Verdugo explained that one dense piece of the skull's temporal bone, called the petrous part, is especially good at preserving ancient DNA.
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Pinhasi had discovered that the inner ear's petrous bone, one of the densest in the body, often preserved vast quantities of genetic material.
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All of those came from the petrous part of the temporal bone, which is the tough part of the skull behind the ear, from five different individuals.
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Next time they'll use the petrous bone at the base of the skull, which is far denser than the femur and thus a more promising source of DNA.
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One of Bedford's colleagues opened the skulls in a workshop warren behind the national museum, extracted the nubbins of petrous bone and shipped them to Dublin, where they were sandblasted.
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But he is optimistic that they can retrieve some genetic material because the team recovered something called the petrous portion of the temporal bone, which is the hard part behind the ear.
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To make the analysis, the researchers used a sample from the petrous bone — a bone in the skull near the ear — that they've found to be best at preserving DNA that's many thousands of years old.
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They analyzed the petrous bones — the hard part of the skull behind the ear that "preserves DNA best," says study co-author Michael Hofreiter, a professor of evolutionary adaptive genomics at the University of Potsdam in Germany.
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I sat in the dark next to Frederique Valentin, a French bioarchaeologist who was an author on Reich's original Vanuatu paper; it was she who made the final contribution that rescued the effort, the Tongan petrous bone.
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Bedford and his archaeologist colleagues on Vanuatu are known for their long tenure in the country and their keen acquaintance with local sensitivities, and it was only on their bond that the Teouma petrous bones were sent abroad for sandblasting.
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When the Jena team heard that the Oceania paper had been found wanting for further regional samples — samples that would allow them to expand their claims beyond simply Vanuatu — one doctoral candidate remembered that their inventory contained a stray petrous bone from a site in Tonga, one already found to contain readable DNA.
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Abnormal development of the skeletal portions of the second arch # Nondifferentiation of the stapes, with resultant absence of round and oval window. # Abnormal course of the facial nerve. Skull base abnormalities # Hypoplasia of the petrous temporal bone. # Hypoplastic and sclerotic petrous apex may mimic labyrinthitis ossificans.
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More commonly longitudinal fracture of petrous bone and fracture of temporal bone can cause facial nerve compression.
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The petrous part of the temporal bone is pyramid-shaped and is wedged in at the base of the skull between the sphenoid and occipital bones. Directed medially, forward, and a little upward, it presents a base, an apex, three surfaces, and three angles, and houses in its interior, the components of the inner ear. The petrous portion is among the most basal elements of the skull and forms part of the endocranium. Petrous comes from the Latin word petrosus, meaning "stone-like, hard".
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The petrosquamous suture is a cranial suture between the petrous portion and the squama of the temporal bone. It forms the Koerner's septum. The petrous portion forms the medial component of the osseous margin, while the squama forms the lateral component. The anterolateral portion (squama) arises from the mesenchyme at 8 weeks of embryogenesis while the petromastoid portion develops later from a cartilaginous center at 6 months of fetal development.
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The sphenopetrosal fissure (or sphenopetrosal suture) is the cranial suture between the sphenoid bone and the petrous portion of the temporal bone. It is in the middle cranial fossa.
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The foramen lacerum () is a triangular hole in the base of skull, located between the sphenoid, the apex of the petrous temporal and the basilar part of the occipital.
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It is one of the densest bones in the body. The petrous bone is important for studies of ancient DNA from skeletal remains, as it tends to contain extremely well-preserved DNA.
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Gradenigo's syndrome, also called Gradenigo-Lannois syndrome, is a complication of otitis media and mastoiditis involving the apex of the petrous temporal bone. It was first described by Giuseppe Gradenigo in 1904.
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The upper third lies inferior to the dorsum sellae and posterior clinoid processes and superior to the petrous apex, the middle third lies at the level of the petrous segments of the internal carotid artery (ICA), and the inferior third extends from the jugular tubercle to the foramen magnum. It is important that the Perneczky triangle is treated carefully. This triangle has optic nerves, cerebral arteries, the third cranial nerve, and the pituitary stalk. Damage to any of these could provide a devastating post-surgical outcome.
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SBO can extend into the petrous apex of the temporal bone or more inferiorly into the opposite side of the skull base. The use of hyperbaric oxygen therapy as an adjunct to antibiotic therapy remains controversial.
