HNN Week 5 Flashcards
What is a carcinoma?
A malignant cancer of epithelial tissue origin
What is betel leaf?
Same as paan, a concoction common in India which is chewed and contains tobacco, areca nut, lime…
What is the aetiology of oral cancer?
- 95% of all HNN cancers are squamous cell carcinomas (HNSCC)
- “field cancerisation” tends to occur -> exposure of epithelium and mucosa of the upper respiratory tract to carcinogens causes multiple tumours to develop independantly so there is 35% chance that an individual will develop and discover a second tumour within 2yrs of first
Name some risk factors and promoters for HNSCC’s:
RF: alcohol, smoking (Betel leafs and cigarettes), FH, radiation
Promoters: irritation from ill-fitting dentures/jagged teeth
What is the pathophysiology of oral cancer?
- multifactorial, activation of oncogenes and inactivation of TSG’s
- No specific mutations found but there is a sequence of genetic steps:
- > regions of chromosomes 3/9 are lost
- > inactivation of the CDK inhibitor gene p16
- > unregulated cell cycle and hyperplasia
- > mutation of p53 TSG which causes dysplasia
- EGFR over-expressed in many HNSCC’s
- popular cancer areas = ventral surface of tongue, floor of mouth, lower lip, soft palate and gums
How would you investigate and diagnose oral cancer?
- take history
- EXAMINE: look for firm, raised, irregular plaques with roughened edges which can be mistaken for ulcers
- take a BIOPSY and carry out lab testing
How would you treat oral cancer?
- prevention: avoid risk factors
- excision surgery + chemo/radiotherapy for metastasis
- medicines:
-> monoclonal antibodies or tyrosine kinase inhibitors are used and act as EGFR blockers to slow/stop cell growth
-> TKI’s include lapatinib/erlotinib
additional considerations:
-> tracheostomy at the level of 2nd tracheal ring
-> bad teeth removed prior to surgery to prevent infection
-> hemiglossectomy
Procedure:
- incision made under mandible on affected side
- mandible cut through to allow access to floor of mouth and mandible retracted
- tumour + margin of heathy tissue removed
- surgeon rewires mandible internally and a donor graph may be needed
Why is dotted line between corner of eye and mandible relevant for lymphatic drainage?
Everything below the line = drained by submandibular nodes
Everything above the line = drained by pre-auricular nodes
What are the main lymph nodes in the head?
- submental (under chin)
- pre auricular (parotid) and post-auricular (infront and behind of ear)
- occipital nodes
- submandibular nodes
- superficial and deep cervical nodes
- supraclavicular nodes
- jugulo-digastric node: large node where posterior belly of digastric muscle meets internal jugular vein
- jugulo-omohyoid node
- Virchow’s node = an enlarged supraclavicular node that is a sign of gastric malignancy
What do the submental nodes drain?
- tip of tongue
- front of lower mouth
- lower lip
- chin
What do the pre-auricular nodes drain?
- temporal region of head
What do the occipital nodes drain?
- tissue at back of head
What do the submandibular nodes drain?
- anterior 2/3 and lateral edges of tongue
- majority of mouth and lower face
- nasal cavity
- maxillary sinus
What do the superficial cervical nodes drain?
- superficial neck
What do the deep cervical nodes drain?
- posterior tongue, deep head, thyroid and larynx
What do the supra-clavicular nodes drain?
- neck and some parts of mediastinum
What is the lymphatic drainage of the tongue?
TIP = sub-mental nodes
LATERAL EDGES = submandibular nodes
MIDDLE = inferior deep cervical nodes
POSTERIOR = superior and deep cervical nodes
What is the function of the tongue and its three main parts?
- mastication, taste, swallowing and oral cleansing
- root: posterior part that attaches between mandible and hyoid
- body: main middle part
- apex: anterior part that rests against incisors
What is the median fibrous lingual septum?
- septum that divides the tongue into 2
What is the terminal sulcus?
- characteristic V-shaped groove on posterior dorsum of tongue
- divides tongue into anterior and posterior portions
- points to the foramen caecum
What is the foramen caecum?
- non functional remnant of the embryological thyroglossal duct from which the thyroid developed from
Describe the locations of the 4 papillae groups on the tongue and what the function of papillae is:
- Vallate = anterior to the terminal sulcus
- Foliate = small folds of lingual mucosa found laterally
- Filiform papillae = found over most of dorsum and especially at tip of tongue with taste buds on surface
- Fungiform = sparse over dorsum and concentrated at tip
Function = to increase the surface area of the tongue to increase friction with food
How do extrinsic muscles differ from intrinsic muscles of the tongue?
- they originate outside the tongue and function to alter the position (not shape) of the tongue
Name the 4 extrinsic tongue muscles and their anatomical locations:
1) Palatoglossus: from the soft palate to the posterior lateral tongue on both sides
2) Genioglossus: from spine of mandible across entire dorsum of tongue and some fibres extend to the hyoid bone
3) Styloglossus: from styloid process to distal sides of tongue posteriorly
4) Hyoglossus: quadrilateral muscle running from hyoid bone to inferior lateral tongue
What is the function of palatoglossus muscle?
pulls soft palate down towards tongue
What is the function of genioglossus muscle?
protrudes tongue and retracts apex
unilateral contraction will move tongue to the opposite side
What is the function of styloglossus muscle?
- retrudes tongue and curles the sides
- works with genioglossus to make trough when swallowing
What is the function of hyoglossus muscle?
depresses and shortens tongue
How do intrinsic tongue muscles differ from the extrinsic and name the 4 intrinsic muscles:
- they originate and insert entirely inside the tongue and alter the SHAPE of the tongue (not position)
1) superior longitudinal
2) inferior longitudinal
3) transverse
4) vertical
Describe the position and function of the superior longitudinal muscle:
- elevates and shortens
- thin layer under mucous membrane of dorsum that runs from median fibrous lingual septum out to the margins of the sides of the tongue
Describe the position and function of the inferior longitudinal muscle:
- depresses and shortens
- narrow band near ventral surface that runs from root to apex
Describe the position and function of the transverse muscle:
- narrows and elongates
- deep to the superior longitudinal muscle
Describe the position and function of the vertical muscle:
- broadens and widens
- fibres intersect with transverse muscle
Describe the arterial supply of the tongue:
- internal carotid artery -> lingual artery -> dorsal lingual arteries supply root -> deep lingual arteries supply body and apex and communicate