Download Welch Notes - Humble ISD

Chapter 8: Joints
Objectives
Classification of Joints
1. Define joint or articulation.
2. Classify joints by structure and function.
Fibrous Joints
3. Describe the general structure of fibrous joints. Name and give an example of each of the three common types
of fibrous joints.
Cartilaginous Joints
4. Describe the general structure of cartilaginous joints. Name and give an example of each of the two common
types of cartilaginous joints.
Synovial Joints
5. Describe the structural characteristics of synovial joints.
6. Compare the structures and functions of bursae and tendon sheaths.
7. List three natural factors that stabilize synovial joints.
8. Name and describe (or perform) the common body movements.
9. Name and provide examples of the six types of synovial joints based on the movement(s) allowed.
10. Describe the elbow, knee, hip, jaw, and shoulder joints in terms of articulating bones, anatomical characteristics of the joint, movements allowed, and joint stability.
Homeostatic Imbalances of Joints
11. Name the most common joint injuries and discuss the symptoms and problems associated with each.
12. Compare and contrast the common types of arthritis.
13. Describe the cause and consequences of Lyme disease.
Developmental Aspects of Joints
14. Discuss factors that promote or disturb joint homeostasis.
Suggested Lecture Outline
I. Classification of Joints (pp. 249–250; Figs. 8.1–8.3; Tables 8.1–8.2) aka: articulation or arthrosis
A. Structural classification focuses on the material binding the bones together and whether or not a joint cavity is
present (p. 249; Table 8.1).
1. Structurally, joints may be fibrous, cartilaginous, or synovial.
B. Functional classification is based on the amount of movement allowed at the joint (p. 250).
1. Functionally, joints may be synarthroses (immovable joints), amphiarthroses (slightly movable joints), or diarthroses (freely movable joints).
II. Fibrous Joints (pp. 250–251; Fig. 8.1; Tables 8.1–8.2)
A. In fibrous joints, bones are (1) joined together by fibrous tissue and (2) lack a joint cavity, and provide (3) little
to no movement (p. 250).
B. There are three types of fibrous joints: sutures, syndesmoses, and gomphoses (pp. 250–251; Fig. 8.1).
86
Copyright © 2013 Pearson Education, Inc.
1. Sutures occur between bones of the skull and use very short connective tissue fibers to hold the bones together. Ex: coronal, sagittal, lambdoid, squamous sutures; synarthroses (immovable) and amphiarthroses
(slightly movable)
2. In syndesmoses, the bones are connected by a ligament, which is a cord or band of fibrous tissue. Ex: distal
tibiofibular joint. Amphiarthroses (slightly movable)
3. A gomphosis is a peg-in-socket fibrous joint. Ex: teeth
4. Interosseous membrane – sheet of DICT; amphiarthroses (slightly movable); Ex: between radial & ulnar
shaft as well as tibia & fibula
III. Cartilaginous Joints (pp. 251–252; Fig. 8.2; Tables 8.1–8.2)
A. In cartilaginous joints, the bones are (1) joined together by cartilage, they (2) lack a joint cavity, and have very
(3) little mobility (p. 251).
B. There are two types of cartilaginous joints: synchondroses, and symphyses (pp. 251–252; Fig. 8.2).
1. In synchondroses, a plate of hyaline cartilage connects the bones, as with the epiphyseal plate. Synarthroses
(immovable)
2. In symphyses, such as the pubic symphysis, the articular surfaces are covered with articular cartilage that is
then fused to an intervening pad or plate of fibrocartilage. Amphiarthroses (slightly movable)
IV. Synovial Joints (pp. 252–269; Figs. 8.3–8.13; Tables 8.1–8.2)
A. Synovial joints have a structure that allows free movement about the joint (p. 252).
B. The general structure of a synovial joint contains six distinguishing features (pp. 252–253; Fig. 8.3).
1. Articular cartilage covers the ends of the articulating bones.
Smooth, slippery hyaline cartilage; reduces friction & absorbs
shock
2. The joint (synovial) cavity is a space that is filled with synovial
fluid.
3. The two-layered articular capsule, consisting of:
a. fibrous layer (outer layer):
 DICT attached to periosteum; permits movement due to
its flexibility with great tensile strength; prevents dislocation.
