Pronunciation: [mˈastɔ͡ɪdə͡l] (IPA) 
Mastoidal is a word used to describe the bony process behind the ear. The word is spelled with the letter 'o' after 'm' and 't' despite the pronunciation that might suggest 'a'. The correct way to pronounce it is /mæsˈtɔɪdəl/ (mas-TOY-dal), where the two letters 'o' represent the sound of the 'ɔɪ' diphthong. The spelling of mastoidal is consistent with other words that have the same diphthong sounds, such as 'avoid' or 'moist'.
Mastoidal is an adjective that is primarily used in the field of anatomy and medicine to describe structures or processes related to the mastoid bone, a roughened, pyramid-shaped bony structure located behind the ear. The mastoid bone is an important part of the skull, and it contains air cells connected to the middle ear. This bone contributes to the formation of the temporal bone, which assists in protecting the delicate structures within the ear.
When referring to the term "mastoidal," it often relates to the mastoid process, a projection on the skull that is made up of the mastoid bone. This process serves as an attachment point for various muscles important for movements of the head and neck. Furthermore, the presence of air cells within the mastoid bone aids in the drainage of fluids and helps to regulate air pressure within the ear.
In medical contexts, mastoidal may also describe conditions or procedures involving the mastoid bone. For instance, mastoiditis refers to an infection of the mastoid process, typically resulting from an unresolved middle ear infection. Treatment may involve antibiotics or, in severe cases, surgical intervention to drain the infected area.
Overall, mastoidal primarily pertains to the mastoid bone and its associated structures, with specific reference to anatomy, medical conditions, or procedures related to the area behind the ear.
Mastoid (2).
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
The word "mastoidal" is derived from the Greek word "mastoeidēs", which comes from "mastos" meaning "breast" and "-oeidēs" meaning "resembling". It refers to the shape or resemblance of the mastoid process, which is a bony protrusion located behind the ear.
