Surgical
anatomy of the nose
The supporting structures of the nose are shown
in Fig. 39.1. The paired nasal bones join in the midline with a suture and are
supported by the septum, which consists of the anterior quadrilateral cartilage,
the perpendicular plate of the ethmoid and the vomer (Fig.
39.2). In children
the length of the nasal bone equals its width, whereas in the adult the length
is three times the width. The lateral wall of the nasal cavity contains the
superior, middle and inferior turbinates (Fig. 39.3). Opening on to the lateral
nasal wall are the ostia of all the nasal sinuses except for the sphenoid sinus
(Fig. 39.4). The nasolacrimal duct opens into the inferior meatus beneath the
inferior turbinate approximately 3 cm posterior to the external nasal opening.
Below the middle turbinate is the middle meatus
into which the nasofrontal duct, the anterior
ethmoid cells and the maxillary antrum open (Fig. 39.5).
The superior
meatus between the middle and superior turbinates contains the opening for the
posterior ethmoid cells. The sphenoid ostium lies at this level on the anterior
wall of the sphenoid sinus. The nasal cavities and sinuses are lined by
respiratory epithelium. The olfactory mucosa, innervated by fibres from the
olfactory nerve, lines the area of the olfactory cleft and the cribriform
plate. The nasal fossae and sinuses receive
their blood supply via the external and internal carotid arteries. The external
carotid artery supplies the interior of the nose via the maxillary and
sphenopalatine arteries. The greater palatine artery supplies the anteroinferior
septum via the incisive canal. The contribution from the internal carotid artery
is via the anterior and posterior ethmoidal arteries which are branches of the
ophthalmic artery (Fig. 39.6). All
of these arteries
anastomose
to form a plexus of vessels (Kiesselbach’s
plexus) on the anterior part of the nasal septum. Venous drainage is via the
ophthalmic and facial veins and the pterygoid and pharyngeal plexus.
Intracranial drainage into the cavernous sinus via the ophthalmic vein is of
particular clinical importance because of the potential for intracranial spread
of nasal sepsis. The nasal cavity and sinuses have a sensory nerve supply
provided by the first and second branches of the trigeminal nerve. The olfactory
epithelium is supplied by the olfactory nerve. Autonomic innervation comprises
sympathetic fibres to the blood vessels via the cervical and pterygopalatine
ganglia. Parasympathetic fibres also synapse in the pterygopalatine ganglion
before passing to the mucous glands.