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Η εργασια (3 μοναδες): Βιβλιογραφικη ανασκοπηση
http://funfive.net/pictures/how-it-s-in-the-hospital/12384.html
Αρχαια Αρχιτεκτονικη και Υλικά
Bio-Engineering
Tissue Engineering
Bio-System Engineering
Medical Physics
BioFluid Mechanics & BioHeat Transfer
Biomechanics
Genetic Engineering
Τι γνωριζετe απο μοχλους (levers);
Force 2 Force 1
The bull - 1945
Watch the Process: https://www.youtube.com/watch?v=Kg4G3x2HSEI
BioMechanics
Dynamics
Statics
Tools/Skills you need: • Anatomy (Da Vinci, Borelli…)
• Mass/Center of Mass, Forces, Moments
• Free body Diagram (διάγραμμα ελευθέρου
σώματος)
• Newton’s Laws
Λίγο από ‘Στατική’...
Διαγραμμα Ελευθερου Σωματος &
Στηρίξεις
Στατικη: εξετάζει τις συνθήκες κάτω από τις οποίες ένας σωμα (φορέας) στέκεται, δηλαδή ισορροπεί
Τι ειναι ο ‘Φορεας’;
Φορεας ειναι ενα στερεο σωμα που ΔΕΝ μπορει να παραμορφωθει.
Σαν συνεπεια ο φορεας μπορει να μεταφερει ολα τα φορτια στα οποια ασκουνται πανω του.
Free body Diagram (FBD) From Wiki: A free body diagram is a sketch, used by engineers and physicists, to analyze the forces and moments acting on a body.
https://voer.edu.vn/c/normal-tension-and-other-examples-of-forces/0e60bfc6/ca96f97a#import-auto-id2149297
Question: why it is called the ‘free’ body?
Τι είναι Στήριξη; Στηριξη: μια διαταξη που στηριζει ενα φορεα,
δηλαδη μπορει να ‘παραλαβει’ καποιο φορτιο (δυναμεις, ροπες) απο το φορεα.
Στήριξη ΙIΙ : Πάκτωση
Εχουμε ΠΑΚΤΩΣΕΙΣ μεσα στον ανθρώπινο οργανισμό;
Στήριξη ΙΙ : Αρθρωση
Εχουμε ‘αρθρωσεις’ μεσα στον ανθρώπινο οργανισμό;
Παραδειγμα Αρθρωσης: Τραμπάλα
Στήριξη Ι : Κύλιση
Εχουμε ΚΥΛΙΣΕΙΣ μεσα στον ανθρώπινο οργανισμό;
Τεστ.
Στηρίξεις στην καθημερινή ζωή;
1. Κύλιση
3. Πάκτωση 2. Αρθρωση Roller Skating, 1905
Hinge
Test Problem 1.
1. Draw the Free Body Diagram (?) 2. Calculate the unknown force F 3. Calculate the Reaction Forces at the Joint ‘O’.
Force F
Object of Weight W1 Ραβδος βαρους W2
Αρθρωση Ο
Test Problem 2.
1. Draw the Free Body Diagram (?) 2. Calculate the Reaction Forces & Moment at the fixed
end of the beam (is F needed?)
Force F
Object of Weight W1 Ραβδος βαρους W2
Πακτωση (fixed end of the
beam)
Test Problem 3.
1. Draw the Free Body Diagram (?) 2. Calculate the Reaction Forces moment at the fixed ends
Object of Weight W1 Ραβδος βαρους W2
Πακτωση 2
Πακτωση 1
BioMechanics MECHANICS: study of physical action of forces (and moments) Mechanics is divided into: (Α) Statics: Study of systems that are in a constant state of motion (with zero or constant velocity) (Β) Dynamics: study of systems in motion with acceleration
Static BioMechanics Calculate Forces & Moments in Muscles, Bones & Joints
Applications: Sports, Rehabilitation (exercise in elderly arthritis patients, muscle strengthening in rheumatoid arthritis)…
OSTEOPOROSIS: Loss of Bone
http://beyondspine.com/2015/03/04/osteoporosis/
Ladies: the Weak Sex
Journal Paper: Exercise and the skeleton: How it works and what it really does
Sedentary: Καθιστικος
Static BioMechanics Calculate Forces and Moments in Muscles, Joints and Bones
More Applications: Ergonomics, Arthroplasty… http://news.bbc.co.uk/2/hi/6187080.stm
Types of Bone Fractures
The Process of Solving a Problem
1. What is the Problem?
2. Get to know the Anatomy
Connect the Anatomy to the Problem… (anatomy also gives you geometrical distances)
3. Modelling: A Reduction Process
REALITY
Assumptions
MODELLING
Force F
A Physical Model
Modelling and Picasso?
