Bone, Joint, Muscle Biomechanics Flashcards
(46 cards)
What is the function of bone?
- stability- provide a frame to support body
- mobility- attachment for muscle sites and therefore moving limbs
- protection- spinal cord
What are the two types of bone?
- corticol (hard)- dense, forms outer layer
2. trabecular (spongy bone)- low density, fills interior
How do we fracture a bone?
apply excessive amount of force to the bone
How do we get compression fracture?
two forces move to each other in same line of action
ex. compression fracture
How do we get torsion fracture?
two torques rotate the object in different directions
ex. tibia fracture- turning the tibia forcefully while foot is on ground
How do we get tension fracture?
two forces move away from each other in same line of action
ex. transverse patella fracture
How do we get bending fracture?
compression force applies to one side of the object while tension force applies to the other side of object
ex. FOOSH, colles fracture
How do we get shear fracture?
two forces move towards or away from each in different lines of action
ex. tibia fracture- blow to tibia while foot is planted
Wolff’s law
if loading on a particular bone increases the bone will remodel itself overtime to become stronger to resist that sort of loading
What is stiffness in biomechanics terms?
stress/ strain
the object is stiff if a large amount of force can be applied and only a small amount of change in shape
Which bone is more stiff a normal bone or immobilized bone?
normal
What are the three types of joints?
- synarthrosis- joint that can hardly move (skull)
- ampiarthrosis- joints that can slight move usually fibrocartilage (IV discs, SI joint)
- diarthrosis- joints that can move freely and have DOF
In biomechanics how is DOF defined?
as the number of axis that the joint can rotate around
What is a plane joint?
articular surfaces are flat, allow gliding motions
ex. intercarpal bones
0 DOF
ligaments always support these joints
What is a hinge joint?
modeled like a door hinge
ex. humeroulnar joint
1 DOF
What is a pivot joint?
a ring shape bone rotates on the longitudinal axis of the other bone
ex. AA joint, supination/pronation
1 DOF, facilitates transverse rotation
What is a saddle joint?
joint surface looks like a saddle that has both convex-concave configurations
ex. CMC jt
allows 2 DOF
What is a condyloid joint?
an oval head sits on an elliptical cavity
ex. radiocarpal joints
allows 2 DOF
What is a ball and socket joint?
ball head sits on a round socket
ex. shoulder (deep) and hip (shallow)
allow 3 DOF
What factors contribute to joint stability?
- joint configuration- less mobility more stability
- Soft tissues- ligaments, muscles and jt capsule
- joint position
What does a close packed jt position mean?
the joint space is minimized
most ligaments and joints around joint are taut
ex. closed pack knee- full extension and ER
closed pack ankle- DF
What does a loose packed jt position mean?
jt space is maximized
most ligaments and capsule are loose around jt
ex. loose pack for knee= 25 flexion
this is important for joint mobs
What involves a muscle biggest to smallest?
muscle belly—–muscle fibers—-sacromere
What compromises a motor unit?
- alpha motor neuron
- axon
- muscle fiber innervated
CNS controls muscle activities through motor units
