chapter 02 week 2 lecture 1

PTHA 1513FUNCTIONAL ANATOMY

Week 2: Lecture 1 Elaine Wilson, PT

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Today’s Theme Song 2

Goals for Today3

Describe the components of the axial versus appendicular skeleton

Define the primary components found in bone

Describe the 5 types of bones found in the human skeleton

Describe the 3 primary classifications of joints and give an anatomic example of each

Identify the components of a synovial joint

Goals for Today - cont’d4

Describe the seven different classifications of synovial joints in terms of mobility (degrees of freedom) and stability

Provide an anatomic example of each of the 7 different classifications of synovial joints

Describe the 3 primary materials found in connective tissue

Explain how tendons and ligaments support the structure of a joint

Explain how muscles help to stabilize a joint Describe the effects of immobilization on the

connective tissues of a joint

CHAPTER 2Structure & Function of Joints

Axial versus Appendicular Skeleton

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Axial skeleton Skull, hyoid bone, ribs, and vertebral

column Forms central, semi-rigid bony axis

of body Appendicular skeleton

Bones of appendages—or extremities Includes scapula in upper extremity

and pelvis in lower extremity

Bone Tissue Types7

Cortical (compact) bone Dense and extremely strong Typically lines outermost bone portion Absorbs compressive forces

Cancellous bone Porous and lightweight Typically composes inner bone portions Redirects forces toward weight-bearing

sources

Bone Anatomy8

Diaphysis Central shaft of bone, a thick hollow

tube Composed mostly of cortical bone

Epiphyses Portions of bone arising from diaphysis Primarily composed of spongy bone Transmits weight-bearing forces across

body

Bone Anatomy – cont’d9

Articular cartilage Lines articular surface of each epiphysis Acts as shock absorber between joints

Periosteum Thin, tough membrane covering long bones

Secures attachment of muscles and ligaments to bone

Bone Anatomy – cont’d10

Medullary canal Central hollow tube within long bone

diaphysis Stores bone marrow; provides passage for

arteries Endosteum

Membrane that lines medullary canal surface

Houses cells important for forming and repairing bones

Bone Types11

Long bones Contains an obvious axis or shaft Expanded bone portion at each shaft end Examples include femur, humerus, and

radius Short bones

Length, width, and height are about equal An example includes carpal bones of the

hand

Bone Types – cont’d12

Flat bones Typically flat or slightly curved Often base for expansive muscular

attachments Examples include scapula and sternum

Irregular bones Wide variety of shapes and sizes Sesamoid (appear similar to sesame seed)

Encased within muscle tendonsProtect the tendon and increase the

muscle’s leverage

Joint Classification13

Synarthrosis Junction between bones allowing little to no

movement Primary function: firmly bind bones

together and transmit forces from one bone to another

Amphiarthrosis Formed primarily by fibrocartilage and

hyaline cartilage Allow limited amounts of motion Primary function: provide shock absorption

Joint Classification – cont’d14

Diarthrosis (synovial joint) Articulation that contains a fluid-filled joint cavity between two or more bones

Includes seven uniquely functioning categories

All synovial joints share seven common attributes

7 Common Elements of Synovial Joints

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1. Synovial fluid: provides joint lubrication and nutrition

2. Articular cartilage: dissipates and absorbs compressive forces

3. Articular capsule: connective tissue that surrounds and binds the joint together

Mosby items and derived items © 2009 by Mosby, Inc., an affiliate of Elsevier Inc.

7 Common Elements of Synovial Joints – cont’d

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4. Synovial membrane: produces synovial fluid

5. Capsular ligaments: thickened regions of connective tissue that limit excessive joint motion

6. Blood vessels: provide nutrients to the joint

7. Sensory nerves: transmit signals regarding pain and proprioception

Mosby items and derived items © 2009 by Mosby, Inc., an affiliate of Elsevier Inc.

