Chapter 9
0.45
a certain lever has a fulcrum at one end, has a tendon exerting an effort 5 cm distal to the fulcrum, and acts against a resistance another 6 cm distal to the effort. what is the mechanical advantage of this lever?
amphiarthrosis
a fibrous joint cannot also be what?
fulcrum
a lever is a rigid object that rotates around a fixed point called what?
bursa
a tendon sheath is a modified
arthroses
another name for articulations (joints)
united by fibrous connective tissue have no joint cavity allow little or no movement
characteristics of the fibrous joints
joint cavity synovial membrane synovial fluid
components of synovial joints
tendon sheaths
cylinders of connective tissue lined with synovial membrane and wrapped around a tendon
shoulder hip joint
examples of ball-and-socket joints
atlantooccipital
examples of ellipsoid joints
elbow ankle interphalangeal
examples of hinge joints
articulation between dens of axis and atlas proximal radioulnar distal radioulnar
examples of pivot joints
intervertrebral intercarpal intertarsal
examples of plane joints
thumb intercarpal sternoclavicular
examples of saddle joints
symphysis pubis intervertebral disks
examples of symphyses
epiphyseal plates sternocostal sphenooccipital
examples of synchondroses
accessory ligaments
extra capsular/intracapsular and stabilize joints
articular discs
fibrocartilage pads in the knee
symphyses
fibrocartilage uniting two bones slightly movable
suture
fibrous joint composed of a thin layer of dense irregular connective tissure
diarthrosis
freely movable
give the skeleton mobility hold the skeleton together
functions of the joints
Mechanical advantage = (length of the effort arm/length of the resistance arm)
how to calculate mechanical advantage
structural and functional
how to classify joints
fibrous joint
if two bones are joined so firmly together they cannot move, they form what?
interference by bones/cartilage tension in tendons at the joint
movement of synovial joints is limited by what?
monoaxial
movement that occurs around one axis
multiaxial
movement that occurs around several axes
biaxial
movement that occurs around two axes at right angles to each other
synarthrosis
non-movable
effort resistance
rotation occurs when ___ overcomes _____
bursae
saclike extension of joint capsule between nearby structures so slide more easily past each other
amphiarthrosis
slightly movable
synchondrosis
the hyaline costal cartilage that attaches a rib to the sternum forms what?
synovial joints
these are complex joints that are freely movable joints in the body
synchondroses
these are joined by hyaline cartilage little or no movement
gomphoses
these are pegs that fit into sockets
cartilaginous joints
these are united two bones by means of cartilage
syndesmoses
these bones are farther apart than suture and joined by ligaments
periodontal ligaments
these hold teeth in place
functional
this classification is based on degree of motion
structural
this classification is based on major connective tissue type that binds bones
synarthrosis amphiarthrosis diarthrosis
three types of functional classifications
fibrous cartilaginous synovial
three types of structural classifications
true
true or false: a single joint may combine features of condyloid, hinge, and gliding joints.
lever that helps increase output of force lever that moves objects further and faster
two kinds of mechanical levers
synchondroses and symphyses
two types of cartilaginous joints are?
sutures (synostosis) syndesmoses gomphoses
types of fibrous joints
speed/force
types of levers produce either increase in what two things?
plane saddle hinge pivot ball-and-socket ellipsoid
types of synovial joints
gomphosis
unlike other joints, a ____ does not join two bones to each other
hinge joints
what type of synovial joint? concave and convex surfaces monoaxial
pivot joints
what type of synovial joint? cylindrical projection inside a ring monoaxial rotation around a single axis
ellipsoid joints
what type of synovial joint? modified ball-and-socket ellipsoid concave and convex surfaces biaxial
ball-and-socket joints
what type of synovial joint? rounded surface into a socket multiaxial
plane joints
what type of synovial joint? two flat surfaces monoaxial some rotation possible but limited by surrounding structures
saddle joints
what type of synovial joint? two saddle-shaped surfaces biaxial
MA < 1.0
which of the following is true of joints that are first-class levers? MA (>, =) 1.0 MA < 1.0 their output forces > the input force resistance is between the joint and the distal end of the bone the fulcrum is at the opposite end from the tendinous insertion