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BONES. Chapter 5 – Vertebrate Anatomy. Major Functions of Bone. Support Backbone, etc. Protection Skull, ribs Movement Levers against which muscles work Mineral storage Blood cell formation. Two Major Types of Bone. Compact Bone Spongy Bone. Compact Bone. Dense
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BONES Chapter 5 – Vertebrate Anatomy
Major Functions of Bone • Support • Backbone, etc. • Protection • Skull, ribs • Movement • Levers against which muscles work • Mineral storage • Blood cell formation
Two Major Types of Bone • Compact Bone • Spongy Bone
Compact Bone • Dense • Smooth and solid in appearance
Spongy Bone • Honeycombed • Contains marrow in spaces
Bones are Classified by Shape • Long Bones • Short Bones • Flat Bones • Irregular Bones
Long Bones • Bones that are longer than they are wide. • Shaft with two ends • Primarily compact bone • Spongy bone at interior • All bones of the limbs are long bones
Short Bones • Roughly cubelike in shape • Contain mostly spongy bone • Bones of the wrist and ankle
Flat Bones • Thin, flattened and usually a bit curved • Two roughly parallel compact bone surfaces with spongy bone within • Skull bones; scapulae (shoulder blades)
Irregular Bones • Bones that fit none of the other classes • Vertebrae • Hip bones (pelvic bones) • These bones have complex shapes • Consist mainly of spongy bone
Bones are Organs • Bones are supplied and associated with many other tissues, thus they are organs • Supplied with nerves, blood vessels, lymph vessels • Covered with membranes (epithelial tissues)
Structure of a Typical Long Bone • Diaphysis – shaft of the long bone • Thick collar of compact bone surrounds a central marrow cavity • Epiphysis – ends of a long bone • Exterior of epiphyses are formed by compact bone • interior contains spongy bone • Joint surface of each epiphysis is covered with articular cartilage • Epiphyseal line • Remnant of a structure called the epiphyseal PLATE • Epiphyseal plate is the disk-like plate which allows for growth of the long bone during childhood • Cushions opposing bone ends during movement
Epiphysis detail • Click here for a detailed view of the epiphysis
Structure of Long Bone, cont. • Both internal and external surfaces are covered with membranes • Outer membrane – periosteum • Covers shaft • Richly supplied with blood vessels, nerves, etc. • Vessels enter through holes in the bone called nutrient foramen • Membrane also is anchoring point for tendons and ligaments • Inner membrane - endosteum
Structure of Short, Irregular and Flat bones • Simple design • Outside – compact bone • Inside – spongy bone
Blood forming tissue in bones • Red marrow • Typically found in cavities of spongy bone in long bones and flat bones • In adults, most blood formation occurs in • Head of femur/humerus • Sternum • Hip bones • In adults, the marrow cavity containing yellow marrow (fat) extends well into the epiphyses of most long bones
Chemical Composition of Bone • Both inorganic and organic compounds make up bone • Proper combination of organic and inorganic components allows bones to be durable without being brittle • Organic components • Composed of • Cells • Organic portion of matrix • Provide flexibility and tensile strength (strength under tension) • Inorganic components • Mineral salts • Calcium phosphate is the main mineral salt • Provide hardness
Bone Markings • Bones have many bumps, bulges, depressions, holes, etc. • “Bumps” are typically are points for muscle attachment • Holes are typically points for blood vessels or nerves to pass through
Terms for Bone Markings • Condyle – smooth rounded projection that allows for articulation • Articulation – usually a place where two bones meet and move against each other, but sometimes no movement occurs. • The image shows the occipital condyles at the base of the skull. These articulate with the first vertebra.
Terms for Bone Markings • Crest • A narrow ridge of bone • The images show the sagittal crest of a badger
Terms for Bone Markings • Foramen • A hole • Usually for passage of blood vessels and/or nerves
Terms for Bone Markings • Process • Any bony prominence or projection • To the right is the mastoid process • Also visible is the styloid process • Both are sites of muscle attachment to the skull
Terms for Bone Markings • Spine • A sharp slender process or projection • This photo shows the neural spines on vertebrae of a dinosaur
Terms for Bone Markings • Suture • A seam • Irregular lines produced by interlocking bones • An immovable joint • The photo shows sutures of the skull
Terms for Bone Markings • Fossa • A depression • Often an articulating surface • May meet with a condyle on another bone
Types of Fractures • Simple – • only bone damage – little or no tissue damage • Complete break
Types of Fractures • Compound – bone breaks through the soft tissue to the outside • High risk of infection
Types of Fractures • Compression • This type of bone fracture generally occurs after a fall where the vertebral column is compressed and then under the extreme pressure cracks or breaks. • Crushing of bone
Types of Fractures • Comminuted – more than two fragments of bone broken off.
Types of Fractures • Impacted • Ends of bone become wedged together
Types of Fractures • Spiral • Fracture caused by twisting force that creates an oblique fracture around and through the bone
Types of Fractures • Greenstick • incomplete fracture in which only one side of the bone has been broken.
Types of Fractures • Depression
Homeostatic Imbalances of Bone • Osteoporosis • Diseases in which bone resorption outpaces bone replacement • Bone marrow becomes porous and lighter • Spine is most vulnerable; also neck of femur • Estrogen and testosterone are important in maintaining normal bone density • After menopause, estrogen secretion in women diminishes and contributes to bone loss • Other causes of bone loss • Lack of exercise • smoking
Preventing Osteoporosis • Take calcium beginning at age 35-40 • Drink flouridated water • Do weight bearing exercise
Other diseases of bone • Osteomalacia • Bones inadequately mineralized • Rickets • Bones bend/deform • Children mostly affected • Caused by low calcium; vitamin D