Research Article A study on morphology and morphometry of mandibular fossa Aditya Jain1, Thenmozhi M S2* ABSTRACT Introduction: The mandibular fossa is the depression in the temporal bone that articulates with the head of the mandible. In the temporal bone, the mandibular fossa is bounded anteriorly by the articular tubercle and posteriorly by the tympanic portion of the temporal bone, which separates it from external acoustic meatus. Mandibular fossa performs an important role in the act of mastication. As a part of the temporomandibular joint (TMJ), together with the articular tubercle and mandibular condyle, they become responsible for opening (depression of the mandible) and closing (elevation of the mandible) the mouth, as well as for moving it forward (protraction), backward (retraction), and side to side. Hence, the aim of the research is to study about the morphology and morphometry of mandibular fossa. Materials and Methods: Dry human skulls were obtained from the Department of Anatomy, Saveetha Dental College and Hospitals, Chennai. The mandibular fossa was measured by taking its length, breadth, and height using digital Vernier calipers in millimeters. Results: Length, breadth, and height of mandibular fossa of 40 skulls were measured, and their mean values were taken as follows: (a) Average height (mm) - 6.8, (b) average breadth (mm) - 15.0, and (c) average length (mm) - 20.9. Conclusion: The morphometry of mandibular fossa gives a clear orientation of the intra-articular topography. Thorough knowledge of the dimensions of the fossa is helpful in treating several temporomandibular joint-related problems. KEY WORDS: Articular tuburcle, Condyle of mandible, External acoustic meatus, Mandibular fossa, Mastication, Temporomandibular joint INTRODUCTION The anterior part is the larger one, and it joins with the condyle of the mandible. It expands up to the external Mandibular fossa is a depression in the temporal acoustic meatus. The posterior part of the mandibular bone that articulates with the head of the mandible. fossa, formed by the tympanic part of the bone, is non- In the temporal bone, anteriorly the mandibular fossa articular and sometimes lodges a portion of the parotid is bounded by the articular tubercle and posteriorly gland. The petrotympanic fissure leads into the middle by the tympanic plate of the temporal bone, which ear or tympanic cavity; it lodges the anterior process separates it from external acoustic meatus. The fossa of the malleus and transmits the tympanic branch of is divided into two parts by a narrow slit and the the internal maxillary artery squamotympanic fissure.[1] The anterior part, formed by the squama, is smooth, covered in the fresh state The posterior part contains a part of the parotid with cartilage, and articulates with the condyle gland.[2] Posteriorly, squamotympanic fissure separates of the mandible. Behind this, part of the fossa is a the mandibular fossa to the tympanic plate.[3] It is also small conical eminence; this is the representative referred to as the glenoid fossa in dental literature.[3] of a prominent tubercle which, in some mammals, descends behind the condyle of the mandible and Mandibular fossa performs an important role in the prevents its backward displacement.[2] act of mastication. As a part of the temporomandibular joint (TMJ), together with the articular tubercle and Access this article online mandibular condyle, they become responsible for opening (depression of the mandible) and closing Website: jprsolutions.info ISSN: 0975-7619 (elevation of the mandible) the mouth, as well as for 1Department of Anatomy, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, Tamil Nadu, India, 2Department of Anatomy, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, Tamil Nadu, India *Corresponding author: Mrs. Thenmozhi M S, Department of Anatomy, Saveetha Dental College, Saveetha University, 162, Poonamallee High Road, Chennai - 600 077, Tamil Nadu, India. Phone: +91-7073130945. E-mail: [email protected] Received on: 21-04-2018; Revised on: 23-05-2018; Accepted on: 01-07-2018 Drug Invention Today | Vol 10 • Issue 11 • 2018 2289 Aditya and M. S. Thenmozhi moving it forward (protraction), backward (retraction), Structural variations in the TMJ related to mandibular and side to side.[4,5] fossa depth in cadaveric material remain a topic of interest.[17] The TMJ presents a morphology in which the temporal surface constituent has an S-shape in adults sagittal Hence, the aim of the research is to study about the configuration, consisting of a prominent articular morphology and morphometry of mandibular fossa. tubercle (eminence) and a concave mandibular fossa.[6] TMJ submits intracapsular structures (condyle, disc, MATERIALS AND METHODS ligaments, and mandibular fossa) to constant remodeling (adaptation) due to increased mechanical Dry human skulls were obtained from the Department load between the TMJ osseous structures.