 Some ligamentous bundles (DRCT) – approximates bones
close; resists strains
b. synovial membrane: inner layer; areolar CT with elastic fibers; many include articular fat pads.
Double-jointed – increase flexibility of capsule & ligaments.
4. Synovial fluid is a viscous, slippery fluid that fills all free space within the joint cavity. Contains hyaluronic acid – lubrication & phagocytic cells – engulf wear & tear debris
5. Reinforcing (Accessory) ligaments cross synovial joints to strengthen the joint. Extracapsular & intracapsular. Additional Accessory Structures:
a. Articular Discs (Menisci) – fibrocartilage.
b. Labra – ball & socket; Fibrocartilaginous; deepens socket to increase contact.
6. There is a rich supply of nerves innervating the capsule that detect proprioception, pain and stretch and
blood vessels supplying the synovial membrane, giving rise to capillaries that provide filtrate that becomes
synovial fluid.
C. Bursae and tendon sheaths contain lubricant that reduces friction at synovial joints (p. 253; Fig. 8.4).
1. Bursae – saclike; located between skin and bones, tendons and bones, muscles and bones, or ligaments and
bones.
2. Tendon (Synovial) Sheath – tube-like bursae wrapped around tendons forming a tunnel.
Copyright © 2013 Pearson Education, Inc.
CHAPTER 8
Joints
87
D. Factors Influencing the Stability of Synovial Joints (pp. 255–256)
1. Structure & Shape of bones – The shapes of the articular surfaces of bones found at a synovial joint determine the movements that occur at the joint, but play a minimal role in stabilizing the joint.
2. Strength & tension of ligaments – Ligaments at a synovial joint prevent excessive or unwanted movements
and help to stabilize the joint; the greater the number of ligaments at the joint, the greater the stability.
3. Muscle tone keeps tendons crossing joints taut, which is the most important factor stabilizing joints.
4. Contact of soft tissue – ex. Pregnant woman bending over to tie her shoes; flexing arm at elbow limited by
biceps brachii
5. Hormones – relaxin via placenta & ovaries and effects on pelvic outlet & ligaments of pelvis
6. Disuse – don’t use it; you lose it; due to decrease synovial fluid diminished flexibility of ligaments & tendons, muscular atrophy (wasting away).
E. Movements Allowed by Synovial Joints (pp. 256–258; Figs. 8.5–8.6; Table 8.2)
1. Skeletal muscles attach to bones or other connective structures at two points: the origin, attached to the
immovable bone; and the insertion, attached to the movable bone.
2. Gliding movements occur when one flat, or nearly flat, bone surface glides or slips over another.
3. Angular movements increase or decrease the angle between two bones.
a. Flexion decreases the angle of the joint and brings the articulating bones closer together.
b. Extension increases the angle between the articulating bones.
c. Dorsiflexion decreases the angle between the top of the foot (dorsal surface) and the anterior surface of
the tibia. Specific to ankle.
d. Plantar flexion decreases the angle between the sole of the foot (plantar surface) and the posterior side
of the tibia. Specific to ankle.
e. Abduction is the movement of a limb (or fingers) away from the midline body (or of the hand).
f. Adduction is the movement of a limb (or fingers) toward the midline of the body (or the hand).
g. Circumduction is moving a limb so that it describes a cone in the air.
4. Rotation is the turning of a bone along its own long axis.
5. Special Movements
a. Supination is rotating the forearm laterally so that the palm faces anteriorly or superiorly. Ex: holding a
bowl of soup with both hands.
b. Pronation is rotating the arm medially so that the palm faces posteriorly or inferiorly. Palms face posteriorly.
c. Inversion turns the sole of the foot so that it faces medially.
d. Eversion turns the sole of the foot so that it faces laterally.
e. Protraction moves the mandible anteriorly, juts the jaw forward.
f. Retraction returns the mandible to its original position.
g. Elevation means lifting a body part superiorly.
h. Depression means to move an elevated body part inferiorly.
i. Opposition occurs when you touch your thumb to the fingers on the same hand.
F. Types of Synovial Joints (p. 258; Fig. 8.7; Table 8.2)
1. Plane joints have flat articular surfaces and allow gliding and transitional movements.
2. Hinge joints consist of a cylindrical projection that nests in a trough-shaped structure, and allow movement
along a single plane.
