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It refers to the portion of the teeth that forms a convex protuberance at the cervical third of the anatomic crown. It represents the lingual or palatal developmental lobe of these teeth. [1] In zoology and palaeontology, cingulum refers to this feature only in the upper teeth. When this occurs in the lower teeth it is called the cingulid.
Cingula are often incomplete ridges that pass around the base of the crown. [2] Mammalian, multicusped cheek teeth probably evolved from single-cusped teeth in synapsids, although the diversity of therapsid molar patterns and the complexity in the molars of the earliest mammals make determining how this happened impossible. According to the ...
Some animals don't have a cingulid. Those that do may have them on only some, or all of the teeth, though most often on the molar teeth. It can be on the upper or lower teeth, or both. There are four common descriptions of the position of the cingulid: Lingual cingulid - a cingulid on the side of the tooth that is next to the tongue
The evolution of the mammalian middle ear appears to have occurred in two steps. A partial middle ear formed by the departure of postdentary bones from the dentary, and happened independently in the ancestors of monotremes and therians. The second step was the transition to a definite mammalian middle ear, and evolved independently at least ...
The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates , the inner ear is mainly responsible for sound detection and balance. [ 1 ] In mammals , it consists of the bony labyrinth , a hollow cavity in the temporal bone of the skull with a system of passages comprising two main functional parts: [ 2 ]
The central portion of the tympanic part is thin, as it gives rise to the bony inner two-thirds of the ear canal, and in 5 - 20% of skulls the lower surface is perforated by a hole, the foramen of Huschke [1] that opens onto the temporomandibular joint due to incomplete fusion of the anterior and posterior prominences during development.
External auditory meatus is the ear canal; Fossa triangularis is the depression in the fork of the antihelix; Helix is the folded over outside edge of the ear; Incisura anterior auris, or intertragic incisure, or intertragal notch, is the space between the tragus and antitragus; Lobe (lobule) Scapha, the depression or groove between the helix ...
The anterior auricular branches of the superficial temporal artery are distributed to the anterior portion of the auricula, the lobule, and part of the external meatus, anastomosing with the posterior auricular. They supply the external acoustic meatus and the visible part of the ear. Arterial vascular pattern of the auricle: