Bones and Biomechanics

Question 1

If you broke your femur immediately adjacent to the head, would it be mostly compact or cancellous cone that would be damaged?

Answer 1

cancellous bone

Question 2

Why does compact bone tissue need to have a different arrangement for the blood vessels compared to cancellous bone?

Answer 2

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

Question 3

Where is the primary ossification centre located?

Answer 3

in the diaphysis

Question 4

Why is it that cartilage cells proliferate at the growth/epiphyseal plate, but this layer does not get relatively thicker over time?

Answer 4

Osteoblasts ossify the tissue during growth

Question 5

List two possible uses for an accurate knowledge of the age at which growth plates became ossified

Answer 5

1. allows age estimation of human remains

2. treatment of bone damage as types and regions of fractures may differ with age

Question 6

What factors contribute to the disease process of osteoporosis?

Answer 6

osteoclastic activity outpacing osteoblastic activity

Question 7

Will everyone with osteoporosis be affected by fractured bone?

Answer 7

no - trauma would be required for fracturing long bones and the severity of the disease would be a factor incompression fractures of vertebrae

Question 8

What muscle produces abduction at the shoulder joint?

Answer 8

deltoid

Question 9

Why would biceps brachii not be a supinator of it attached to the ulna, instead of the radius?

Answer 9

supination requires the radius to move over the ulna. ulna is fixed and doesn’t rotate

Question 10

Why are screws normally threaded so they tighten by being turned clockwise in wrist?

Answer 10

because right handed people supinate to turn something clockwise

Question 11

Why is triceps brachii not a supinator or pronator?

Answer 11

because it attaches to the ulna

Question 12

Given that triceps brachii is an extensor of the elbow joint, which aspect of the joint does it cross?

Answer 12

posterior

Question 13

Which muscle produces hip joint extension?

Answer 13

gluteus maximus and hamstrings

Question 14

Why would a person with paralysis of the gluteus maximus muscle chose not to live in a two storey house?

Answer 14

climbing stairs would be difficult as the gluteus maximus is a strong hip extensor and paralysis would make it difficult to extend the joint

Question 15

Which muscle produces knee joint extension?

Answer 15

quadriceps femoris

Question 16

Why will triceps surae plantarflex, not dorsiflex the ankle?

Answer 16

Because it crosses the posterior aspect of the ankle joint

Question 17

When a muscle is active and develops tension but there is no visible change in joint position, what type of action is this?

Answer 17

isometric

Question 18

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?

Answer 18

concentric

Question 19

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?

Answer 19

eccentric

Question 20

Thinking about the microscopic structure of muscle, why does a muscle create the greatest tension in the middle of the range of movement?

Answer 20

optimal overlap between actin and myosin myofilaments

Question 21

Draw the most common arrangement if anatomical lever in the body and name two joints that have this arrangement

Answer 21

force weight
Axis______/\_________
\/
resistance
Third class lever e.g biceps brachii at elbow, hamstrings at knee

Question 22

Name one joint that has the most effective arrangement for transferring forces from the muscle to the bone

Answer 22

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.

Question 23

When kicking a ball, what muscle group in the thigh is acting as the antagonist at the point of contact and why?

Answer 23

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

Question 24

When you flex your elbow joint, which muscle is acting as the agonist and which is the antagonist?

Answer 24

biceps brachii - agonist

triceps brachii - antagonist

Question 25

Which muscle is the agonist in extension of the hip during mid-to-late stance phase?

Answer 25

gluteus maximus

Question 26

In which position is the knee joint held during the first half of stance phase?

Answer 26

extension

Question 27

During which phase of the gait cycle is the knee flexed?

Answer 27

second half of the stance phase and first half of swing phase to allow foot to clear the ground

Question 28

Which group of muscles is the agonist in extension of the knee at the end of swing phase?

Answer 28

quadriceps femoris

Question 29

Which group of muscles is the agonist in plantarflexion of the ankle, just prior to toe-off

Answer 29

triceps surae

Question 30

Which position is the ankle held in at heel strike?

Answer 30

dorsiflexion

Question 31

During bone growth ____________ in the periosteum increase the width of the bone; while ____________ in the endosteum form the bone shape and medullary cavity.

Answer 31

osteoblasts; osteoclasts

Question 32

the extracellular component of bone includes the inorganic component ____________, which resists ____________

Answer 32

hydroxyapatite; compression

Question 33

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?

Answer 33

rotation

Question 34

Agonist

Answer 34

Muscle shortens concentrically and therefore creates movement at a joint

Question 35

Antagonist

Answer 35

Muscle lengthens eccentrically to counteract a movement created at a joint

Question 36

Stabiliser

Answer 36

Muscle stays the same length isometrically to hold a joint still

Question 37

Another word for a growth plate is:

Answer 37

epiphyseal plate

Question 38

According to the principles of anatomical structure, how many bones does the arm have?

Answer 38

one

Question 39

osteoblasts ____________ ECM; osteoclasts ____________ ECM; and osteocytes ____________ ECM

Answer 39

build; break down; maintain

Question 40

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 ____________

Answer 40

flexion; sagittal; gluteus maximus

Question 41

in the image below, the muscle labelled A is ____________ and it crosses the hip joint ____________

Answer 41

rectus femoris; anteriorly