3. Pivot joints consist of a rounded structure that protrudes into a sleeve or ring, and allow uniaxial rotation of
a bone around the long axis.
4. Condylar joints consist of an oval articular surface that nests in a complementary depression, and permit all
angular movements.
88
INSTRUCTOR GUIDE FOR HUMAN ANATOMY & PHYSIOLOGY, 9e
Copyright © 2013 Pearson Education, Inc.
5. Saddle joints consist of each articular surface bearing complementary concave and convex areas, and allow
more freedom of movement than condylar joints.
6. Ball-and-socket joints consist of a spherical or hemispherical structure that articulates with a cuplike structure. They are the most freely moving joints and allow multiaxial movements.
G. Selected Synovial Joints (pp. 262–269; Figs. 8.8–8.13; Table 8.2)
1. Knee Joint - largest and most complex joint; modified hinge joint.
a. The single cavity of the knee joint is actually three joints in one: the femoropatellar joint, the lateral and
medial joints between the femoral condyles, and the menisci of the tibia, known collectively as the tibiofemoral joint. Patellar ligament – strengthen anterior aspect; contains infrapatellar fat pad.
i. The tibiofemoral joint is a hinge joint, allowing mostly flexion and extension, although limited rotation
is possible when the knee is bent.
ii. The femoropatellar joint is a plane joint that allows the patella to glide across the knee when the knee
is flexed.
b. Three types of ligaments stabilize and strengthen the capsule of the knee joint: capsular and extracapsular ligaments prevent hyperextension and rotation when the knee is extended, and intracapsular ligaments, the cruciates, keep the articulating bones of the knee aligned.
i. Collateral ligaments
a. Tibial (medial) – Strengthens medial aspect; crossed by sartorius, gracilis & semitendinosus
muscles. Attached to medial meniscus.
b. Fibular (lateral) – Strengthens lateral aspect; biceps femoris muscle.
ii. Intracapsular ligaments – 2 cruciate ligaments; crisscross
a. ACL – limits hyperextension of knee; involved in 70% of all knee injuries. Injuries more common
in women than men.
b. PCL – Prevents posterior sliding of the tibia and anterior sliding of the femur; important when
walking down stairs or steep incline.
Injuries: “Terrible Triad” – medial collateral, ACL & medial meniscus
c. The knee capsule is reinforced by muscle tendons such as the strong tendons of the quadriceps muscles
and the tendon of the semimembranosus.
d. Articular discs (menisci) – fibrocartilage
i. Medial meniscus – C-shaped
ii. Lateral meniscus – O-shaped
2. Shoulder (Glenohumeral) Joint
a. The shoulder joint is a ball-and-socket joint that is the most freely moving joint in the body, although it is
not a very stable joint. Similar to a golf ball on a tee; glenoid labrum deepens socket
b. The joint capsule surrounding the shoulder joint is thin and loose, and supporting ligaments are located
mostly on the anterior aspect, and are weak.
c. The tendons that cross the shoulder joint form the rotator cuff, encircling the joint, and providing the
most stabilizing effect on the joint. RC: Supraspinous, infraspinous, subscapularis, & teres minor
Injuries: dislocation – mc inferiorly, separated – @ AC joint, mc RC tear – supraspinatus
3. Elbow Joint
a. The joint between the ulna and humerus provides a stable and smoothly operating hinge joint that allows
flexion and extension only.
b. The thin articular capsule of the elbow provides substantial flexion and extension, but side-to-side movements are restricted by strong capsular ligaments.
c. Tendons of several arm muscles, the biceps and the triceps, also provide additional stability by crossing
the elbow joint.
d. The radius is not involved in flexion or extension at the elbow, but rotates within the annular ligament to
provide pronation and supination of the forearm. Annular ligament of the radius – holds radial head in
Copyright © 2013 Pearson Education, Inc.
CHAPTER 8
Joints
89
place. Injuries: Describe Tennis Elbow – lateral epicondylitis, Little-League Elbow – inflammation of medial epicondyle, and Nursemaids Elbow – radial head dislocation.
