Torque = Force x Force Arm
= Resistance x Resistance Arm
= 45 kg x 0.25 m
= 11.25 Nm
So the force needed is 11.25 N
Therefore, the torque needed is 1.125 Nm (11.25 N x 0.1 m)
Goniometry is the measuring of angles created by the bones of the body at the joints.1, 2, 3
The term goniometry is derived from two Greek words, gonia meaning angle and metron, meaning measure. 1, 2, 3, 4, 5,
System to measure the joint ranges in each plane of the joint is termed goniometry. 4
These measurements are done with instrument such as goniometer, a tape measure, inclinometers or by visual estimate.
Femoral Head (Superiorly, Medially, Anteriorly).
Acetabulum (Inferiorly, Laterally, Anteriorly).
Horseshoe-shaped (Acetabular Notch).
The deepest portion (Acetabular Fossa).
Labrum Acetabular:
Is a wedged fibrocartilaginous ring inserted into the acetabular rim to increase the acetabular concavity.
Goniometry is the measuring of angles created by the bones of the body at the joints.1, 2, 3
The term goniometry is derived from two Greek words, gonia meaning angle and metron, meaning measure. 1, 2, 3, 4, 5,
System to measure the joint ranges in each plane of the joint is termed goniometry. 4
These measurements are done with instrument such as goniometer, a tape measure, inclinometers or by visual estimate.
Femoral Head (Superiorly, Medially, Anteriorly).
Acetabulum (Inferiorly, Laterally, Anteriorly).
Horseshoe-shaped (Acetabular Notch).
The deepest portion (Acetabular Fossa).
Labrum Acetabular:
Is a wedged fibrocartilaginous ring inserted into the acetabular rim to increase the acetabular concavity.
Elbow complex is designed to serve hand.
They provide MOBILITY for Hand in space by apparent shortening and Lengthening of upper extremity.
They provide Stability for skillful and forceful movements
A chronicle on muscle strengthening:
MMT is a procedure for the evaluation of strength of individual
muscle or muscles group, based upon the effective performance of a movement in relation to the forces of gravity or manual resistance through the available ROM.
Effects of various types of lifting like stoop lifting, squat lifting, semi-squat lifting on the body and also when to use which type of lift to help prevent or minimize the risk of musculoskeletal injury.
Introduction to kinesiology (Biomechanics- Physiotherapy) vandana7381
Chapter 1: Introduction to Kinesiology ( Biomechanics) for physical therapy students.
Reference: JOINT STRUCTURE AND FUNCTION - by Pamela K. Levangie.
Easy to understand and with lot of examples.
Elbow complex is designed to serve hand.
They provide MOBILITY for Hand in space by apparent shortening and Lengthening of upper extremity.
They provide Stability for skillful and forceful movements
A chronicle on muscle strengthening:
MMT is a procedure for the evaluation of strength of individual
muscle or muscles group, based upon the effective performance of a movement in relation to the forces of gravity or manual resistance through the available ROM.
Effects of various types of lifting like stoop lifting, squat lifting, semi-squat lifting on the body and also when to use which type of lift to help prevent or minimize the risk of musculoskeletal injury.
Introduction to kinesiology (Biomechanics- Physiotherapy) vandana7381
Chapter 1: Introduction to Kinesiology ( Biomechanics) for physical therapy students.
Reference: JOINT STRUCTURE AND FUNCTION - by Pamela K. Levangie.
Easy to understand and with lot of examples.
Different orders of Levers for novice learners. This content also has anatomical as well as mechanical examples. This is one of the foundation concepts in biomechanics for physiotherapy students.
This is uploaded as part of MOOC SWAYAM course- Academic writing
Rotator Cuff Update 2022 for Medbelle Len Funk.pptxLennard Funk
the common questions patients will ask once they have had a scan and a tear has been reported, particularly if they have had no injury of trauma, they ask what caused my tear. If I have a tear what can you do to fix it, it’s got to be fixed. How can I get better if it is not fixed. I have already had physiotherapy and that didn’t fix it so how will more physiotherapy. Some patients who are not keen on surgery, do I really need to have an operation. I have not had an injury.
there are multiple options thrown into the mix here which we need to consider for an individual patient.
