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MRCS A: Systems > Head and Neck > Flashcards

Flashcards in Head and Neck Deck (56)
1

Salivary glands

Salivary glands have secretory end pieces, the acini

About 1.5 litres of saliva is secreted daily.
pH of saliva varies from 7–8.

2

Content of saliva

1) Alpha-amylase and lipase (mostly from the lingual glands)
2) Mucins (glycoproteins) for lubrication and mucosa protection.

Saliva also contains bacteriostatic agents such as IgA, lysozyme and lactoferrin as well as proline-rich proteins which protect tooth enamel.

3

Electrolyte balance of saliva

Saliva is initially isotonic, with concentrations of Na, K, Cl and HCO3 close to those in plasma.

As this passes through the duct system the duct cells remove Na+ and Cl- in exchange for K+ and HCO3- and therefore becomes hypotonic.

Saliva in oral cavity is therefore:
A) Hypotonic
B) Alkaline
C) Rich in K+

4

Parotid, sublingual, submandibular acini secretion

The acini of the
1) Parotid is serous
2) Sublingual is mucous
3) Submandibular is mixed

5

Saliva secretion

1) Salivary secretion is under neural control.

2) Parasympathetic nerves stimulation (acetylcholine) increases secretion of watery saliva low in enzymic contents.

3) Also produces vasodilation through VIP

4) Atropine and other cholinergic antagonists reduce salivary secretion.

5) Food in the mouth and stimulation of vagal afferents increase secretion.

6

Function of saliva

1) It keeps the mouth moist, facilitates swallowing, stimulates taste buds and aids speech.

2) It has a bacteriocidal function.

3) Reduced salivary secretion = Dental caries.

4) Buffering action and neutralises any acid regurgitation on the oesophageal mucosa.

7

Phonation and larynx

Phonation is via adduction of the vocal cords. This involves the transverse arytenoid muscle and the recurrent laryngeal nerve.

Adduction of the vocal cords raises the subglottic pressure. When the air is exhaled it pushes the cords apart. The consequent drop in infraglottic pressure adducts the cords again and the cycle is repeated. The movements of the tensed cords will produce sound.

There are three important variables in sound:

• loudness
• pitch
• quality of sound

8

Loudness

This varies with the level of infraglottic pressure needed to separate the cords and the degree of adduction of the cords.

Loudness is increased by tightly adducting the cords and building a higher infraglottic pressure.

The latter can be increased further by the contraction of expiratory muscles (as in shouting).

9

Pitch determined by?

This is determined by the frequency of vibration. Higher pitch is achieved by increasing the tension of the cord.

10

Muscle tone across the vocal cord for pitch

The cricothyroid muscle STRETCHES the cord by reducing the cricothyroid interval.

Simultaneous isometric contraction of the thyroarytenoid muscle increases the muscle tone contributing to an increase in the tension of the cord.

11

Quality of sound

The size and relationship of the resonating chambers such as the larynx, the pharynx and the paranasal sinuses contribute and maintain the quality of sound.

People with a good quality voice are born with it. They cannot be trained to produce it.

12

Articulation of sounds

1) Achieved by varying the size and shape of the oral cavity as well as interrupting the flow of exhaled air by lips, tongue, and palate.

2) Speech sounds are classified according to the structures used in modification of the expired jet of air.

3) The vowels are produced by altering the shape of the oral cavity by adjusting the jaws, cheek, tongue, and palate.

4) Consonants are produced by exhalation through the mouth, isolating the nasal cavity by raising the soft palate. By blocking the exhaled air by lips labial consonants such as P and B are articulated whereas T and D which are lingual consonants need approximation of the tongue against the palate. In nasal sounds such as M and N the soft palate is relaxed and air passes through both the nasal cavity and the oral cavity.

13

Articulation of sounds: Speech abnormality

1) Abnormalities in any structures involved in articulation can produce a speech defect.

2) In cleft palate, air always enters the nasal cavity giving nasal quality for the voice and affecting sounds which require contact between tongue and palate.

3) In unilateral paralysis of the recurrent laryngeal nerve the vocal cord on the paralysed side is in the cadaveric position and cannot be adducted. It will be at a lower level compared to the normal side.

4) Aphonia results at the onset of paralysis. Within a few days the opposite cord will cross the midline on phonation and approximate itself to the paralysed cord and the voice will return. However complete apposition of the two cords is impossible especially posteriorly. The voice will be harsh and low and it will never return to its normal quality.

5) Bilateral recurrent laryngeal nerve paralysis results in aphonia due to inability to adduct the vocal cords.

6) External laryngeal nerve paralysis which rarely happens in thyroid surgery paralyses the cricothyroid muscle resulting in inability to produce certain high- pitched sounds.

14

Articulation of sounds: CNS abnormalities

1) Disturbances in coordination of motor pathways as in cortical damages and extrapyramidal lesions pro- duce dysarthria.

2) In Parkinsons disease the tremor and muscular rigidity affect the muscles involved in speech causing rapid and monotonous speech with slurring of consonants and repetition of syllables.

3) Slurred speech is also characteristic of cerbellar lesions. Dysphasia results from lesions in the sensory cortex and some of the associated areas connected with speech.

4) The speech in these patients sounds normal but makes little sense. They are unable to comprehend what was heard or seen and hence produce inappropriate responses and often are unable to find appro- priate words or formulate sentences.

5) Such patients are capable of initiating speech but are unable to converse. Problems affecting the lower region of the primary sensory cortex (Warnicke’s area) and auditory association area will produce dysphasia.

15

Visual pathways

Impulses produced in the rods and cones in the retina by light reaches the visual cortex through the visual pathway. The visual pathway consists of:

• optic nerve
• optic chiasma
• optic tract
• lateral geniculate body
• optic radiation
• visual cortex

16

Optic nerve anatomy

1) The optic nerve commences at the lamina cribrosa, where the axons of the ganglion cells of the retina pierce the sclera.

2) The nerve fibres, about 1–1.2 million of them, acquire a myelin sheath at this point.

3) The optic nerve is covered by the dura, arachnoid and pia runs postero-medially in the orbit to enter the optic canal.

4) The nerve which is longer than the distance it has to transverse lies loosely in the orbital fat surrounded by the four recti muscles.

5) The ophthalmic artery accompanies the nerve. The artery which is superolateral to the nerve posteriorly crosses above the nerve to its medial side. It gives off the central artery of the retina which sinks into its inferomedial aspect.

6) In the optic canal the ophthalmic artery lies superolateral to the optic nerve. More proximally the nerve has a short course in the middle cranial fossa before uniting with the nerve of the opposite side at the chiasma.

17

Optic chiasma

See diagram

1) At the chiasma nerve fibres from the temporal half of the retina lie laterally and those from the medial half lie in the middle.

2) The middle fibres decussate. All the fibres that arise from the ganglion cells medial to a line passing through the fovea centralis cross from the optic nerve of that side to the optic tract of the opposite side.

3) The left optic tract thus contains fibres from the temporal half of the left retina and nasal half of the right retina.

4) As the temporal half of the retina perceives light from the nasal half of the visual field and the nasal half of the retina from the temporal visual field, the left optic tract transmits data from the right half of the visual field (and the right tract from the left half of the visual field).

18

Sella turcica and diaphragma sellae

Inferior to the optic chiasma lies the sella turcica containing the pituitary gland. The diaphragma sellae separates the pituitary gland from the optic chiasma. A tumour of the hypophysis cerberi may bulge the diaphragma sellae or break through it and press on the optic chiasma. The internal carotid artery lies lateral to the chiasma. Aneurysm of the artery at this level will compress the lateral fibres in the chiasma.

19

Optic tract

The optic tract passes postero-laterally from the chiasma. The tract forms the anterolateral boundary of the interpenduncular fossa crossing the cerebral peduncle to terminate in the lateral genicualte body.

Not all fibres of the optic tract end in the lateral geniculate body. Some enter the midbrain ending in the superior colliculus or the pretectal nucleus.

These fibres form the afferent limb of the light reflex.

20

Lateral geniculate body and optic radiation

The great majority of the fibres in the optic tract end in the lateral geniculate body. The six-layered lateral geniculate body has point-to-point representation at the retina. From the lateral geniculate body fibres of the optic radiation sweep laterally and backwards to the visual cortex in the occipital lobe.

