the skeletal system - henry county schools /...

The Skeletal SystemThe Skeletal System

Slide 5.1Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

• Parts of the skeletal system

• Bones (skeleton)

• Joints: hold bone together & mobility

• Cartilages:

• Ligaments & Tendons

• Divided into two divisions

• Axial skeleton

• Appendicular skeleton

Functions of BonesFunctions of Bones


• Support of the body

• Protection of soft organs

• Movement due to attached skeletal muscles

• Storage of minerals and fats

• Blood cell formation

Bones of the Human BodyBones of the Human Body


• The skeleton has 206 bones

• Two basic types of bone tissue

•Compact bone

•Homogeneous

•Spongy bone

•Small needle-like pieces of bone

•Many open spaces

Figure 5.2b

Classification of BonesClassification of Bones

Slide 5.4aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

• Long bones

•Typically longer than wide

•Have a shaft with heads at both ends

•Contain mostly compact bone

• Examples: Femur, humerus


Slide 5.4bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

• Short bones

•Generally cube-shape

•Contain mostly spongy bone

•Examples: Carpals, tarsals

Classification of Bones on the Basis Classification of Bones on the Basis of Shapeof Shape

Slide 5.4cCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 5.1



• Flat bones

•Thin and flattened

•Usually curved

•Thin layers of compact bone around a layer of spongy bone

•Examples: Skull, ribs, sternum



• Irregular bones

•Irregular shape

•Do not fit into other bone classification categories

•Example: Vertebrae and hip

Gross Anatomy of a Long BoneGross Anatomy of a Long Bone


• Diaphysis

•Shaft

•Composed of compact bone

• Epiphysis

•Ends of the bone

•Composed mostly of spongy bone

Figure 5.2a

Structures of a Long BoneStructures of a Long Bone


• Periosteum

• Outside covering of the diaphysis

• Fibrous connective tissue membrane

• Sharpey’s fibers

• Secure periosteum to underlying bone

• Arteries

• Supply bone cells with nutrients

Figure 5.2c



• Articular cartilage

• Covers the external surface of the epiphyses

• Made of hyaline cartilage

• Decreases friction at joint surfaces Figure 5.2a



• Medullary cavity

•Cavity of the shaft

•Contains yellow marrow (mostly fat) in adults

•Contains red marrow (for blood cell formation) in infants Figure 5.2a

Bone MarkingsBone Markings


• 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

Microscopic Anatomy of BoneMicroscopic Anatomy of Bone


• Osteon (Haversian System)

•A unit of bone

• Central (Haversian) canal

•Opening in the center of an osteon

•Carries blood vessels and nerves

• Perforating (Volkman’s) canal

•Canal perpendicular to the central canal

•Carries blood vessels and nerves



Figure 5.3



• Lacunae

•Cavities containing bone cells (osteocytes)

•Arranged in concentric rings

• Lamellae

•Rings around the central canal

•Sites of lacunaeFigure 5.3



• Canaliculi

•Tiny canals

•Radiate from the central canal to lacunae

•Form a transport system Figure 5.3

Changes in the Human SkeletonChanges 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

Bone GrowthBone Growth


• Bones are remodeled and lengthened until growth stops

• 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

Long Bone Formation and GrowthLong Bone Formation and Growth


Figure 5.4a

Long Bone Formation and GrowthLong Bone Formation and Growth


Figure 5.4b

Types of Bone CellsTypes of Bone Cells


• Osteocytes• 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

Bone FracturesBone 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

Bone FractureTypes

Quiz on Types of Fractures

Repair of Bone FracturesRepair of Bone Fractures


• Hematoma (blood-filled swelling) is formed

• Break is splinted by fibrocartilage to form a callus. Osteoclasts break down bone.

• Fibrocartilage callus is replaced by a bony callus. Osteoblasts form bone and become Osteocytes .

• Bony callus is remodeled to form a permanent patch.

Stages in the Healing of a Bone Stages in the Healing of a Bone FractureFracture


Figure 5.5

Self-Care for Broken Bones

Check Out Dem Bones!

Facial Bones Quiz

Classification of Bones Quiz

Fetal Skull• Adult skull is 1/8 body length (infant

is ¼)

• When born, skeleton is unfinished –fontanels(soft spots)

• Largest are anterior and posterior

• Allow skull to compress in birth, room for brain to grow

Paranasal SinusesParanasal Sinuses


• Functions of paranasal sinuses

•Lighten the skull

•Give resonance and amplification to voice

Figure 5.10

Structural Classification of JointsStructural Classification of Joints


• Fibrous joints

•Generally immovable; bones connected by fibrous tissue: sutures

• Cartilaginous joints

• Immovable or slightly moveable; bones connected by cartilage: spine

• Synovial joints

•Freely moveable; have joint cavity with synovial fluid: elbow, wrist

Functional Classifications of Joints

• Synarthrosis

-immovable joint

• Amphiarthrosis

-a slightly movable joint

• Diarthrosis

-a freely movable joint

Let’s see the joints move.

• Don’t click on the cowboy, just hit next.

Moving Joints

Different Joint StructuresDifferent Joint Structures


Figure 5.27d, e

Structures Associated with the Structures Associated with the Synovial JointSynovial Joint


• Bursae – flattened fibrous sacs

• Lined with synovial membranes

• Filled with synovial fluid

• Not actually part of the joint

The Synovial JointThe Synovial Joint


Figure 5.28

52aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 5.29a–c

Types of Synovial Joints Based on Types of Synovial Joints Based on ShapeShape

Types of Joints Quiz

Inflammatory Conditions Associated Inflammatory Conditions Associated with Jointswith 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

Clinical Forms of ArthritisClinical 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

Two types of arthritis explained.

• Click on both boxes

Rheumatoid Arthritis Osteoarthritis

Gouty Arthritis (gout)• Uric acid accumulates in blood and

deposited in soft tissues of joints –painful attack of single joint (big toe)

• Males after 30, genetic

• Treatment – drugs, weight management

Developmental Aspects• Fetal development – flat and long

bones are converted to bone

• Birth – fontanels still remain for brain growth up to 2 years

• Adolescence – epiphyseal plates of long bones are ossified (quit growing)

Developmental Aspects• Puberty – female pelvis broadens

for childbearing, male skeleton becomes more robust

• Osteoporosis– loss of bone mass leading to thin, fragile bones

• In women – menopause estrogen deficiency, diet poor in Ca, smoking, or inactivity

Osteoporosis

Normal Osteoporosis

Herniated Disc

• Pressure on a disc ruptures the outer layer and forces the soft center (nucleus pulposus) out, which then puts pressure on a spinal nerve

• Most occur in lumbar region

Abnormalities of Spine• Scoliosis – abnormal lateral

curvature, can result in having one leg longer than the other

• Kyphosis (hunchback) – exaggerated thoracic curve

• Lordosis (swayback) – exaggerated lumbar curve

Scoliosis Kyphosis Lordosis

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