Normally the middle ear is closed externally and is rather remotely open to the posterior part of the nasal cavity. Rarely does any substance enter the middle ear. In cases of infection, one has the best chance to observe absorption from that area. The rapid rise of temperature to a high level, especially in children, is the result of absorbed toxic substances. The development of leukocytosis and general malaise is caused by the same process.
The diameter of the tympanic cavity of an adult is approximately 15 mm. The area of absorption is therefore small. The depth of this cavity is from 2 to 6 mm., limiting the capacity of the middle ear to about 1 cc.
Because of the difficulties involved in making observations on man, it was considered worth while to study the absorption of toxic substances from the middle ear of animals.
ROSS EL, RAWSON RW. ABSORPTION FROM THE MIDDLE EAR. Arch Otolaryngol. 1935;22(3):312–316. doi:10.1001/archotol.1935.00640030326005
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