21

Visual cortex

The visual cortex lies above and below the calcalcarine sulcus as well as on the walls of the sulcus. There is a point-to-point representation of the retina in the visual cortex. The upper half of the retina is represented on the upper lip of the calcarine fissure and the lower half on the lower lip. The macular region has a greater cortical representation than the peripheral retina facilitating acuity of vision for the macular region.

22

Visual tract lesions

Lesions of the retina or optic nerve result in uni- lateral blindness of the affected segment. Lesions of the optic tract and optic radiations produce controlateral homonymous hemianopia. Lesions of the middle fibres of the optic chiasma, as caused by a pituitary tumour, will cause bitemporal hemianopia.

23

Hearing

1) Alternate phases of condensation and rarefaction of molecules produce sound waves. The loudness of the sound is proportional to the amplitude of the wave and its pitch is correlated with the frequency.

2) The ear converts sound waves in the air to action potentials in the auditory (cochlear) nerves. The waves are transmitted by the tympanic membrane (ear drum) through the movements of the auditory ossicles into the internal ear.

3) These produce movements in the fluid in the internal ear which in turn produce waves of movement of hair cells of the organ of Corti which generate action potentials in the nerve fibres.

4) Liquid is more difficult to move than air. The sound pressure in the air as it passes through the middle ear must, therefore, be amplified. Because the tympanic membrane is so much larger than the oval window the pressure (force per unit area) is increased 15–20 times when transmitted from the larger membrane to the smaller. The lever action of the ossicles also accentuates the pressure.

5) The auricle collects the sound waves and they pass along the external auditory meatus to produce vibra- tions of the tympanic membrane. The tympanic membrane is most efficient when the pressure on either side of it is equal. This is achieved by opening of the auditory tube which equalises the middle ear air pressure to that of the external auditory meatus.

6) The vibrations of the tympanic membrane are transmitted to the malleus, incus, and stapes. The malleus rocks on an axis through its long and short processes. When the handle of the malleus moves medially with the tympanic membrane, the head of the malleus and the body of the incus move laterally. As the body of the incus moves laterally its long

24

Tympanic reflex

When the middle ear muscles – the tensor tympani and stapedius contract they pull the malleus inwards and the stapes outwards, thus decreasing sound transmission.

Loud sounds initiate a reflex contraction of these muscles known as the tympanic reflex. It prevents strong sound waves from causing excessive stimulation of the hair cells and thus protects them from being damaged.

25

Conductive deafness

Conductive deafness results from failure of the conductive mechanism to transmit sound waves from the external ear to the inner ear. This can be due to various diseases of the external ear and middle ear. Sensory neuronal deafness is due to diseases of the organ of Corti, cochlea or the auditory nerve or its central pathway.

26

Physiology of smell

1) The olfactory receptors are located in the olfactory mucosa in the roof and upper part of the lateral wall and nasal septum.

27

Olfactory mucus

The olfactory mucus, produced by the Bowman’s glands in the olfactory mucosa may contain odour-binding proteins which will facilitate the passage of lipophylic odour producing substances through hydrophillic mucus. These proteins thus act as carrier proteins.

28

Sniffing

Most of the air passing through the nasal cavity will not come into contact with the olfactory mucosa. It passes mainly through the respiratory portion of the mucosa.

The turbinates warms the air and some of it rises by convection to come in contact with the olfac- tory region in and around the roof.

Sniffing, done by compression of the ala against the nose, helps to deflect the air upwards. It is a reflex response which occurs when a new or pleasant smell attracts attention.

29

Oral cavity:

Herpes simplex

Infections with the herpes simplex virus result in vesicles surrounded by a red margin appearing on the gingiva, cheek, lips or tongue. The vesicles break down to form shallow ulcers.

They may become encrusted and are frequently secondarily infected. These lesions are often very painful but heal spontaneously. The lesions are commonly associated with infections of the upper respiratory tract and pneumonia.

The virus may be in a dormant state in the squamous cells of many individuals and is activated by febrile illness. They also occur in the immunocompromised patient.

