Skeletal System Chapter 7 Copyright 2016 by Elsevier

Learning Objectives Lesson 7. 1: Skeletal System 1. 2. 3. 4. 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 © 2016 by Elsevier Inc. All rights reserved. 2

Learning Objectives Lesson 7. 1: Skeletal System (Cont. ) 5. 6. 7. Identify the two major divisions of the skeleton and list the bones found in each area. Explain why individual human skeletons can vary from each other. List and compare the major types of joints in the body and give an example of each. Copyright © 2016 by Elsevier Inc. All rights reserved. 3

Functions of the Skeletal System Supports and gives shape to the body � Protects internal organs � Helps make movements possible when bones at moveable joints are pulled by muscles � Stores calcium � Ø Ø Ø � Hormones regulate calcium storage Calcitonin (CT) increases storage Parathyroid hormone (PTH) reduces stores of calcium Hemopoiesis Ø Blood cell formation in red bone marrow Copyright © 2016 by Elsevier Inc. All rights reserved. 4

Gross Structure of Bones � Four major bone types, according to overall shape of the bone Ø Ø Ø Long bones: For example, humerus (arm) Short bones: For example, carpals (wrist) Flat bones: For example, frontal (skull) Irregular bones: For example, vertebrae (spinal cord) Some scientists also recognize a sesamoid (round) bone category: For example, patella (kneecap) Copyright © 2016 by Elsevier Inc. All rights reserved. 5

Gross Structure of Bones (Cont. ) � Structure of long bones (Figure 7 -1) Ø Ø Ø Diaphysis or shaft: Hollow tube of hard compact bone Medullary cavity: Hollow area inside diaphysis bone that contains yellow bone marrow Epiphyses, or ends of the bone: Spongy bone that contains red bone marrow Articular cartilage: Covers epiphyses and functions as a cushion Periosteum: Strong membrane covering bone everywhere except at joint surfaces Endosteum: Thin membrane lining medullary cavity Copyright © 2016 by Elsevier Inc. All rights reserved. 6

Long Bone Copyright © 2016 by Elsevier Inc. All rights reserved. 7

Gross Structure of Bones (Cont. ) � Structure of flat bones (Figure 7 -2) Ø Ø Spongy bone layer sandwiched between two compact bone layers Diploe • Spongy bone layer of a flat bone Copyright © 2016 by Elsevier Inc. All rights reserved. 8

Flat Bone Copyright © 2016 by Elsevier Inc. All rights reserved. 9

Microscopic Structure of Bones � Bone tissue structure (Figures 7 -3 and 7 -4) Ø Cancellous (spongy) • • • Ø Texture results from needlelike threads of bone called trabeculae surrounded by a network of open spaces Found in epiphyses of bones Spaces contain red bone marrow Compact • • Structural unit is an osteon: Calcified matrix arranged in multiple layers or rings called concentric lamella Bone cells are called osteocytes and are found inside spaces called lacunae, which are connected by tiny tubes called canaliculi Copyright © 2016 by Elsevier Inc. All rights reserved. 10

Microscopic Structure of Bone Copyright © 2016 by Elsevier Inc. All rights reserved. 11

Compact Bone Courtesy Dennis Streete. Copyright © 2016 by Elsevier Inc. All rights reserved.

Microscopic Structure of Bones (Cont. ) � Cartilage tissue structure (Figure 7 -5) Ø Ø Cell type called chondrocyte Matrix is gel-like and lacks blood vessels Copyright © 2016 by Elsevier Inc. All rights reserved. 13

Cartilage Tissue Courtesy Dennis Streete. Copyright © 2016 by Elsevier Inc. All rights reserved.

Bone Development Early bone development (before birth) consists of cartilage and fibrous structures � Osteoblasts form new bone, and osteoclasts reabsorb bone; osteocytes are inactive osteoblasts (Figure 7 -6) � Cartilage models are gradually replaced by calcified bone matrix � Ø Process called endochondral ossification (Figures 7 -7 and 7 -8) Copyright © 2016 by Elsevier Inc. All rights reserved. 15

Bone Remodeling Adapted from Mc. Cance K, Huether S: Pathophysiology, ed 7, St Louis,

Endochondral Ossification Copyright © 2016 by Elsevier Inc. All rights reserved. 17

Bone Development in a Newborn Courtesy Network Graphics. Copyright © 2016 by Elsevier Inc.