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The pathophysiological mechanism of sixth nerve palsy with increased intracranial pressure has traditionally been said to be stretching of the nerve in its long intracranial course, or compression against the petrous ligament or the ridge of the petrous temporal bone. Collier, however, was “unable to accept this explanation”, his view being that since the sixth nerve emerges straight forward from the brain stem, whereas other cranial nerves emerge obliquely or transversely, it is more liable to the mechanical effects of backward brain stem displacement by intracranial space occupying lesions.
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The internal auditory meatus (also meatus acusticus internus, internal acoustic meatus, internal auditory canal, or internal acoustic canal) is a canal within the petrous part of the temporal bone of the skull between the posterior cranial fossa and the inner ear.
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On transverse section, the horizontal portion exhibits a prismatic form, the curved portion has a semicylindrical form. They receive the blood from the superior petrosal sinuses at the base of the petrous portion of the temporal bone; they communicate with the veins of the pericranium by means of the mastoid and condyloid emissary veins; and they receive some of the inferior cerebral and inferior cerebellar veins, and some veins from the diploë. The petrosquamous sinus, when present, runs backward along the junction of the squama and petrous portion of the temporal, and opens into the transverse sinus.
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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.
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The trigeminal ganglion (or Gasserian ganglion, or semilunar ganglion, or Gasser's ganglion) is a sensory ganglion of the trigeminal nerve (CN V) that occupies a cavity (Meckel's cave) in the dura mater, covering the trigeminal impression near the apex of the petrous part of the temporal bone.
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The foramen lacerum () is a triangular hole in the base of skull located between the sphenoid, apex of petrous temporal and basilar part of occipital. It is the juncture of the petroclival, sphenopetrosal, and pterygosphenoidal sutures. The foramen lacerum is a foramen situated anteromedial to the carotid canal.
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The middle cranial fossa, deeper than the anterior cranial fossa, is narrow medially and widens laterally to the sides of the skull. It is separated from the posterior fossa by the clivus and the petrous crest. It is bounded in front by the posterior margins of the lesser wings of the sphenoid bone, the anterior clinoid processes, and the ridge forming the anterior margin of the chiasmatic groove; behind, by the superior angles of the petrous portions of the temporal bones and the dorsum sellæ; laterally by the temporal squamæ, sphenoidal angles of the parietals, and greater wings of the sphenoid. It is traversed by the squamosal, sphenoparietal, sphenosquamosal, and sphenopetrosal sutures.
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The trigeminal cave is formed by the two layers of dura mater (endosteal and meningeal) which are part of an evagination of the cerebellar tentorium near the apex of the petrous part of the temporal bone. It envelops the trigeminal ganglion. It is bounded by the dura overlying four structures: #cerebellar tentorium superolaterally #lateral wall of the cavernous sinus superomedially #clivus medially #posterior petrous face inferolaterally Within the dural confines of the trigeminal cave, there is a continuation of subarachnoid space along the posterior aspect of the cave, representing a continuation of the cerebral basal cisterns.Burr HS, Robinson GB: An anatomical study of the gasserian ganglion with particular reference to the nature and extend of Meckel’s Cave (M,C).
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The jugular foramen is a large foramen (opening) in the base of the skull, located behind the carotid canal. It is formed in front by the petrous portion of the temporal bone, and behind by the occipital bone; it is generally larger on the right than on the left side.
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In 2017, researchers successfully extracted the DNA from both the petrous and squamous part of the Darra-e Kur temporal bone. The Darra-e Kur specimen is the first ancient human remain from Afghanistan from which DNA has been successfully sequenced. The individual was found to belong to Haplogroup H2a.
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The petrosal process is a sharp process below the notch for the passage of the abducent nerve on either side of the dorsum sellae of the sphenoid bone. It articulates with the apex of the petrous portion of the temporal bone, and forms the medial boundary of the foramen lacerum.
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In 2016, researchers extracted the DNA from the petrous bone of three of the individuals buried at Teouma. This is the first successful DNA extraction from ancient samples taken from the tropics. The remains date to around 3,110 to 2,710 years old. DNA analysis confirmed that all three of the individuals were female.
