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1 Chapter 7 The Skeletal System

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 2 Objectives List and discuss the generalized functions of the skeletal system. Identify the major anatomical structures found in a typical long bone. Discuss the microscopic structure of bone and cartilage, including the identification of specific cell types and structural features. Explain how bones are formed, how they grow, and how they are remodeled.

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 3 Objectives (Cont’d.) Identify the two major subdivisions of the skeleton and list the bones found in each area. List and compare the major types of joints in the body and give an example of each. Name and describe major disorders of bones and joints.

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 4 Chapter 7 Lesson 7.1

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 5 Functions of Skeletal System Support—provides body’s supporting framework Protection –Bony “boxes” protect delicate enclosed structures Skull—protects brain Thorax (breastbone and ribs)—protects heart and lungs

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 6 Functions of Skeletal System Movement—muscles pull on bones to cause movement Storage—storage of calcium helps maintain body’s calcium homeostasis Hemopoiesis—blood cell formation in red bone marrow

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 7 Types of Bones Long—example: humerus (upper arm) Short—example: carpals (wrist) Flat—example: frontal (skull) Irregular—example: vertebrae (spinal bones)

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 8 Structure of Long Bones Structural components –Diaphysis or shaft –Medullary cavity containing yellow marrow –Epiphyses or ends of the bone; spongy bone contains red bone marrow –Articular cartilage—covers epiphyses as a cushion –Periosteum—strong membrane covering bone except at joint surfaces –Endosteum—lines medullary cavity

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 9 Microscopic Structure of Bone and Cartilage Skeletal system composed of two major types of tissue—bone and cartilage –Bone cells called osteocytes –Cartilage cells called chondrocytes

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 10 Microscopic Structure of Bone and Cartilage Types of bone—have different appearance, microscopic structure and location –Dense or compact bone Outer layer of bone covered by periosteum Appears solid to naked eye

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 11 Microscopic Structure of Bone and Cartilage Structural unit called osteon or Haversian system composed of: –Concentric lamella — circular layers of calcified matrix –Lacunae — spaces in matrix between lamella containing osteocytes –Canaliculi — canals or passageways that connect lacunae and all nutrients to reach osteocytes –Central canal of osteon contains blood vessel

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 12 Microscopic Structure of Bone and Cartilage Structural unit called osteon or Haversian system composed of: –Spongy bone Found in epiphyses of bones Appears “porous” to naked eye with many open spaces in matrix Spaces contain red bone marrow Texture results from needlelike threads of bone called trabeculae

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 13 Microscopic Structure of Bone and Cartilage Cartilage –Chondrocytes located in lacunae –Matrix is flexible plastic-like gel reinforced with collagenous fibers –Matrix is free of blood vessels—nutrients reach chondrocytes by diffusion –Injured cartilage heals slowly

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 14 Bone Formation and Growth New bone forming cells are called osteoblasts and bone resorbing cells are called osteoclasts The ability of bone to ossify, grow, change shape, heal after injury and respond to stress occurs because of continuous “sculpting” by osteoblasts and osteoclasts

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 15 Bone Formation and Growth Bone is formed by two processes –Most bones develop from a process called endochondral ossification –Some flat bones (e.g., skull bones) form in connective tissue membranes by another process

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 16 Bone Formation and Growth Endochondral bone formation –Bones develop from cartilage models –Center of ossification first appears in diaphysis –Centers of ossification then develop in epiphyses

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 17 Bone Formation and Growth Endochondral bone formation –Epiphyseal plate of cartilage between epiphyses and diaphysis remains until skeletal maturity –Epiphyseal line (bone) replaces epiphyseal plate (cartilage) when growth ceases

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 18 Chapter 7 Lesson 7.2

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 19 Divisions of Skeleton Skeleton (total bones = 206) composed of the following divisions and their subdivisions –Axial skeleton (80 bones) Skull –Cranium (8 bones) »Paranasal sinuses (4 pairs) »Mastoid air sinus »Fontanels (6 bones) –Ear (6 bones) –Face (14 bones)

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 20 Divisions of Skeleton Skeleton composed of the following divisions and their subdivisions –Spine or vertebral column Four normal curves Three abnormal curves –Lordosis or “swayback” –Kyphosis or “hunchback” –Scoliosis

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 21 Divisions of Skeleton Skeleton composed of the following divisions and their subdivisions –Divisions Cervical (7 bones) Thoracic (12 bones) Lumbar (5 bones) Sacrum (1 bone) Coccyx (1 bone)