Axial Skeleton Human skeleton has two divisions: the axial and the appendicular skeleton (Table 7 -1) � Axial skeleton � Ø � Appendicular skeleton Ø Ø � Bones of the skull, spine, chest, and hyoid bone in the neck Upper extremities, including shoulder (pectoral) girdle Lower extremities, including hip (pelvic) girdle Location and description of bones Ø See Figures 7 -9 to 7 -22 and Tables 7 -2 to 7 -6 Copyright © 2016 by Elsevier Inc. All rights reserved. 19

Human Skeleton Copyright © 2016 by Elsevier Inc. All rights reserved. 20

The Skull Courtesy Barbara Cousins. Copyright © 2016 by Elsevier Inc. All rights reserved.

Paranasal Sinuses Copyright © 2016 by Elsevier Inc. All rights reserved. 22

Hyoid Bone Copyright © 2016 by Elsevier Inc. All rights reserved. 23

The Vertebral Column Copyright © 2016 by Elsevier Inc. All rights reserved. 24

The Third Lumbar Vertebra Courtesy Barbara Cousins. Copyright © 2016 by Elsevier Inc. All

Atlas and Axis Adapted from Drake R, Vogl W, Mitchell AWM: Gray’s anatomy for

Spinal Curvature of an Infant From Hockenberry MJ, Wilson D: Wong’s essentials of pediatric

Bones of the Thorax Copyright © 2016 by Elsevier Inc. All rights reserved. 28

Bones of the Right Arm, Elbow, and Forearm (Anterior View) From Vidic B, Suarez FR: Photographic atlas of the human body, St Louis, 1984, Mosby. Copyright © 2016 by Elsevier Inc. All rights reserved. 29

Bones of the Right Arm, Elbow, and Forearm (Posterior View) From Vidic B, Suarez FR: Photographic atlas of the human body, St Louis, 1984, Mosby. Copyright © 2016 by Elsevier Inc. All rights reserved. 30

Bones of the Right Hand Wrist Copyright © 2016 by Elsevier Inc. All rights

Bones of the Right Thigh, Knee Joint, and Leg B and D: From Vidic

Bones of the Right Foot Copyright © 2016 by Elsevier Inc. All rights reserved.

Arches of the Foot Courtesy Yvonne Wylie Walston. Copyright © 2016 by Elsevier Inc.

Bones of the Skull Copyright © 2016 by Elsevier Inc. All rights reserved. 35

Bones of the Vertebral Column Copyright © 2016 by Elsevier Inc. All rights reserved.

Bones of the Thorax Copyright © 2016 by Elsevier Inc. All rights reserved. 37

Bones of the Upper Extremities Copyright © 2016 by Elsevier Inc. All rights reserved.

Bones of the Lower Extremities Copyright © 2016 by Elsevier Inc. All rights reserved.

Skeletal Variations � Size Ø � Shape of pelvis Ø Ø � Male pelvis deep and narrow Female pelvis broad and shallow Size of pelvic inlet Ø � Male skeleton generally larger Female pelvic inlet generally wider, normally large enough for baby’s head to pass through it (Figure 7 -23) Pubic angle Ø Angle between pubic bones of female generally wider Copyright © 2016 by Elsevier Inc. All rights reserved. 40

Comparison of the Male Pelvis and Female Pelvis Copyright © 2016 by Elsevier Inc.

Skeletal Variations (Cont. ) � Age differences Ø Ø � The human skeleton reaches its mature state around age 25 After age 50, the density of bone often decreases slowly Environmental factors Ø Ø Without enough calcium or vitamin D, the skeleton may show signs of degeneration Exercise has a profound effect on the skeleton Copyright © 2016 by Elsevier Inc. All rights reserved. 42

Joints � Articulation of bones Ø Ø Ø � Joints are also called articulations Joints hold our bones together and make it possible for movement to occur Every bone except the hyoid (which anchors the tongue) connects to at least one other bone Kinds of joints (Figures 7 -24 to 7 -26) Ø Ø Synarthroses (no movement): Fibrous connective tissue grows between articulating bones; for example, sutures of skull Amphiarthroses (slight movement): Cartilage connects articulating bones; for example, symphysis pubis Copyright © 2016 by Elsevier Inc. All rights reserved. 43

Joints (Cont. ) � Kinds of joints Ø 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 joints � Synovial membrane: Lines joint capsule and secretes lubricating fluid � Joint cavity: Space between joint ends of bones � Bursa: Fluid-filled pouch that absorbs shock; inflammation of bursa is called bursitis � Copyright © 2016 by Elsevier Inc. All rights reserved. 44

Joints (Cont. ) � Kinds of joints Ø Diarthroses • Functions of freely moveable joints: ball-and-socket, hinge, pivot, saddle, gliding, and condyloid � Allow different kinds of movements determined by the structure of each joint Copyright © 2016 by Elsevier Inc. All rights reserved. 45