4. Hip (Coxal) Joint
a. The hip joint is a ball-and-socket joint that provides a wide range of motion.
b. Several strong ligaments reinforce the capsule of the hip joint.
i. Iliofemoral ligament – body’s strongest ligament; prevents ______________________.
ii. Pubofemoral ligmnet – prevents _______________.
iii. Ischiofemoral ligament – slackens with adduction & tenses during abduction.
iv. Femoral head ligament – usually with small artery to head of femur.
c. The muscle tendons that cross the joint contribute to the stability and strength of the joint, but the majority of the stability of the hip joint is due to the deep socket of the acetabulum and the ligaments.
i. Acetabular labrum – fibrocartilage ring deepens socket
5. Temporomandibular Joint
a. The temporomandibular joint allows both hinge-like movement and side-to-side lateral excursion.
b. The joint contains an articular disc (fibrocartilage) that divides the synovial cavity into compartments that
support each type of movement.
c. The lateral aspect of the articular capsule contains a lateral ligament that reinforces the joint. Covered by
parotid gland.
V. Homeostatic Imbalances of Joints (pp. 269–272; Figs. 8.14–8.15)
A. Common Joint Injuries (pp. 269–270; Fig. 8.14)
1. Sprains and dislocations are the most common joint injuries.
2. Cartilage tears often occur at the knee, when a meniscus is subjected to compression and shear stress at the
same time.
3. Sprains result from stretching or tearing of the ligaments and may repair themselves, although surgical repair may be necessary. Strains – stretching or tearing of tendon
4. Dislocations occur when the bones are forced out of alignment and are usually accompanied by sprains, inflammation, and immobility of the joint.
5. Subluxation – partial or incomplete dislocation
B. Inflammatory and Degenerative Conditions (pp. 270–272; Fig. 8.15)
1. Bursitis, an inflammation of the bursa, is usually caused by a blow or friction, while tendonitis is inflammation of the tendons, and is usually caused by overuse.
2. Arthritis describes many inflammatory or degenerative diseases that damage the joints, resulting in pain,
stiffness, and swelling of the joint.
a. Osteoarthritis (OA) is the most common chronic arthritis “wear & tear” arthritis. It is the result of breakdown of articular cartilage and subsequent thickening of bone tissue, which may restrict joint movement.
Afflicts larger joints (knees, hips) first
b. Rheumatoid arthritis (RA) is a chronic inflammatory disorder that is an autoimmune disease. Inflammation of synovial membrane causing swelling, pain, & loss of function. After time, membrane thickens &
synovial fluid accumulates resulting in abnormal granulation tissue (pannus). Cartilage erosion exposes fibrous tissue which ossifies and fuses the joint. Bilateral and smaller joints.
c. Gouty arthritis results when uric acid is deposited in the soft tissues of the joints. Uric acid is a waste
product from NA metabolism. Urate crystals form when uric acid reacts with sodium then accumulate in
kidneys, cartilage of ear & joints. Most commonly effects great toe.
d. Lyme disease is an inflammatory condition caused by a type of spirochete bacteria (Borrelia burgdorferi)
transmitted by ticks living on deer and mice. Bull’s-eye rash, joint stiffness, fever, chills,, headaches, stiff
neck, nausea, low back pain.
90
INSTRUCTOR GUIDE FOR HUMAN ANATOMY & PHYSIOLOGY, 9e
Copyright © 2013 Pearson Education, Inc.
e. Ankylosing Spondylitis – idiopathic inflammatory disease affecting IVDs & SI joints; onset mc 20-40 year
old males. Inflammation can lead to ankylosis (stiff) & kyphosis (hunchback)
VI. Developmental Aspects of Joints (pp. 272–273)
A. In an embryo, joints develop at the same time as bones, and resemble adult joints by week 8 (p. 272).
B. During childhood, use defines the size, shape, and flexibility of joints (p. 272).
C. At late middle age and beyond, ligaments and tendons shorten and weaken, intervertebral discs become more
likely to herniate, and there is onset of osteoarthritis (pp. 272–273).
Review all Homeostatic Imbalances, A Closer Look captions throughout the chapter and At-the-Clinic & Medical Terminology located in all chapters.
This is only a general outline. There may be material that has been discussed in lecture that is not included in this outline and there may be material
on this outline that has not been discussed in lecture. Any material discussed in lecture or listed in this outline is "fair game" for the test.
Copyright © 2013 Pearson Education, Inc.
CHAPTER 8
Joints
91