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 22 Divisions of Skeleton Skeleton composed of the following divisions and their subdivisions –Thorax Composed of: –12 pairs of ribs –Sternum or breastbone –Thoracic vertebrae Ribs –True ribs—rib pairs 1 through 7 –False ribs—rib pairs 8 through 10 –Floating ribs—rib pairs 11 and 12

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 23 Divisions of Skeleton Skeleton composed of the following divisions and their subdivisions –Appendicular skeleton (126 bones) Bones in shoulder or pectoral girdle connect bones of upper extremity (arm, forearm, wrist, and hands) to axial skeleton Bones in hip or pelvic girdle connect bones of lower extremity (thigh, leg, ankle, and foot) to axial skeleton

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 24 Divisions of Skeleton Skeleton composed of the following divisions and their subdivisions –Upper extremity Shoulder or pectoral girdle formed by: –Scapula –Clavicle (frequently fractured) Arm—humerus Forearm—radius and ulna Wrist—8 carpal bones Hand—5 metacarpal bones Fingers—14 phalanges or finger bones

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 25 Divisions of Skeleton Skeleton composed of the following divisions and their subdivisions –Lower extremity Hip or pelvic girdle formed by the two coxal or pelvic bones (one on each side) with sacrum and coccyx behind –Each coxal bone in infant consists of separate ilium, ischium and pubic bones—bones are fused into a single coxal bone in the adult –Acetabulum is cup shaped socket—articulates with head of femur

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 26 Divisions of Skeleton Skeleton composed of the following divisions and their subdivisions –Thigh bone—femur Patella or knee cap articulates with femur and tibia Lower leg—tibia (“shinbone”) and fibula

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 27 Divisions of Skeleton Skeleton composed of the following divisions and their subdivisions –Foot 5 metatarsal bones 7 tarsal bones (calcaneus or heel bone is largest tarsal) 14 phalanges or toe bones 3 arches of foot—two longitudinal (medial and lateral) and a transverse or metatarsal arch—if weakened, result is “flat feet”

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 28 Differences Between a Man’s and a Woman’s Skeleton Size—male skeleton generally larger Shape of pelvis—male pelvis deep and narrow, female pelvis broad and shallow Size of pelvic inlet—female pelvic inlet generally wider, normally large enough for baby’s head to pass through it Pubic angle—angle between pubic bones of female generally wider

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 29 Joint (Articulations) Kinds of joints –Synarthroses (no movement)—fibrous connective tissue grows between articulating bones (e.g., sutures of skull) –Amphiarthroses (slight movement)—cartilage connects articulating bones (e.g., symphysis pubis)

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 30 Joint (Articulations) Kinds of joints –Diarthroses (free movement)—most joints belong to this class Structures of freely movable joints—joint capsule and ligaments hold adjoining bones together but permit movement at joint Articular cartilage—covers joint ends of bones and absorbs jolts Synovial membrane—lines joint capsule and secretes lubricating fluid Joint cavity—space between joint ends of bones

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 31 Joint (Articulations) Kinds of joints –Types of freely movable joints—ball-and- socket, hinge, pivot, saddle, gliding, and condyloid

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 32 Skeletal Disorders Malignant tumors of bone and cartilage –Osteosarcoma Most common and serious type of malignant bone neoplasm Frequent sites include distal femur and proximal tibia and humerus Incidence in males is twice as high as females Occurs most frequently between 20 and 40 years of age Characterized by severe, unrelenting pain Treatment involves surgical resection with pre- and postoperative chemotherapy

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 33 Skeletal Disorders Malignant tumors of bone and cartilage –Chondrosarcoma Cancer of skeletal hyaline cartilage Second most common cancer of skeletal tissues Frequent sites include medullary cavity of humerus, femur, ribs and pelvic bones Occurs most frequently between 40 and 70 years of age

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 34 Skeletal Disorders Malignant tumors of bone and cartilage –Chondrosarcoma Incidence slightly higher in males Pain is common but not universal and generally less severe than in osteosarcoma Treatment is surgical resection—chemotherapy is not effective

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 35 Skeletal Disorders Metabolic bone diseases –Osteoporosis One of the most common bone diseases Cause unknown—associated most often with low estrogen levels and postmenopause status in women (genetics may play a part) Risk factors include certain drugs, low blood calcium, lack of exercise and smoking Occurs most frequently in elderly white women Characterized by loss of calcified bone matrix and reduction in number of trabeculae in spongy bone