The below illustration shows a very rough decision making tool that I would use in determining surgical or treatment options for particular patients.
A younger patient who has both pain and weakness with a massive cuff tear, if it is partially repairable a biological augment would be suitable.
If their predominant weakness is external rotation i.e. a positive Hornblower sign but good elevation, a lat dorsi tendon transfer.
For an older patient who has a predominant weakness but no significant pain, deltoid rehabilitation programme is indicated.
If they do have pain, a suprascapular nerve procedure such as an ablation would be beneficial.
For those that have significant pain and weakness with failed non-operative options, a reverse shoulder replacement would be the best option.
The balloon as we said, has a very limited place and this is for the older patient with slight loss of function and pain with higher demands.
For those that have more significant pain and elevation weakness, a superior capsular reconstruction would be my preferred option.
Should We Repair Rotator Cuff Tears OPN 2017.pdfLennard Funk
Lennard Funk & Puneet Monga
Prepared for Orthopaedic Product News, 2017
Rotator cuff disease is very common. There is as much enthusiastic discussion and debate on its management as there was 80 years ago when Codman (1937) first described the pathology and surgical management. There is great variation amongst surgeons as to the management of rotator cuff tears biased by experience and their understanding of the literature, skills levels and regional variations. There has been a lot of research done on the pathology, non-operative and operative treatments over the last two decades. Also, over the last decade there have been massive strides in the development of new surgical techniques and technologies. However, despite these advances there is as much discussion and debate!
Superior Capsular Reconstruction Outcomes Wrightington 2020Lennard Funk
Hariharan Mohan, Jagwant Singh, Michael Walton, Lennard Funk, Puneet Monga
Cautious optimism following SCR may be offered to this challenging subset of patients with symptomatic irreparable rotator cuff tears. It is likely that the relatively low re-operation rates can be further improved by considering the negative prognostic factors in defining indications for surgery. Further studies with longer term followup are recommended.
Isolated scapula pain is uncommon, but very difficult to diagnose and manage. In this presentation I run through the known causes and an approach to the diagnosis, in order to guide best treatment.
The Incidence of Traumatic Posterior and Combined Labral Tears in Patients Un...Lennard Funk
Presentation at ISAKOS, 2019
There were 442 primary arthroscopic labral repair procedures performed over the three-year period. The total cohort had a mean age of 25.91±9.09 years (range, 14-67 years) and consisted of 89.6% males. There was no significant difference in mean age or gender between the isolated anterior, posterior or combined groups (p=0.383 and p=0.541, respectively).
• Of the 442 patients who underwent a shoulder labral repair, isolated anterior labral pathology occurred in 52.9% (n=234), with posterior and combined labral tears accounting for 16.3% (n=72) and 30.8%, respectively (n=136) (Table 3).
• Patients were stratified as either sporting or non-sporting; 74.9% of patients were categorised as sporting (n=331) and had a mean age of 24.91±5.69 years, which was significantly lower than the mean age of 35.40±11.94 years in the non-sporting population (p<0.001). In the non-sporting population 68.5% (n=76) of patients had isolated anterior labral tears with 12.6% (n=14) posterior and 18.9% (n=21) combined. In the sporting population isolated anterior labral tears accounted for 47.7% (n=158), posterior 17.5% (n=58) and combined labral tears 34.7% (n=115). The sporting population had a significantly greater proportion of posterior and combined labral tears with the non-sporting population a significantly greater proportion of anterior labral tears (p=0.013).
• Rugby players had the greatest incidence of shoulder instability within the sporting cohort accounting for 231 cases. Of the 231 cases, 47.2% were isolated anterior labral tears, 12.6% isolated posterior and 40.3% combined lesions.
Posterior and combined shoulder labral tears are more prevalent than previously reported in the civilian population. The rates are higher in young, sporting populations and especially in contact sports such as rugby.
