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OMM Study Guide
LECTURE 16 – Joints
1. What’s a joint? How do you name/classify it? Do they all involve cartilage or bone?
a. junction between bones and/or cartilage
b. 3 classifications of joints: function, anatomy or structure, composition
c. some joints do not involve cartilage or bone. (ex gomphosis)
2. Explain the 3 joint types (based on function), note any special cases/examples: Synarthrosis,
Amphiarthrosis, Diarthrosis.
a. Immovable (Synarthrosis)



fibrous joints
synostis-fusion of 2 bones
synchondrosis-cartilaginous joint when connecting medium is hyaline cartilage.
Ex: epiphyseal growth plate (cartilage converted into bone in adult)
b. Slightly Movable (Amphiarthrosis)
 cartilaginous joints
 syndesmosis- fibrous joint uniting bones with sheet of fibrous tissue
Ex: radioulnar interosseous membrane and tibiofibular interosseous membrane;
symphysis Ex: pubic symphysis
c. Freely Movable (Diarthrosis)
 synovial joints
o synovium- viscous fluid in a cavity between 2 bones
o joint capsule- fibrous layer and synovial membrane
3. If you were given an array of test tubes with synovial fluid in them, what would they look like
if a sample was: normal, noninflammatory, inflammatory, septic, hemorrhage?
A
B
C
D
Synovial fluid:
A normal
B noninflammatory
C inflammatory
D septic
E E hemorrhage
4. Name 3 functions of synovial fluid.
a. Lubricates surfaces to reduce friction
b. Shock absorption
c. Movement of nutrients and wastes
5. Name and describe the 5 accessory of diarthrotic joints.
a. Ligaments – dense regular CT (collagen); stabilizes and prevents excessive
movements of joints joint; contain proprioceptors
b. Articular Discs – fibrocartilage discs between bones; modify articular surfaces to
stabilize joint; C shaped; temporomandibular joint, ulnocarpal joint (Complex)
c. Fat Pads – collection of adipocytes enclosed within a fibrous CT sheath; fill space
created during movement; absorb shock; seen in knee
d. Bursae-connective tissue sacs lined with synovial cells; contains synovial fluid;
decrease friction between tendon/bone/skin
e. Labrum – fibrocartilage extension at ball and socket joints (ex. scapula, os coxa);
accommodates head of humerus/femur
6. Where would the following be? (and give and example) : extracapsular ligaments,
intracapsular ligaments, intrinsic ligaments, extrinsic ligaments?
a. extracapsular ligaments – outside joint capsule; ex. medial (tibial) collateral
ligament
b. intracapsular ligaments – inside joint capsule, but outside synovial membrane; ex.
anterior cruciate ligament (ACL)
c. intrinsic ligaments – part of the fibrous joint capsule; thickened bands of the
capsule; ex. medial (tibial) collateral ligament of the knee
d. extrinsic ligaments –separate from the joint capsule; ex. lateral (fibular) collateral
ligament of the knee
7. Define a sprain. Describe the 3 types of sprain.
a. sprain- ligament injury; occurs when the ligament is stretched beyond capacity.
Ligament has collagen (not stretchable) and elastic fibers. Cartilage doesn’t repair



because avascular.
Type 1- ligaments stretched
Type 2-ligaments torn slightly
Type 3- ligaments torn completely
8. How do you get a meniscal tear? What are the red and white zones? What causes pain in such
a case?
a. torn cartilage
b. occurs during a twisting or pivoting motion with the foot planted on the ground
c. outer 1/3 of a meniscus- greater access to the blood (called the red zone) ; when
torn, has the best chance of healing
inner 2/3- no blood supply (called the white zone) and thus no ability to heal.
d. the menisci have no nerve endings, pain associated with a tear is actually due to
swelling and injury to the surrounding tissue.
9. Discuss operative vs. non-operative treatment for meniscal tears.
a. Non-Operative treatment - physical therapy and anti-inflammatories. May only
provide a temporary relief (depends on (zone) location of tear).
b. Operative treatment - arthroscopic surgery The torn portion is either removed or
sutured
10. What are bursae? Where are they? What is bursitis?


sacs of synovial fluid
most commonly located between skin and bone (subcutaneous) and between a tendon
and bone (subtendinous)