[7-9] Likewise, of Anatomy, Saveetha Dental College and Hospitals, such remodeling in the glenoid fossa and condyle that Chennai. A total of 40 dry human skulls were used for also occurs throughout life (from childhood to adult) this study. seems to respond to a variety of conditions.[10] The mandibular fossa was measured by taking its The characteristics of the mandibular fossa have been length, breadth, and height using digital Vernier recorded by different means: Pantography, tomography, calipers in millimeters [Figures 1 and 2]. magnetic resonance, panoramic radiography, and Height of the mandibular fossa was measured using anteroposterior and lateral radiography. Correlation a horizontal reference line which was drawn, joining has been sought between articular morphology and the maximum height of the articular tubercle and characteristics such as dental state, craniofacial the pre-auricular tubercle which is located posterior morphology, age, and gender. Attempts have been made and lateral to the squamous-tympanic fissure. to classify the mandibular fossa based on its vertical A perpendicular line was drawn from the deepest depth (deep, medium, or flat), taking the perpendicular area of the fossa to this horizontal reference line. The to a horizontal anatomical plane as reference.[11-16] vertical measurement obtained represented the depth of the mandibular fossa.[5] RESULTS Length, breadth, and height of mandibular fossa of 40 skulls were measured, and their mean values were taken. a) Average height (mm) - 6.8 b) Average breadth (mm) -15.0 c) Average length (mm) - 20.9. The height of the right mandibular fossa was found to be greater than the height of the left mandibular fossa. There was only a minute difference between the heights of the left and right mandibular fossa Figure 1: Measurement with Vernier calipers [Graph 1]. The breadth of the left mandibular fossa was found to be greater than that of the right mandibular fossa. There was only a minute difference between the breadths of the left and right mandibular fossa [Graph 2]. The length of the right mandibular fossa was found to be greater than that of the left mandibular fossa. There was only a minute difference between the breadths of the left and right mandibular fossa [Graph 3]. DISCUSSION Average height was 6.8 mm in our findings, this being less than prehistoric specimens having 7.5 mm presented by Owen et al. (1992), Galan et al. have reported a 6.83 mm depth, and Meng et al. show in Figure 2: Mandibular fossa a study with computed tomography scanner depths of 2290 Drug Invention Today | Vol 10 • Issue 11 • 2018 Aditya and M. S. Thenmozhi natural dentition or complete prosthetic state, which have shown deep fossae.[8,19,20] It is understood that the posterior or anterior partial edentulism generates less flattened mandibular fossae than those observed in total edentulous people who have had no restoration.[13,21] CONCLUSION Graph 1: Comparison between heights of the left and right The morphometry of mandibular fossa gives a clear mandibular fossa orientation of the intra-articular topography. Thorough knowledge of the dimensions of the fossa is helpful in treating several TMJ-related problems. REFERENCES 1. Baker EW, Schuenke M. Head and Neck Anatomy for Dental Medicine. New York: Thieme 2011. p. 35-7. 2. Standring S. Gray’s anatomy the anatomical basis of clinical practice. 41st ed, London, Elsevier 2016;1405-15. 3. Snell RS. Clinical Anatomy by Regions. 9th ed. Sydney: Lippincott Williams & Wilkins; 2012. p. 532. Graph 2: Comparison between breadths of the left and right 4. Di Giovanna EL, Schiowitz S. An Osteopathic Approach to mandibular fossa Diagnosis and Treatment. Seiten; Verlag: Lippincott Williams & Wilkins; 2005. p. 607. 5. Ballesteros LE, Ramirez LM, Muñoz G. Mandibular fossa depth variations: Relation to age and dental state. Int J Morphol 2011;29:1189-94. 6. Nickel JC, McLachlan KR, Smith DM. A theoretical model of loading and eminence development of the postnatal human temporomandibular joint. J Dent Res 1988;67:903-10. 7. Moffett BC Jr., Johnson LC, Mccabe JB, Askew HC. Articular remodeling in the adult human temporomandibular joint. Am J Anat 1964;115:119-41. 8. Yamada K, Tsuruta A, Hanada K, Hayashi T. Morphology of the articular eminence in temporomandibular joints and Graph 3: Comparison between lengths of the left and right condylar bone change. J Oral Rehabil 2004;31:438-44. mandibular fossa 9. Devaraj SD, Pradeep D. Internal derangement of temporo mandibular joint-a review. IOSR J Dent Med Sci (IOSR- JDMS) 2014;13:66-73. 7.17 mm ± 1.56. The findings of Floridi and Matson 10. Meng F, Liu Y, Hu K, Zhao Y, Kong L, Zhou S, et al. were 7.17 mm in males and 6.72 mm in females. A comparative study of the skeletal morphology of the temporo-mandibular joint of children and adults. J Postgrad There seems to be a direct proportional relationship Med 2008;54:191-4. between age and articular remodeling.