. Osteoclasts Large cells that secrete acid and enzymes that break down the matrix – 50 or more nuclei Osteoblasts Produce new bone through a process called ossification © 2013 Pearson Education, Inc.  Three Bone Cells Figure 12. Types of Bone Cells Canaliculi Osteocyte Matrix Osteoid Matrix Matrix Osteoblast Osteocyte: Mature bone cell that Osteoblast: Immature bone cell that maintains the bone matrix secretes organic components of matrix Osteoprogenitor cell Osteoclast Matrix Medullary cavity Medullary Endosteum cavity Osteoprogenitor cells: Stem cell whose Osteoclast: Multinucleate cell that divisions produce osteoblasts secretes acids and enzymes to dissolve bone matrix © 2013 Pearson Education, Inc. https://classconnection.s3.amazonaws.com/585/flashcards/6013585/jpg/4_type_of_blood_cell-148BB631CF0424FD9EC.jpg  Osteoporosis literally “porous bone,” is a disease that thins the framework inside bones. caused by the increase in rate of bone breaking than bone deposition. Risk factors: Unchangeable Risks – Age, Sex, Race, Body frame size Hormone Levels – Low sex hormones, Too much thyroid hormone Dietary Factors- Low calcium intake, Eating disorders, Gastrointestinal surgery Lifestyle choices – Sedentary lifestyle, Excessive alcohol consumption, Tobacco use Prevention: Increase calcium intake Vitamin D Exercise  Figure 13. Healthy bone and Osteoporotic Bone © 2013 Pearson Education, Inc.  THE END © 2013 Pearson Education, Inc.