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maxillary hiatus is reduced? Mention their lining epithelium,
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development and functions of air sinuses. What is sinusitis? Paranasal
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air sinus:
T
These are air filled cavities lined by muco-periosteum present within some bones
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around the nasal cavities.
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Paranasal Air Sinus T T Draining Sites T
1. Frontal Air Sinuses (1 pair)
T T T T T Anterior part of the middle meatus T T T T T T
through the ethmoidal infundibulum
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or frontonasal duct T T
a. Anterior (up to 2)
T T T T Middle meatus through ethmoidal
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2. Ethmoidal
T T infundibulum
Air Sinuses
T b. Middle (3)
T T Middle meatus on or above the bulla
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c. Posterior (1-7)
T T Superior meatus T
3. Sphenoidal Air Sinuses (1 pair)
T T T T T Superior meatus T
4. Maxillary Air Sinuses (1 pair)
T T T T T Middle meatus through the lowest
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part of hiatus semilunaris T T T
All the air sinuses drains into middle meatus except the posterior part of ethmoidal
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air sinus and sphenoidal air sinus which drains into superior meatus.
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,Maxillary hiatus is reduced in living conditions by the following factors:
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Above: By uncinate process of Ethmoid bone and Lacrimal bone
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Below: By inferior nasal concha
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Behind: By maxillary process of perpendicular plate of Palatine bone. It
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is further reduced by thick mucosa of the nasal cavity.
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Lining epithelium of paranasal air sinuses:
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- Pseudostratified ciliated columnar epithelium.
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Development:
Paranasal air sinuses developed as diverticula of the lateral nasal wall and extends
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into the maxilla, ethmoid, frontal and sphenoid bones.
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Functions:
1. Lightening of the skull. T T T
2. Humidification of ais T T
3. Resonance of voice T T
4. Gives the shape of the face. T T T T T
Sinusitis:
Inflammation of mucosa of paranasal air sinuses producing inflammatory exudate or
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pus, is known as sinusitis.
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2. Mention cartilages, lining epithelium and nerve supply of the larynx.
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Give a short description of interior of larynx (with diagram). What is
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hoarseness of voice? What is laryngitis? T T T T T
Cartilages of larynx: T T
1. Unpaired cartilages: T
a. Cricoid cartilage T
b. Thyroid cartilage T
c. Epiglottic cartilage T
2. Paired cartilages: T
a. Arytenoid cartilage T
b. Cuneiform cartilage. T
c. Corniculate cartilage T
,Nice to know
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[Types:
A. Elastic fibrocartilage: T
Corniculate, cuneiform, epiglottic & the apices of the arytenoids. T T T T T T T T
B. Hyaline Cartilage: T
Thyroid, Cricoid & greater part of the arytenoids.]
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Lining epithelium of larynx:
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1. Anterior surface and upper part of the posterior surface of Epiglottis, upper
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part of the aryepiglottic folds and vocal fold are lined by Non-keratinized
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stratified squamous epithelium. T T
2. The rest of the larynx is lined by Pseudo-stratified ciliated columnar
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epithelium.
Nerve supply of larynx:
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Motor supply:
T
All the intrinsic and extrinsic muscles of larynx are supplied by Recurrent
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laryngeal nerve, except Cricothyroid which is supplied by External laryngeal
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nerve.
Sensory supply: T
- Mucous membrane above the vocal fold is supplied by internal laryngeal nerve
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- Below the vocal fold is supplied by Recurrent laryngeal nerve.
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Autonomic Innervation: T
- Parasympathetic secretomotor fibers – run with both the superior and recurrent
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laryngeal nerves T
- Postganglionic sympathetic fibers – Originate in the superior and middle cervical
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ganglia.
, Interior of larynx: T T
Cavity of larynx extends from laryngeal inlet to the lower border of cricoid cartilage.
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It is divided into 3 parts by Vestibular and vocal folds,
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i. Upper part or Vestibule of larynx:
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- It extends from the laryngeal inlet to the vestibular folds. Vestibular folds are the
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mucosal folds which project medially and the gap between two vestibular fold is
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known as “Rima vestibuli.”
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ii. