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Chapter 9
Joints
Lecture Outline
Principles of Human Anatomy and Physiology, 11e
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Chapter 9
Joints
• Joints hold bones together but
permit movement
• Point of contact
– between 2 bones
– between cartilage and bone
– between teeth and bones
• Arthrology = study of joints
• Kinesiology = study of motion
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Types of Joints
• Fibrous Joints
• Cartilaginous Joints
• Synovial Joints
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Fibrous Joints
• Bones touch each other directly
with no space between (called a
synovial cavity)
• They permit little or no
movement and hold bones
tightly together.
• Examples: between skull bones,
between tibia and fibula, holding
the teeth in place
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Cartilaginous Joints
• Also connect bones tightly (via cartilage) with no space
between them
• Allows little or no movement
• Examples: joints between the ribs and sternum, or holding
the vertebrae together
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• Allow movement
Synovial Joints
• Have space between the
bones
• Articular cartilage
– reduces friction
– absorbs shock
• Articular capsule
– surrounds joint
• Synovial membrane
– inner lining of capsule
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Torn Cartilage
• Commonly occurs in athletes
• Cartilage between joints is torn
• Can be surgically repaired, often results in arthritis later in
life
• Arthroscopy is used to see the inside of a joint and repair it
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Sprain versus Strain
• Sprain
– twisting of joint that stretches or tears ligaments
– no dislocation of the bones
– may damage nearby blood vessels, muscles or
tendons
– swelling & hemorrhage from blood vessels
– ankle is frequently sprained
• Strain
– generally less serious injury
– overstretched or partially torn muscle
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TYPES OF MOVEMENT AT SYNOVIAL JOINTS
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•
•
•
Gliding
Angular Movements
Rotation
Special Movements
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Gliding Movements
• Gliding movements occur when relatively flat bone surfaces
move back and forth and from side to side with respect to
one another.
• In gliding joints there is no significant alteration of the angle
between the bones.
• Gliding movements occur at plantar joints.
• Example: waving your hand back and forth
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Angular Movements
• In angular movements there is an increase or a decrease in
the angle between articulating bones.
– Flexion results in a decrease in the angle between
articulating bones
– Extension results in an increase in the angle between
articulating bones
– Hyperextension is a continuation of extension beyond the
anatomical position and is usually prevented by the
arrangement of ligaments and the anatomical alignment
of bones
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Flexion, Extension & Hyperextension
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Abduction, Adduction, and Circumduction
• Abduction refers to the movement of a bone away from the
midline
• Adduction refers to the movement of a bone toward the
midline
• Circumduction refers to movement of the distal end of a part
of the body in a circle
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Rotation
• Bone revolves around its own
longitudinal axis
– medial rotation is turning of
anterior surface in towards the
midline
– lateral rotation is turning of
anterior surface away from
the midline
• At ball & socket and pivot type
joints
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Special Movements of Mandible
•
•
•
•
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Elevation = upward
Depression = downward
Protraction = forward
Retraction = backward
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Special Movements
• Inversion is movement of the soles medially at the
intertarsal joints so that they face away from each other
• Eversion is a movement of the soles laterally at the
intertarsal joints so that they face away from each other
• Dorsiflexion refers to bending of the foot at the ankle in the
direction of the superior surface
• Plantar flexion involves bending of the foot at the ankle joint
in the direction of the plantar surface
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Special Movements
• Supination is a movement of the forearm at the proximal
and distal radioulnar joints in which the palm is turned
anteriorly or superiorly
• Pronation is a movement of the forearm at the proximal and
distal radioulnar joints in which the distal end of the radius
crosses over the distal end of the ulna and the palm is
turned posteriorly or inferiorly
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Special Movements
• Opposition is the movement of the thumb at the
carpometacarpal joint in which the thumb moves across the
palm to touch the tips of the finger on the same hand.
• Review
– A summary of the movements that occur at synovial
joints is presented in Table 9.1.
• A dislocation or luxation is a displacement of a bone from a
joint.
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TYPES OF SYNOVIAL JOINTS
• Planar Joints: permit gliding at the wrists and ankles
• Hinge Joints: open and closing motions; knee, elbow,
fingers
• Pivot Joints: Allows your head to turn from side to side
• Condyloid Joints: knuckles
• Saddle Joints: joints in the thumb
• Ball and socket joints: shoulders and hips
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Tempromandibular Joint (TMJ) (Exhibit 9.1 and
Figure 9.11)
• The TMJ is a combined hinge and planar joint formed by the
condylar process of the mandible, the mandibular fossa, and
the articular tubercle of the temporal bone.
• Movements include opening and closing and protraction and
retraction of the jaw.
• When dislocation occurs, the mouth remains open.
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FACTORS AFFECTING CONTACT AND RANGE OF
MOTION AT SYNOVIAL JOINTS
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•
•
•
•
•
Structure and shape of the articulating bone
Strength and tautness of the joint ligaments
Arrangement and tension of the muscles
Contact of soft parts
Hormones
Disuse
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Aging and Joints
•
•
•
•
•
Decreased fluid and increased pain in joints
Cartilage becomes thinner
Joints become less flexible
You become more hunched over
Arthritis is common
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Arthroscopy & Arthroplasty
• Arthroscopy = examination of joint
– instrument size of pencil
– remove torn knee cartilages & repair ligaments
– small incision only
• Arthroplasty = replacement of joints
– total hip replaces acetabulum & head of femur
– plastic socket & metal head
– knee replacement common
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Techniques for cartilage replacement
• In cartilage transplantation chondrocytes are removed from
the patient, grown in culture, and then placed in the
damaged joint.
• Eroded cartilage may be replaced with synthetic materials
• Researchers are also examining the use of stem cells to
replace cartilage.
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DISORDERS: HOMEOSTATIC IMBALANCES:
• Lyme disease is a bacterial disease which is transmitted by
deer ticks. Symptoms include joint stiffness, fevers, chills,
headache, and stiff neck.
• Ankylosing spondylitis affects joints between the vertebrae
and between the sacrum and hip bone. Its cause is
unknown, and is common in males between 20 and 40
years old.
• Ankle Sprains: ankles are the most commonly sprained
bones in the bodies
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Rheumatoid Arthritis
•
•
•
•
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Autoimmune disorder
Cartilage attacked
Inflammation, swelling & pain
Final step is fusion of joint
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Osteoarthritis
• Degenerative joint disease
– aging, wear & tear
• Noninflammatory---no swelling
– only cartilage is affected not synovial membrane
• Deterioration of cartilage produces bone spurs
– restrict movement
• Pain upon awakening--disappears with movement
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Gouty Arthritis
• Urate crystals build up in joints---pain
– waste product of DNA & RNA metabolism
– builds up in blood
– deposited in cartilage causing inflammation & swelling
• Bones fuse
• Middle-aged men with abnormal gene
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