The petrotympanic fissure (also known as the squamotympanic fissure or the glaserian fissure) is a fissure in the

temporal bone The temporal bone is a paired bone situated at the sides and base of the skull, lateral to the temporal lobe of the cerebral cortex. The temporal bones are overlaid by the sides of the head known as the temples where four of the cranial bone ...

that runs from the

temporomandibular joint In anatomy, the temporomandibular joints (TMJ) are the two joints connecting the jawbone to the skull. It is a bilateral Synovial joint, synovial articulation between the temporal bone of the skull above and the condylar process of mandible be ...

to the

tympanic cavity The tympanic cavity is a small cavity surrounding the bones of the middle ear. Within it sit the ossicles, three small bones that transmit vibrations used in the detection of sound. Structure On its lateral surface, it abuts the external audit ...

. The mandibular fossa is bounded, in front, by the articular tubercle; behind, by the tympanic part of the bone, which separates it from the external acoustic meatus; it is divided into two parts by a narrow slit, the petrotympanic fissure. It opens just above and in front of the ring of bone into which the tympanic membrane is inserted; in this situation it is a mere slit about 2 mm. in length. It lodges the anterior process and anterior ligament of the

malleus The ''malleus'', or hammer, is a hammer-shaped small bone or ossicle of the middle ear. It connects with the incus, and is attached to the inner surface of the eardrum. The word is Latin for 'hammer' or 'mallet'. It transmits the sound vibra ...

, and gives passage to the anterior tympanic branch of the

internal maxillary artery The maxillary artery (eg, internal maxillary artery) supplies deep structures of the face. It branches from the external carotid artery just deep to the neck of the mandible. Structure The maxillary artery, the larger of the two terminal branche ...

Eponym

It is also known as the "Glaserian fissure", after Johann Glaser.

The contents of the fissure include communications of cranial nerve VII to the infratemporal fossa. A branch of cranial nerve VII, the

chorda tympani Chorda tympani is a branch of the facial nerve that carries gustatory (taste) sensory innervation from the front of the tongue and parasympathetic ( secretomotor) innervation to the submandibular and sublingual salivary glands. Chorda tymp ...

, runs through the fissure to join with the lingual nerve providing special sensory (taste) innervation to the tongue. Anterior tympanic artery and tympanic veins also pass through the structure. Petrotympanic fissure contains some of the fibers of the anterior ligament of malleus, which run on the base of skull and eventually attach onto the spine of sphenoid bone.

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* * {{Authority control Foramina of the skull

Eponym

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