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At the tip of the petrous part of the temporal bone it makes a sharp turn forward to enter the cavernous sinus. In the cavernous sinus it runs alongside the internal carotid artery. It then enters the orbit through the superior orbital fissure and innervates the lateral rectus muscle of the eye.
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For example, fractures of the petrous temporal bone can selectively damage the nerve, as can aneurysms of the intracavernous carotid artery. Mass lesions that push the brainstem downward can damage the nerve by stretching it between the point where it emerges from the pons and the point where it hooks over the petrous temporal bone. The central anatomy of the sixth nerve predicts (correctly) that infarcts affecting the dorsal pons at the level of the abducens nucleus can also affect the facial nerve, producing an ipsilateral facial palsy together with a lateral rectus palsy. The anatomy also predicts (correctly) that infarcts involving the ventral pons can affect the sixth nerve and the corticospinal tract simultaneously, producing a lateral rectus palsy associated with a contralateral hemiparesis.
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The lateral half of the great wing of the sphenoid bone articulates, by means of a synchondrosis, with the petrous part of the temporal bone. Between these two bones on the under surface of the skull, is a furrow, the 'sulcus of auditory tubule, for the lodgement of the cartilaginous part of the auditory tube.
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This is a very rare tumor, since only about 1 in 35,000 to 40,000 people have VHL, of whom about 10% have endolymphatic sac tumors. Patients usually present in the 4th to 5th decades without an gender predilection. The tumor involves the endolymphatic sac, a portion of the intraosseous inner ear of the posterior petrous bone.
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This grooved surface of the foramen magnum is separated on either side from the petrous portion of the temporal bone by the petro-occipital fissure, which is occupied in the fresh state by a plate of cartilage; the fissure is continuous behind with the jugular foramen, and its margins are grooved for the inferior petrosal sinus.
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In 2018, researchers successfully extracted low coverage nuclear DNA from the petrous bone of 8 of the individuals from the cemetery at Mán Bạc. The individuals at Mán Bạc appear to be genetically homogenous. The individuals at Mán Bạc show a mix of East Asian farmer and east Eurasian hunter-gatherer ancestry, with close genetic affinity for modern Austroasiatic speakers.
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In 2015, researchers were able to extract the entire mitochondrial genome from both individuals. In 2018, researchers successfully sequenced the nuclear DNA from the petrous bone of both individuals, yielding around 17-fold coverage from USR1 and low coverage from USR2. Based on osteological analysis, the two infants were previously thought to be female; this assessment is corroborated by evidence from DNA analysis.
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The inferior tympanic canaliculus is a small passage of the tympanic branch of the glossopharyngeal nerve and inferior tympanic artery. In the bony ridge dividing the carotid canal from the jugular fossa is the small inferior tympanic canaliculus. The inferior tympanic canaliculus is near the fossula petrosa which houses inferior ganglion of glossopharyngeal nerve/petrous ganglion from which the tympanic nerve arises.
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The nerve passes adjacent to the mastoid sinus and is vulnerable to mastoiditis, leading to inflammation of the meninges, which can give rise to Gradenigo's syndrome. This condition results in a VIth nerve palsy with an associated reduction in hearing ipsilaterally, plus facial pain and paralysis, and photophobia. Similar symptoms can also occur secondary to petrous fractures or to nasopharyngeal tumours.
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At the apex of the petrous part of the temporal bone the free and attached borders meet, and, crossing one another, are continued forward to be fixed to the anterior and posterior clinoid processes (respectively) of the sphenoid bone. To the middle line of its upper surface the posterior border of the falx cerebri is attached, the straight sinus being placed at their line of junction.
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The inferior tympanic artery is a small branch of the ascending pharyngeal artery. It is a small branch which passes through a minute foramen in the petrous portion of the temporal bone which is called tympanic canaliculus or inferior tympanic canaliculus, in company with the tympanic branch of the glossopharyngeal nerve, to supply the medial wall of the tympanic cavity and anastomose with the other tympanic arteries.
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In human anatomy, the Pars flaccida of tympanic membrane or Shrapnell's membrane (also known as Rivinus’ ligament) is the small, triangular, flaccid portion of the tympanic membrane, or eardrum. It lies above the malleolar folds attached directly to the petrous bone at the notch of Rivinus. On the inner surface of the tympanic membrane, the chorda tympani crosses this area. It is named after Henry Jones Shrapnell.