Synovial Joint Classification17

Hinge joint Allows motion in only one plane about a single axis of rotation, similar to the hinge of a door

Ex- the humeroulnar joint (elbow)

Pivot joint Allows rotation about a single longitudinal axis of rotation, similar to the rotation of a doorknob

Ex- the proximal radioulnar joint

Synovial Joint Classification – cont’d

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Ellipsoid joint Convex elongated surface mated with a

concave surface Allows motion to occur in two planes Ex- radiocarpal (wrist) joint

Ball-and-socket joint Articulation between spherical convex

surface and cup-like socket Allows wide ranges of motion in all three

planes Ex- hip joint

Synovial Joint Classification – cont’d

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Plane joint Articulation between two relatively flat

bony surfaces Allows limited amount of motion; may slide

and rotate in many different directions Ex- intercarpal joints of the hand

Saddle joint One concave and one convex surface Allows extensive motion, primarily in two

planes Ex- carpometacarpal joint of the thumb

Synovial Joint Classification – cont’d

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Condyloid joints Articulation between a large, rounded, convex member and a relatively shallow concave member

Most often these joints allow 2 degrees of freedom

Ex- tibiofemoral (knee) joint Mosby items and derived items © 2009 by Mosby, Inc., an affiliate of Elsevier Inc.

Composition of Connective Tissues

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All connective tissues supporting the joints of the body are composed of fibers, ground substance, and cells

These biologic materials are blended in various proportions on the basis of the joint’s mechanical demands

Mosby items and derived items © 2009 by Mosby, Inc., an affiliate of Elsevier Inc.

Fiber Types 22

Type I collagen fibers Thick, rugged fibers that resist elongation Compose ligaments, tendons, and fibrous

capsules Type II collagen fibers

Thinner and less stiff than type I fibers Provide a flexible woven framework for

maintaining the general shape and consistency of structures

Fiber Types – cont’d23

Elastin Elastic in nature Resist (tensile) forces but have more “give” when elongated

Can be useful in preventing injury because they allow the tissue to “bend, but not break”

Ground Substance and Cells24

Ground substance Composed primarily of

glycosaminoglycans (gags), water, and solutes

Allows body fibers to exist in a fluid-filled environment, dispersing repetitive forces

Cells Responsible for the maintenance and

repair of tissues that constitute joints

Types of Connective Tissue 25

Four basic types of connective tissue form the structure of joints: Dense, irregular connective tissue

Articular cartilage Fibrocartilage Bone

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Dense, Irregular Connective Tissue

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Binds bones together and restrains unwanted movement of joints

Composes ligaments and the tough external layer of joint capsules

Primarily type I collagen fibers, low elastin fiber content

Mosby items and derived items © 2009 by Mosby, Inc., an affiliate of Elsevier Inc.

Articular Cartilage 27

Resists and distributes compressive and shear forces transferred through articular surfaces

Covers the ends of articulating bones in synovial joints

High type II collagen fiber content; fibers help anchor the cartilage to bone

Mosby items and derived items © 2009 by Mosby, Inc., an affiliate of Elsevier Inc.

Fibrocartilage 28

Provides support and stabilization to joints

Provides shock absorption by resisting and dispersing compressive and shear forces

Composes the intervertebral discs of the spine and the menisci of the knee

Multidirectional bundles of type I collagen

Mosby items and derived items © 2009 by Mosby, Inc., an affiliate of Elsevier Inc.

Bone 29

Forms primary supporting structure of the body and provides a rigid lever to transmit muscle force to move and stabilize the body

Forms internal levers of musculoskeletal system

Specialized arrangement of type I collagen providing a framework for hard mineral salts

Functional Considerations: Tendons and Ligaments 30

The fibrous composition of tendons and ligaments is similar, but arrangement and functions differ significantly

Tendons connect muscle to bone and convert muscular force into bony motion, with parallel alignment of collagen fibers

Ligaments connect bone to bone and maintain a joint’s structure, with irregular crossing patterns of collagen fibers

Functional Considerations:Active Joint Stabilization

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Bony conformation and ligamentous networks provide static stability

Muscles function as active stabilizers

Muscles cannot respond as quickly as ligaments to external force, but allow a graded and more controlled response

Mosby items and derived items © 2009 by Mosby, Inc., an affiliate of Elsevier Inc.

Immobilization and Connective Tissues

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Joint immobilization increases stiffness and decreases tissue ability to withstand forces

Immobilization may be necessary but makes joints susceptible to injury/instability

Rehabilitation programs involve a relatively quick return to weight bearing and possibly specific strengthening exercises

Mosby items and derived items © 2009 by Mosby, Inc., an affiliate of Elsevier Inc.

Summary33

Each type of joint has specific functional capabilities

Range of motion and relative stability of a joint depend on bony structure, surrounding muscles, and connective tissues

Trade-off between stability and mobility of a joint

Every joint in the body must find the balance between mobility and stability to function properly

Homework34

Please read Chapter 3 in textbook prior to lecture/lab on Thursday 01/26/12

Quiz #2: Chapters 3 & 4 – Tuesday 01/31/12