Watch the Process: https://www.youtube.com/watch?v=Kg4G3x2HSEI
Modelling the Human Muscoloskeletal System
1) Bones: as Rigid Bodies (φορεις) 2) Muscles: as Forces (need to know the location of the muscle attachment) 3) Human Joints: Σαν Αρθρωσεις
What about Ligaments & Tendons?
Modelling Bones
Φορεας
Bone
Force due to Weight
Is the above a FBD?
Bone Weight
Modelling Human Joints
http://www2.estrellamountain.edu/faculty/farabee/BIOBK/BioBookMUSSKEL.html
Human joints are modelled as ΑΡΘΡΩΣΕΙΣ...
Q: What type of Joint is the Elbow Joint?
http://www.physioroom.com/injuries/arm_and_elbow/elbow_arthritis_full.php
εξαρταται...
4. Free Body Diagram (for EACH element of the model)
Force F
Free Body Diagram
Weight of Object Reaction Forces
5. Mathematical Description (based on physical laws):
Newton’s 1st Law.
Ενας φορεας σε ισορροπια:
�𝐹𝑖
𝑛
𝑖=1
= 0 �𝑀𝑖
𝑚
𝑖=1
= 0
Do not forget: Moment With Respect to a Point!
An Example
Lifting weight with your biceps
How Much Force your Muscles generate?
BIC: Biceps (δικέφαλος μυς) BRA: Brachialis (βραχιόνιος μυς)
(Why lifting weight?)
Edouard Manet
The Luncheon on the Grass, 1863
Created in 1933
Rehab
http://www.sportsposterwarehouse.com/detail_FI-NFC09__458__bicepsforearm05fi_htm.html
How Much Force your Muscles
generate?
It is a Complicated Problem!
1. What is the Problem?
2. Anatomy of a Forearm
http://www.maloneyperformance.com/Blog/?p=390
What Muscles are Important?
Three Major Muscles involved
BIC: Biceps (δικέφαλος μυς) BRR: Brachioradialis (βραχιοκερκιδικός μυς) BRA: Brachialis (βραχιόνιος μυς)
http://vonblancofitness.com/quick-tip-of-the-day-do-hammer-curls-to-develop-your-outer-biceps-brachialis/
Modelling: Version I
http://www.engrevo.com/blog/biomechanics-of-bicep-curls/
BIC: Biceps BRR: Brachioradialis BRA: Brachialis
Free Body Diagram of the Model
Weight Reaction Forces
Rigid Body
Muscle Forces
Can the problem be (mathematically) solved?
How many Equations, how many Unknowns?
Anatomy of a Forearm (again)
http://www.angelfire.com/la/Ivan/PT.html
Neglect BRR & BRA…
http://www.ib.bioninja.com.au/higher-level/topic-11-human-health-and/112-muscles-and-movement.html
Modelling: Version II
REALITY Assumptions
MODELLING
http://www.bcit.ca/bettermath/example1submitted.shtml
4. Free Body Diagram (for EACH element of the model)
Muscle Forces
Reaction Forces
Weight
Weight Reaction Forces
Rigid Body Muscle Forces
Weight
1. UPPER ARM
2. LOWER ARM
Is this a correct FBD?
Ασκηση: Υπολογιστε τη δυναμη που αναπτυσσει ο δικέφαλος βραχιόνιος μυς (biceps brachii) οταν
κραταμε ενα βιβλιο που ζυγιζει 1 kg
Bone Weight (0.5 kg) Reaction Forces
Muscle Forces (M)
Weight
Διαγραμμα Ελευθερου Σωματος
75Ο
�𝐹𝑖
𝑛
𝑖=1
= 0 �𝑀𝑖
𝑚
𝑖=1
= 0 Εξισωσεις Ισορροπιας:
Απαντηση: M =
Ax
Ay
Can the problem be (mathematically) solved? Equations: Unknowns: 3
3
Example 2: Push Ups
http://cnx.org/contents/d703853c-6382-4035-8d6a-dcbca00a15ca@5/Forces_and_Torques_in_Muscles_
Question 1: What force should the woman exert on the floor with each hand to do a push-up? (Ans: 147 N)
Example 2: Push Ups
http://cnx.org/contents/d703853c-6382-4035-8d6a-dcbca00a15ca@5/Forces_and_Torques_in_Muscles_
Question 2: Calculate the magnitude of the force in each triceps muscle, and compare it to her weight.