30

Oral cavity:

Thrush

Oral candidiasis (thrush)
Seen in neonates and in immunocompromised patients such as those suffering from AIDS or those who are on immunosuppressant drugs and/or long term antibiotics is caused by the fungus Candida albicans. Lesions seen as white plaques in the mucous membrane, are con- fined to the epithelium and comprise of fungal hyphae, polymorphs and fibrin.

31

Oral cavity:

Aphthous stomatitis

Aphthous stomatitis
This relatively common condition manifests as recur- rent small ulcers of the oral mucosa. Ulcers are shallow with a necrotic base and a hemorrhagic periphery. They heal spontaneously. The exact aetiology is unknown but some cases are associated with inflammatory bowel disease and coeliac disease suggesting an immuno- logical aetiology.

32

Oral cavity:

Epulis

Epulis
Epulis is a small pedunculated fibrovasular swelling in the oral cavity caused by repeated minor trauma. It starts as a scar tissue in the submucous layer which later develops a stalk probably by suction forces generated during deglutition.

33

Oral cavity: Leukoplakia

Leukoplakia
Leukoplakia is seen as white patches on the oral mucosa, its importance being that it may be a pre-malignant condition.
Traditionally the condition is thought to be associated with the six ‘S’s:
• Smoking;
• Sepsis;
• Spirits (or excessive alcohol);
• Spices (or the habit of chewing betel nut and lime
wrapped in betel leaf as practiced in the Indian subcontinent);
• Sharp teeth causing repetitive traumas;
• Syphilis. (Though syphilis is now rare candidiasis has become an additional factor.)

34

Oral cavity:

Most common tumour

Squamous-cell carcinoma is the most common malignant tumour of the oral cavity, the most frequent sites being the lower lip and tongue.

35

Oral cavity:

Cheek cancer

Carcinoma of the cheek is very prevalent in the Indian subcontinent. Oral cancers occur more in elderly men. Social and environmental factors such as pipe and tobacco smoking, betel nut and tobacco chewing as practiced in Asian countries as well as prolonged exposure to strong sunlight (lower lip cancers) are contributing factors.

36

Oral cavity:

Lip cancers

Carcinoma of the lower lip is more common than that of the upper lip.
Tumour of the lip has better prognosis because of their early detection. 75 per cent of the lingual cancers arise in the anterior two-third of the tongue. Metastasis occurs unilaterally to the submental, submandibular and then to the lower deep cervical lymph nodes.
Rarer posterior one-third tumours spread bilaterally to the upper deep cervical nodes. Poor prognosis of this variety is due to late detection.

37

Salivary glands: Mumps

Mumps is more common in children (4–12 years) than in adults. The incubation period is about 21 days and the active state of the disease when viruses are present in the saliva lasts about ten days. There is diffuse interstitial parotid inflammation in mumps which is usually bilateral but occasionally unilateral.
In 20% of cases the submandibular and other salivary glands are involved. Epidydimitis, orchitis, and occasional meningo-encephalitis may occur.

38

Salivary glands: Acute bacterial sialadenitis

Acute bacterial sialadenitis is often caused by infection spreading into the parotid or submandibular gland from the oral cavity. The condition is associated with poor dental hygiene, periodontal disease, hyposecretion of saliva due to any cause, and stones in the duct causing obstruction.

Neonates, elderly and post-surgical patients have a higher risk of developing this condition. Acute bacterial sialadenitis manifests with fever, trismus, dysphagia and painful enlargement of parotid or submandibular gland.

The common organisms involved are Staphylococcus aureus, Streptococcus viridans, and Eschericia coli. The condition usually responds to treatment with broad spectrum antibiotics and restoration of good oral hygiene. Duct stones should be removed surgically. If an abscess is formed it may need drainage.

39

Salivary glands: Sialolithiasis

Primary calculi are more commonly seen in the submandibular gland ducts (slope upwards) than in the parotid (slope down). They contain phosphate and carbonate.

Due to:
1) Stasis of salivary secretion associated with changes in its physiochemical characteristics.
2) Secondary salivary gland stone formation may occur in hyperparathyroidism, hyperuricaemia and hypercalcaemia.
3) Presents as recurrent and progressive glandular swelling which in the early stages is associated with meals. Palpation may reveal a stone along the course of the Wharton’s or Stensen’s duct.
4) Calculi are usually radio-opaque. Stones in the distal part of the duct can be excised and the opening may be stented or marsupialised. Stones in the proximal region are best treated by excision of the gland and the duct. Acute sialadenitis with suppuration may occur as a complication.

40

Salivary glands: Sjogrens

Clinical syndrome affecting
1) Salivary glands
2) Lacrimal glands associated with dry eyes (keratoconjunctivitis sicca)
3) Dry mouth (xerostomia)

Often associated with rheumatoid arthritis, systemic lupus erythematosus and other sys- temic auto-immune diseases.

Affected glands are painless and have progressively enlarged. Usually follows a slow benign progression, but there is a sig- nificant risk of development of lymphoma.

41

Salivary glands: Tumours

Less than 4% of all tumours of the head and neck.
80% occur in the parotid, 60% of these are benign.

42

Salivary glands tumours: Pleomorphic adenoma or mixed parotid tumour

70% of the benign salivary gland tumours are Pleomorphic adenoma

The lateral or superficial lobe of the parotid gland (lying superficial to the facial nerve) is most commonly affected. Typically it is a slow growing painless mass.
The facial nerve is NOT involved.

Surgical excision is performed, preserving the facial nerve and its branches. However recurrence may occur if the pseudocapsule is ruptured during dissection. Recurrent tumour may encapsulate the facial nerve and its removal will necessitate sacrificing the nerve and its branches.

43

Salivary glands tumours: Warthin tumours

About 10% of the benign tumours of the parotid gland
Warthin’s tumour is rare in the submandibular gland and in the minor salivary glands.

It is an adenolymphoma characterised by cystic spaces surrounded by eosinophilic columnar cells.
Malignant transformation is rare and the treatment of choice is long term observation or surgical removal.

44

Salivary glands tumours: Muco-epidermoid tumour

This is the most common MALIGNANT tumour of the parotid gland.

The tumour may metastasise into regional lymph nodes, brain and lungs.

45

Salivary gland tumours: Adenocystic tumour

Affects the submandibular gland and the minor salivary glands more frequently than the parotid gland.

Early perineural invasion occurs causing facial palsy. Metastases may occur to brain and lungs but is a late event. Total eradicaton by surgical excision is difficult because of extensive infiltration into local tissues and perineural infiltration

46

Nasal cavity and paranasal sinuses: Nasal polyps

Nasal polyps are islands of oedematous pedunculated mucosa resembling a bunch of peeled grapes occurring in the nasal as well as sinus mucosa, the usual sites being
1) Middle meatus
2) Middle turbinate
3) Ethmoid sinuses

There is associated hyperplasia of the mucous glands. Obstruction develops affecting the drainage of sinuses resulting in sinusitis.
It is often bilateral.

If uni- lateral, malignancy should be ruled out. The condition is rare in children and if seen in a child is associated with cystic fibrosis.

47

Nasal cavity and paranasal sinuses: Inverted papilloma

Inverted papillomas resemble unilateral polyps, but about 3% of them are malignant and 3% of the rest may turn malignant.

A common site is the lateral wall of the nasal cavity. They are more vascular than the ordinary polyps.

They are locally aggressive and can erode the underlying bones. Treatment aims at surgical removal and histological examination for malignancy.
Recurrence after removal is common.

48

Nasal cavity and paranasal sinuses: Malignant tumours of the paranasal sinuses

1) Almost always squamous cell carcinomas
2) Develop usually in middle-aged or elderly men.
3) Twice as common in men as in women.
4) The maxillary sinus is the most common site.

The symptoms are unilateral obstruction with haemorrhage and purulent and sanguinous discharge.
CT and MRI scans show the extent of the tumour.
Site and size of the tumour will dictate the surgical approach.

For a tumour in the maxillary sinus total or radical maxillectomy followed by radiotherapy is the treatment of choice. Extension into sphenoid sinus, spread to nasopharynx or middle cranial fossa as well as distant metastsis are contraindications for a major surgi- cal procedure.

49

Pharynx: adenoids

Adenoid tissue is organized as vertical ridges in the posterosuperior wall of the nasopharynx close to the opening of the Eustachian tube.

Hypertrophy is maximal between the ages two and five years. Large adenoids cause nasal obstruction, nasal discharge, hyponasal speech, snoring and mouth breathing.

Blockage of the Eustachian tube can lead on to otitis media. Adenoidectomy helps to relieve the symptoms.

50

Nasopharyngeal carcinoma

Nasopharyngeal carcinoma (squamous cell) is silent in the early stages and the presentation is often as metastasis in the regional lymph nodes by which time the tumour is unresectable.

Higher in Southeast Asia than elsewhere, males being affected more than females. It is the most common tumour occurring in Hong Kong males.

Associated with Epstein–Barr virus.

51

Acute tonsillitis

Streptococci, Staphylococci, Pneumococci and Haemophilus influenzae are usual culprits

52

Peritonsillar abscess (Quinsy)

Complication of acute tonsillitis.
Infection passes though the capsule of the tonsil into the loose areolar tissue around the tonsil causing cellulitis and then abscess formation.

Symptoms are severe sore throat, dysphagia and otalgia on the affected side. On examination the mucosa is oedematous and red, the soft palate may bulges downwards and forwards and the uvula is pushed to the opposite side.

Trismus may make inspec- tion of the throat difficult. The jugulodigastric lymph node may be palpable and tender. Antibiotics may be effective in the cellulitic stage, but if there is abscess formation it will need incision and drainage followed by a course of appropriate antibiotics.

53

Pharyngeal pouch

Abnormal increase in pharyngeal pressure during swallowing can cause protrusion of the mucous membrane posteriorly at Killian’s dehiscence, gap between cricopharyngeus and thyropharyngeus (inferior constrictor of the pharynx).

Pouch first protrudes posteriorly. As it enlarges, backward extension is prevented by the prevertebral fascia and it, therefore, has to project to one side of the pharynx and this usually occurs on the left side.

On further enlargement the pouch pushes the oesophagus aside and lies directly in line with the pharynx. In this case, most of the food swallowed then passes into the pouch with resulting dysphagia.

Diagnosis can be made by barium swallow which shows the blind ending pouch behind the oesophagus. Treatment is surgical and involves cricopharyngeal myotomy and excision of the pouch.

54

Pyriform fossa tumours

Pyriform fossa tumours have a poor prognosis as they are never detected in the early stage. They are asymptomatic in the early stage and spread rapidly locally and into the regional lymph nodes.
Males are about eight times more commonly affected than females. Most patients give a history of heavy smoking and excessive drinking.
95% are squamous cell carcinoma
5% are adenocarcinoma.

Treatment is a combination of radiotherapy and surgery but because of late detection the five-year survival rate is only about 5%.

55

Larynx: Acute epiglottitis

Life threatening inflammation of the epiglottis in children often caused by Haemophilus influenzae type B.

The posterior part of the tongue and larynx also may be affected. The epiglottis is markedly swollen and is red in colour. Airway obstruction is common and hence all examination should be done in the theatre.

Treatment is by maintenance of airway by intubation or tracheostomy along with administration of intravenous fluids and antibiotics.

56

Larynx: Carcinoma of the larynx

The larynx is the most common site of carcinoma in the upper airway.
> men than in women, affecting mostly the middle-aged and the elderly.
Smoking is a significant predisposing factor and it is enhanced by excessive drinking.
Classified according to their location as glottic (60%), supraglottic (35%) and subglottic (5%).

Glottic:
Arise from vocal cord. They present as a raised warty lesion on one vocal cord. Any unilateral growth on the cord should be viewed with suspicion. As the vocal cord has a poor lymphatic drainage the tumour remain localised in the cord for a long time before metastasis appear in the regional lymph nodes. The treatment is irradiation and/or local resection. Prognosis is good, the five-year survival rate being about 80%.

Supra- glottic are stratified squamous cell carcinomas. The tumour may involve the false cords, ventricle, or the epiglottis. It spreads early into the pre-epiglottic space and into the regional lymph nodes. Treatment of choice is total laryngectomy with postoperative radio- therapy. The five-year survival rate is about 60%.

Subglottic tumours are rare. They can spread to the thyroid gland, cricoid cartilage, trachea and also into the cervical lymph nodes. The treatment is surgical resection and irradiation.