Chapter 5 The Skeletal System

The Skeletal System 4 Parts of the skeletal system Bones (skeleton) Joints Cartilages Ligaments -bone to bone and Tendon-bone to muscle Divided into two divisions Axial skeleton - torso Appendicular skeleton – limbs and girdle Slide 5.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Functions of Bones Support of the body-provides a framework Protection of soft organs-spinal cord, heart, etc. Movement due to attached skeletal muscles- for walking, breathing Storage of minerals and fats- calcium and phosphate Blood cell formation- in the marrow of long bones Slide 5.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Bones of the Human Body The skeleton has 206 bones Two basic types of bone tissue Compact bone Homogeneous External layer Spongy bone Also called cancellous bone Needle-like pieces are called trabeculae Figure 5.2b Slide 5.3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Classification of Bones Long bones Typically longer than wide Have a shaft with heads at both ends Contain mostly compact bone Examples: Femur, humerus Slide 5.4a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Classification of Bones Short bones Generally cube-shape Contain mostly spongy bone Examples: Carpals, tarsals Slide 5.4b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Classification of Bones on the Basis of Shape Figure 5.1 Slide 5.4c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Classification of Bones Flat bones Thin and flattened Usually curved Thin layers of compact bone around a layer of spongy bone Examples: Skull, ribs, sternum Slide 5.5a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Classification of Bones Irregular bones Irregular shape Do not fit into other bone classification categories Example: Vertebrae and hip Slide 5.5b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Classification of Bones on the Basis of Shape Figure 5.1 Slide 5.5c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Gross Anatomy of a Long Bone Diaphysis Shaft, or long axis Composed of compact bone Center is medullary canal Epiphysis Ends of the bone Composed mostly of spongy bone Medullary Canal Also called the marrow cavity Composed mostly of yellow fat (Adipose) in adults Use for reserves Figure 5.2a Slide 5.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Structures of a Long Bone Periosteum Protective outer covering of the diaphysis Fibrous connective tissue membrane Consists of dense irregular CT and osteoblasts/osteoclasts Sharpey’s fibers Secure periosteum to underlying bone Arteries Supply bone cells with nutrients Transport RBC out to body Figure 5.2c Slide 5.7 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Structures of a Long Bone Articular cartilage Covers the external surface of the epiphyses Made of hyaline cartilage Decreases friction at joint surfaces during movement Epiphyseal Line The line is the remnant of the epiphyseal plate, a disc of cartilage that grows during childhood to lengthen the bone. Figure 5.2a Slide 5.8a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Chemical Composition of Bones Organic Components Cells (osteoblasts, clasts, cytes) Osteoid ( ground substance and collagen) Slide 5.8a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Chemical Composition of Bones Inorganic Components Hydroxyapatites (Mineral Salts) Calcium phosphate Form tiny crystals that lie around the collagen fibers Healthy bone is ½ as strong as steel! Slide 5.8b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Microscopic Anatomy of Bone Osteon are also called Haversian Systems. They are a unit of bone Central canal is also called a Haversian canal Opening in the center of an osteon Carries blood vessels and nerves to bone cells Perforating (Volkman’s) canal Canal perpendicular to the central canal Slide 5.10a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Microscopic Anatomy of Bone Figure 5.3 Slide 5.10b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Microscopic Anatomy of Bone Lacunae Cavities (holes) containing bone cells (called osteocytes) Arranged in concentric (circular) rings Lamellae Rings around the central canal Sites of lacunae Figure 5.3 Slide 5.11a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Microscopic Anatomy of Bone Canaliculi Tiny canals Radiate from the central canal to lacunae Form a transport system for blood and nutrients Figure 5.3 Slide 5.11b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Changes in the Human Skeleton In embryos, the skeleton is primarily hyaline cartilage During development, much of this cartilage is replaced by bone Cartilage remains in isolated areas Bridge of the nose Parts of ribs Joints Slide 5.12 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Bone Growth Epiphyseal plates allow for growth of long bone during childhood New cartilage is continuously formed Older cartilage becomes ossified Cartilage is broken down Bone replaces cartilage