Pectoralis major allograft reconstructionLennard Funk
Presentation at ISAKOS, 2019
We performed a total of 142 pectoralis major repairs over a ten year period, of which 19 required allograft reconstruction. Of these 19 patients, 11 were available for response. All 11 patients were male with a mean age of 38.3 years (21 to 48 years). The mean time between injury and surgery was 12.2 months (4 to 30 months). Ten patients (91%) were unable to perform their previous level of work pre-operatively, with all patients returning to pre-injury occupation levels post-operatively.
The main complaint prior to surgery was pain on pushing and moving the affected arm across the body, which improved in nine patients (82%), with no improvement reported in two patients. Strength improved significantly post-operatively, with only three patients reporting no improvement (paired t-test p=0.01). Six patients reported an improvement in cosmesis (50%).
Hydrodistention is a treatment for frozen shoulder (FS) that is gaining popularity again. However, no large, long-term outcome data has been published yet. Our aims were to evaluate hydrodistension for the treatment of primary frozen shoulder (FS) in a large cohort of patients with long follow-up period.
We present a case series of eighty-nine patients (36 males and 53 females) with a mean age of 52 years (33-73). Eleven (12.4%) had disease associations. We excluded post-operative secondary stiff shoulders. The mean volume injected was 33.7ml (16-66). 36/89 (40%) had capsular rupture. Six (6.7%) had adverse effects. The mean follow-up was 104.5 weeks (8-238).
Mean improvement in forward flexion was 165.4, abduction 111.6, external rotation was hand above head with elbow back (and internal rotation in extension to T12. Mean improvement in quickDASH score was 17.1 (p<0.001) and Constant Score was 70.0 (p<0.001). Mean improvement in VAS was 7.3 (p<0.001). No patients had night pain (p<0.001). Eighty-eight (99%) returned to their previous occupation. Seventy-six (85%) returned to their previous level of sport. Gender, previous intra-articular steroid injection, volume of the injectate, type of steroid used, capsular rupture and underlying aetiology had no impact on outcome.
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
9. Joint Mobility and
Mobility sometimes has very distinct
endpoints
– Elbow or knee hyperextension
In other cases variable soft tissue
properties and other factors limit ROM
Some see stability as the joint’s ability to
resist dislocation.
Stability
10. Joint Mobility and
Mobility sometimes has very distinct
endpoints
– Elbow or knee hyperextension
In other cases variable soft tissue
properties and other factors limit ROM
Some see stability as the joint’s ability to
resist dislocation.
Stability
hi p!
pt the
e
Exc
11. Lever Systems
Most motion at the major joints results
from the body’s structures acting as a
system of levers
– Multiple “classes” of lever systems
Functions:
– Increase the effect of an applied force
• Moment arms
– Increase the effective velocity of
movement
• v=rω
13. Levers
• Levers are used to alter the resulting
direction of the applied force
14. Levers
• Levers are used to alter the resulting
direction of the applied force
• A lever is a rigid bar (bone) that turns
about an axis of rotation or fulcrum (joint)
15. Levers
• Levers are used to alter the resulting
direction of the applied force
• A lever is a rigid bar (bone) that turns
about an axis of rotation or fulcrum (joint)
• The lever rotates about the axis as a result
of a force (from muscle contraction)
16. Levers
• Levers are used to alter the resulting
direction of the applied force
• A lever is a rigid bar (bone) that turns
about an axis of rotation or fulcrum (joint)
• The lever rotates about the axis as a result
of a force (from muscle contraction)
• The force acts against a resistance
(weight, gravity, opponent, etc.)
19. Levers
The relationship of the points
determines the type of lever
The axis (joint), force (muscle
insertion point), and the resistance
(weight, etc.)
31. First Class
Designed for speed and range of motion
when the axis is closer to the force
Designed for strength when the axis is
closer to the resistance
F R
A A
45. FUNCTIONAL RELATIONSHIP PRACTICAL HUMAN
CLASS ARRANGEMENT ARM MOVEMENT DESIGN TO AXIS EXAMPLE EXAMPLE
1ST F-A-R Resistance arm Balanced Axis near Seesaw Erector
and force arm movements middle spinae neck
in opposite extension
direction
Speed and Axis near Scissors Triceps
range of force
motion
Force Axis near Crow bar
(Strength) resistance
2ND A-R-F Resistance arm Force Axis near Wheel Gatroc and
and force arm (Strength) resistance barrow, soleus
in same nutcracker
direction
3RD A-F-R Resistance arm Speed and Axis near Shoveling Biceps
and force arm range of force dirt, catapult brachii
in same motion
direction
54. Factors In Use of
Anatomical Levers
A lever system can become unbalance when
enough torque is produced
55. Factors In Use of
Anatomical Levers
A lever system can become unbalance when
enough torque is produced
Torque is the turning effect of a force; inside
the body it caused rotation around a joint.
56. Factors In Use of
Anatomical Levers
A lever system can become unbalance when
enough torque is produced
Torque is the turning effect of a force; inside
the body it caused rotation around a joint.
Torque = Force (from the muscle) x Force
Arm (distance from muscle insertion from
the joint)
59. Practical Application
Force is produced by the
muscle
FA the distance from
Resistance
Force
joint (i.e. axis or
folcrum) to insertion of
the force
60. Practical Application
Force is produced by the
muscle
FA the distance from
Resistance
Force
joint (i.e. axis or
folcrum) to insertion of
the force
Resistance could be a
weight, gravity, etc.
61. Practical Application
Force is produced by the
muscle
FA the distance from
Resistance
Force
joint (i.e. axis or
folcrum) to insertion of
the force
Resistance could be a
weight, gravity, etc.
RA the distance from
joint to the center of
the resistance
63. Examples
1. How much torque needs
to be produced to move
45 kg when the RA is 0.25
m and the FA is 0.1
Resistance
Force
meters?
64. Examples
1. How much torque needs
to be produced to move
45 kg when the RA is 0.25
m and the FA is 0.1
Resistance
Force
meters?
Use the formula F x FA = R
x RA
65. Examples
1. How much torque needs
to be produced to move
45 kg when the RA is 0.25
m and the FA is 0.1
Resistance
Force
meters?
Use the formula F x FA = R
x RA
Note: A Newton is the unit of force
required to accelerate a mass of one
kilogram one meter per second per
second.
71. Example 2: Increasing the
FA
2. What if the FA was increased to 0.15 meters?
RA = 0.25
FA = 0.15
?
45
A
72. Example 2: Increasing the
FA
2. What if the FA was increased to 0.15 meters?
F x 0.15 meters = 45 Kg x 0.25 meters
RA = 0.25
FA = 0.15
?
45
A
73. Example 2: Increasing the
FA
2. What if the FA was increased to 0.15 meters?
F x 0.15 meters = 45 Kg x 0.25 meters
F x 0.15 = 11.25 Kg-meters
RA = 0.25
FA = 0.15
?
45
A
74. Example 2: Increasing the
FA
2. What if the FA was increased to 0.15 meters?
F x 0.15 meters = 45 Kg x 0.25 meters
F x 0.15 = 11.25 Kg-meters
F = 75 Kg
RA = 0.25
FA = 0.15
?
45
A
76. Example 3: Decreasing the
RA
3. What if the RA was decreased to 0.2 meters?
RA = 0.2
FA = 0.1
?
45
A
77. Example 3: Decreasing the
RA
3. What if the RA was decreased to 0.2 meters?
F x 0.1 meters = 45 Kg x 0.2 meters
RA = 0.2
FA = 0.1
?
45
A
78. Example 3: Decreasing the
RA
3. What if the RA was decreased to 0.2 meters?
F x 0.1 meters = 45 Kg x 0.2 meters
F x 0.1 = 9 Kg-meters
RA = 0.2
FA = 0.1
?
45
A
79. Example 3: Decreasing the
RA
3. What if the RA was decreased to 0.2 meters?
F x 0.1 meters = 45 Kg x 0.2 meters
F x 0.1 = 9 Kg-meters
F = 90 Kg
RA = 0.2
FA = 0.1
?
45
A
81. Summary
• The actual torque needed to move a
given resistance depends on the
length of the FA and RA
82. Summary
• The actual torque needed to move a
given resistance depends on the
length of the FA and RA
• As the FA increases or RA
decreases, the required torque
decreases.
83. Summary
• The actual torque needed to move a
given resistance depends on the
length of the FA and RA
• As the FA increases or RA
decreases, the required torque
decreases.
• As the FA decreases or RA
increases, the required torque
85. Levers Continued
Inside the body, several joints can be
“added” together to increase
leverage (e.g. shoulder, elbow, and
wrist.
86. Levers Continued
Inside the body, several joints can be
“added” together to increase
leverage (e.g. shoulder, elbow, and
wrist.
An increase in leverage can increase
velocity
96. Lever
Length
A longer lever would
increase speed at
the end of the
racquet unless the
extra weight was
too great. Then the
speed may actually
be slower.
99. Wheels and Axles
Wheels and axles can
enhance speed and
R = 3”
range of motion
They function as a form of
lever
R = 1”
100. Wheels and Axles
Wheels and axles can
enhance speed and
R = 3”
range of motion
They function as a form of
lever
Mechanical advantage
= radius of wheel /
radius of axle
R = 1”
103. Wheels and Axles
Consider the humerus as an
axle and the forearm/hand
as the wheel
The rotator cuff muscles
inward rotate the humerus
a small amount
H
104. Wheels and Axles
Consider the humerus as an
axle and the forearm/hand
as the wheel
The rotator cuff muscles
inward rotate the humerus
a small amount
The hand will travel a large
amount
H
105. Wheels and Axles
Consider the humerus as an
axle and the forearm/hand
as the wheel
The rotator cuff muscles
inward rotate the humerus
a small amount
The hand will travel a large
amount
A little effort to rotate the
humerus, results in a
significant amount of
movement at the hand
H
106. Joints and
moments
Note, as a joint moves through its
ROM, two things change:
– Instantaneous Center of Rotation
• Rotation
• Sliding
• Rolling
– Muscle Line of Action
These combine to change the moment
arm
Synovial joint lubrication: in spite of the massive loads generated in them, synovial joints are efficient bearings with very low friction. The coefficient of friction of a synovial joint is around 0.02. This compares to 0.03 for ice sliding on ice. A coefficient of friction of 0.01 means that a load of 100 lb could be made to slide by applying a force of 1lb. Joint lubrication is the key to reduced friction. So, it is helpful to understand them in order to better understand and treat joint wear. It is still unclear how lubrication works, but there are many theories, based on man-made ball-bearings. What is clear is that no single mechanism is responsible and different modes of lubrication work at different stages of joint function. The joint is lined by wear resistant hyaline cartilage and is bathed by synovial fluid. Unlike a typical newtonian fluid synovial fluid has a viscosity that decreases with increasing shear rate. The function of a lubricant is to provide an intermediate layer with low shear resistance in between the two sliding surfaces to reduce friction. A thixotropic fluid would fit the bill perfectly.\nBasic lubrication is of two types: fluid-film, boundary and mixed.\nFluid film : a thin fluid film separates the bearing surfaces. Of two types: hydrodynamic and squeeze film. Hydrodynamic lubrication is unlikely to be feasible in vivo as the sliding velocity of joints are too low to generate a substantial fluid film. Squeeze film lubrication takes place by the production of a fluid film under pressure as the two bearing surfaces move perpendicularly towards each other. Fluid film and resultant load bearing capacity depends on fluid viscosity. It could explain lubrication under sudden loading but is not suitable for prolong loading conditions.\nBoundary: the bearing surfaces come to contact with each other, but "lubricin" from synovial fluid is attached to the cartilage surface and offers an interposed layer which when rubbed provides less resistance to shear.\nMixed: weeping lubrication: on load application synovial fluid is released or "wept" from articular cartilage. It separates the two bearing surfaces and reduces friction due to the hydrostatic pressure. On unloading the fluid is squeezed back in. This mechanism is not dependent on sliding speed .\n