Quiz: What is that?
The number of Unknown Variables of muscle forces and joint forces and moments Exceeds the number of Available Equations. This is primarily because of the redundant nature of anatomic structures. There are multiple muscles that can execute synergistic functions. Mathematically, this problem has NO unique solution.
Text taken from: ‘Estimation of Muscle and Joint Forces during Push-up’
http://avmedia.info/blog/how-to-do-perfect-push-ups-for-beginners/
When Multiple Muscles are involved, then the problem CANNOT (probably) be solved….
We: - Need to make further Assumptions (reduction process) Or -add more Equations (physical laws) that connect the unknowns… Or -Run Experiments
Making Assumptions…
Assumptions: -Only the Triceps muscle are involved. -The triceps muscle at the back of her upper arm has an effective lever arm of 1.75 cm, and she exerts force on the floor at a horizontal distance of 20.0 cm from the elbow joint.
Ans: 1680 N, 3.4 times her weight http://mybodyisblank.tumblr.com/post/4406344604/diamond-pushups
When Multiple Muscles are involved, then the problem CANNOT (probably) be solved….
We: - Need to make further Assumptions (reduction process) Or -add more Equations (physical laws) that connect the unknowns… Or -Run Experiments
Run Experiments? ElectroMyoGraphy (EMG)
To diagnose Neuromuscular Diseases & study Kinesiology Skin (surface) Electrodes
…A technique for recording the ELECTRICAL activity produced by muscles.
Two types of Electrodes
Needle Electrodes
Skin (surface) Electrodes
Pros and Cons between the 2 types of electrodes?
Skin electrodes measure the differential voltage from two electrodes on the skin.
How does it work?
http://www.medicalexhibits.com/medical_exhibits.php?exhibit=07030_03X&query=treatment%20nerve..
Needle electrodes detect Ions in muscle contractions & their strength
EMG & The Nerve Conduction Test
EMG & Push-ups
More info :‘ANALYSIS OF PUSHING EXERCISES: MUSCLE ACTIVITY AND SPINE LOAD WHILE CONTRASTING TECHNIQUES ON STABLE SURFACES WITH A LABILE SUSPENSION STRAP TRAINING SYSTEM’
EMG Experimental Data
Remember the Brain-Computer Interface?
http://en.wikipedia.org/wiki/Electroencephalography
- Electroencephalography (EEG) uses Surface Electrodes to record electrical activity along the scalp.
Hans Berger, 1924
- To diagnose epilepsy, sleep disorders, coma, encephalopathies
Resting Potential in Neurons
http://higheredbcs.wiley.com/legacy/college/tortora/0470565101/hearthis_ill/pap13e_ch12_illustr_audio_mp3_am/simulations/hear/membrane_potential.html
Action Potential in Neurons
http://biology4isc.weebly.com/7-nervous-system.html
Remember the Brain-Computer Interface?
http://en.wikipedia.org/wiki/Electroencephalography
Time
Bone Calcium and Weight Lifting?
Exercise plays an important role in maintaining bone calcium and strength as people age. Studies show that exercises requiring
muscles to pull on bones (resistance exercise) cause the bones to retain and possibly gain calcium (density).
http://www.nytimes.com/health/guides/specialtopic/physical-activity/exercise%27s-effects-on-bones-and-muscles.html Q: What is the big deal?
EXAMPLE 3: Spinal Load
Spinal Mechanics Why studying it?
• 90% of adults experience back pain at some point in their lifetimes.
• Most common cause of job-related disability and a leading contributor to missed work days.
Back Pain…
http://www.mposition.pl/en/Accept-mPosition/Ergonomics
Architecture of a Spine
http://trikonansan.blogspot.gr/2010/07/your-lumbar-curve-keeping-it-healthy.html
Q: Can you identify: Kyphosis, Lordosis, Scoliosis?
