The TMJ-ear connection

Evaluation of morphological variations of petrotympanic fissure using computed tomography imaging of the temporal bone

PURPOSE

Petrotympanic fissure (PF) is important for both dentists and otolaryngologists to know the temporal anatomy well especially for pre-surgical radiological evaluations. Computed tomography (CT) is indispensable method for temporal bone imaging. The purpose of this study was to evaluate PF morphology and position using CT.

METHODS

CT scans of 300 patients (600 PFs) were retrospectively evaluated. PF types were recorded by dividing into 3 groups (Type 1,2 and 3). Length of the mandibular fossa (MF) and PF, vertical diameter (VD) of the PF at the MF level, midpoint and tympanic cavity (TC) level were measured. PF position types were subdivided as low, midline and high.

RESULTS

Type 1, 2 and 3 was found in 18.7%, 51.5% and 29.8% of the cases, respectively. The mean length of the MF and PF was 18.33 mm and 3.77 mm, respectively. The mean VD of the PF at the MF level, midpoint and TC level was 1.71, 0.98 and 0.97 mm, respectively. The low, midline and high position of PF was observed 14.5%, 54.3% and 31.2% of the cases, respectively.

CONCLUSION

Length of the MF and PF in males was significantly higher than females. VD of the PF at the MF level in Type 1 and Type 3 was significantly higher than type 2. In type 1,VD of the PF at the midpoint was significantly higher than type 2 and type 3. VD of the PF at the TC level in Type 1 and Type 3 was significantly higher than type 2.

The discomallear ligament: anatomical, microscopical, and radiologic analysis

BACKGROUND

Several anatomic relationships between the ear and the temporo-mandibular joint have been proposed to account for the presence of tinnitus during temporo-mandibular disorders. Among the otomandibular structures, the discomallear ligament (DML) is interposed between the malleus and the retrodiscal capsular complex. The aim of present paper was to study through dissection the frequency and morphology of DML, to characterize its type of collagen, and to evaluate the DML on routine computed tomography (CT).

METHODS AND RESULTS

The study has been conducted on five un-embalmed adult cadavers, and in all cases, the DML was present (100%). It was constituted mainly by fibers of collagen I, with abundant elastic fibers. On CT exams of 40 patients with no reported pathology of the ear, on axial images, a dense structure, going from the upper end of the petrotympanic fissure to the neck of the malleus, was present in all the cases. In 90%, it showed a triangular shape, in 5% a rectangular shape, and in 5% a curved course. The mean length of the antero-medial side was 2 ± 0.6 mm and that of the antero-lateral side was 1.63 ± 0.5, and the mean area was 1.29 ± 0.83 mm².

CONCLUSION

The DML could represent an anatomical structure that joining the temporo-mandibular joint and the malleus may play a role in the otologic symptoms during temporo-mandibular disorders.

Oral sensory nerve damage: Causes and consequences

Oral sensations (i.e., taste, oral somatosensation, retronasal olfaction) are integrated into a composite sense of flavor, which guides dietary choices with long-term health impact. The nerves carrying this input are vulnerable to peripheral damage from multiple sources (e.g., otitis media, tonsillectomy, head injury), and this regional damage can boost sensations elsewhere in the mouth because of central interactions among nerve targets. Mutual inhibition governs this compensatory process, but individual differences lead to variation in whole-mouth outcomes: some individuals are unaffected, others experience severe loss, and some encounter sensory increases that may (if experienced early in life) elevate sweet-fat palatability and body mass. Phantom taste, touch, or pain sensations (e.g., burning mouth syndrome) may also occur, particularly in those expressing the most taste buds. To identify and treat these conditions effectively, emerging clinical tests measure regional vs. whole-mouth sensation, stimulated vs. phantom cues, and oral anatomy. Scaling methods allowing valid group comparisons have strongly aided these efforts. Overall, advances in measuring oral sensory function in health and disease show promise for understanding the varied clinical consequences of nerve damage.