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The greater wings of the sphenoid are two strong processes of bone, which arise from the sides of the body, and are curved upward, laterally, and backward; the posterior part of each projects as a triangular process that fits into the angle between the squamous and the petrous part of the temporal bone and presents at its apex a downward-directed process, the spine of sphenoid bone.
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At the hinder part of the medial wall of the vestibule is the orifice of the vestibular aqueduct, which extends to the posterior surface of the petrous portion of the temporal bone. It transmits a small vein, and contains a tubular prolongation of the membranous labyrinth, the ductus endolymphaticus, which ends in a cul-de-sac, the endolymphatic sac, between the layers of the dura mater within the cranial cavity.
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From the posterior wall of the saccule a canal, the endolymphatic duct, is given off; this duct is joined by the ductus utriculosaccularis, and then passes along the aquaeductus vestibuli and ends in a blind pouch (endolymphatic sac) on the posterior surface of the petrous portion of the temporal bone, where it is in contact with the dura mater. Disorders of the endolymphatic duct include Meniere's Disease and Enlarged Vestibular Aqueduct.
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It arises from the under surface of the apex of the petrous part of the temporal bone and from the medial lamina of the cartilage of the auditory tube. After passing above the upper concave margin of the superior pharyngeal constrictor muscle it spreads out in the palatine velum, its fibers extending obliquely downward and medially to the middle line, where they blend with those of the opposite side.
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Many secondary conditions have been reported to be possible causes of CPH, according to Mehta et al., most of which are arterial abrasions or tumors. These include aneurysms in the circle of Willis, middle cerebral artery infarction, parietal arteriovenous malformation, cavernous sinus and petrous ridge meningiomas, pituitary adenoma, Pancoast tumor, gangliocytoma of the sella turcica, and malignant frontal tumors.Mehta, Noshir R., George E. Maloney, Dhirendra S. Bana, and Steven J. Scrivani.
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When the mouth is closed the meniscus is bordered medially and superiorly by the glenoid fossa of the petrous portion of the temporal bone. When the mouth is opened maximally, the meniscus is distracted anteriorly and inferiorly along the slope of the inferior portion of the temporal bone towards the tubercle, or articular eminence, in order to remain interposed between the condyle and the temporal bone in all jaw positions.
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The lateral approach is then used to reach the medial cavernous sinus and petrous apex. Lastly, the inferior approach is used to reach the superior clivus. Endoscopic endonasal transclival approaches are often described according to which segment of the clivus is involved in the approach, with the clivus typically divided into three regions. Depending on which segment of the clivus is involved in the surgical approach, different neurovascular structures are placed at risk.
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The bone that is most often used for DNA extraction is the petrous bone, since its dense structure provides good conditions for DNA preservation. Several other sources have also yielded DNA, including paleofaeces, and hair. Contamination remains a major problem when working on ancient human material. Ancient pathogen DNA has been successfully retrieved from samples dating to more than 5,000 years old in humans and as long as 17,000 years ago in other species.
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The great wings, or alae-sphenoids, are two strong processes of bone, which arise from the sides of the body, and are curved upward, lateralward, and backward; the posterior part of each projects as a triangular process which fits into the angle between the squama and the petrous portion of the temporal bone and presents at its apex a downwardly directed process, the spina angularis (sphenoidal spine). It serves as the origin for the sphenomandibular ligament.
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The posterior semicircular canal is a part of the vestibular system that detects rotation of the head around the antero-posterior (sagittal) axis, or in other words rotation in the coronal plane. This occurs, for example, when you move your head to touch your shoulders, or when doing a cartwheel. It is directed superiorly, as per its nomenclature, and posteriorly, nearly parallel to the posterior surface of the petrous bone. The vestibular aqueduct is immediately medial to it.
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The constellation of symptoms was first described as a consequence of severe, advanced ear infection which has spread to a central portion of the temporal bone of the skull. This type of presentation was common prior to development of antibiotic treatments, and is now a rare complication. In persons with longstanding ear infection and typical symptoms, medical imaging such as CT or MRI of the head may show changes that confirm disease involvement of the petrous apex of temporal bone.
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CT in patient with VHL syndrome through the petrous ridge demonstrates bone erosion at the site of the endolymphatic sac tumor, typical of the locally aggressive behavior of this tumor (curved arrow). Imaging studies help to identify the tumor and the specific anatomic site of involvement. Magnetic resonance images show a hyperintensity (hypervascularity) of a heterogeneous mass by T1 weighted images. Computed tomography shows a multilocular, lytic destructive temporal bone mass, centered on the vestibular aqueduct (between internal auditory canal and sigmoid sinus).
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Within the facial canal at the geniculate ganglion the axons branch from the facial nerve forming the greater petrosal nerve. This nerve exits the facial canal through the hiatus for the greater petrosal nerve in the petrous part of the temporal bone. It emerges to the middle cranial fossa and travels anteromedially to enter the foramen lacerum. Within the foramen lacerum it joins to the deep petrosal nerve to form the nerve of the pterygoid canal and then passes through this canal.
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Its lateral border is free and rough, and gives attachment to the cartilaginous part of the ear canal. Internally, the tympanic part is fused with the petrous portion, and appears in the retreating angle between it and the squama, where it lies below and lateral to the orifice of the auditory tube. Posteriorly, it blends with the squama and mastoid part, and forms the anterior boundary of the tympanomastoid fissure. Its upper border fuses laterally with the back of the postglenoid process, while medially it bounds the petrotympanic fissure.
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Covering the surface of the otolithic membrane are otoliths, which are crystals of calcium carbonate. For this reason, the saccule is sometimes called an "otolithic organ." From the posterior wall of the saccule is given off a canal, the ductus endolymphaticus (endolymphatic duct). This duct is joined by the ductus utriculosaccularis, and then passes along the aquæductus vestibuli and ends in a blind pouch saccus endolymphaticus (endolymphatic sac) on the posterior surface of the petrous portion of the temporal bone, where it is in contact with the dura mater.
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The hiatus for lesser petrosal nerve is a hiatus in the petrous part of the temporal bone which transmits the lesser petrosal nerve. It is located posterior to the groove for the superior petrosal sinus and posterolateral to the jugular foramen. The hiatus for lesser petrosal nerve receives the lesser petrosal nerve as it branches from the glossopharyngeal nerve (CN IX) before the glossopharyngeal enters the posterior cranial fossa through the jugular foramen. The lesser petrosal nerve then travels anteriorly from the hiatus toward the foramen ovale, through which it exits the cranial cavity.
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The superior or anterior semicircular canal is a part of the vestibular system and detects rotations of the head in around the lateral axis, or in other words rotation in the sagittal plane. This occurs, for example, when nodding your head. It is 15 to 20 mm in length, is vertical in direction, and is placed transversely to the long axis of the petrous part of the temporal bone, on the anterior surface of which its arch forms a round projection. It describes about two-thirds of a circle.
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From the anterior portion of the medulla oblongata, the glossopharyngeal nerve passes laterally across or below the flocculus, and leaves the skull through the central part of the jugular foramen. From the superior and inferior ganglia in jugular foramen, it has its own sheath of dura mater. The inferior ganglion on the inferior surface of petrous part of temporal is related with a triangular depression into which the aqueduct of cochlea opens. On the inferior side, the glossopharyngeal nerve is lateral and anterior to the vagus nerve and accessory nerve.
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From 1835, he worked at the universities of Zurich, Freiburg and Tübingen, returning to Heidelberg in 1852 as a professor of anatomy and physiology. Following his retirement, he was replaced at Heidelberg by Carl Gegenbaur (1826-1903). Heidelberg University Library (biography) The auricular branch of the vagus nerve was nicknamed "Arnold's nerve" after he described the reflex of coughing when the ear is stimulated.Arnold's nerve cough @ Who Named It Other eponyms that contain his name are "Arnold's ganglion" (otic ganglion) and "Arnold's canal" (a passage of the petrous portion of the temporal bone for the auricular branch of the vagus nerve.
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The cerebellar tentorium is an arched lamina, elevated in the middle, and inclining downward toward the circumference. It covers the top of the cerebellum, and supports the occipital lobes of the brain. Its anterior border is free and concave, and bounds a large oval opening, the tentorial incisure, through which pass the cerebral peduncles. It is attached, behind, by its convex border, to the transverse ridges upon the inner surface of the occipital bone, and there encloses the transverse sinuses; in front, to the superior angle of the petrous part of the temporal bone on either side, enclosing the superior petrosal sinuses.
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The transpterygoidal approach enters through the posterior edge of the maxillary sinus ostium and posterior wall of the maxillary sinus. This involves penetrating three separate sinus cavities: the ethmoid sinus, the sphenoidal sinus, and the maxillary sinus. Surgeons use this method to reach the cavernous sinus, lateral sphenoid sinus, infra temporal fossa, pterygoid fossa, and the petrous apex. Surgery includes a uninectomy (removal of the osteomeatal complex), a medial maxillectomy (removal of maxilla), an ethmoidectomy (removal of ethmoid cells and/or ethmoid bone), a sphenoidectomy (removal of part of sphenoid), and removal of the maxillary sinus and the palatine bone.
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The upper body of the Cheddar Man Nuclear DNA was extracted from the petrous part of the temporal bone by a team from the Natural History Museum in 2018. The genetic markers suggested (based on their associations in modern populations whose phenotypes are known) that he probably had green eyes, lactose intolerance, dark curly or wavy hair, and dark to very dark skin. These features are typical of the Western European population of the time, now known as West European Hunter-Gatherers. This population forms about 10%, on average, of the ancestry of Britons without a recent family history of immigration.
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Koerner's septum is an anatomic boundary in the temporal bone formed by the petrosquamous suture between the petrous and squamosal portions of the mastoid air cells, at the anatomic level of the antrum. Along with the middle ear ossicles, it is usually eroded in middle ear cholesteatomas. Superiorly, this continues as the petrosquamous suture, a normal anatomic structure that can be mistaken for fractures on temporal bone CT. It is surgically important as it may cause difficulty in locating the antrum and the deeper cells and thus may lead to incomplete removal of disease at mastoidectomy.
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The pharyngeal aponeurosis (or pharyngobasilar fascia, or fibrous coat), is situated between the mucous and muscular layers. It is thick above where the muscular fibers are wanting, and is firmly connected to the basilar portion of the occipital and the petrous portions of the temporal bones. As it descends it diminishes in thickness, and is gradually lost. It is strengthened posteriorly by a strong fibrous band, which is attached above to the pharyngeal spine on the under surface of the basilar portion of the occipital bone, and passes downward, forming a median raphé, which gives attachment to the Constrictores pharyngis.
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Within the jugular foramen, there are two glossopharyngeal ganglia that contain nerve cell bodies that mediate general, visceral, and special sensation. The visceral motor fibers pass through both ganglia without synapsing and exit the inferior ganglion with CN IX general sensory fibers as the tympanic nerve. Before exiting the jugular foramen, the tympanic nerve enters the petrous portion of the temporal bone and ascends via the inferior tympanic canaliculus to the tympanic cavity. Within the tympanic cavity the tympanic nerve forms a plexus on the surface of the promontory of the middle ear to provide general sensation.
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On the anterior surface of the petrous portion of the temporal bone are seen the eminence caused by the projection of the superior semicircular canal; in front of and a little lateral to this a depression corresponding to the roof of the tympanic cavity; the groove leading to the hiatus of the facial canal, for the transmission of the greater superficial petrosal nerve and the petrosal branch of the middle meningeal artery; beneath it, the smaller groove, for the passage of the lesser superficial petrosal nerve; and, near the apex of the bone, the depression for the semilunar ganglion and the orifice of the carotid canal.
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The lacerum segment, or C3, is a short segment that begins above the foramen lacerum and ends at the petrolingual ligament, a reflection of periosteum between the lingula and petrous apex (or petrosal process) of the sphenoid bone. The lacerum portion is still considered 'extra-dural', as it is surrounded by periosteum and fibrocartilage along its course. It is erroneously stated in several anatomy text books that the internal carotid artery passes through the foramen lacerum. This at best has only ever been a partial truth in that it passes through the superior part of the foramen on its way to the cavernous sinus.
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The orifice of the aquæductus vestibuli is the hind part of the medial wall; it extends to the posterior surface of the petrous portion of the temporal bone. It transmits a small vein and contains a tubular prolongation of the membranous labyrinth, the endolymphatic duct, which ends in a cul-de- sac between the layers of the dura mater within the cranial cavity. On the upper wall or roof, there is a transversely oval depression, the recessus ellipticus, separated from the recessus sphæricus by the crista vestibuli already mentioned. The pyramid and adjoining part of the recessus ellipticus are perforated by a number of holes (macula cribrosa superior).
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The x-ray can be taken with the patient in either an erect or supine position, although most usually erect. The x-ray is taken PA (postero-antero), meaning that the patient faces towards the receiver and away from the x-rays source. The patients chin rests on the image receiver, which tilts the head up allowing the orbits to be clear of the internal structure of the Petrous ridge. This view is called Occipital-Mental or OM. An orbital x-ray usually requires only one view unless the requester is looking for evidence of metallic fragments, in which case two projections can be made.
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The petrotympanic fissure leads into the middle ear or tympanic cavity; it lodges the anterior process of the malleus, and transmits the tympanic branch of the internal maxillary artery. The chorda tympani nerve passes through a canal (canal of Huguier), separated from the anterior edge of the petrotympanic fissure by a thin scale of bone and situated on the lateral side of the auditory tube, in the retiring angle between the squamous part and the petrous portion of the temporal bone. The internal surface of the squamous part is concave; it presents depressions corresponding to the convolutions of the temporal lobe of the brain, and grooves for the branches of the middle meningeal vessels.
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Drowning would be considered as a possible cause of death when the body was recovered from a body of water, or near a fluid which could plausibly have caused drowning, or when found with the head immersed in a fluid. A medical diagnosis of death by drowning is generally made after other possible causes of death have been excluded by a complete autopsy and toxicology tests. Indications of drowning are seldom completely unambiguous and may include bloody froth in the airway, water in the stomach, cerebral oedema and petrous or mastoid hemorrhage. Some evidence of immersion may be unrelated to the cause of death, and lacerations and abrasions may have occurred before or after immersion or death.
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After arising in the tympanic plexus, the lesser petrosal nerve passes forward and then through the hiatus for lesser petrosal nerve on the anterior surface of the petrous part of the temporal bone into the middle cranial fossa. It travels across the floor of the middle cranial fossa, then exits the skull via canaliculus innominatus to reach the infratemporal fossa. The fibres synapse in the otic ganglion, and post-ganglionic fibres then travel briefly with the auriculotemporal nerve (a branch of V3) before entering the body of the parotid gland. The lesser petrosal nerve will distribute its parasympathetic post-ganglionic (GVE) fibers to the parotid gland via the intraparotid plexus (or parotid plexus), the branches from the facial nerve in the parotid gland.
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The mastoid antrum (tympanic antrum, antrum mastoideum, Valsalva's antrum) is an air space in the petrous portion of the temporal bone, communicating posteriorly with the mastoid cells and anteriorly with the epitympanic recess of the middle ear via the aditus to mastoid antrum (entrance to the mastoid antrum). These air spaces function as sound receptors, provide voice resonance, act as acoustic insulation and dissipation, provide protection from physical damage and reduce the mass of the cranium. The roof is formed by the tegmen antri which is a continuation of the tegmen tympani and separates it from the middle cranial fossa. The lateral wall of the antrum is formed by a plate of bone which is an average of 1.5 cm in adults.
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Yet, these features are associated with several archaic aspects of the cranium and dentition that place them outside the range of variation for modern humans, like a large face, a large crest of bone behind the ear and big teeth that get even larger toward the back. This mosaic of Neanderthal and modern human resembles similar traits found in a 25,000 years old fossil of a child in Abrigo do Lagar Velho or in the 31,000 years old site of Mladeč, by Cidália Duarte, et al. (1999). Researchers sequenced the genome of "Oase 2" to high coverage (20-fold) from its petrous bone. Around 6% of "Oase 2"'s genome is Neanderthal in origin, which is lower than for "Oase 1"; however, this is still much higher than expected based on its age and what is seen in other Upper Palaeolithic genomes.
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The anterior boundary of the sella turcica is completed by two small eminences, one on either side, called the middle clinoid processes, while the posterior boundary is formed by a square-shaped plate of bone, the dorsum sellae, ending at its superior angles in two tubercles, the posterior clinoid processes, the size and form of which vary considerably in different individuals. The posterior clinoid processes deepen the sella turcica, and give attachment to the tentorium cerebelli. On either side of the dorsum sellae is a notch for the passage of the abducent nerve, and below the notch a sharp process, the petrosal process, which articulates with the apex of the petrous portion of the temporal bone, and forms the medial boundary of the foramen lacerum. Behind the dorsum sellae is a shallow depression, the clivus, which slopes obliquely backward, and is continuous with the groove on the basilar portion of the occipital bone; it supports the upper part of the pons.
