Preliminary results on a study to locate the pterygopalatine fossa using mathematical formulae.

Blocking the contents of the pterygopalatine fossa (PPF) has been shown to be effective in treating most orofacial pain including that associated with trigeminal neuralgia. However, the technique is not widely used, and we propose it to be due to the vague descriptions of the techniques in the literature. The aim of this study was therefore to achieve an alternative method of locating the PPF. One hundred and sixty skulls from the department of Anatomy, University of Pretoria, were used. Distinct landmarks (both anthropometric and clinical) accompanied by existing and new anthropometric measurements were used to define the location of the PPF. Regression analysis was used to measure the reliability of predicting the location of the PPF. From the results, two mathematical formulae were devised (one for each side). These formulae were tested on 47 cadavers by inserting a needle at the calculated points after which the areas where dissected to determine whether or not the needle had entered the PPF. Our results showed an accuracy of 65.2% on the right and 54.4% on the left. In conclusion, improvement in the accuracy of the technique could aid in the management of various pain disorders as well as pain management during surgery.

Dimensions of the neonatal cricothyroid membrane - how feasible is a surgical cricothyroidotomy?

BACKGROUND: Airway management of the neonate remains a cornerstone in neonatal resuscitation which in most cases involves tracheal intubation. However, difficult intubations do occur. Cricothyroidotomy is recognized as an entry point below the vocal cords. This procedure becomes increasingly difficult in young children and is not recommended in children under the age of 5 years. Little is known about the anatomy of the neonatal airway, especially the size of the cricothyroid membrane. The aim of the study was to determine the dimensions of the cricothyroid membrane in neonates. METHODS: Twenty-seven neonatal cadavers (mean height of 44.89 cm and a mean weight of 2.05 kg) were carefully dissected and the dimensions of the cricothyroid membrane recorded with a digital caliper (accuracy 0.01 mm) by two independent observers. RESULTS: The cricothyroid membrane has a mean height of 2.61 mm (sd: 0.71) and width of 3.03 mm (sd: 0.63). CONCLUSIONS: Results of this study indicate that the dimensions of the cricothyroid membrane are too small for passing a tracheal tube as the dimensions of the tube exceeds that of the cricothyroid membrane. This could fracture the cartilages of the larynx. The performance of a surgical cricothyroidotomy with passing of a tracheal tube is therefore strongly discouraged in neonatal patients.

Evaluation of clinical relevance of a problem-orientated head and neck module.

Current trends in medical education focus on outcomes-based learning as a means to facilitate student learning. The aim of this study was to evaluate a clinically applied module in head and neck anatomy for third-year dental students. The module linked clinical examination, regional dental blocks simulated on cadaver specimens, radiographic images and clinical case scenarios. A Likert-type questionnaire, completed by all students (n = 49), was used to evaluate student perceptions of this module objectively. The results indicate that an average number of students found that clinical examination received sufficient time (mean: 2.98) during the module, while a substantial number of students agreed that the integration of dental procedures stimulated them to study specific regional anatomy (mean: 3.82) and increased their interest in their future careers as dentists (mean: 4.04). The radiographs improved their understanding of anatomy (mean: 3.41) while the clinical case studies were a positive learning experience (mean: 3.10). The majority of students (mean: 4.12) felt that they were continuously made aware that they were studying appropriate matter for their future work as dentists. It seems evident that the integration of clinically relevant content facilitates and encourages the understanding of anatomy.

A quantitative assessment of the jugular foramen.

While it is generally accepted that the right jugular foramen is larger than the left, little quantitative evidence exists on the exocranial and endocranial openings of this foramen. The present study set out to clarify and quantify measurements of the two openings. The dimensions of the exocranial and endocranial openings of the jugular foramen and the volume and height of the jugular fossa were examined in a total sample of 93 skulls from white and black, male and female South Africans. The volume of the jugular fossa was determined with the use of a dental impression material. The exocranial area of the right jugular foramen was significantly larger (p < 0.05) than the left in the black group, while the endocranial area of the right foramen was significantly larger (p < 0.05) than the left only in black males. The height of the jugular fossa was significantly larger (p < 0.05) on the right side only in the black group. The volume of the jugular foramen was significantly larger (p < 0.05) on the right side only in females of both groups. Although the jugular foramen is generally larger on the right side than on the left, its size as well as the volume and height of the jugular fossa is variable in different groups and sexes.

Tooth and cusp size reduction in second molars.

The present study examined the cusp reduction pattern of molars in two San-Hybrid groups, namely, the Vassekela and Barakwena. Cusp and crownbase area measurements were undertaken on enlarged photographs of maxillary molars and on camera lucida drawings of mandibular molars. The protocone values for the Barakwena were significantly larger than those of the Vassekela and were also the largest of the four maxillary molar cusps (especially in M2). The metacone was the second largest cusp in M1, the paracone the second largest cusp in M2 and M3, while the hypocone was the smallest cusp in all maxillary molars. Maxillary crownbase areas were larger in the Barakwena than in the Vassekela but these differences were not statistically significant. The protoconid, entoconid and metaconid were the largest of the mandibular molar cusps. Generally, the cusp area values in first and third molars were larger in the taller Barakwena than in the shorter Vassekela. These differences were not statistically significant. In second molars, however, an unexpected finding was that crownbase and cusp areas (except the metaconulid) were significantly larger in the Vassekela than in the Barakwena. This study indicates that second molars show more cusp size differences in the two groups than do the other two molars. This may be regarded as a conservative tendency (Korenhof, 1960) in which case it would indicate that some second molar cusps are in a less active phase of evolutionary reduction than the same cusps in first and third molars.