Anatomy of External NOSE By Dr Farooq Aman Ullah Khan PMC 24 th Nov. 2017
The External Nose Descriptions of the nose always begin with that part of it which is covered by the skin, i.e., the EXPOSED PART The External Nose. Quite often, no mention is made of an internal nose. Perhaps this is due to the susceptibility of this portion that sticks out to lie in the path of a fist, a hit, or any object which will injure it even to a state of its being smashed flat (not an uncommon occurrence).
The Skeleton The external nose has a free tip and is attached to the forehead by the root or bridge of the nose. The external orifices of the nose are the two Nares/ Nostrils. The shape of the nose is determined by the ethmoid bone and nasal septum which separates the nostrils.
Introduction The skeleton of the nose is formed by three types of tissues: Bones. Cartilage and Fibro-fatty cartilage. When looking at the structure it is ease to divide the nose into external nasal skeleton and internal nasal septum.
The Skeleton The bones are the two nasal bones (1) and part of the frontal process of each of the two maxillary bones (2) The cartilages are usually described as consisting of five major ones, which are: The septal cartilage (6), Two lateral cartilages (3), Two greater alar cartilages (4),
The Skeleton and a variable number of minor ones, which include: Two or three lesser alar cartilages (5) and one or more accessory (sesamoid) cartilages.
The Skeleton The two lateral nasal cartilages (3) and the septal cartilage (6), are described as being three of the five major cartilages. They are really parts of a single mass of cartilage.
The Skeleton The superior margin of each lateral cartilage is attached to its respective nasal bone (1) and frontal process (2) of the maxilla;
The Skeleton Medially, each lateral cartilage (3) is structurally continuous with the septal cartilage (6) above but, lower down, is separated from the septal cartilage by a cleft.
The Skeleton Inferiorly, the lateral nasal cartilages articulate with the lateral wings of the greater alar cartilages (4).
The Skeleton This lateral part of each greater alar cartilage is the prime support for the flaring expansion which forms the outer wall of each nostril, the so called ala nasi.
The Skeleton In supporting the ala of the nose, the greater alar cartilages are assisted by the lesser alar cartilages (5). The lateral part of the greater alar cartilage is known as the lateral crus (4). It also has a medial part, the medial crus
The Skeleton The two junctions of the two medial and two lateral crura of the greater alar cartilages form the skeleton of the apex of the nose.
The Skeleton One can verify this by placing the index finger on the tip of the nose and gently moving it from side to side. Two points are felt.
The Skeleton The medial crura contribute to the formation of the nasal septum and are best understood if one views the skeleton of the external nose via the nostrils.
Soft Tissue: Nasal Skin: Like the underline bone and cartilage support framework of the nose. The external skin is divided into vertical third anatomical sections. From the glabella. (B/w the eyebrows). To the bridge.(mid dorsal section) To the tip.
Nasal Muscles: Following are the muscles groups of the nose: Elevators muscles: Procerus Levator labii superiorris alaque nasi Depressors: Nasalis Depressor septi nasi. Compressor Muscles: Transverse nasalis Dialator Muscles: Dialator Naris
The Nerve Supply to the External Nose The three pairs of sensory nerves which supply the skin and subcutaneous tissues of the external nose are: 1. The infratrochlear nerve (1) (ophthalmic division of V nasociliary nerve infratrochlear nerve).
The Nerve Supply to the External Nose 2. The external nasal nerve (2) (ophthalmic division of V nasociliary nerve anterior ethmoidal nerve external nasal nerve).
The Nerve Supply to the External Nose 3. The infraorbital nerve (3) (maxillary division of V Infraorbital nerve nasal branches of infraorbital nerve).
The Arterial Supply to the External Nose The external nose receives most of its blood from the facial artery (1) via the lateral nasal (2), angular (3), and septal branches of the superior labial (5) arteries.
The Arterial Supply to the External Nose Less important are the nasal branches of the anterior ethmoidal (6) branch of the ophthalmic artery, the nasal branches of the ophthalmic artery (7), and the nasal branches of the infraorbital artery (8).
The Arterial Supply to the External Nose The septal branch of the superior labial (4) artery is one of the arteries which lead to Kiesselbach's area of the nasal septum. The Kiesselbach's area is the commonest site of nose bleed.
Venous Drainage of the External Nose The external nose lies within the danger area of the face. The blood from the skin of this region drains into the anterior facial vein (1), which unites with the posterior facial (2) to form the common facial vein (3), a tributary of the internal jugular vein (4).
Venous Drainage of the External Nose The anterior facial vein in the angle between nose and orbit (angular) communicates with the ophthalmic veins (5), which drain into the cavernous sinus (6) on each side
Venous Drainage of the External Nose The anterior facial vein also communicates with the pterygoid venous plexus (7), via direct venous connections and via the infraorbital vein (8), and the pterygoid venous plexus in turn communicates with the cavernous sinus
Venous Drainage of the External Nose An infection in the skin of the danger area of the face, e.g., the nose, may spread to the anterior facial vein and, via its connections with the ophthalmic veins and pterygoid venous plexus, reach the cavernous sinus to produce a cavernous sinus thrombosis that may result in meningitis.
Clinical Relevance: Nasal Fracture Due to the Prominence of the external nasal skeleton, nasal fractures are common- the most common facial fracture. Fractures usually occur as a result of blunt trauma to the nose. A common sequale of nasal fractures is permanent deformity, due to the disruption of the bones and cartilages.
Nasal subunits To plan, map, and execute the surgical correction of a nasal defect or deformity. The structure of the external nose is divided into nine (9) aesthetic nasal subunits. It provide the plastic surgeon with the measures for determining the size, extent, and topographic locale of the nasal defect or deformity.
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