Chapter 5 The Skeletal System Essentials of Human Anatomy & Physiology Seventh Edition Elaine N. Marieb Chapter 5 The Skeletal System Slides 5.1 – 5.15 Lecture Slides in PowerPoint by Jerry L. Cook Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Skeletal System Consists of: Bones (skeleton) Joints Cartilages Ligaments Slide 5.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Functions of Bones Support of soft tissues and maintains body’s shape and posture Protection- soft organs Serve as levers for the movement skeletal muscles Storage of minerals (P, K+, Na+, Ca++)and energy (fats) Blood cell formation - hematopoiesis Slide 5.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Gross Anatomy of a Long Bone Diaphysis Shaft Composed of compact bone Metaphysis Borderline between epiphysis and diaphysis Epiphysis Ends of the bone Composed mostly of spongy bone Figure 5.2a Slide 5.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Gross Anatomy of a Long Bone Periosteum Dense white fibrious membrane covering bone Functions- bone growth, nutritition, repair, and attachement site Endosteum Articular cartilage Thin layer of hyaline cartilage Covers ends of bones where joints form Reduce friction during movement Figure 5.2a Slide 5.6

Gross Anatomy of a Long Bone Medullary Cavity w/in the diaphysis contains yellow marrow – fat and a few blood cell (adults) Infants – red marrow Compact bone Forms bulk of diaphysis and covers epiphysis Spongy bone Forms small portion of diaphysis at the ends of medullary cavity Contains red bone marrow Figure 5.2a Slide 5.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Bones of the Human Body Two basic types of bone tissue Compact bone Homogeneous Spongy bone Small needle-like pieces of bone Many open spaces Figure 5.2b Slide 5.3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Microscopic Anatomy of Bone Osteon (Haversian System) Structural unit of bone Central (Haversian) canal Opening in the center of an osteon Carries bld. Vessels, lymphatic vessels, and nerves Volkman’s (Perforating) canal Canal perpendicular to the central canal Carries blood vessels and nerves Slide 5.10a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Types of Bone Cells Osteoblasts – bone building cells Osteocytes – bone maintaining cells Osteoclasts – bone remodeling cells (remove bone; resorption) Slide 5.2 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 arranged in concentric rings contain osteocytes Lamellae Rings of calcified matrix are 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 Radiate from the central canal to lacunae Tiny canals that connect lacunae to haversian canal Form a transport system Figure 5.3 Slide 5.11b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Bone Development (Osteogenesis/Ossification) Embryonic Development – skeletal system => fibrous membrane called hyaline cartilage In young children – cartilage is replaced by bone. Types of Ossification: Intramembranous ossification Bone forms from a fibrous membrane to form membrane bone; occurs during embryonic development forms flat bones, and some irregular bones including bones of skull and clavicles Slide 5.13a

Bone Development (Osteogenesis/Ossification) Endochondrial ossification bone forms from hyaline cartilage to form cartilage bone occurs during 3rd month of embryonic development by birth most hyaline cartilage-> bone except for 2 regions: 1. Articular cartilage 2.Epiphyseal plate

Bone Development Appositional Growth (thickness/diameter) Osteoblasts secrete bony matrix on external surface of bone (periosteum) Osteoclasts destroy bone on the endosteal surface of compact bone. Slide 5.13a

Bone Growth - longitudinally Hyaline cartilage of epiphyseal plates grow by mitosis of the cell on the proximal face. Hyaline cartilage at the distal face of plate (towards medullary cavity) mature and die, and matrix calcifies; osteoblasts invade to form spongy bone -> compact bone

Long bone growth is regulated by hormones: 1. growth hormone produced in pituitary gland 2. sex hormones produced by ovaries and testes secreted during puberty and end during adolescence when epiphyseal plates are converted to bone (males – testosterone females – estrogen)

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

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

Repair of Bone Fractures Formation of a Hematoma (blood-filled swelling) Break is splinted by fibrocartilage to form a callus Fibrocartilage callus is replaced by a bony callus Bony callus is remodeled in response to mechanical stress to fracture to form a permanent patch

