General osteology. General anatomy of the human skeleton. Development and classification of bones. The bone as a multifunctional organ. Composed by Natalia Leonidovna Svintsitskaya, Associate professor of the Chair of Human Anatomy, Candidate of Medicine
Osteology Interesting Facts 206 bones Axial skeleton: 80 bones Appendicular: 126 bones Composed of calcium carbonate, calcium phosphate, collagen, & water 60-70% of bone weight - calcium carbonate & calcium phosphate 25-30% of bone weight water ~1/5 th of the skeleton replaces itself in one year in young adults
Skeletal Functions 1. Protection of inner organs, brain, spinal cord etc. 2. Support to maintain posture 3. Movement by serving as points of attachment for muscles and acting as levers 4. Mineral storage such as calcium & phosphorus 5. Hemopoiesis in vertebral bodies, femur, humerus, ribs, & sternum process of blood cell formation in the red bone marrow Types of bones Long bones - humerus, fibula Short bones - carpals, tarsals Flat bones - skull, scapula Irregular bones - pelvis, ear ossicles Sesamoid bones - patella
Types of Bones Long bones Composed of a long cylindrical shaft with relatively wide, protruding ends Shaft contains the medullary canal Ex. Phalanges, metatarsals, metacarpals, tibia, fibula, femur, radius, ulna, & humerus Function: Levers
Types of Bones Short bones Small, cubical shaped, solid bones that usually have a proportionally large articular surface in order to articulate with more than one bone Ex. Carpals & tarsals Function: Shock absorption
Types of Bones Flat bones Usually have a curved surface & vary from thick where tendons attach to very thin Ex. ilium, ribs, sternum, clavicle, & scapula Function: Protection, large surface area for muscle/tendon attachment
Types of Bones Irregular bones Include bones throughout entire spine & ischium, pubis, & maxilla Function: Varies Sesamoid bones Patella, flexor tendon of thumb and big toe Function: Improvement of mechanical advantage
Typical Bony Features Diaphysis long cylindrical shaft Cortex - hard, dense compact bone forming walls of diaphysis Periosteum - dense, fibrous membrane covering outer surface of diaphysis Endosteum - fibrous membrane that lines the inside of the cortex Medullary (marrow) cavity between walls of diaphysis, containing yellow or fatty marrow From Shier D, Butler J, Lewis R: Hole s human anatomy & physiology, ed 9, New York, 2002, McGraw-Hill.
CLASSIFICATION of BONES According to structure 1. Сompact = solid mass; dense & hard = forms the outer layer of bone structure = functional unit --- Haversian system 2. Сancellous or spongy = contain spaces filled with bone marrow = incomplete Haversian system
Typical Bony Features Epiphysis ends of long bones formed from cancelleous (spongy or trabecular) bone Epiphyseal plate - (growth plate) thin cartilage plate separates diaphysis & epiphyses Articular (hyaline) cartilage covering the epiphysis to provide cushioning effect & reduce friction Modified from Van De Graaff KM: Human anatomy, ed 6, New York, 2002, McGraw-Hill.
Bone Development Two Ways: 1) Intramembrannous bone formed between sheets of connective tissue as skull bones 2) Endochondral formed from hayaline cartilage model long bones Nutrition Factors Affecting Bone Growth adequate levels of minerals and vitamins calcium and phosphorus for bone growth vitamin C for collagen formation vitamins K and B12 for protein synthesis Sufficient levels of specific hormones during childhood need insulinlike growth factor promotes cell division at epiphyseal plate need hgh (growth), thyroid (T3 &T4) and insulin sex steroids at puberty growth spurt and closure of the epiphyseal growth plate estrogens promote female changes -- wider pelvis
Bone Growth Grow rapidly into structures shaped similar to the bones which they will eventually become Growth continues and gradually undergoes significant change to develop into long bone Longitudinal growth continues as long as epiphyseal plates are open Shortly after adolescence, plates disappear & close Most close by age 18, but some may be present until 25 Growth in diameter continues throughout life
Bone Properties Bone size & shape are influenced by the direction & magnitude of forces that are habitually applied to them Bones reshape themselves based upon the stresses placed upon them (remodeling) Bone mass increases over time with increased stress
Bone Deformation Rickets can result from insufficient vitamin D in the diet or from insufficient amounts of ultraviolet radiation from the sun. It can lead to skeletal deformation, such as vertebral or leg curvature.
Osteomalacia Failure of adult bone to ossify hip fractures are common most common in elderly Asian Common Fractures greenstick fracture The bone does not break all of the way through. simple, or closed When the bone breaks but the skin does not. compound, or open When the broken bone tears through the skin, introducing the dangerous possibility of infection. The area around a break swells and discolors, but some fractures can be detected only by X-ray. The weakened bones of the elderly are especially susceptible to fractures.
The curvatures of the vertebral column Lordoses anterior curvatures (curving forward), present in the cervical and lumbar redions. Kyphoses posterior curvatures (hump), present in the thoracic and sacral regions. The curvatures are associated with the upright body posture in humans. They absorb shocks placed on the vertebral column, aid in balance maintenance, and increase the thoracic and pelvic cavities. In the thoracic region, there is a slight curvature to the right (a physiological scoliosis) caused by a well-developed right upper limb. Clinical applications. In the old age, the thoracic kyphoses significantly increases due to the decrease in the elasticity of ligaments and cartilages. This results in the formation of a hump. From a long-term, incorrect child s body posture, especially in school children, pathological curvatures of the spine (scoliosis) may develop.