ANATOMY OF THE NOSE AND PARANASAL SINUSES

OUTLINE

Introduction

Parts

External Nose

Nasal cavity

Paranasal sinuses

Introduction

The nose is for breathing; the design of its cavity results in warming and moistening the inspired air, and in cleaning it too , Since odours are airborne, the olfactory receptors are placed in the nose.

Parts

The nose consists of the external nose and the nasalcavity, which is divided into right and left halves by the midline nasal septum.

External Nose

The external nose projects from the face its skeleton is largely cartilaginous

The external nose consists of the nasal bones (the 'bridge' of the nose) and the lateral (upper) and greater (alar or lower) nasal cartilages, supported in the midline by the cartilaginous part of the nasal septum

Innervation

External nasal nerve ; tip of the nose

Infraorbital nerve: around the nostril

Blood supply

dorsal nasal arteryLateral nasal arteryExternal nasal artery

Neurovascularization

The supratrochlear and infratrochlear nerves : lateral part

NASAL CAVITYThe nasal cavity extends from the nostrils (anterior nares) to the posterior end of the nasal septum. Posteriorly it opens into the nasopharynx through the posterior nasal apertures. It is divided into two nares by the nasal septum.Boundaries

Roof: It is divided into three parts (frontonasal, ethmoidal, and sphenoidal)Floor: Palatine processes of the maxilla and the horizontal plates of the palatine bone.

Medial wall:Nasal septum.

Lateral wall:The nasal conchae,

Features:

Sphenoethmoidal recess

Superior concha

Superior meatus

Middle concha Middle meatus

Inferior concha Inferior meatus

sphenopalatine

Blood supply

Ascending branch of the greater palatineSeptal branch of the superior labial

Little’s area

Anterior and posterior ethmoidal vessels supply the roof and anterior part of the lateral wall.

Veins accompany the arteries and drain in various directions: to the pterygoid plexus via the sphenopalatine foramen, to the facial vein, to ophthalmic and inferior cerebral veins via the ethmoidal foramina andcribriform plateLymph drainageLymphatics tend to run with the veins rather thanarteries, and drain to submandibular, deep cervical andretropharyngeal nodes.Nerve supplyThe olfactory area of the roof, superior concha and corresponding part of the septum has the olfactory receptors and lhe cell bodies of the bipolar cells embedded within the mucosa

The vestibular area is supplied by the infraorbital nerve whose branches have 'crept in' from the face

The rest of the lateral wall, the respiratory area, is supplied as follows: at the front by the anterior ethmoidal nerve in the upper part, and in the lower part by some filaments from the anterior superior alveolar nerve; at the upper back part by the nasal branches from the pterygopalatine ganglion and at me lower back part by the nasal branches of the greater palatine nerve.the septum is supplied by four nerves:

olfactory in the upper part, anterior ethmoidal at the front, medial, posterior, and superior nasal nerve at the back

the nasopalatine nerve

PARANASAL SINUSES

Maxillary sinus

The maxillary sinus is the space within the body of themaxilla, known in earlier days as the maxillary antrurn(of Highmore).

BoundariesRoof: floor of the orbit

Floor: alveolar part of the maxilla, which is the roof of the mouth

Anterior and posterior walls are the corresponding walls of the maxilla

The maxillary sinus is present at birth, but is no more than a shallow slit, slightly overgrown into a short cul-de-sac anteriorly and posteriorly.

The ostium of the sinus is high up and well back onits nasal wall. It is 2-4 mm in diameter.

Blood supply. By small arteries that pierce the bone, mostly from the facial, maxillary, infraorbital and greater palatine arteries, and veins accompany these vessels to the facial vein and to the pterygoid plexus.

Lymph drainage. For the most part via the infraorbital foramen or the ostium; in either case the lymphatics flow to the submandibular nodes.

Nerve supply. By various branches of the maxillary nerve: superior alveolar (posterior, middle and anterior), the greater palatine and infraorbital.

Each ethmoidal sinus lies between the orbit and the nose, in the ethmoidal labyrinth. The sinus is not a single cavity) being divided by bony septum into a variable number of ethmoidal air cells There may be only 3 or as many as 18, each with their own ostium, and they are called anterior, middle or posterior according to where they drain

Ethmoidal air cells

The anterior ethmoidal air cells occupy the anterior part of the sinus. Roofed in by the frontal bone, the bony walls are completed by the lacrimal bone. The ostia open into the anterior part of the semilunar hiatus in the middle

meatus The middle ethmoidal air cells also drain into the middle meatus.

At the back of the labyrinth the posterior ethmoidal air cells are completed by fusion of the orbital process of the palatine bone and the sphenoidal concha. They are roofed in by the orbital pan of the frontal bone

The posterior air cells drain into me superior meatus

.Nerve supply. By small branches from various nerves which include the supraorbital, anterior ethmoidal, lateral posterior superior nasal, orbital and posterior ethmoidal nerves

Blood supply. By branches from the supraorbital, anterior and posterior ethmoidal and sphenopalatine arteries

Lymph drainage. To submandibular and retropharyngeal nodes

The pair of sphenoidal sinuses occupy the body of the sphenoid bone. The two are separated by a septum which is usually not in the midline, and they can vary greatly In size. When smallthe sinus lies in front of the pituitary fossa

The ostium is in the anterior wall of the sinus and opens into the sphenoethmoidal recess (behind the superior concha)

Lymph drainage. To retropharyngeal nodes.

Blood supply. From the posterior ethmoidal and sphenopalatine branches of the maxillary artery.

Nerve supply: The posterior ethmoidal nerve and the orbital branch of the pterygopalatine ganglionmaxillary nerve.

Sphenoidal sinus

The frontal sinuses are the only sinuses not present atbirth; they appear during the second year as excavations into the diploe of the frontal bone, and are really anterior ethmoidal air cells that have migrated upwards.

The sinus drains through an ostium at its lower medial corner into the front end of the semilunar hiatus

Frontal sinus

Nerve supply. By the supraorbital and supratrochlear nerves by branches that pierce the frontal bone.

Blood supply. By supratrochlear, supraorbital and anterior ethmoidal arteries. Venous drainage is into diploic and superior ophthalmic veins.Lymph drainage. Across the face to the submandibular nodes