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)…

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?

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

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

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

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 and amplify the signal.

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