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The jaw adductor resultant vector in primates
Author(s) -
Perry Jonathan M. G.,
Logan Rachel L.
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.449.3
Subject(s) - bite force quotient , adductor muscles , anatomy , joint (building) , magnitude (astronomy) , molar , orientation (vector space) , allometry , orthodontics , biology , mathematics , geometry , medicine , physics , paleontology , architectural engineering , astronomy , engineering
To optimize bite force, the jaw adductor resultant force is predicted to pass directly behind the last molar, crossing the jaw at 30% of jaw length from the joint (Greaves, 2000). We estimated the location, orientation, and magnitude of the resultant in strepsirrhine and platyrrhine primates using empirical data. To estimate vector location and orientation for each muscle (temporalis, masseter, and medial pterygoid) we outlined areas of attachment on lateral images of skulls. To estimate vector magnitude for each muscle we used published data on muscle cross‐sectional area. Individual muscle vectors were summed to obtain the resultant. In all cases, the resultant passes significantly posterior to the 30% mark (mean = 21%) and posterior to the last molar. This suggests that bite forces are less than optimal and joint reaction forces are greater than optimal. However, this vector location lowers the risk of dislocating the jaw joint and increases the potential for gape. The magnitude of the resultant scales with significant negative allometry to species mean body mass. Thus larger primates might be at a disadvantage for generating bite force. Grant Funding Source : Master of Biomedical Science Program, MWU