PowerPoint Presentation...Tools/Skills you need: • Anatomy (Da Vinci, Borelli…) • Mass/Center...
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Transcript of PowerPoint Presentation...Tools/Skills you need: • Anatomy (Da Vinci, Borelli…) • Mass/Center...
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 and Moments in Muscles, Joints and Bones
Applications: Sports, Rehabilitation (exercise in elderly arthritis patients, muscle strengthening in rheumatoid arthritis)…
Presenter
Presentation Notes
Rehabilitation: apokatastasi, epanentaxi
Static BioMechanics Calculate Forces and Moments in Muscles, Joints and Bones
More Applications: Ergonomics, Arthroplasty… http://news.bbc.co.uk/2/hi/6187080.stm
The Process of Solving a Problem
1. What is the Problem?
2. Get to know the Anatomy
Connect the Anatomy to the Problem…
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 Humans
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?
Presenter
Presentation Notes
A tendon is a tough band of fibrous connective tissue that usually connects muscle to bone A ligament is the fibrous connective tissue that connects bones to other bones
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...
Presenter
Presentation Notes
A hinge joint is a bone joint in which the articular surfaces are molded to each other in such a manner as to permit motion only in one plane.
Q: What type of Joint is the Elbow Joint?
http://www.physioroom.com/injuries/arm_and_elbow/elbow_arthritis_full.php
Presenter
Presentation Notes
Pivot joints also provide for the twisting movement of the bones of the forearm (radius and ulna) against the upper arm, a movement used, for instance, in unscrewing the lid of a jar. Pivot and hinge joints can be both considered cylindrical joints
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?
(Why lifting weight?)
Edouard Manet
The Luncheon on the Grass, 1863
Created in 1933
Rehab
Presenter
Presentation Notes
Image taken from: http://www.hygenicblog.com/2012/10/08/thera-band-versus-nautilus-machine-resistance-whos-better/20070605dsc_0365/
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
http://en.wikipedia.org/wiki/Anatomical_terminology
BIC: Biceps BRR: Brachioradialis BRA: 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?
Can the problem be (mathematically) solved? Equations: Unknowns:
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
Presenter
Presentation Notes
147 x 20 / 1.75 = 1680.
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
Presenter
Presentation Notes
The goal of the reduction method is to reduce the degree of redundancy by reducing the number of unknown forces until the number of unknown forces is equal to the number of equations. Muscles with similar functions or common anatomic insertions and orientations can be grouped together, whereas qualitative electromyographic data can be used to eliminate inactive muscles.This would be make the calculation become more easier. Although this method gives the joint force, the detailed behavior of individual muscles is lost from the solution.
Run Experiments? ElectroMyoGraphy (EMG)
To diagnose Neuromuscular Diseases & study Kinesiology Skin (surface) Electrodes
…A technique for recording the ELECTRICAL activity produced by muscles.
Presenter
Presentation Notes
Neuromuscular Diseases: Multiple sclerosis (MS), also known as disseminated sclerosis or encephalomyelitis disseminata, is an inflammatory disease in which the insulating covers of nerve cells in the brain and spinal cord are damaged. This damage disrupts the ability of parts of the nervous system to communicate
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 and amplify the signal.
Presenter
Presentation Notes
Generally, in surface EMG, the electrodes are located on the skin above the belly of the muscle of interest, in a region between the tendon and the innervation zone [11]. The electric currents generated by depolarization of the muscle fibers travel through the connective tissues, fat, vessels, skin (all of which comprises the volume conductor), reaching the region underneath the electrodes. The volume conductor has the property of a low-pass filter [12] and the signals reach the electrodes placed over the skin with a slower time course and decreased amplitude. On the other hand, a needle electrode is much closer to the source of the electrical activity than a surface electrode and hence it does not suffer the low-pass filtering and amplitude attenuation caused by volume conduction [6, 12]. This explains why the needle EMG signals have better signal-to-noise ratios and why their power spectra have components at higher frequencies (see the lower panel in Figure 2). The main advantage of invasive techniques such as needle or wire EMG is its high selectivity (one or very few MUs can be recorded with a high signal-to-noise ratio). Conversely, this may be a disadvantage when the purpose is to evaluate a larger number of MUs to obtain a more comprehensive view of muscle activation. In this case, surface EMG is more indicated. The main shortcomings of surface EMG are that (1) not all muscles are superficial and (2) the possibility of interference from nearby muscles’ electrical activities on the EMG signal recorded from the desired muscle. These recorded interferences are attenuated or perhaps distorted versions of the electrical activities from the nearby muscles and are known as crosstalk [13, 14]. The crosstalk effect can sometimes be minimized by a careful placement of the electrodes.
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
Presenter
Presentation Notes
EEG measures voltage fluctuations resulting from ionic (ιοντική) current flows within the neurons of the brain.
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
Presenter
Presentation Notes
the term lordosis refers to the normal inward curvature of the lumbar and cervical regions of the spine. οσφυϊκή
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
Presenter
Presentation Notes
Pliable = ευκαμπτος Ligaments connect bone to bone
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.
Presenter
Presentation Notes
Κήλη-- αναφέρεται η προβολή ενός οργάνου δια μίας ασθενούς περιοχής των μυών ή ιστών που την περιβάλλουν Ο μεσοσπονδύλιος δίσκος είναι ένα μαλακό μόρφωμα σε σχήμα πεπλατυσμένου δίσκου το οποίο βρίσκεται ανάμεσα στα σώματα των σπονδύλων . Αποτελείται από δυο βασικά μέρη , τον πηκτοειδή πυρήνα στο κέντρο του ως το ζελατινοειδές και εύπλαστο μέρος και τον ινώδη δακτύλιο που τον περιβάλει συγκρατώντας τον στην θέση του , ως το πιο σκληρό και ινώδες μέρος .
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?
Presenter
Presentation Notes
Spinal decompression works through a series of 15 one minute alternating decompression (using a logarithmic decompression curve) and relaxation cycles with a total treatment time of 30 minutes
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
Presenter
Presentation Notes
Ligaments = συνδεσμοι, act as mechanical reinforcements. Some ligaments limit the mobility of articulations, or prevent certain movements altogether, therefore they provide stability
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
Presenter
Presentation Notes
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?
Presenter
Presentation Notes
This constant muscle contraction with more effort, creates muscle fatigue and myofascial pain syndromes. Rene Cailliet, MD states “This increase [in muscle tension] not only is fatiguing, but acts as a compressive force on the soft tissues, including the disk.” (14).
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
