Head and Neck onco

Facial nerve pointers

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Q) What is the most consistent anatomical landmark of the facial nerve?

A) Anterior border of the posterior belly of the digastric muscle.
B) Posterior border of the posterior belly of the digastric muscle.
C) Superior border of the posterior belly of the digastric muscle.
D) Inferior border of the posterior belly of the digastric muscle.

C) Superior border of the posterior belly of the digastric muscle.

Why This Landmark Matters: The superior aspect of the posterior belly of the digastric muscle serves as a reliable intraoperative landmark for locating the facial nerve. Understanding this landmark can enhance surgical precision and reduce complications.

Key Anatomical Landmarks for Facial Nerve Identification:

  1. Posterior Belly of the Digastric Muscle:
    • The facial nerve is located about 2 to 4 mm inferior to the tympanomastoid suture line, making the superior border of the posterior belly a consistent guide.
  2. Tragal “Pointer” (of Conley):
    • The tragal cartilage, found in front of the ear, provides a helpful reference. The facial nerve lies approximately 1 cm deep, slightly anterior and inferior to this point, making it an essential landmark during dissection.
  3. Tendon of the Posterior Belly of the Digastric Muscle:
    • The attachment of the digastric muscle to the mastoid bone conceals the facial nerve about 1 cm deep. Careful dissection in this area is crucial to uncover this hidden structure.
  4. Tympanomastoid Suture/Fissure:
    • This area within the temporal bone marks another critical point for identifying the facial nerve, which is situated about 6-8 mm deep.
  5. Styloid Process:
    • Located laterally to the styloid process, the facial nerve resides in proximity, making it a significant marker during surgical approaches.

Conclusion: Understanding the superior border of the posterior belly of the digastric muscle as the most consistent anatomical landmark of the facial nerve is essential for safe surgical practice. Mastering these landmarks not only enhances surgical outcomes but also promotes patient safety.

Inoperability criteria of ca oral cavity

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Q) Inoperability criteria in ca oral cavity is  ( MCH Onco 2020) 

a) Pterygoid plate involvement

b) Tooth socket involvement

c) Cheek involvement

d)

Ans a) Pterygoid

T4b in oral cancer is Very advanced local disease.

Tumor invades masticator space, pterygoid plates, or skull base and/or encases internal carotid artery, skull base and/or encases the internal carotid artery.

Note: Superficial erosion alone of bone/tooth socket by gingival primary is not sufficient to classify as T4

Tumour involvement of the following structures are considered technically unresectable

Erosion of pterygoid plates, sphenoid bone, widening of foramen ovale

Extension to superior nasopharynx or deep extension into Eustachian tube or lateral nasopharyngeal wall

Encasement of internal carotid artery, defined radiologically as tumor surrounding the carotids> 270 degrees.

Involvement of mediastinal structures

Involvement of prevertebral fascia or cervical vertebrae

Ref is here 

 

Adenoid Cystic Tumors

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Q) All are true for adenoid cystic tumor of the hard palate except

a) Perineural invasion

b) Lung metastasis

c) Lymph node metastasis

d) Increased risk of local recurrence

Ans c 

Adenoid cystic carcinoma is a rare tumor arising from the minor salivary glands;, the palate being the commonest site.

Distant metastasis and perineural invasion are common in adenoid cystic carcinoma.

The lesion is uncapsulated and infiltrative; invasion of underlying bone is common.

Incidence of cervical metastasis is low.

Distant metastasis occurs through blood stream to lung and bones. Direct extension of lesion of the base of skull has been reported as a cause of death.

Ref - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3633292/

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