Exam 2 Flashcards
Study of mechanics as it relates to the function and anatomy of biological systems
Biomechanics
Mechanical variables that describe the characteristics of a motion in time and space (things we can see with our own eyes)
Kinematics
vector
direction and magnitude
scalar
distance
The vector change in position of an object in a 2 or 3 dimensional space
Displacement
Rate of change of displacement with respect to time
velocity
rate of change of velocity with respect to time
acceleration
Mechanical variables representing the forces responsible for causing changes in kinematics, resulting in movements (things we can’t see)
Kinetics
Newtons first law
a body in motion tends to remain in motion at a constant velocity unless acted upon by an external force
Newtons second law
net force applied to a body will act to accelerate the object in the direction of force
newtons third law
for every action, there is an equal and opposite reaction
may propel the body or associate with the absorption of an impact.
Acts to change the kinematics of the human body
ground reaction force
a shear force expressed between two surfaces
friction
expression of forces that cause angular motion
torque
to produce torque what 2 components are needed
- axis of rotation (joint center)
- Force applied at a perpendicular distance away from the joint center
1st class lever
effort force and resistance force are located on opposite sides of the lever
2nd class lever
the effort force and resistance force are located on same side of lever. effort force is located further away from the axis
3rd class lever
the effort force and resistance force are located on same side of lever. effort force is located closer to axis
main contributions to human movement in the foot and ankle
- foot and ankle apply forces to the ground and receive ground reaction forces
- disperse body weight and GRFs across bone and soft tissue
What are the two arches that help to distribute impact forces, maintain balance, and propel the body forward in gait
Longitudinal arch (medial and lateral)
Transverse arch
Characteristics of the medial longitudinal arch
- highly elastic
- assists in distributing forces through the foot
- assists in propelling the body forward in gait
Characteristics of the lateral longitudinal arch
- Rigid (good for stability)
- Assists in maintaining balance
- Assists in distributing forces through the foot
Characteristics of the transverse arch
- assists in distributing forces through the foot
- assists in propleling the body forward in gait
what gives arches their elasticity in the foot
helps stabilize the longitudinal arches
plantar fascia
what is the order of body weight transfer from the tibia and down
tibia to talus to calcaneus
Bone that is wider on the anterior side with provides more ankle stability when the foot moves into doriflexion vs plantar flexion
Talus
What are the 5 tarsals in the foot
Navicular
3 cuneiforms (medial, intermediat, lateral)
cuboid
these act as pulleys for muscles wrapping around posteriorly on the tibia and fibula
Lateral and medial malleoli
Skeletal muscle insersions in the foot
- Inner surface of medial cuneiform
- basses of all metatarals
- superior and inferior surfaces of distal phalanxes
- posterior calcaneus
Talocrural joint
Articulation
Motion
articulation - talus tibia and fibula
motion- plantarflexion (20 degrees from neutral) and dorsiflexion (50 degrees from neutral)
internal and external rotation
Subtalar and Transverse tarsal joints
Articulation
motion
articulation - talus and calcaneus (subtalar) Navicular, cuneiforms, cuboid and calcaneus (transverse tarsal)
Motion - inversion (30 degrees) and eversion (15 degrees)
High ankle sparin
distal interosseous membrane can be sprained. Usually from inversion of the ankle while positioned in dosriflexion
What is injured during a lateral ankle sprain with neutral foot alignment
Calcaneofibular ligament
What is injuring during a lateral ankle sprain with planar flexed alignment
Anterior talofibular ligament
What joint helps with foot clearance
knee joint
what muscles work together to take stress off the knee joint
hamstrings and quadriceps (dynamic stabilizers)
what allows the feet to push into the ground with more force
the knee joint transferring muscle force from the large muscles of the thigh and core to the lower leg
two major rigid structures supporting the knee joint
femur and tibia
these articulate to form the knee joint
femoral and tibial condyles
why is the medial femoral condyle larger than the lateral femoral condyle
the long axis of the femur runs slightly toward the midline of the body (q line)
does the fibula have articulation with the knee
no
sesamoid bone that pushes the quadriceps muscle force further away from the joint center
patella
Key bony landmarks in the knee
superior/inferior poles of patella
tibial tuberosity
gerdys tubercle
medial/lateral femoral epicondyles
upper anteromedial surface of tibia
head of fibula
gliding joint that increases the mechanical advantage of the quadriceps muscle group
patellofemoral joint
When the knee is flexed 30 degrees what motion can it also do
internal and external rotation
Static stability in the knee
bony stability
strong ligaments
menisci