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From the posterior wall of the saccule a canal, the endolymphatic duct, is given off; this duct is joined by the utriculosaccular duct, and then passes along the vestibular aqueduct and ends in a blind pouch, the endolymphatic sac, on the posterior surface of the petrous portion of the temporal bone, where it is in contact with the dura mater. Studies suggest that the endolymphatic duct and endolymphatic sac perform both absorptive and secretory,Schuknecht HF. Pathology of the Ear. Philadelphia, Pa: Lea & Febiger; 1993:45–47, 50–51, 62, 64, 101Wackym PA, Friberg U, Bagger-Sjo¨ba¨ck D, Linthicum FH Jr, Friedmann I, Rask-Andersen H. Human endolymphatic sac: possible mechanisms of pressure regulation. J Laryngol Otol 1987; 101:768–779Yeo SW, Gottschlich S, Harris JP, Keithley EM. Antigen diffusion from the perilymphatic space of the cochlea. Laryngoscope 1995; 105:623–628Rask-Andersen H, Danckwardt-Lilliestrom N, Linthicum FH, House WF. Ultrastructural evidence of a merocrine secretion in the human endolymphatic sac.
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The cartilaginous part of the Eustachian tube is about 24 mm in length and is formed of a triangular plate of elastic fibrocartilage, the apex of which is attached to the margin of the medial end of the bony part of the tube, while its base lies directly under the mucous membrane of the nasal part of the pharynx, where it forms an elevation, the torus tubarius or cushion, behind the pharyngeal opening of the auditory tube. The upper edge of the cartilage is curled upon itself, being bent laterally so as to present on transverse section the appearance of a hook; a groove or furrow is thus produced, which is open below and laterally, and this part of the canal is completed by fibrous membrane. The cartilage lies in a groove between the petrous part of the temporal bone and the great wing of the sphenoid; this groove ends opposite the middle of the medial pterygoid plate. The cartilaginous and bony portions of the tube are not in the same plane, the former inclining downward a little more than the latter.
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The path of the facial nerve can be divided into six segments: # intracranial (cisternal) segment # meatal (canalicular) segment (within the internal auditory canal) # labyrinthine segment (internal auditory canal to geniculate ganglion) # tympanic segment (from geniculate ganglion to pyramidal eminence) # mastoid segment (from pyramidal eminence to stylomastoid foramen) # extratemporal segment (from stylomastoid foramen to post parotid branches) The motor part of the facial nerve arises from the facial nerve nucleus in the pons, while the sensory and parasympathetic parts of the facial nerve arise from the intermediate nerve. From the brain stem, the motor and sensory parts of the facial nerve join together and traverse the posterior cranial fossa before entering the petrous temporal bone via the internal auditory meatus. Upon exiting the internal auditory meatus, the nerve then runs a tortuous course through the facial canal, which is divided into the labyrinthine, tympanic, and mastoid segments. The labyrinthine segment is very short, and ends where the facial nerve forms a bend known as the geniculum of the facial nerve (genu meaning knee), which contains the geniculate ganglion for sensory nerve bodies.
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The transverse sinuses are of large size and begin at the internal occipital protuberance; one, generally the right, being the direct continuation of the superior sagittal sinus, the other of the straight sinus. Each transverse sinus passes lateral and forward, describing a slight curve with its convexity upward, to the base of the petrous portion of the temporal bone, and lies, in this part of its course, in the attached margin of the tentorium cerebelli; it then leaves the tentorium and curves downward and medialward (an area sometimes referred to as the sigmoid sinus) to reach the jugular foramen, where it ends in the internal jugular vein. In its course it rests upon the squama of the occipital, the mastoid angle of the parietal, the mastoid part of the temporal, and, just before its termination, the jugular process of the occipital; the portion which occupies the groove on the mastoid part of the temporal is sometimes termed the sigmoid sinus. The transverse sinuses are frequently of unequal size, with the one formed by the superior sagittal sinus being the larger; they increase in size as they proceed, from back to center.
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