Anatomy of NoseZeeshan Ali

M-1036

External NoseInternal NoseMusculature of NoseVascular Supply, Nervous Innervation and Lymphatic DrainageParanasal Sinuses

External NoseIt is pyramidal in shape with its root up and the base directed downwardsNares – external opening of noseChoanae - open into the nasopharynx1. Bony Part: Posterior 1/3rd is bony

1. Nasal Bone2. Frontal Process of Maxilla3. Nasal Part of Frontal Bone

2. Cartilaginous Part: Anterior 2/3rd is cartilaginous1. Upper Lateral Cartilage2. Lower Lateral Cartilage/Alar Cartilage3. Septal Cartilage

• (a) Upper lateral cartilages. They extend from the undersurface of the nasal bones above, to the alar cartilages below. They fuse with each other and with the upper border of the septal cartilage in the midline anteriorly. • (b) Lower lateral cartilages (alar cartilages). Each alar cartilage is U-shaped.

It has a lateral crus which forms the ala and a medial crus which runs in the columella. Lateral crus overlaps lower edge of upper lateral cartilage on each side.• (c) Lesser alar (or sesamoid) cartilages. Two or more in number. They lie

above and lateral to alar cartilages. The various cartilages are connected with one another and with the adjoining bones by perichondrium and periosteum. Most of the free margin of nostril is formed of fibrofatty tissue and not the alar cartilage.• (d) Septal cartilage. Its anterosuperior border runs from under the nasal

bones to the nasal tip. It supports the dorsum of the cartilaginous part of the nose

Internal NoseNasal Cavity• Extends from Nostrils externally to Choanae internally• Nasal Septum divides Nasal Cavity into two compartments

Nasal Septum1. Septal Cartilage2. Perpendicular Plate of Ethmoid Bone3. Vomer

Boundaries of Nasal Cavity• Floor1. Palatine Process of Maxilla2. Horizontal Process of Palatine Bone

Roof1. Nasal Bone2. Frontal Bone3. Cribriform Plate of Ethmoid Bone4. Sloping body of Sphenoid Bone

Medial Wall1. Septal Cartilage2. Perpendicular Process of Ethmoidal Bone3. Vomer

Lateral Wall• 3 ProjectionsSuperior, Middle and Inferior Conchae/VestibuleSpace below each Concha is called Meatus

Spenoethmoidal Recess – Above superior concha > Sphenoid Air SinusSuperior Meatus – Below superior concha > Posterior ethmoid sinusesMiddle Meatus – Below middle conchaI. Bulla Ethmoidalis > formed by Middle ethmoidal air sinusesII. Hiatus semilunaris – Lies below bulla > Maxillary Sinus

Infundibulum – continuous with frontal sinus

Inferior Meatus – Below inferior concha > Nasolacrimal Duct

Regions of Nasal Cavities• Each nasal cavity consists of three general regions• Nasal vestibule– small dilated space just internal to the naris that is lined by skin and contains hair follicles• Respiratory region– Largest part of the nasal cavity– Rich neurovascular supply– Lined by respiratory epithelium composed mainly of ciliated and mucous cells• Olfactory region – small, is at the apex of each nasal cavity– Lined by olfactory epithelium which contains the olfactory receptors

• Vestibular Region• From anterior nostrils to inferior

concha• Respiratory Region• From inferior concha to the

posterior nostril and up to the superior concha• Olfactory Region• Above the superior concha up to

the roof of nose and adjoining part of septum

Musculature of Nose

1. the elevator muscle group — which includes the procerus muscle and the levator labii superioris alaeque nasi muscle.

2. the depressor muscle group — which includes the alar nasalis muscle and the depressor septi nasi muscle.

3. the compressor muscle group — which includes the transverse nasalis muscle.

4. the dilator muscle group — which includes the dilator naris muscle that expands the nostrils

Innervation and Vasculature of Muscles• Facial Nerve• Maxillary and Ophthalmic Arteries• Anterior facial and Ophthalmic Vein • Ophthalmic Vein drains into cavernous sinus – Septic Cavernous

Thrombosis• Lymphatics – Along Anterior facial vein to Submandibular nodes or

Preauricular nodes

Nasal Skin • The skin over the nasal bones and upper lateral cartilages is thin and

freely mobile while that covering the alar cartilages is thick and adherent, and contains many sebaceous glands.

Blood Supply (i) branches from the internal carotid artery, the branch of the anterior ethmoid artery, the branch of the posterior ethmoid artery, which derive from the ophthalmic artery(ii) branches from the external carotid artery, the sphenopalatine artery, the greater palatine artery, the superior labial artery, and the angular artery.

• The external nose is supplied with blood by the facial artery, which becomes the angular artery that courses over the superomedial aspect of the nose. The sellar region (sella turcica, “Turkish chair”) and the dorsal region of the nose are supplied with blood by branches of the internal maxillary artery (infraorbital) and the ophthalmic arteries that derive from the internal common carotid artery system.

• Internally, the lateral nasal wall is supplied with blood by the sphenopalatine artery (from behind and below) and by the anterior ethmoid artery and the posterior ethmoid artery (from above and behind). The nasal septum also is supplied with blood by the sphenopalatine artery, and by the anterior and posterior ethmoid arteries, with the additional circulatory contributions of the superior labial artery and of the greater palatine artery. These three (3) vascular supplies to the internal nose converge in the Kiesselbach plexus (the Little area), which is a region in the anteroinferior-third of the nasal septum, (in front and below)

• Veins follow Arterial Pattern

Nerve Supply of Nose

• • Three cranial nerves• – Olfaction - the olfactory nerve [I]• – General sensation - the trigeminal nerve [V], • • Anterior - ophthalmic nerve [V 1 ] • • Posterior - maxillary nerve [V 2 ]• – Glands - parasympathetic fibers in the facial nerve [VII] (greater

petrosal nerve), • • Sympathetic fibers

Nerve Supply • (a) Olfactory nerves • They carry sense of smell and supply olfactory region of nose. They

are the central filaments of the olfactory cells and are arranged into 12-20 nerves which pass through the cribriform plate and end in the olfactory bulb

• (b) Nerves of common sensation • They are: • (i) Anterior ethmoidal nerve.• (ii) Branches of sphenopalatine ganglion.• (iii) Branches of infra-orbital nerve. They supply vestibule of nose both on its medial and lateral

side. • • Most of the posterior two-thirds of nasal cavity (both septum and lateral wall) is supplied by

branches of sphenopalatine ganglion which can be blocked by placing a pledget of cotton soaked in anaesthetic solution near the sphenopalatine foramen situated at the posterior extremity of middle turbinate. Anterior ethmoidal nerve which supplies anterior and superior part of the nasal cavity (lateral wall and septum) can be blocked by placing the pledget high up on the inside of nasal bones where the nerve enters.

• (c) Autonomic nerves • Parasympathetic nerve fibres supply the nasal glands and control nasal

secretion. They come from greater superficial petrosal nerve, travel in the nerve of pterygoid canal (vidian nerve) and reach the sphenopalatine ganglion where they relay before reaching the nasal cavity. They also supply the blood vessels of nose and cause vasodilation. • Sympathetic nerve fibres come from upper two thoracic segments of spinal

cord, pass through superior cervical ganglion, travel in deep petrosal nerve and join the parasympathetic fibres of greater petrosal nerve to form the nerve of pterygoid canal (vidian nerve). They reach the nasal cavity without relay in the sphenopalatine ganglion. Their stimulation causes vasoconstriction.

Lymphatic Drainage • Lymphatics from the external nose and anterior part of nasal cavity

drain into submandibular lymph nodes while those from the rest of nasal cavity drain into upper jugular nodes either directly or through the retropharyngeal nodes. Lymphatics of the upper part of nasal cavity communicate with subarachnoid space along the olfactory nerves.

• Lymphatics• • Anterior regions • – drains forward onto • the face by passing • around the margins of • the nares -• submandibular nodes• • Posterior regions of • the nasal cavity and • the paranasal sinuses• • drains into upper deep • cervical nodes through the • retropharyngeal nodes

paranasal sinuses• four paired paranasal sinuses• The paranasal air sinuses are lined with respiratory epithelium• The maxillary sinuses, the largest of the paranasal sinuses, are under the

eyes, in the maxillary bones (open in the back of the semilunar hiatus of the nose).• The frontal sinuses, superior to the eyes, in the frontal bone, which forms

the hard part of the forehead.• The ethmoidal sinuses, which are formed from several discrete air cells

within the ethmoid bone between the nose and the eyes.• The sphenoidal sinuses, in the sphenoid bone.

Maxillary sinus • Medial wall – This is the base of the pyramidal shaped maxillary sinus. This corresponds to the lateral wall of the nasal

cavity. This wall has its convexity towards the maxillary sinus. The central portion of this wall is very thin and could even be membranous in places. The natural ostium is present in this wall. The natural ostium is present closer to the roof of the sinus.

• Anterior wall – Corresponds to the cheek area of the face. This portion also constitutes the lateral wall of the maxilla. Hence it would be appropriate to call it as antero lateral wall. The most important feature of this wall is the canine fossa.

• Roof – Forms the floor of the orbit. This wall is thin. It is through this wall the infraorbital vessels and nerve traverses.

• Floor – Is formed by the alveolar process of maxilla and the hard palate. The roots of the first and second molars may reach up to the floor of the sinus.

• Posterior wall – Formed by temporal surface of maxilla and is very thick

Frontal Sinus• It is shaped more or less shaped like L• Posterior wall – Related to the anterior cranial fossa• Floor – Is formed by the upper part of orbit• Drains into the anterior part of middle meatus

Ethmoidal sinus • Lateral wall – Is formed by the orbital plate of ethmoid. It is paper

thin and is known as lamina papyracea. It separates the ethmoid air cells from the orbit. Infections involving the Ethmoidal air cells may spread to the orbit via this thin plate of bone.• Roof – It is formed by the frontal bone anteriorly, by the face of

sphenoid and orbital process of palatine bone posteriorly.

Sphenoid• Superiorly – Pituitary gland• Lateral wall – Optic nerve and internal carotid artery• Floor – Nerve of pterygoid canal• Infections of sphenoid sinus may involve optic nerve if the nerve is

dehiscent.

Functions of paranasal sinuses• The presence of these sinuses lightens the skull• They add resonance to speech