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

Parathyroid hormone (PTH) Bones are remodeled continually in response to 2 factors: 1. Pull of gravity and muscles on skeleton. 2. Ca++ levels in blood If blood Ca++ , then Parathyroid hormone (PTH) activates Osteoclasts breaksdown bone matrix and releases Ca++ ions If blood Ca++ , then Calcitonin (Thyroid gland) activates Osteoblasts deposits Ca++ ions into bone matrix

Bone Markings Surface features of bones Sites of attachments for muscles, tendons, and ligaments Passages for nerves and blood vessels Categories of bone markings Projections and processes – grow out from the bone surface Depressions or cavities – indentations Slide 5.9 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Classification of Bones Long bones 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 cube-shape mostly spongy bone Examples: Carpals, tarsals Slide 5.4b 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 shapes Do not fit into other bone classification categories Example: Vertebrae and hip Slide 5.5b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Skeletal System Consists of 206 bones: Divided into two divisions (Informational) Consists of 206 bones: Divided into two divisions Axial skeleton – 80 bones Appendicular skeleton – 126 bones Slide 5.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Axial skeleton – 80 bones (Informational) Consists of: Skull – 22 bones 8 crainal bones 14 facial bones hyoid bone – 1 bone Auditory ossicles – 6 bones stapes, incus, malleus Vertebrae – 26 bones Thorax – 25 bones sternum 24 ribs Slide 5.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Appendicular skeleton – 126 bones Consists of: Pectoral girdles – 4 bones 2 clavicles 2 scapulas Upper extremities – 60 bones 2 humerus 2 ulnas 2 radius 16 carpals 10 metacarpals 28 phalanges Pelvic girdle - 2 bones Lower extremities - 60 bones 2 femurs 10 metatarsals 2 fibulas 28 phalanges 2 Tibias 2 Patellas 14 Tarsals (Informational) Slide 5.1

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 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

The Bony Thorax Forms a cage to protect major organs Made-up of three parts Sternum Ribs Thoracic vertebrae Figure 5.19a Slide 5.31a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Arches of the Foot Bones of the foot are arranged to form three strong arches Two longitudinal One transverse Figure 5.26 Slide 5.42 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

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

Joints Articulations of bones Functions of joints ● Hold bones together ● Allow for mobility Ways joints are classified Function - Movement Immovable joints – synarthrosis (sutures) Slightly movable joints – ampiarthrosis Freely movable joints – diarthrosis (synovial joints) Structure Fibrious joints – immovable joints = synarthrosis Cartilaginous joints –Ampiarthrosis = slightly moveable Synovial joints – diarthrosis = freely movable

Fibrous Joints = synarthrosis Bones united by fibrous tissue Examples Sutures Syndesmoses Allows more movement than sutures Example: distal end of tibia and fibula Figure 5.27d, e Slide 5.46 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Cartilaginous Joints Bones connected by cartilage Examples of Synarthrosis Epiphyseal plate Verterbrae between ribs & sternum Examples of ampiarthrosis Pubic symphysis Intervertebral joints Figure 5.27b, c Slide 5.47

Synovial Joints General structure: Articular cartilage – acts as a lubricant joint cavity filled w/Synovial fluid Articular capsule – fibrious CT Reinforcement ligament Figure 5.27f–h Slide 5.48

Types of Synovial Joints Based on Shape 1. non-axial joints – found/located where bones are flat or slightly curved; allowed for only slipping movements betweeen bones (joints of wrist)

Types of Synovial Joints Based on Shape 2. uniaxial joints – movement of bone in only 1 plane Ex: pivot joint, hinge joint

Types of Synovial Joints Based on Shape 3. biaxial joints – move in 2 planes Ex: condyloid joints, saddle joints

Types of Synovial Joints Based on Shape 4. multiaxial joints – moves in all planes Ex: ball and socket joints

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

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

Developmental Aspects of the Skeletal System At birth, the skull bones are incomplete Bones are joined by fibrous membranes – fontanelles Fontanelles are completely replaced with bone within two years after birth Slide 5.55 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings