Joints

Question 1

What are joints

Answer 1

a connection between two bones in the skeletal system (whether or not the bones are movable at that interface)

Question 2

why are joints important

Answer 2

they allow movement
they protect the softer organs

Question 3

how are joints classified

Answer 3

they can be classified by the type of tissue present or by the degree of movement permitted

Question 4

from where are joint names derived

Answer 4

from the names of the bones involved

Question 5

what are the main categories of joints

Answer 5

bony
synovial
cartilaginous
fibrous

Question 6

bony joints

Answer 6

immovable joint formed when the gap between two joints hardens and the bones become a single bone

Question 7

fibrous joints

Answer 7

adjacent bones are bound by collagen fibres that emerge from one bone, cross the space between them and penetrate into the other
require strength and stability over a range of movement

Question 8

what are the types of fibrous joints

Answer 8

syndesmoses
sutures
gomphoses

Question 9

sutures

Answer 9

immovable or slightly movable fibrous joints that closely bind the bones of the skull to each other
joints are held together by short, interconnecting fibres and bone edges interlock
only found in the skull

Question 10

how can sutures be classified as

Answer 10

serrate- interlocking wavy lines
lap (squamous)- overlapping beveled edges
plane (butt)- straight, non overlapping edges

Question 11

gomphosis

Answer 11

attachment of tooth to its socket
held in place by fibrous periodontal ligament
collagen fibres attach to tooth jawbone
allows the tooth to move a little under the stress of chewing

Question 12

syndesmosis

Answer 12

a fibrous joint where two bones are bound together by collagen fibres
e.g interosseous membrane joining radius to ulna allowing supination and pronation

Question 13

cartilaginous joint/ amphiarthrosis

Answer 13

two bones linked by cartilage

Question 14

types of cartilaginous joints

Answer 14

synchondroses
symphyses

Question 15

synchondroses

Answer 15

bones joined by hyaline cartilage

Question 16

symphyses

Answer 16

two bones joined by fibrocartilage

pubic symphysis joins left and right pubic bones with interpubic disc

bodies of vertebrate joined by intervertebral discs

Question 17

synovial joints/ diarthorsis

Answer 17

joint in which two bones are separated by a joint cavity
most familiar type of joint
free mobile
their mobility makes them important to quality of life

Question 18

types of synovial joints

Answer 18

joint cavity- separates articular surfaces (joints)
synovial fluid- slippery lubricant in joint cavity, rich in albumin and hyaluronic acid, gives it a viscous slippery texture, nourishes articular cartilage and removes waste, makes movement of synovial joints almost friction free
articular cartilage- layer of hyaline cartilage that covers the facing surfaces of two bones

Question 19

exercise and articular cartilage

Answer 19

exercise warms synovial fluid so that it becomes less viscous and more easily absorbed by cartilage
cartilage then swells and provides a more effective cushion
warm up period helps protect cartilage from undue wear and tear
repetitive compression of non vascular cartilage during exercise squeezes fluid and metabolic waste out of cartilage
when weight is removed cartilage absorbs synovial fluid like a sponge taking in oxygen and nutrients to the chondrocytes
without exercise cartilages deteriorates more rapidly from inadequate nutrition and waste removal

Question 20

joint (articular) capsule

Answer 20

connective tissue that encloses the cavity and retains the fluid

Question 21

synovial membrane

Answer 21

composed mainly of fibroblast like B cells that secrete synovial fluid and macrophages that remove debris from the joint cavity

Question 22

meniscus

Answer 22

moon shaped cartilage in knee
absorbs shock and pressure
guides bones across each other and improve their fit together
stabilize joints, reducing the chance of dislocation

Question 23

accessory structures of synovial joints

Answer 23

tendons- strip of collagenous tissue attaching muscle to bone
ligament- strip of collagenous tissue attaching bone to bone
bursa- fibrous sac filled with synovial fluid located between muscles where tendons pass over bone or between bone and skin (cushion muscles help tendon slide more easily over joints, modifies direction of tendon pull)
tendon sheath- elongated cylindrical bursa wrapped around a tendon (found in hand/foot)

Question 24

what are the 6 classes of synovial joints

Answer 24

ball and socket joints- smooth hemispherical head fits within cup like socket- multiracial joints in the body- allows free movement

ellipsoid joints- oval convex surface of one bone fits into a complementary shaped depression on the other- biaxial joint (movement in 2 planes)

saddle joints- both bones have an articular surface that is shaped like a saddle, one concave the other convex- biaxial joint

plane joints- flat articular surfaces, bones slide over each other- biaxial joints

hinge joints- one bone with convex surface fits into a concave depression of another bone- monoaxial joint (moves freely in one plane)

pivot joints- bone spins on it longitudinal axis- monoaxial joint- allows for rotation only

Question 25

zero position

Answer 25

the position of a joint when the person is in the standard anatomical position

Question 26

flexion and extension

Answer 26

flexion- movement that decreases the joint angle
extension movement that straightens a joint and returns a body part to the zero position

Question 27

hyperextension

Answer 27

extension of a joint beyond the zero position

Question 28

abduction and adduction

Answer 28

abduction- movement of a body part in the frontal plane away from the midline of the body
adduction- movement in the frontal plane back toward the midline

Question 29

hyperabduction and hyperadduction

Answer 29

hyperabduction- raise arm over back or front of head
hyperadduction- crossing fingers or ankles

Question 30

elevation and depression

Answer 30

elevation- movement that raises a body part vertically in the frontal plane
depression- movement that lowers a body part in the frontal plane

Question 31

protraction and retraction

Answer 31

protraction- anterior movement of a body part in the transverse plane
refraction- posterior movement

Question 32

circumduction

Answer 32

one end of an appendage remains stationary while the other ends make a circular motion

Question 33

rotation

Answer 33

movement in which a bone spins on its longitudinal axis

Question 34

medial (internal) and lateral (external) rotation

Answer 34

medial rotation- turns the bone inward
lateral rotation- turns the bone outward

Question 35

forearm movements

Answer 35

supination- turns palm to face upward- radius is parallel to the ulna
pronation- turns palm to face downward- radius crosses stationary ulna like an x

Question 36

movement of the mandible (lower jaw)

Answer 36

lateral excursion- right or left movement from the zero position
medial excursion- movement back to the median, zero position
protraction-retraction
elevation-depression

Question 37

movement of hand and digits

Answer 37

radial flexion- tilting hand toward thumb
ulnar flexion- tilting hand toward middle finger
abduction vs adduction of the fingers- spreading them apart vs bringing them together
flexion vs extension of fingers- curling them vs straightening them
palmar abduction- moving thumb away from hand and pointing it anteriorly
radial abduction- moving thumb away from index finger
flexion of thumb- tip of thumb directed towards palm
extension of thumb- straightening the thumb
opposition- moving thumb to touch the tip of the finger
reposition- returning thumb to the zero position

Question 38

movement of the foot

Answer 38

dorsiflexion- elevating toes as you do while swinging foot forward to take a step
plantar flexion- extending foot so that toes point downward as in standing on tiptoe
inversion- movement in which soles are turned medially
eversion- movement in which soles are turned laterally