Page 10 - Edited - Webster HEAD AND NECK - part 2-Merge PDF

HN 208

LININGS OF THE NASAL CAVITY & PARANASAL AIR SINUSES,
NASAL MUCUS PRODUCTION

The external nose is lined with stratified squamous epithelium. The remainder (and greater part) of the nose (the
nasal cavity proper) and the paranasal air sinuses, is lined with respiratory epithelium - pseudostratified, ciliated
columnar, with goblet cells - on a richly vascular mucosa which contains numerous mucous glands.

The secretomotor supply to these glands is parasympathetic from the facial nerve (CrNVII) via the
pterygopalatine ganglion (HN 211, Fig. B; 212; 214). (Postsynaptic axons "hitch a lift" with nasal branches of the
maxillary division of the trigeminal nerve, V3 - HN 218).

Sympathetic postsynaptic axons arise in the superior cervical ganglion (HN 214) and travel on the
maxillary artery (HN 95-97: they (a) inhibit mucous secretion, and (b) cause vasoconstriction, which will
"decongest" an oedematous mucosa. This is why sympathetomimetic drugs (e.g. ephedrine), usually as nasal
drops, are sometimes used as "decongestants" during colds or hayfever. Their use is unwise: (a) as their effects
tail off, there is a re-bound vasodilation; (b) prolonged constriction of the mucosal vessels can cause localized
death and sloughing of the mucosa. This is also a hazard run by persistent sniffers of cocaine and “crac” powder
- which drugs prevent re-uptake by sympathetic postsynaptic terminals of released adrenaline/noradrenaline.

The sensory nerves of the nasal mucosa are from the maxillary division (V2) of the trigeminal nerve
(CrNV), subserving general sensation - touch, temperature and pain. The last includes nasal irritation by powders
(e.g. pepper, snuff - powdered tobacco) and gases (smoke, ammonia gas). Such stimulation is not only unpleasant,
but also initiates reflex nasal mucus production (see above) to attempt to wash out the noxious substance
(cf. reflex blinking and lacrimation following corneal/conjunctival irritation – HN 185). The olfactory epithelium is
limited to a small part of the roof of the nasal cavity, below the cribriform plates of the ethmoid bone, above which
lie the olfactory bulbs of the brain (HN 203). The olfactory nerve bundles (CrNl) pass through the holes of the
cribriform plate. In life, the olfactory epithelium can be identified by its yellow colour. Patients who are truly anosmic
(i.e. have lost their sense of smell) can still detect irritant gases and powders because these are detected by the
trigeminal innervation of the general nasal mucosa: this observation helps to distinguish true anosmia from false
(i.e. pretend, or psychiatric).

DEVIATED NASAL SEPTUM is quite common, even in those who have not suffered facial trauma (Fig. A, HN
209). lf the septum is deviated in infancy, the conchae (or at least their mucosa) undergo differential growth on the
two sides of the nose, so that the total capacity of the cavity is normal. In adults, a deviated septum sometimes
causes unilateral nasal obstruction which, oddly enough, is not compensated for pari passu by the increase volume
of the opposite half of the cavity. The only remedy is to correct the deviation surgically.

"BROKEN NOSE" The simplest cases involve fracture of one or both nasal bones. In more complicated cases,
the lacrimal and ethmoid air cells may be fractured (HN 146), as may the nasal septum. The latter may repair in a
deviated position, unless realigned during early treatment.

EPISTAXIS This is the technical term for "'bleeding nose". Epistaxes (plural; pronounced "epistacksees") are
divided into those arising in the anterior nose, and those arising from the posterior cavity. Both types can be
associated with the presence of a large, thin-walled vessel, but
anterior epistaxis is usually the result of habitual nose-picking. Bleeding is virtually always from the lower
anterior nasal septum - "Little's area" - (Fig. B, HN 209). No reason for this is known, other than ready
accessibility to picking fingers. Pinching the external nose between finger and thumb for up to 5 minutes
is generally a successful treatment; otherwise a cotton-bud soaked in 0.1% adrenaline solution applied to
the bleeding point will do the trick. [Pressure or ice on the "bridge" (i.e. nasal bones), keys down the back,
reciting the whole ''Rhyme of the Ancient Mariner" standing with your feet in ice-cold warer, etc. etc. -
useless.]
Posterior bleeds are more difficult to deal with. Contrary to popular belief, they are not especially
associated with hypertension, but systemic anti-coagulants and vaso-dilators (including aspirin and

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