Bones and Biomechanics Flashcards
If you broke your femur immediately adjacent to the head, would it be mostly compact or cancellous cone that would be damaged?
cancellous bone
Why does compact bone tissue need to have a different arrangement for the blood vessels compared to cancellous bone?
compact bone tissue has different properties to cancellous bone. compact bone is composed of osteons which are tightly packed hence blood vessels are in the central canal of each osteon. cancellous bone has a great surface area with spaces between trabeculae filled with bone marrow and vessels, blood diffuses in
Where is the primary ossification centre located?
in the diaphysis
Why is it that cartilage cells proliferate at the growth/epiphyseal plate, but this layer does not get relatively thicker over time?
Osteoblasts ossify the tissue during growth
List two possible uses for an accurate knowledge of the age at which growth plates became ossified
- allows age estimation of human remains
2. treatment of bone damage as types and regions of fractures may differ with age
What factors contribute to the disease process of osteoporosis?
osteoclastic activity outpacing osteoblastic activity
Will everyone with osteoporosis be affected by fractured bone?
no - trauma would be required for fracturing long bones and the severity of the disease would be a factor incompression fractures of vertebrae
What muscle produces abduction at the shoulder joint?
deltoid
Why would biceps brachii not be a supinator of it attached to the ulna, instead of the radius?
supination requires the radius to move over the ulna. ulna is fixed and doesn’t rotate
Why are screws normally threaded so they tighten by being turned clockwise in wrist?
because right handed people supinate to turn something clockwise
Why is triceps brachii not a supinator or pronator?
because it attaches to the ulna
Given that triceps brachii is an extensor of the elbow joint, which aspect of the joint does it cross?
posterior
Which muscle produces hip joint extension?
gluteus maximus and hamstrings
Why would a person with paralysis of the gluteus maximus muscle chose not to live in a two storey house?
climbing stairs would be difficult as the gluteus maximus is a strong hip extensor and paralysis would make it difficult to extend the joint
Which muscle produces knee joint extension?
quadriceps femoris
Why will triceps surae plantarflex, not dorsiflex the ankle?
Because it crosses the posterior aspect of the ankle joint
When a muscle is active and develops tension but there is no visible change in joint position, what type of action is this?
isometric
When a muscle is active and develops tension and there is a visible change in joint position due to shortening of the muscle, what type of action is this?
concentric
When a muscle is active and develops tension and there is a visible change in joint position due to the lengthening of the muscle, what type of action is this?
eccentric
Thinking about the microscopic structure of muscle, why does a muscle create the greatest tension in the middle of the range of movement?
optimal overlap between actin and myosin myofilaments
Draw the most common arrangement if anatomical lever in the body and name two joints that have this arrangement
force weight
Axis______/\_________
\/
resistance
Third class lever e.g biceps brachii at elbow, hamstrings at knee
Name one joint that has the most effective arrangement for transferring forces from the muscle to the bone
biceps brachii, a third class lever with parallel muscle attaching to the scapula proximally and to the radius distally, crossing the elbow joint and allowing a wide range of movement and force.
When kicking a ball, what muscle group in the thigh is acting as the antagonist at the point of contact and why?
Hamstrings is antagonist and opposes and controls the movement as it is a knee flexor, quad femoris is the agonist to extend the knee whilst kicking the ball
When you flex your elbow joint, which muscle is acting as the agonist and which is the antagonist?
biceps brachii - agonist
triceps brachii - antagonist
Which muscle is the agonist in extension of the hip during mid-to-late stance phase?
gluteus maximus
In which position is the knee joint held during the first half of stance phase?
extension
During which phase of the gait cycle is the knee flexed?
second half of the stance phase and first half of swing phase to allow foot to clear the ground
Which group of muscles is the agonist in extension of the knee at the end of swing phase?
quadriceps femoris
Which group of muscles is the agonist in plantarflexion of the ankle, just prior to toe-off
triceps surae
Which position is the ankle held in at heel strike?
dorsiflexion
During bone growth ____________ in the periosteum increase the width of the bone; while ____________ in the endosteum form the bone shape and medullary cavity.
osteoblasts; osteoclasts
the extracellular component of bone includes the inorganic component ____________, which resists ____________
hydroxyapatite; compression
The ellipsoid joint shown below (the wrist) is capable of circumduction - meaning it can flex, extend, adduct and adduct.
What other movement, which is possible at ball and socket joints, is NOT possible at this joint?
rotation
Agonist
Muscle shortens concentrically and therefore creates movement at a joint
Antagonist
Muscle lengthens eccentrically to counteract a movement created at a joint
Stabiliser
Muscle stays the same length isometrically to hold a joint still
Another word for a growth plate is:
epiphyseal plate
According to the principles of anatomical structure, how many bones does the arm have?
one
osteoblasts ____________ ECM; osteoclasts ____________ ECM; and osteocytes ____________ ECM
build; break down; maintain
During the swing phase of the gait cycle, the muscle labelled A causes ____________ of the hip joint to bring the lower limb forward in the ____________ plane. A major antagonist to this movement is ____________
flexion; sagittal; gluteus maximus
in the image below, the muscle labelled A is ____________ and it crosses the hip joint ____________
rectus femoris; anteriorly