bursitis- inflammation of bursa
 caused by repetitive motions or positions at a joint; trauma
 Ex. housemaids knee and students elbow
11. Where would you find a labrum/lip? What’s a labral tear?
a. Ex. acetabular labrum, glenoid labrum
b. labral tear:
i. cartilage damage due to overuse, trauma, or structural abnormalities
ii. often requires surgery (cartilage undergoes minimal regeneration)
12. Define rheumatoid arthritis.
a. autoimmune disease in which the immune system attacks joint tissues (and other
organs).
b. pattern of joints affected is usually symmetrical, involves the hands and other joints
and is worse in the morning.
c. systemic (body-wide) disease, whereas osteoarthritis is limited to the joints. Both
forms of arthritis can be crippling.
d. typically occurs after age 40 and is more common in women
e. can affect the skin, eyes, lungs and blood vessels
13. Define osteoarthritis. When do you get it? Is it curable? Common risk factors?
a.
b.
c.
d.
e.
most common form of arthritis
called wear-and-tear arthritis
occurs when articular cartilage wears down
it most commonly affects joints in your hands, neck, lower back, knees and hips.
treatable, not curable, and worsens over time.
f. age, sex (female), obesity, and injury are the common risk factors
14. Why would someone need a joint replacement? What would it do for you?
a. becomes necessary to reduce joint pain, restore/maintain joint motion, and
improve alignment/function
b. synovial joints throughout the body may be replaced.
c. surgery involves the removal of abnormal bone and linings, followed by the
implantation of synthetic joints (typically metal, plastic, or carbon-coated
implants).
d. artificial joints may need to be placed over time (not permanent)
15. Why should you eat broccoli/brussel sprouts?
a. sulforaphane- a chemical found mainly in broccoli (also in Brussels sprouts and
cabbage), reduces joint damage.
16. What actions occur at movement of synovial joints? ________________ determines the type
of joint and actions possible.
a. actions: flexion; extension; abduction; adduction; circumduction; opposition;
pronation; supination; rotation; inversion; eversion
b. actions are specific to each joint.
c. shapes of the bones making up the synovial joint determine the TYPE of joint and
the ACTIONS possible.
17. Discuss the synovial joint types based on shape: glide, hinge, pivot, ellipsoid, saddle, ball and
socket.
a. glide-permits gliding movement
b.
c.
d.
e.
f.
hinge- permits flexion and extension; uniaxial
pivot-permits rotation around axis
ellipsoid- permits flexion, extension,abduction, & adduction; biaxial aka condyloid
saddle-permits flexion, extension,abduction, & adduction; biaxial
ball and socket-permits many actions; broad contact surfaces
18. Discuss the joint types based on tissue: synovial, fibrous, cartilaginous.
a. synovial-bones separated by joint cavity; lubriacted by synovial fluid
Ex: shoulder, elbow, carpal, hip, knee, etc
b. fibrous- bones held together by collaginous fibers; no joint cavity
Ex:skull suture, teeth sockets, radioulnar and tibiofibular joints
c. cartilaginous- bones held together by cartilage; no joint cavity
i. Ex: epiphyseal plate, pubic symphyisis
19. What kind of relationship exists b/t joint mobility and stability?
a. inverse relationship
20. Discuss the factors maintaining the stability at a joint (as described here in order from most to
least important): Muscles, ligaments, bones.
a. Muscles: The tone of different groups of muscles acting on the joint is the most
important factor in maintaining stability. Without muscles, the knee and shoulder,
for example, would be unstable. The arches of foot would have collapsed.
b. Ligaments: Important in preventing any over-movement and in guarding against
sudden stresses. However, continuous strain (stretching) causes the ligament to
remain elongated. In this respect, the elastic ligaments (e.g., some those of the
vertebral column) are superior to fibrous (collagen) ligaments
c. Bones: Help in maintaining the stability of only a few joints. Otherwise in most
of the joints there role is negligible
21. What are fontanelles?
a. soft spot in developing skull
b. membranous areas not yet ossified in the developing cranium
c. once they fully ossify no further expansion of the braincase is possible
d. brain is only about 25% of its adult volume at birth, has only reached 50% of
adult size by one year, and continues growing until about 20 years
22. How long do you have patent sutures?
a. sutures remain patent until the mid-to-late 20s.
23. 2 main functions of fontanelles?
a. allow stretching of the cranium for brain growth (the brain expands faster than the
surrounding bone)
b. allow for molding (skull shape change as the fetus passes through the birth canal
during birth). Results in conehead babies. Shape returns to normal within 24 hours
24. List the timing of fontanelle closures: posterior, sphenoidal, mastoidal, anterior.
a.
b.
c.
d.
posterior fontanelle at 2-3 months
sphenoidal fontanelle at 6 months
mastoidal fontanelle 6-18 months
anterior fontanelle 1-3 years
25. Discuss craniosynostosis.
a. one or more of the sutures of an infant skull prematurely fuses, changing the
growth pattern of the skull.
b. the skull cannot expand perpendicular to the fused suture; this causes growth to
be limited to an orientation parallel to the closed sutures
c. sometimes there is adequate space for the growing brain, but abnormal head shape
and facial features develop
d. when there is not enough space for brain development, the result is an increase in
intracranial pressure that often leads to visual impairment, sleeping impairment,
eating difficulties, and/or impaired mental development (reduced IQ). Incidence =
1 in 2000 births.
e. craniosynostosis may be part of a syndrome, but most commonly occurs as an
isolated condition. The genes responsible have been “tentatively” identified.
26. Discuss joint vascularity (ie, anastomoses).
a. synovial joints are typically supplied by several arteries (articular branches), which
form anastomoses
b. arterial anastomosis- connection of two separate arteries.
c. multiple sources of blood flow ensure adequate supply of oxygen and nutrients
27. What is Hilton’s law? Discuss joint innervation.
a. Hilton's law states that the nerve supplying a muscle that moves a joint, also
carries sensory information (pain, proprioception) from the joint. For example, the
muscles that move the knee joint (primarily flexion and extension) exist in 3
groups (anterior, medial, and posterior).
b. these muscle groups are mostly innervated by femoral, obturator, and sciatic
nerves, respectively.
c. the three nerves then give off branches (articular branches) that carry sensory
information from the knee joint.
28. What is hypermobility syndrome? Causes?
a. double jointedness
b. many potential causes including: bone shape, collagen composition (genetic),
hypotonia (decreased muscle tone, often caused by conditions such as Muscular
Dystrophy), and proprioception deficits