Lower Back Οσφυϊκό Κυρτωμα
Anatomy: A Closer View The SPINAL CORD is the
pliable main nerve that runs from your
brain through your spine
Vertebrae = σπονδυλοι
MUSCLES help to hold up your spine and permit
movement by contraction
The Facet Joints
http://www.mycdi.com/knowledge_center/pain_management/facet_joint_injection/
The Facet Joints can suffer from OsteoArthritis
The Disc (μεσοσπονδύλιος δίσκος)
Herniated = Κήλη
THE DISC: a pillow between two bones. It softly resists the downward forces placed on the vertebrae from the weight and movement of the head. A good pillow is THICK & SOFT.
Spine Disc Problems
Damage in the Lower Back (L1-L5 vertebrae)
causes LOW BACK PAIN
LOW BACK PAIN causes 40% of missed days of
work (in the US)
Spinal Decompression
http://www.mayfieldclinic.com/PE-BackPain.htm#.VOtLjC6znqo http://drkenandersen.com/how-spinal-decompression-can-help/
Spinal decompression can be achieved both surgically and non-surgically
Spinal Decompression
http://www.espritwellness.com/blog/spinal-decompression-faqs/
From Wiki: Spinal Decompression is the relief of pressure on one or many pinched nerves of the spinal column.
Q: How does it work?
Arthritis in the Spine: Facet Joint Injection
http://www.drpatriciagrant.com/FacetJointInjection.html
THE PROCEDURE A steroid medication and an anesthetic are injected into the capsule surrounding the small facet joints... The RESUTLS The injections do not cure the arthritis, but they give pain relief for up to 3 months…
Q: How can you visualize the location of injection?
Example of Spine Mechanics
How to Model the Spinal Joints?
https://ittcs.wordpress.com/2010/06/10/anatomy-and-physiology-spinal-stenosis/
1. Facet joints are hinge–like joints 2. intervertebral discs act as ligaments to hold the vertebrae
together
1) Calculate the force FB in the back muscles that is
needed to support the upper body plus the box. The mass
of the upper body is 55 kg and the mass of the box is 30
kg.
2) Calculate the force Fv– exerted by the vertebrae on
the spine at the indicated pivot point
Lifting a Box
http://cnx.org/contents/d703853c-6382-4035-8d6a-dcbca00a15ca@5/Forces_and_Torques_in_Muscles_#fs-id1169738061293
Spinal Muscles Role In Lifting
• Spinal Muscles Have Small Moment Arms With Respect To the Vertebral Joints.
• Need To Generate Large Forces To Counteract the Torque Produced About the Spine by Body Weight and Objects Being Lifted.
Erector Spinae Muscles
A Simple Model of the Spine
http://imgarcade.com/1/first-class-lever-examples-in-the-body/
Assumptions: -The spine is a Rigid Body -Rotation around the L5/Sacrum Joint
Class One Lever Force Load
L5
Can you draw the FBD?
Again: Lifting a Box
http://cnx.org/contents/d703853c-6382-4035-8d6a-dcbca00a15ca@5/Forces_and_Torques_in_Muscles_#fs-id1169738061293
Why Lift With The Legs?
Back Muscles (Moment Arm ~ 6 cm), Must Counter The Torque Produced by the Weights of the Body Plus Any External Loads.
A More Sophisticated Spine Model
Reference: ‘Effect of the Intra-Abdominal Pressure and the Center of Segmental Body Mass on the Lumbar Spine Mechanics – A Computational Parametric Study’
COR: the vertebral Centers Of Rotation
What Does The Research Show?
Compression Increases More with Spinal Flexion, and Increases Still Further with a Slouched Sitting Position.
Position and Spine Load
https://ittcs.wordpress.com/author/brucemcfarlane/page/3/
What about few extra kilos?
https://chiro-trust.org/back-pain/the-key-to-preventing-spinal-pain-understanding-levers/
..Few Extra Kilos move the Center of Mass away from the pivot point
Can you draw the FBD?
In Summary
-Statics: Important in understanding everyday loads in our muscles and bones. -Bones, Muscles and Joints can be modelled by simple mechanical lever systems (muscles are attached close to joints) -Good posture: the center of gravity lies directly above the pivot point in their hips, thereby avoiding back strain and damage to disks.
Summary taken from: http://cnx.org/contents/d703853c-6382-4035-8d6a-dcbca00a15ca@5/Forces_and_Torques_in_Muscles_#fs-id1169738061293