What is the petrous apex?
The petrous apex is a pyramid-shaped structure that is formed by the medial portions of the temporal bone. It is obliquely positioned within the skull base, with its apex pointing anteromedially and its base located posterolaterally.
What is Pneumatization of the petrous apices?
Pneumatization of the petrous apex occurs when epithelium-lined air cells develop as medial communications from the mastoid air cells. This occurs in 9–30% of patients, and in general there is a positive correlation between the degree of mastoid segment pneumatization and aeration of the petrous apex [1].
What is petrous apex cholesterol granuloma?
Petrous apex cholesterol granulomas are expansile, cystic lesions containing cholesterol crystals surrounded by foreign body giant cells, fibrous tissue reaction and chronic inflammation.
What is petrous part of temporal bone?
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.
What does petrous mean in anatomy?
Definition of petrous
: of, relating to, or constituting the exceptionally hard and dense portion of the human temporal bone that contains the internal auditory organs.
What is a petrous lesion?
Inflammatory or congenital lesions of the petrous apex include: Cholesteatoma or epidermoid tumors (benign cysts filled with dead skin) Cholesterol granuloma (benign cysts filled with a thick material much like crankcase oil) Fat in the bone marrow of a petrous apex that does not contain any air space.
What does Pneumatized mean?
: having air-filled cavities.
What causes Pneumatization of the petrous apex?
In this study, the anterior type of anterior epitympanic space was found to be closely related to more well-pneumatized petrous apices, which implies that the anterior saccule of the saccus medius may be the main factor influencing pneumatization of the petrous apex.
Is cholesterol granuloma a tumor?
Cholesterol granulomas are rare, benign tumors or cysts that develop at the tip of the petrous apex, a part of the skull next to the middle ear.
How is cholesterol granuloma diagnosed?
Tests for diagnosing cholesterol granuloma
Imaging tests such as MRI and CT scans aid in differentiating the cholesterol granuloma from other types of lesions. These studies also are useful for revealing its size and precise location. Your doctor may also perform an audiogram to assess hearing loss.
What does the term petrous mean?
What are the three parts of the temporal bone?
The temporal bone is divided into several main parts/portions 1-3:
- squamous part (temporal squama)
- petrous part (petrous pyramid)
- tympanic part.
- mastoid part (usually considered a separate part but it is formed by both the squamous and petrous parts)
What is a CT petrous bones scan for?
Because of the excellent imaging of bone structures with MSCT, this technique is especially suitable for the diagnosis both of acquired pathologies and of congenital abnormalities of the external auditory meatus, the middle ear and the mastoid, of trauma-induced pathologies of the entire petrous bone, and of osteogenic …
Is the petrous bone part of the skull?
The petrous portion of the temporal bone or pyramid is pyramidal and is wedged in at the skull base between the sphenoid and occipital bones. 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”.
Where is petrous bone?
temporal bone
Found near our ears, this pyramid-shaped portion of the temporal bone is nicknamed the petrous bone. The bone is very hard, possibly because it needs to protect fragile structures such as the cochlea, which translates sound into brain signals, and the semicircular canals, which help us maintain our balance.
Why does Pneumatization happen?
Pneumatization is a normal physiologic process (the process of air-filled cells developing as per the size and function of the sinus, which is an air-filled cavity) that is associated with an increase in the size and volume of the paranasal sinuses of the face till adulthood.
What causes Pneumatization?
The cause and extent of sinus pneumatization remain unclear, but the following reasons are suspected: heredity, craniofacial configuration, bone density, growth hormones, and air pressure in the sinus cavity [3,4,5].
Is Pneumatization of petrous apex normal?
Asymmetric pneumatization of the petrous apex is a frequent normal anatomic variant resulting in an appearance that can be mistaken for pathology within the petrous apex; see petrous apex lesions (differential).
What is gradenigo’s syndrome?
Gradenigo Syndrome (GS) is classically described as a clinical triad of otitis media, facial pain and abducens palsy that is most commonly developed from infection in the petrous temporal bone (i.e., petrous apicitis). The full triad of GS however may not always be present especially in the post-antibiotic era .
Is a cholesterol granuloma serious?
They usually have no symptoms or serious effects. However, cholesterol granulomas of the petrous apex are dangerous because of their proximity to the ear and several important nerves. If left untreated and the mass continues to expand, cholesterol granulomas of the petrous apex can cause: Permanent hearing loss.
How rare is a cholesterol granuloma?
The incidence of petrous apex cholesterol granuloma has been estimated at 0.6 cases per 1 million population. Thus these lesions are exceedingly rare. Cholesterol granulomas are 10 times more common than petrous apex cholesteatomas (Isaacson, 2015).
Where is the petrous part?
The petrous portion of the temporal bone or pyramid is pyramidal and is wedged in at the skull base between the sphenoid and occipital bones. 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”.
Where is the petrous bone located?
The petrous part is a wedge shaped mass of bone located between the sphenoid and occipital bones within the cranial cavity. It is the most medial part of the temporal bone, and it is the landmark dividing the middle and posterior cranial fossae from each other.
What happens if the temporal bone is damaged?
On physical examination, patients with temporal bone fractures may present with hemorrhagic or clear otorrhea, hemotympanum, vertigo, nystagmus, facial paralysis, conductive or sensorineural hearing loss, ear canal laceration, or Battle’s sign (bruising over the mastoid process).
What are the two temporal bones called?
Squamosal: the squama including the zygomatic process. Tympanic bone: the tympanic part: this is derived from the angular bone of the reptilian lower jaw. Periotic bone: the petrous and mastoid parts.