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 36 Skeletal Disorders Metabolic bone diseases –Osteoporosis Bones fracture easily especially in wrists, hips, and vertebrae Compression fractures of vertebrae cause shortened stature and “dowagers hump” Treatment includes drug therapy, exercise, and dietary supplements of calcium and vitamin D –Rickets and osteomalacia—both diseases characterized by loss of bone minerals related to vitamin

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 37 Skeletal Disorders Deficiency –Rickets Loss of bone minerals occurs in infants and young children before skeletal maturity Lack of bone rigidity causes gross skeletal changes (bowing of legs)

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 38 Skeletal Disorders Deficiency –Osteomalacia First described by British surgeon Sir James Paget in 1882 Mineral content is lost from adult bones that have already matured Involves localized hyperactivity of osteoclasts and osteoblasts Faulty remodeling results in deformed bones that fracture easily May involve one or many bones—often appears in spine, skull, and long bones of extremities

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 39 Skeletal Disorders Deficiency –Osteomalacia Unique symptoms (e.g., deafness, headache, facial paralysis) often caused by bone deformity of skull bones pressing on nerves Affects about 3% of people over age 50 (1% of cases may develop into osteosarcoma) Cause may be genetic or triggered by viral infections

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 40 Skeletal Disorders Bone infection –Osteomyelitis General term for bacterial (usually staphylococcal infection of bone) Bone infections may also be caused by viruses, fungi, and other pathogens Infection may be spread to bone via bloodstream, adjacent soft tissue infection, open fractures, failed surgical aseptic technique, or infected donor tissues or prostheses Symptoms caused by collection of pus and decreased blood flow

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 41 Skeletal Disorders Bone fractures –Open (compound) fractures pierce the skin and closed (simple) fractures do not –Complete fractures involve total separation of bone fragments, and incomplete fractures involve partially separated fragments; comminuted fractures involve many fragments –Fracture lines can be classified by their angle relative to a bone’s axis: linear, transverse, and oblique

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 42 Skeletal Disorders Joint disorders –Noninflammatory joint disorders—do not usually involve inflammation of the synovial membrane. Symptoms tend to be local and not systemic Osteoarthritis or degenerative joint disease (DJD) –Most common noninflammatory disorder of movable joints—often called “wear and tear” arthritis. –Characterized by bone spurs and degeneration of articular cartilage –Hips, lumbar spine, and knees often involved

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 43 Skeletal Disorders Joint disorders –Noninflammatory joint disorders Osteoarthritis or degenerative joint disease (DJD) –Symptoms include joint pain, morning stiffness, appearance of Bouchard’s nodes (at proximal interphalangeal joints), and Heberden’s nodes (at distal interphalangeal joints) of the fingers –Most common cause for partial and total hip and knee replacements

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 44 Skeletal Disorders Joint disorders –Noninflammatory joint disorders Traumatic injury –Dislocation or subluxation — articular surfaces of bones in joint are no longer in proper contact –Sprain—acute injury to ligaments around joints (e.g., whiplash type injuries)

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 45 Skeletal Disorders Joint disorders –Noninflammatory joint disorders Traumatic injury –Strain—acute injury to any part of the “musculotendinous unit” (muscle, tendon, junction between the two, and attachments to bone) –Most strain injuries involve muscle tears –However, some strains may involve a weaker component of the musculotendinous unit. In children avulsion and epiphyseal fractures may occur

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 46 Skeletal Disorders Joint disorders –Inflammatory joint disorders—arthritis is a general name for several types of inflammatory joint diseases that may be caused by infection, injury, genetic factors, and autoimmunity. Inflammation of the synovial membrane occurs, often with systemic signs and symptoms.

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 47 Skeletal Disorders Joint disorders –Inflammatory joint disorders Rheumatoid arthritis –Systemic autoimmune disease—chronic inflammation of synovial membrane with involvement of other tissues such as blood vessels, eyes, heart, and lungs –Pain, anemia, severe crippling, fever, fatigue, and ulnar deviation of fingers are common symptoms –Juvenile rheumatoid arthritis, most common in girls and often severe, may destroy growth cartilage and arrest growth of long bones

Copyright © 2007, 2005, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 48 Skeletal Disorders Joint disorders –Inflammatory joint disorders Gouty arthritis—synovial inflammation caused by gout, a condition in which sodium urate crystals form in joints and other tissues Infectious arthritis—arthritis resulting from infection by a pathogen, as in Lyme arthritis caused by the Lyme disease bacterium