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In all extant and extinct primates, including humans, the auditory bulla is formed by the petrosal bone (the petrous part of the temporal bone). This is a diagnostic trait that can be used to distinguish primates, including anthropoids, tarsiers, lemurs, and lorises, from all other mammals. [3]
In many mammals this is a separate tympanic bone derived from the angular bone of the reptilian lower jaw, and, in some cases, it has an additional entotympanic bone. The auditory bulla is homologous with the tympanic part of the temporal bone. [8] Two parts of the hyoid arch: the styloid process.
In many mammals, the middle ear also becomes protected within a cavity, the auditory bulla, not found in other vertebrates. A bulla evolved late in time and independently numerous times in different mammalian clades, and it can be surrounded by membranes, cartilage or bone. The bulla in humans is part of the temporal bone. [7]
In anatomy, the zygomatic arch, or cheek bone, is a part of the skull formed by the zygomatic process of the temporal bone (a bone extending forward from the side of the skull, over the opening of the ear) and the temporal process of the zygomatic bone (the side of the cheekbone), the two being united by an oblique suture (the zygomaticotemporal suture); [1] the tendon of the temporal muscle ...
In the temporal bone, the mandibular fossa is bounded anteriorly by the articular tubercle and posteriorly by the tympanic portion of the temporal bone, which separates it from the external acoustic meatus. The fossa is divided into two parts by a narrow slit, the petrotympanic fissure (Glaserian fissure).
These extended margins of thinned bone are called supratemporal fossae. Synapsids, including mammals, have one temporal fenestra, which is ventrally bordered by a zygomatic arch composed of the jugal and squamosal bones. This single temporal fenestra is homologous to the infratemporal fenestra, as displayed most clearly by early synapsids. [2]
In therian mammals, the lagena is extended still further, becoming a coiled structure (cochlea) in order to accommodate its length within the head. The organ of Corti also has a more complex structure in mammals than it does in other amniotes. [12] The arrangement of the inner ear in living amphibians is, in most respects, similar to that of ...
The floor of the fossa features the pterion (the junction of these four bones). [1]: 357 Lateral/roof: temporal fascia. [1]: 357 Anterior: (posterior surface of) the frontal process of zygomatic bone, [citation needed] (the posterior surface of [citation needed]) the zygomatic process of frontal bone, and the maxilla. [1]: 357