Jaws Resolution Template

Topics: Muscle, Muscular system, Case study Pages: 7 (2011 words) Published: December 5, 2014
AJ Petto & RD Clare

Case Studies in Human Anatomy and Physiology

Case Resolution Template Instructions:

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...

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/
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