Inflammatory diseases and polyposis
Sinusitis. Secondary sinusitis can develop due to a radicular cyst originating from the palatal root of a maxillary molar. Fungal infection on CT is characterized by high-density contents and can erode bone walls, threatening the optic nerve (nervus opticus).
Nasal polyposis. Develops against the background of chronic rhinosinusitis. Polyps are usually multiple and bilateral, located in the middle nasal meatuses, the nasal vault, and the ethmoid labyrinth, blocking drainage pathways. In children, cystic fibrosis must always be ruled out in cases of polyposis.
Antrochoanal polyp. A solitary dumbbell-shaped lesion. It originates from the maxillary sinus, extends through the ostium into the nasal cavity, and then passes through the choanae down into the nasopharynx. Most common in young adults.
Mucocele. Represents an expanded sinus with thinned, smooth walls (in 90% of cases, the frontal or ethmoid sinus). It is painless until a mass effect develops (exophthalmos, headache). When infected, it can cause osteomyelitis and subperiosteal abscess—the so-called Pott's puffy tumor. On MRI, mucocele contents show a hyperintense signal on T2-weighted images.
Benign neoplasms
Osteoma. A dense bony lesion on a broad base or stalk, most commonly found in the frontal sinus (80%). It grows slowly. Surgery is indicated if the tumor blocks drainage or occupies more than half of the sinus volume.
Inverted papilloma. Causes unilateral nasal obstruction. On CT, it has lobulated contours (a calcification at the attachment site is visible in 10% of cases), and on MRI, a characteristic "cerebriform" pattern. Requires mandatory subperiosteal resection to prevent recurrence.
Juvenile angiofibroma. Occurs in adolescent males and presents with profuse epistaxis. It is a benign yet locally destructive tumor originating from the sphenopalatine foramen, widening the pterygopalatine fossa, and eroding the skull base. Contrast-enhanced MRI and embolization of feeding vessels are mandatory before surgery.
Malignant tumors
Malignant sinonasal neoplasms grow asymptomatically for a long time within the hollow spaces. Early signs mimic chronic sinusitis: unilateral pain, discharge, obstruction. Late symptoms include exophthalmos, visual impairment, epiphora, trismus, and sensory deficits in the distribution of the maxillary nerve (V2).
- The most common histological type (65–70%) is squamous cell carcinoma.
- Adenocarcinoma, lymphoma, melanoma, and sarcoma are less common.
- Esthesioneuroblastoma (olfactory neuroblastoma) is a rare tumor filling the olfactory cleft. On MRI, it often has a dumbbell shape with an intracranial component and is accompanied by peritumoral cyst formation.
For staging and assessing orbital or skull base invasion, the modality of choice is multiplanar gadolinium-enhanced MRI with fat suppression. It is important to distinguish the destruction of the lamina papyracea on CT from true invasion through the orbital periosteum, which is better visualized on MRI.
Oral cavity anatomy and tongue innervation
The oral cavity is bounded by the hard palate superiorly, the cheeks laterally, the floor inferiorly, and the lips anteriorly. Posteriorly, it transitions into the oropharynx at the level of the posterior third of the tongue.
Tongue innervation:
- Motor: supplied by the ipsilateral hypoglossal nerve (XII cranial nerve). The exception is the palatoglossus muscle, which is innervated by the vagus nerve (X cranial nerve).
- Sensation of the anterior 2/3: supplied by the lingual nerve (nervus lingualis), a branch of the mandibular nerve (V3).
- Taste innervation of the anterior 2/3: chorda tympani (chorda tympani), a branch of the facial nerve (VII cranial nerve).
- Taste and general sensation of the posterior third: glossopharyngeal nerve (IX cranial nerve).
Briefly: answers to topical questions
What anatomical structures are affected by juvenile angiofibroma during its locally destructive growth?
During locally destructive growth, juvenile angiofibroma affects structures of the skull base and nasal cavity. The tumor destroys and involves the following anatomical formations:
- Sphenopalatine foramen (sphenopalatine foramen) is the origin site of the neoplasm.
- Pterygopalatine fossa (PPF) expands as the tumor grows.
- Medial pterygoid plate (medial pterygoid plate) undergoes erosion.
- Sphenoid bone (sphenoid) is destroyed in the area of the vidian canal aperture.
The mass also actively extends into the nasal cavity, filling and widening it.
What pathologies should a solitary lesion in the upper nasal cavity be differentiated from?
A solitary lesion in the upper parts of the nasal cavity requires careful evaluation of the anterior skull base to rule out meningocele, encephalocele, or sinonasal neoplasia.
Which specific tongue muscles are innervated by the hypoglossal nerve (XII cranial nerve)?
The hypoglossal nerve (n. hypoglossus, XII cranial nerve) provides motor innervation to the genioglossus muscle, styloglossus muscle, and hyoglossus muscle. The palatoglossus muscle (m. palatoglossus) is innervated by the vagus nerve (X cranial nerve), not the hypoglossal nerve.
How to memorize the innervation of the anterior 2/3 of the tongue: general sensation (pain, temperature) is provided by the stern trigeminal nerve (V cranial nerve), while delicate taste sensations are transmitted by the delicate chorda tympani from the facial nerve (VII cranial nerve).
Class and exam questions
Why does a polyp in the upper nasal cavity require special attention?
Behind the mask of such a polyp may lie a meningoencephalocele—herniation of the meninges and brain tissue (e.g., the gyrus rectus) through a defect in the anterior skull base.
In which cases is diagnostic imaging needed for epistaxis?
In most cases, imaging is not required. Arterial-phase CT angiography is indicated only for severe, uncontrolled, or recurrent bleeding to locate the source and perform subsequent embolization.
How to differentiate an antrochoanal polyp on CT data?
It has a characteristic dumbbell shape: it fills the maxillary sinus, extends through the widened ostium into the nasal cavity, and spreads posteriorly through the choanae into the nasopharynx.
What else to study on this topic
- CT anatomy of the ostiomeatal complex and drainage pathways
- Differential diagnosis of fungal and bacterial sinusitis
- Assessment of orbital and skull base invasion in malignant tumors
- Techniques of selective embolization in severe epistaxis
- MRI semiotics of rare tumors (esthesioneuroblastoma, melanoma)
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