Petrotympanic fissure
Encyclopedia
The petrotympanic fissure (also known as the squamotympanic fissure) is a fissure in the temporal bone
that runs from the temporomandibular joint
to the tympanic cavity
.
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
, and gives passage to the anterior tympanic branch of the internal maxillary artery
.
. A branch of cranial nerve VII, the chorda tympani
, runs through the fissure to join with the lingual nerve providing special sensory (taste) innervation to the tongue. The tympanic nerve branches off of cranial nerve IX to pass through the fissure as the lesser petrosal nerve
, which passes through the foramen ovale
and joins V3 of the trigeminal nerve
, synapses in the otic ganglion
, to provide parasympathetic innervation to the parotid gland
.
Temporal bone
The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebrum.The temporal bone supports that part of the face known as the temple.-Parts:The temporal bone consists of four parts:* Squama temporalis...
that runs from the temporomandibular joint
Temporomandibular joint
The temporomandibular joint is the joint of the jaw and is frequently referred to as TMJ. There are two TMJs, one on either side, working in unison. The name is derived from the two bones which form the joint: the upper temporal bone which is part of the cranium , and the lower jaw bone called the...
to the tympanic cavity
Tympanic cavity
The tympanic cavity is a small cavity surrounding the bones of the middle ear.It is formed from the tubotympanic recess, an expansion of the first pharyngeal pouch....
.
The mandibular fossa
Mandibular fossa
The mandibular fossa is the depression in the temporal bone that articulates with the mandibular condyle. In the temporal bone, 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...
is bounded, in front, by the articular tubercle
Articular tubercle
The anterior root of the posterior end of the outer surface of the Squama temporalis, continuous with the lower border, is short but broad and strong; it is directed medialward and ends in a rounded eminence, the articular tubercle .This tubercle forms the front boundary of the mandibular fossa,...
; 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
Malleus
The malleus or hammer is a hammer-shaped small bone or ossicle of the middle ear which connects with the incus and is attached to the inner surface of the eardrum...
, and gives passage to the anterior tympanic branch of the internal maxillary artery
Internal maxillary artery
The maxillary artery is an artery that supplies deep structures of the face. It branches from the external carotid artery just deep to the neck of the mandible.-Structure:...
.
Contents
The contents of the fissure include communications of cranial nerves VII and IX to the infratemporal fossaInfratemporal fossa
The infratemporal fossa is an irregularly shaped cavity, situated below and medial to the zygomatic arch.* anteriorly, by the infratemporal surface of the maxilla and the ridge which descends from its zygomatic process...
. A branch of cranial nerve VII, the chorda tympani
Chorda tympani
The chorda tympani is a nerve that branches from the facial nerve inside the facial canal, just before the facial nerve exits the skull via the Stylomastoid foramen...
, runs through the fissure to join with the lingual nerve providing special sensory (taste) innervation to the tongue. The tympanic nerve branches off of cranial nerve IX to pass through the fissure as the lesser petrosal nerve
Lesser petrosal nerve
The lesser petrosal nerve consists of parasympathetic fibres. It leaves the tympanic plexus to synapse in the otic ganglion, and eventually provide parasympathetic innervation to the parotid gland....
, which passes through the foramen ovale
Foramen ovale
There are multiple structures in the human body with the name foramen ovale :* In the fetal heart, the foramen ovale is a shunt from the right atrium to left atrium....
and joins V3 of the trigeminal nerve
Trigeminal nerve
The trigeminal nerve contains both sensory and motor fibres. It is responsible for sensation in the face and certain motor functions such as biting, chewing, and swallowing. Sensory information from the face and body is processed by parallel pathways in the central nervous system...
, synapses in the otic ganglion
Otic ganglion
The otic ganglion is a small, oval shaped, flattened parasympathetic ganglion of a reddish-gray color, located immediately below the foramen ovale in the infratemporal fossa. It gives innervation to the parotid gland for salivation....
, to provide parasympathetic innervation to the parotid gland
Parotid gland
The paired parotid glands are the largest of the salivary glands. They are each found wrapped around the mandibular ramus, and secrete saliva through Stensen's ducts into the oral cavity, to facilitate mastication and swallowing and to begin the digestion of starches.-Location:The parotid glands...
.