Chapter 008

The Human Body in Health and Illness, 4th edition

Barbara Herlihy

Chapter 8:Skeletal System

Lesson 8-1 Objectives

• List the functions of the skeletal system.• Describe the structure of a long bone.• Compare compact and spongy bone.• Describe how bones grow.• Describe the roles of osteoblasts and

osteoclasts.

Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights

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Skeletal System Overview

• The skeletal system is composed of– Bones– Joints– Cartilage– Ligaments


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Functions of the Skeletal System

• Supports body weight• Supports and protects soft organs• With muscles, enables body movement• Stores important minerals, including calcium

and phosphorus• Contains bone marrow, which produces blood

cells


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Sizes and Shapes of Bones

• Long• Short• Flat• Irregular


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Two Types of Bone

• Compact or hard– Osteons– Shafts: Long bones

• Spongy or soft– Trabecular plates– Swiss cheese– Bone marrow


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Parts of Long Bone • Diaphysis• Epiphysis• Epiphyseal disc• Medullary cavity• Endosteum• Periosteum• Articular cartilage• Marrow


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Two Types of Ossification

• Intramembranous ossification– Replacement of thin connective tissue membrane

with bone– In flat bones

• Endochondral ossification– Replacement of fetal cartilage skeleton with bone– In long, irregular, and short bones


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Ossification in the Fetus

• Intramembranous ossification– In flat bones of skull

• Endochondral ossification– In all other bones


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Bones Growing Taller

• Occurs at the epiphyseal disc– Osteoblasts invade cartilage in disc.– They mature into osteocytes (bone).

• Affected by hormones– Growth hormone– Estrogen– Testosterone


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Bones Growing Wider

• Sculptor (osteoclasts) hollows bone.

• Builder (osteoblasts) deposits bone on outer surface.

• Osteoclastic activity is called resorption.


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Bone Markings: Projections• Condyle: Large knob• Epicondyle: Enlargement near a condyle• Head: Enlarged, rounded end • Facet: Small flattened surface• Crest: Ridge • Spine: Sharp projection• Tuberosity: Knoblike projection• Trochanter: Large tuberosity only on femur


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Bone Markings: Depressions and Openings

• Foramen: Opening, usually passage for nerves, blood vessels, ligaments

• Fossa: Groove• Meatus: Tunnel or tubelike passageway• Sinus: Cavity or hollow space


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Types of Fractures

• Simple• Compound• Greenstick


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• List the bones of the axial skeleton.• List the bones of the appendicular skeleton.• Label important landmarks for selected bones

on the skeleton.


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Bones of the Axial Skeleton

• Skull: Cranium, facial, middle ear bones

• Hyoid• Vertebral column• Thoracic cage: Ribs,

sternum, thoracic vertebrae


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Bones of the Skull• Cranial

– Held together by sutures

– Little movement

• Facial– Mandible contains

only movable joint

• Middle ear bones


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Special Markings • Temporal bone

– External auditory meatus

– Zygomatic process– Styloid process – Mastoid process

• Occipital bone– Foramen magnum– Occipital condyles


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Paranasal Sinuses

• Frontal• Ethmoidal• Sphenoidal• Maxillary


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Fetal Skull and Fontanels• Fontanels are

soft spots– Not yet

converted to bone

– Covered with fibrous tissue

– Allow for cranial growth


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Vertebral Column• Sections

– Cervical – Thoracic – Lumbar – Sacrum and coccyx

• Curves– Cervical– Thoracic– Lumbar– Sacral


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Vertebrae • Atlas (C1): Nods “yes”• Axis (C2): Rotates

“no”• Other vertebral parts

– Vertebral foramen– Body– Lamina– Spinous process– Padded by

intervertebral discs


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Disorders of the Vertebral Column

• Scoliosis: Lateral curve

• Kyphosis: Hunchback

• Lordosis: Swayback


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Thoracic Cage• Sternum

– Manubrium– Body– Xiphoid process

• Ribs (12 pairs)– Seven pairs of true ribs– Five pairs of false ribs,

including two pairs of floating ribs

• Thoracic vertebraeCopyright © 2011, 2007 by Saunders,

an imprint of Elsevier Inc. All rights reserved.

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Landmarks of Thoracic Cage

• Xiphoid process• Suprasternal notch• Sternomanubrial joint• Costal angle• Costal margin


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Bones of the Appendicular Skeleton

• Pectoral girdle – Scapulae– Clavicles

• Upper limbs• Pelvic girdle

– Coxal bones

• Lower limbs


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Pectoral Girdle and Upper Limb• Pectoral girdle

– Clavicle– Scapula

• Upper limb– Humerus – Radius and ulna – Carpals – Metacarpals – Phalanges


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Pelvic Girdle: Coxal Bones• Functions

– Weight bearing– Attachment for

lower limbs– Protection of organs

• Coxal bone – Ilium– Ischium– Pubis

• Acetabulum• Symphysis pubis


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Lower Limb• Thigh

– Femur ( with trochanters)

• Leg bones– Patella– Tibia (with medial

malleolus)– Fibula (with lateral

malleolus)


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Lower Limb: Ankle and Foot

• Foot bones– Tarsals – Metatarsals – Phalanges

• Arches– Form instep


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• List the main types and functions of joints.• Describe the types of joint movement.


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Types of Joints

• Immovable• Slightly movable• Freely movable


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Structure of Freely Movable Joints• Articular cartilage• Joint capsule• Synovial membrane• Synovial fluid• Cartilage• Some joints also have

– Bursae– Ligaments


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Types of Freely Movable Joints• Hinge: Elbows, knees• Ball-and-socket: Shoulders,

hips• Pivot: Atlas-axis joint• Saddle: Carpometacarpal• Gliding: Wrist• Condyloid: Knuckles


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Joint Names: Articulating Bones• Tibiofemoral

– Tibia and femur• Humeroulnar

– Humerus and ulna• Metacarpophalangeal

– Metacarpal bone and phalange

• Glenohumeral– Glenoid cavity and humerus


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Types of Joint Movement• Flexion-extension• Inversion-eversion• Supination-pronation• Abduction-adduction• Dorsiflexion-plantar

flexion• Hyperextension• Circumduction


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Health & Medicine

Chapter 008