I-131 (or 131I) is a radioisotope used in the diagnosis and treatment of thyroid lesions. It is one of the oldest radiotracers used in nuclear medicine, in use for over 50 years. It is predominately used in thyroid ablation therapy, for patients post thyroidectomy, and for metastatic thyroid ca...
The ice cream cone sign may refer to:
the appearance of the malleus head and the incus body on axial CT scan: failure of this normal configuration suggests incudomalleolar dysarticulation. Ball of the icecream is formed by head of malleus and cone is formed by body of incus. Space between ice c...
The maxillary incisive canal runs through the maxilla in the midline. It connects the inferior nasal cavity with the superior oral cavity, opening at the incisive foramen posterior to the central maxillary incisor teeth. It contains the descending palatine artery and the nasopalatine nerve.
Incisive canal cysts, also known as nasopalatine duct cysts (NPDC), are developmental, non-neoplastic cysts arising from degeneration of nasopalatine ducts. These ducts usually regress in fetal life. The persistence of ductal epithelium leads to formation of cyst.
It is considered the most comm...
The incisive foramen (also known as nasopalatine foramen or anterior palatine foramen) is the oral opening of the nasopalatine canal. It is located in the maxilla bone in the incisive fossa, midline in the palate posterior to the central incisiors, at the junction of medial palatine and incisive...
The incus is the middle of the ossicles articulating with the head of the malleus anteromedially and the stapes inferomedially.
Its parts include:
a body which articulates with the head of the malleus, and to which the superior ligament of the incus is attached (to the roof of the middle ear c...
The inferior alveolar artery is a branch of the maxillary artery. It runs with the inferior alveolar nerve as it descends through the infratemporal fossa and enters the mandibular canal and supplies mandibular teeth. In the region of the first premolar it bifurcates into the incisive and mental ...
The inferior median clival canal also known as the canalis basilaris medianus is a rare anatomical variant of the clivus, which passes in the sagittal plane from the intracranial surface of the clivus to its retropharyngeal surface. It is generally thought to represent a remnant of the notocord....
The inferior nasal concha is one of the conchae in the nose. It extends horizontally along the lateral wall of the nasal cavity and consists of a lamina of spongy bone, curled upon itself like a scroll. Each inferior nasal concha is considered a facial pair of bones since they arise from the max...
The inferior oblique muscle is one of six extraocular muscles that control eye movements.
origin: orbital surface of the maxilla
insertion: globe (posterior, inferolateral surface)
innervation: inferior branch of the oculomotor nerve (CN III)
primary function: one of two ocular external rota...
The inferior rectus muscles is one of the 6 extraocular muscles that control eye movements.
innervation: inferior branch of the oculomotor nerve (CN III)
origin: Annulus of Zinn (tendinous ring)
insertion: globe (anterior, inferior surface)
primary function: one of two ocular depressors
The infrahyoid muscles or strap muscles are a group of four paired muscles in the anterior neck below the hyoid bone. They are responsible for elevating the hyoid during swallowing.
The four muscles are:
sternohyoid: superficial and medial
omohyoid: superficial and lateral
The infraorbital artery, is a branch of the third part of the maxillary artery. It runs through the inferior orbital fissure, orbit, then the infraorbital foramen. Here it gives off the anterior superior alveolar artery which supplies the anterior teeth and the anterior part of the maxillary sin...
The infraorbital foramen is located in the maxilla bone its facial surface superior to the canine fossa and inferior to the lower margin of orbit. It transmits the superior maxillary nerve (infraorbital nerve) and infraorbital artery.
The infraorbital nerve is a one of three cutaneous branches of the maxillary division of the trigeminal nerve. The other branches include the zygomaticofacial nerve and the zygomaticotemporal nerve.
emerges through the infraorbital foramen lying between levator labii sup...
The infratemporal fossa is a complex space that lies posterolateral to the maxillary sinus and many important nerves and vessels traverse it.
The infratemporal fossa is the space between the skull base, lateral pharyngeal wall and the ramus of mandible.
medially - ...
Ingested bones that become lodged in the throat or gastro-intestinal tract are a common presentation to the emergency department. Recognition is important because these cases can be potentially fatal.
Patients may present with a 'foreign body' feeling in the throat after eating fish...
The inion is the tip of external occipital protuberance, the midline bony prominance in the occipital bone where the ligamentum nuchae and trapezius muscle attaches. It is usually easily palpable.
It is the the surface marking of the internal attachment of the tentorium cerebelli.
It is one of...
The inner ear refers to the bony labyrinth and its contents and the membranous labyrinth. It is divided into three sections:
A useful mnemonic to remember innervation of the muscles of the middle ear is:
S for Stapedius
T for Tensor Tympani
S: Stapedius is supplied by a branch of the facial nerve- the Seventh cranial nerve. It is also the Smallest muscle in the body, and inserts onto the neck of Stapes
The internal acoustic canal (IAC), also known as the internal auditory canal or meatus (IAM), is a bony canal within the petrous portion of the temporal bone that transmits nerves and vessels from within the posterior cranial fossa to the auditory and vestibular apparatus.
A mnemonic to remember the relative position of nerves inside the internal auditory canal (IAC) is:
Seven up coke down
Four nerves pass through the IAC:
facial nerve (CN VII)
three components of the vestibulocochlear nerve (CN VIII)
cochlear nerve (CN VIIIc)
superior vestibular ne...
The internal carotid artery is a terminal branch of the common carotid artery.
It arises most frequently between C3 and C5 vertebral level, where the common carotid bifurcates to form the internal carotid and the external carotid artery (ECA).
Variations in origin
The internal jugular vein (IJV) is the major venous return from the brain, upper face and neck.
Origin and course
It is formed by the union of inferior petrosal and sigmoid dural venous sinuses in or just distal to the jugular foramen (forming the jugular bulb). It descends in ...
A useful mnemonic to remember the branches of the internal jugular vein is:
Medical Schools Let Fun People In
From inferior to superior:
M: middle thyroid vein
S: superior thyroid vein
L: lingual vein
F: facial vein
P: pharyngeal vein
I: inferior petrosal sinus
The internasal suture is a single, midline cranial suture between the two nasal bones. It meets the frontonasal suture to form the nasion 1.
The intraconal orbital compartment is a conical space, the base of which is anterior and is formed by the posterior half of the globe. The sides are formed by the extraocular muscles which pass posteriorly and converge on the tendinous ring at the orbital apex.
This space contains:
Intraconal orbital lesions are broadly divided to two main groups; those with or without involvement of the optic nerves:
Lesions with optic nerve involvement:
optic nerve glioma
optic nerve meningioma
lymphoma and leukaemia
Intracranial dermoid cysts are uncommon lesions with characteristic imaging appearances. They can be thought of as along the spectrum: from epidermoid cysts at one end (containing only desquamated squamous epithelium) and teratomas at the other (containing essentially any kind of tissue from all...
Intraosseous meningioma, also referred as primary intraosseous meningioma, is a rare subtype of meningioma that accounts for less than 1% of all osseous tumours. They fall under the subgroup of primary extradural meningiomas.
It is important to note that this group of meningiomas d...
The intrinsic muscles of the larynx can be considered in two groups:
muscles that control the inlet of the larynx
muscles that move the vocal ligaments
Muscles of the inlet
aryepiglottic muscle: lies within the aryepiglottic fold, runs from the side of the epiglottis and inser...
Inverted papillomas are a type of Schneiderian papilloma. They are uncommon with distinctive pathological and imaging features.
The term inverted papilloma is also used to describe a urothelial lesion. For a discussion of that entity, please refer to inverted papilloma of the urin...
Iodine123 (I123) is a radioisotope of the element Iodine (atomic number 53) used in nuclear medicine imaging including to image the thyroid gland.
Uses, dosages, and time of Imaging
routine scan: 100-400 microCi po, image at 4-6 or 24 hours
thyroid cancer scan: 1.5 mCi po, image at 4-6 or 24...
An isolated cleft palate is a type of facial cleft. This is a much rarer occurrence than a cleft lip +/- palate and is thought to represent a different pathological entity.
The estimated incidence is at ~1 per 2000-2500 pregnancies 4-5. There may be a slight female predilection 4....