Slide 5.13a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Bone Growth Bones are remodeled and lengthened until growth stops Bones change shape somewhat Bones grow in width Slide 5.13b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Long Bone Formation and Growth Figure 5.4a Slide 5.14a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Types of Bone Cells Osteocytes Osteoblasts Osteoclasts Mature bone cells Osteoblasts Bone-forming cells Osteoclasts Bone-destroying cells Break down bone matrix for remodeling and release of calcium Bone remodeling is a process by both osteoblasts and osteoclasts Slide 5.15 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Bone Fractures A break in a bone Types of bone fractures Closed (simple) fracture – break that does not penetrate the skin Open (compound) fracture – broken bone penetrates through the skin Bone fractures are treated by reduction and immobilization Realignment of the bone Slide 5.16 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Bone Fractures Cont… Nondisplaced fractures Bones retain their normal position Displaced fractures Ends are out of their normal position Complete fracture The bone is broken through Incomplete The bone is not broken through Transverse Break is perpendicular to the bone’s long axis Linear Break is parallel to the long axis Slide 5.15 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Common Types of Fractures Table 5.2 Slide 5.17 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Repair of Bone Fractures Hematoma (blood-filled swelling) is formed Break is splinted by fibrocartilage to form a callus Fibrocartilage callus is replaced by a bony callus Bony callus is remodeled to form a permanent patch Slide 5.18 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Stages in the Healing of a Bone Fracture Figure 5.5 Slide 5.19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Paranasal Sinuses Hollow portions of bones surrounding the nasal cavity Figure 5.10 Slide 5.25a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Paranasal Sinuses Functions of paranasal sinuses Lighten the skull Give resonance and amplification to voice Figure 5.10 Slide 5.25b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Hyoid Bone The only bone that does not articulate with another bone Serves as a moveable base for the tongue Figure 5.12 Slide 5.26 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Fetal Skull The fetal skull is large compared to the infants total body length Figure 5.13 Slide 5.27a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Fetal Skull Fontanelles – fibrous membranes connecting the cranial bones Allow the brain to grow Convert to bone within 24 months after birth Figure 5.13 Slide 5.27b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Vertebral Column Vertebrae separated by intervertebral discs The spine has a normal curvature Each vertebrae is given a name according to its location Figure 5.14 Slide 5.28 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Structure of a Typical Vertebrae Figure 5.16 Slide 5.29 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Bones of the Upper Limb The hand Carpals – wrist Metacarpals – palm Phalanges – fingers Figure 5.22 Slide 5.36 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Gender Differences of the Pelvis Figure 5.23c Slide 5.39 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Bones of the Lower Limbs The foot Tarsus – ankle Metatarsals – sole Phalanges – toes Figure 5.25 Slide 5.41 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Joints Articulations of bones Functions of joints Hold bones together Allow for mobility Ways joints are classified Functionally Structurally Slide 5.43 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Types of Synovial Joints Based on Shape Figure 5.29a–c Slide 5.52a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Types of Synovial Joints Based on Shape Figure 5.29d–f Slide 5.52b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Inflammatory Conditions Associated with Joints Bursitis – inflammation of a bursa usually caused by a blow or friction Tendonitis – inflammation of tendon sheaths Arthritis – inflammatory or degenerative diseases of joints Over 100 different types The most widespread crippling disease in the United States Slide 5.53 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Clinical Forms of Arthritis Osteoarthritis Most common chronic arthritis Probably related to normal aging processes Rheumatoid arthritis An autoimmune disease – the immune system attacks the joints Symptoms begin with bilateral inflammation of certain joints Often leads to deformities Slide 5.54a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Clinical Forms of Arthritis Gouty Arthritis Inflammation of joints is caused by a deposition of urate crystals from the blood Can usually be controlled with diet Slide 5.54b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings