Jaws Resolution Template

1. Make a copy of this document on your computer (it can be on your hard drive or on removable media, such as a thumb drive). 2. Save the document before you begin to answer the questions. 3. Save your document frequently as you move through the assignment. 4. Save your final document, and then close it and exit the word processing program. 5. Then open the D2L page for your laboratory section and upload the completed Case Resolution Template into the appropriate drop box. 6. Be sure to save and print the email confirmation of drop box delivery. AJ Petto & RD Clare

Case Studies in Human Anatomy and Physiology
Jaws Case Resolution Template
1) This case study focuses on the “unity of form and function” as represented in the biomechanics of jaw anatomy. What is the relationship between the length of the sarcomere and the tension generated by a muscle? What is the relationship between the length or thickness of the whole muscle and the force produced by the bite? What is the relationship between the length of the mandible, height of the ramus, and the angle of the jaw and the force produced by the bite?

The relationship between the length of the sarcomere and the tension produced is known as the length-tension relationship. The graph produced by the length-tension relationship is a curve that peaks at a comfortable position. For the sarcomere and the muscles have the greatest tension. As the sarcomere continues to be lengthened the tension of the muscles is decreased. In this situation the sarcomere is being overly stretched. On the other end of the graph near zero where the sarcomere has not been stretched it is described as being overly contracted. The tree gouging monkeys most have a longer sarcomere than the opportunistic monkey because they must lengthen it further to create the optimal tension to bite the tree.

Therefore, the S. oedipus’s shorter sarcomere fits its needs as a nongouging monkey. After reviewing the charts and information provided by the case study it is clear that the longer the sarcomere the less forceful bite it is able to have because the muscle is compensating thickness for its ability to stretch further and have a wider gape. ‘Nongouging cotton-top temorins (S. oedipus) have significantly greater masseter and temporalis PCSAs compared with tree-gouging common (C. jacchus) and pygmy (C. pygmaeu) marmosets” (Taylor 2009). This quote proves that there is an anatomical trade off between having a longer sarcomere and having more force. From these findings it seems that the tree-gouging monkeys have less forceful bites than the S. oedipus. In conclusion, the thicker the muscle fibers are the force behind it and the longer the muscle fibers the less force it has.

The S. oedipus, which is a nongouginh monkey, has the smallest angle of movement, tallest ramus, and has only a slightly shorter mandible than the C. jacchus. Meaning the C. jacchus has the longest mandible of the three species. The C. pygmaeus because its whole body is significantly smaller in size compared to the other two species it is hard to use in determining whether or not its ramus height and length of mandible has any relation to the force of its bite. However, the shape of its angle is similar to that of the C. jacchus even though it is smaller in size. Therefore, the monkeys that are tre gouging have a larger range of movements and angles for the jaw because they have to have a larger gape than nongouging monkeys.

It is hard to say if length if t he length of the mandible or height of the ramus have any relationship with the amount of force the jaw can produce in the bite. From the information given the longer the mandible is the less force produced. I concluded because we know from previous answers that the gouging monkeys have less forceful bites than the nongouging S. oebipus. Therefore, the taller the ramus the more forceful the bite will be. In conclusion, the taller the ramus and shorter the mandible the more force that can be produced by the bite. The limited angles a jaw has the more forceful the bite because it doesn’t have as wide range of movement.

2) How is the bite force required of these 3 species in their feeding strategies illustrated in the anatomy of the bone, muscles, and joints that
make up the jaw? What difference does size make?

The C. pygmaeus is the smallest of the three species. Therefore it is difficult to compare it to the nongouging S. oebipus. However, there are certain differences between tree gougnign monekys, such as, C. jacchus and C. pygmaeus and the nongouging monkey, S. oebipus. In an article done by Christopher Vinyard and other scientists, they state a few predictions and statements to back their predictions about the anatomy of the bone, muscles, and joints that make up the jaw and how the bite force is affected. Their findings also explain what difference size can make a difference in the function of the jaw. Mandible length is determined by how long it is. The longer the mandible the less force the bite will produce. Therefore, nongouging have more force behind there bite. The same goes for the length of the sarcomere fibers. The longer the fibers the less for the bite has because the muscle is not as dense and cannot create as great of force. So size does make a difference.

3) In addition to the information in the case presentation (including the web sites contained in the case itself), report the other resources that you used to learn more about the main questions in this research, the place of this article within the field, and the acceptance by the community of scientists of the conclusions in this article.

http://jeb.biologists.org/content/212/24/4040.full.pdf+html
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3098528/
http://onlinelibrary.wiley.com/doi/10.1002/ajpa.10129/full

a) Be sure to include where you found this additional information and to provide specific, complete references to the original research articles that you cite (to learn the proper format for listing references, check on the course D2L page or see a summary here: https://pantherfile.uwm.edu/ajpetto/www/CBE_NameYear_RefList.htm). i) A cited reference search might be helpful in this step of the resolution. b) Almost all of your outside resources should be original, peer-reviewed clinical and/or research papers. i) Be sure that the resources you choose are available for you to read. (1) Abstracts alone are insufficient

(2) If you have an article with an English abstract, but the text is in Russian, be prepared to demonstrate that you can read Russian … or else do not use the article. ii) Avoid newspaper reports, news releases, and materials aimed at the general public. They will not have the information that you need. c) Pay attention to the dates of publication (and revision) of the various sources you cite. 4) What does each of these additional items contribute to the solution of the case? In this case, we want to know which of the steps in the flowchart are represented by these new materials and what they tell us about the original study. Two of my three outside sources that I used to help with the case study were more formation and background about the monkeys and the jaw. I did not really use these sources to answer the questions but to help me understand what the case study was talking about. My third source was were I got much of my information about how the anatomy of the monkeys’ jaws affected the force of the bite.

This source predicts how the size of the mandible and the shape and size of the sarcomere affected the force and tension of the jaw. 5) What other findings or information in this case are consistent with the information you located? Give the facts here, but link the discussion to the items in the flowchart where they reinforce the original case. All the information in my sources supported the relationship between the tension and length sarcomere. They also agreed that the gouging monkeys had longer sarcomere fibers than the nongouging monkey allowing them to create a larger gape. 6) What findings or information are inconclusive or in conflict with the information in 2? Again, give the facts here, but link the discussion to the items in the flowchart where they show areas that the original research did not reach. My first two sources disagreed that the longer the sarcomere fibers the less force they would be able to produce in the bite.

They thought that the tree gouging monkeys would still have a greater force than the nongouging monkey purely because of the fact that the gouging monkeys use their jaw more. Meaning that because the monkeys are actually gouging the tree bark they need to have more force behind their bite than the monkeys that wait for the sap to ooze out of the tree. 7) If your proposed resolution of the case is correct, what other observations might we expect to find in this case?For example, what would we need to do in future clinical investigations or practice; or how would another case be identified in which this problem or a similar one occurred?

The most significant issue I found with the case study was determining the relationship between the height of the ramus, length of the mandible, and angle of the jaw had a relationship with the forcefulness of the bite. The problem come in when evaluating the height and length of the ramus and mandible because the C. pyrgaeus is much smaller than the other two species making it hard to compare its jaw size with the size of the nongouging monkey. It was important to compare the two because one was gouging and one was nongouging. I wanted to see if it was a common trend in gouging monkeys to have a smaller ramus and longer mandible. Therefore, having a few tree gouging and few nongouging monkeys of similar size would make it easier when trying to make comparisons.

8) Give your solution as to the application of the process of scientific inquiry in this case and, on a scale of 1–5, rate how confident you are in your conclusions in questions 1 and 2. I am fairly confident in my conclusions in questions 1 and 2. I would rate my confidence as a 4 on a scale of 1-5. I believe I clearly explained the relationships asked in question 1 with a clear understanding of the case study. In question 2, I describe how the bite force needed by each specie is illustrated in the jaw shape and size of the jaw. 9) In considering your resolution and level of confidence level from question 8, describe how you located the information you used in this case and what you might do differently if you had it to do over again? For example, would you use different resources and strategies … different information

If I were to do the resolution over again. I would of spent more timing searching for research on the individual species and not on the specific relationships. In order to figure out how the muscles and bones of the jaw worked together I first needed to learn about the monkeys. Then go on to how their unique structures worked together to perform a uniformed function.

References
C. M. Eng, S. R. (2009, September 2). The morphology of the masticatory
apparatus facilitates muscle force production at. Retrieved from The Journal of Experimental Biology : http://jeb.biologists.org/content/212/24/4040.full.pdf+html Christopher J. Vinyard, C. E. (2003, January 22). Comparative functional analysis of skull morphology of tree-gouging primates. Retrieved from American Journal of Physical Anthrogology : http://onlinelibrary.wiley.com/doi/10.1002/ajpa.10129/abstract?deniedAccessCustomisedMessage=&userIsAuthenticated=false Taylor, C. J. (2011, May 20). A Preliminary Analysis of the Relationship between Jaw-Muscle Architecture and Jaw-Muscle Electromyography during Chewing Across Primates. Retrieved from NCBI: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3098528/