Functions of bones

Functions of bones • • • • Support Protection Movement Blood cell formation • Storage Support • Strong • Rigid Protection • Surround organ • Protect against damage Movement • Attach to bones • Provide levers Blood Cell Formation • All blood cells formed in the bones • Red marrow (hematoposiesis) Storage • Calcium • Phosphate Bone Tissues • Bone (osseous tissue) • Dense connective tissue • Cartilage • Blood forming tissue • Nervous tissue Types of Bones • Bones can be divided into four classes – – – – Flat bones Long bones Short bones Irregular bones Flat Bones • Thin and flat – Cranium – Ribs – Sternum Short Bones • About equal in length and width – Wrist bones – Ankle bones Long Bones • Greater in length than width • Absorb stress from body weight – – – – Thighs Legs Arms Forearms Irregular bones • Complex shapes – Vertebrae – Facial bones Skeleton • Divided into two parts – Axial – Appendicular Axial Skeleton • Skull • Vertebral column • Bony thorax (thoracic cage) Skull • Cranium • Facial bones Fetal Skull • Newborn infant skull isn’t complete • Not all the hyaline cartilage has yet ossified • Cartilage meets at fontanels Vertebral Column • Divided into three regions – Cervical – Thoracic – Lumbar Sacrum Coccyx Fetal Vertebral Column • Originally a convex curve • As baby learns to lift it’s head, the cervical curve develops • As baby learns to walk, Lumbar curve develops Bony Thorax • Consists of the ribs, sternum and thoracic vertebrae • Provides a bony, protective cage around the organs of the thoracic cavity • Heart, Lungs and major blood vessels Appendicular Skeleton • • • • • • Pelvic Girdle Lower Limbs Pectoral Girdles Clavicles Scapulae Upper limbs Pelvic Girdle • Strong frame • Supports lower limbs Pelvis • Two coxial bones • Sacrum – Three separate bones in the fetus – The three join anteriorly Female and Male Pelvis are Different Pelvic Girdle Differences Feature Orientation Pelvic inlet Male Tilted backward Narrow, heart shaped Female Tilted forward Wide, oval-shaped Pubic arch Sacrum Less than 90o Narrow and long Greater than 90o Wide and short, greater curvature Bone thickness Coccyx Thick and heavy Immovable Thin and light Movable Bone Growth I • Bone begins as a model of hyaline cartilage in an embryo Bone Growth II • A collar forms around the midsection Bone Growth III • Primary ossification center as cartilage is replaced by spongy bone Bone Growth IV • Spongy bone expands as more blood vessels penetrate Bone Growth V • Central cavity is formed and secondary ossification centers develop Bone Growth VI • Ossification continues until spongy bone fills epiphyses and compact bone surrounds the entire structure Bone Growth VII • Hyaline cartilage remains in the epiphyseal plates and articular cartilages Diaphysis • Shaft of the bone – Most of the bones length – Dense bone – Covered by fibrous connective tissue (periosteum) Epiphyses • Ends of long bones – Thin layer of compact bone surrounding spongy bone – Covered by Articular Cartilage – hyaline cartilage – Slippery and smooth Periosteum • Dense, connective tissue firmly attached to bone • Covers everything except the articular cartilage • Large supply of blood vessels Joints or Articulations • There are three groups of joints or articulations binding bones together in the body • They are classified by the amount of movement they allow and the materials forming the joining Fibrous Joints • Consist of fibrous (dense) tissue between articulating bone • Little or no movement allowed – Sutures in the skull Cartilaginous Joints • Binds bones together with cartilage • Allows little or no movement • Shock absorbers – Symphysis Pubis – Intervertebral disks Synovial Joints • There are five types of freely moving or Synovial joints in the human body • • • • • Hinge Ball and Socket Pivot Saddle Gliding Synovial Joint • Permit the greatest freedom of movement • Synovial fluid between bones • Enclosed in the Articular Capsule • The outside layer is the tough fibrous capsule Hinge Joint • Allows movement in only one plane • Convex surface of one bone fits into the concave surface of another – Knee – phalanges Ball and Socket • Maximum allowable movement • Ball-shaped process of one bone fits into the cup-shaped socket of another – Hip joint – Shoulder joint Pivot Joint • Allows rotation around a central axis • Cylindrical surface of one bone rotates in the ring of another – Vertebral column – elbow Saddle Joint • Allows back and forth, side to side and some pivoting • Convex surface of one bone fits concave surface of complimentary bone – Trapezium and metacarpal of the thumb Gliding Joint • Permit a sliding movement • Surfaces are nearly flat – Clavicle and sternum – Some wrist and ankle bones Types of Bone Fracture • There are seven types of fracture – – – – – – – Greenstick Simple Compound Spiral Comminuted Impacted depressed Greenstick Fractures • Also called an incomplete fracture • Break does not extend all the way through the bone • Common in children. Their bones are more flexible Simple Fracture • No tear in the skin • Break extends all the way through the bone Compound Fracture • Broken end of the bone tears skin from the inside • Bone may break into several fragments Comminuted Fractures • Bone has broken into several pieces • Common in the elderly with brittle bones Spiral Fracture • A ragged break that occurs when excessive twisting forces are applied to the bone • Common sports fracture • Common childabuse fracture Impacted Fractures • Ends of the bones are forced into each other • Most common cause: Falling with out streched arms Depressed Fracture • Bone is broken and forced inward • Most common in skull fractures Bone Disorders • Congenital diseases – Spina bifida Abnormal Curvatures of the Spine • Lordosis – Exaggerated curvature of the lumbar region swayback Abnormal Curvatures of the Spine • Kyphosis – Exaggerated curing out of the thoracic region Abnormal Curvatures of the Spine • Scoliosis – Lateral deviation of the spine from the midline Gout • A type of acute arthritis – Accumulation of uric acid crystals in the synovial fluid Osteitis Also called Paget’s Disease • Progressive bone disease – Gross deformation – Bone pain Osteoarthritis • Degerative joint disease – Sclerosis – Loss of articular cartilage – Growth of bone/cartilage within the joint – Inflammation of the synovial membrane Rickets & Osteomalacia • Vitamin deficiency • Lack of Vitamin D – Thinning and softening of the bones – In children • Bowed limbs • Soft skulls Osteomyelitis • Bacterial infection usually caused by compound fracture – May spread through bloodstream – Usually treeted by surgery and antibiotics Staphylococcus aureus Osteoporosis • Decreased bone mass • Imbalance betweenbone formation and bone reabsorbtion – Post menopausal women – Elderly men and women Rheumatoid Arthritis • Degeneration of cartilage and dense connective tissue in a synovial joint Bone Tumor • Grow in the marrow of the bone • Rare, but extremely painful – Malignant myeloma – Osteochondroma – Osteogenic sarcoma Bone Tumor • Most types undergo malignant change