NOSE AND PARANASAL SINUSES -vipin patidar www. vipinpatidar. wordpress NOSE AND PARANASAL SINUSES -vipin patidar www.vipinpatidar.wordpress.com

The external nose The external nose is supported by bone and cartilage. The bony part is formed mainly by the nasal bones on each side, and the frontal process of the maxillary bone. The cartilaginous portion is formed by several cartilages which support and give shape to the lower part of the nose and nasal tip.

The nasal cavity Main route of air entry Consist of large irregular cavity Divide into two equal passage by septum

The septum of nasal cavity The septum is a structure composed partly of cartilage and partly of a bone. Posterior- Ethmoid & vomer Anteriorly- Hyline Cartilage Roof – frontal, nasal, Ethmoid & Sphemoid

Contd.. Floor – roof of mouth Median wall- formed by septum Lateral wall- Maxilla & ethmoid bone

Septum of nasal cavity The lower and anterior area of nasal septum is known as Kisselbach zone. This area is the one from which bleeding commonly occurs in patients due to trauma to the arteries.

Lining of the Nose Nose lined with Ciliated columnar epithelium It contain mucus secretory goblet cells

Opening of Nasal Cavity Anterior Nares- from exterior into the Nasal cavity, nasal hair are found, coated in sticky mucus Posterior Nares- from Nasal cavity into Pharynx

Paranasal sinuses There are eight air sinuses situated around and near the nasal cavity (4 pairs): Maxillary sinuses Frontal sinuses Ethmoidal sinuses (is divided into anterior and posterior) Sphenoidal sinuses.

Paranasal Sinuses Functions They defend our brain against high and low temperature. They protect the brain and the eyes at the time of head injury (like air pillow of the car). They are a strong barrier that prevent vitally important structures (cranial cavity and orbit) from the spreading of the infection.

The Nasal Functions 1. Olfaction(smell). 2. Filtration. 3. Humidification and warming of the air passing to the lung.

Blood Supply Sphenopalatine branch of maxillary artery. Venous drainage in the facial and opthalmic veins.

Nerve Supply Olfactory, infra-orbital nerve, ethmoidal nerve.

Smell Olfactory epithelium - Contains the olfactory receptors and is located in the roof of the nasal cavity.

Specificity of the olfactory receptors – Can distinguish 10,000 chemicals Not clearly understood May be 1000 odorant binding proteins that act in combinations

Activation of olfactory receptors. Chemical comes in contact with the olfactory hair cells on the receptor cells. Depolarization of the receptor cells results in the generation of action potentials.

imbalances of the chemical senses Anosmia – without smell Uncinate fits – temporary distortions of smell due to brain damage, psychological disorders, or even seizures www.vipinpatidar.wordpress.com