The foramen tympanicum, or also known as the foramen of Huschke, is an

anatomical variation An anatomical variation, anatomical variant, or anatomical variability is a presentation of body structure with morphological features different from those that are typically described in the majority of individuals. Anatomical variations are categ ...

of the tympanic part of the

temporal bone The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebral cortex. The temporal bones are overlaid by the sides of the head known as the temples, and house the structures of the ears. ...

in humans resulting from a defect in normal

ossification Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in ...

during the first five years of life. The structure was found in 4.6% to as high as 23% of the population.

Structure

If present, the foramen tympanicum is located at the anteroinferior portion of the

external auditory canal The ear canal (external acoustic meatus, external auditory meatus, EAM) is a pathway running from the outer ear to the middle ear. The adult human ear canal extends from the pinna to the eardrum and is about in length and in diameter. Stru ...

, locating posteromedial to the

temporomandibular joint In anatomy, the temporomandibular joints (TMJ) are the two joints connecting the jawbone to the skull. It is a bilateral synovial articulation between the temporal bone of the skull above and the mandible below; it is from these bones that it ...

. The structure connects the external auditory canal to the infratemporal fossa. Reduction in thickness of the temporal bone may also occur in the same location. During development of the skull, the foramen tympanicum normally closes by the age of 5 years. The foramen, however, may persists in rare cases resulting in its presence in adults. The persistence of this foramen may be the result of abnormal mechanical forces during development of face and/or ossification abnormalities attributed to genetic factors.

Clinical relevance

Persistence of the foramen tympanicum may also predispose the individual to the spread of infection or tumor from the external auditory canal to the infratemporal fossa or vice versa. It is associated with

herniation A hernia is the abnormal exit of tissue or an organ, such as the bowel, through the wall of the cavity in which it normally resides. Various types of hernias can occur, most commonly involving the abdomen, and specifically the groin. Groin hernia ...

of soft tissues from the temporomandibular joint into the external auditory meatus, and with formation of

fistula A fistula (plural: fistulas or fistulae ; from Latin ''fistula'', "tube, pipe") in anatomy is an abnormal connection between two hollow spaces (technically, two epithelialized surfaces), such as blood vessels, intestines, or other hollow or ...

between the

parotid gland The parotid gland is a major salivary gland in many animals. In humans, the two parotid glands are present on either side of the mouth and in front of both ears. They are the largest of the salivary glands. Each parotid is wrapped around the ma ...

and the external auditory canal. During

arthroscopy Arthroscopy (also called arthroscopic or keyhole surgery) is a minimally invasive surgical procedure on a joint in which an examination and sometimes treatment of damage is performed using an arthroscope, an endoscope that is inserted into the ...

of the temporomandibular joint, the

endoscope An endoscope is an inspection instrument composed of image sensor, optical lens, light source and mechanical device, which is used to look deep into the body by way of openings such as the mouth or anus. A typical endoscope applies several modern t ...

may inadvertently pass into the joint via the foramen, with resulting damage.

References

{{Foramina of skull Anatomical variations