The object of this study was to investigate the anatomy, histology, and possible function of a conical structure found in the middle ear of the cat. This conical structure lies across the dorso-caudal compartment of the middle ear. It is directly related to the course of the chorda tympani nerve in the middle ear. Its base is attached by fibrous tissue to the dorso-caudal segment of the tympanic bone adjacent to the tympanic membrane. Its apex rests on the promontory just rostral to the round window niche. Histologically, it is cartilaginous tissue enveloped by a mudous membrane with no trace of bone. Portions of some conical cartilage specimens display extensive calcification. A previous hypothesis suggests that this structure conducts high frequency sounds directly from the tympanic membrane to the round window membrane. This seems unlikely because its length is shorter than the distance between the tympanic membrane and round window membrane. The conical cartilage may be a vestigial remnant of the second arch bar (Reichert's cartilage).

Metastatic tumours of the temporal bone seem to be more common than is recognized. Most of these tumours are microscopic and asymptomatic in nature. Microscopic examination of 22 temporal bones belonging to 13 cases of metastatic tumours is reported. The commonest site of involvement in the temporal bone was the petrous apex followed by the tegmen tympani, mastoid bone and internal auditory canal. Primary tumours were most commonly located in the breast. Other sites of primary tumours included the thyroid gland, brain, lungs, prostate and blood (leukaemia). Two cases had undetermined sites of origin. Full neurotologic evaluation is indicated in every case suspected of having a temporal bone metastasis. All three modalities (of surgery, radiotherapy and chemotherapy) are used in combination for the treatment of these tumours.

A staging system is suggested for carcinomas of the external and middle ear, based on a personal series of 47 patients. Statistical analysis showed that the proposed system was a valid method of identifying significant predictor factors. Other significant predictors of survival were histology, lymph node metastases, and the patients' general condition. Stage-for-stage there was no significant difference in survival between tumours of the external and middle ear.

For the purpose of this study, acoustic signals were generated by an Amplaid MK VI. An Amplaid 702 impedence meter was connected to its averaging section and to its computer. The stimuli were bursts of unfiltered white noise (UWN) and of narrow band white noise (NBWN; 30 db./oct/slope; central frequencies 1,000, 2,000, 4,000 Hz.) lasting 3–1,000 msec, at intensity of 105 db. SPL p.e. The following parameters were evaluated: stapedius contraction latency, amplitude, duration and recruitment time. It was found that latency was independent of the spectrum of the stimulus and its duration. Amplitude and recruitment time, on the other hand, were related to spectrum and duration, while duration of contraction was directly related to the duration of the stimulus only.

Squamous odontogenic tumour (SOT) is a rare benign odontogenic neoplasm, apparently arising from rests of Malassez. It was first described in 1975 and since then only 17 cases have been recorded in the literature.

A new, not previously reported, characteristic case of SOT is presented in connection with a review of the literature.

It is concluded that the lesion occurs with equal frequency in the maxilla and mandible and now and then multifocally. Maxillary lesions seem to grow more aggressively than do mandibular ones. The symptoms are modest.

SOT has a characteristic pathologic picture which differs decisively from ameloblastoma and which, in connection with its benign nature, warrants the classification of SOT. Although most cases have been treated by conservative surgical therapy without recurrence, there are cases, especially in the maxilla with diffuse lesions, which have required en bloc resection or hemimaxillectomy.

The diagnostic problems are stressed and recommendations are made for the pathologist and the surgeon to pay attention to this rare but benign tumour.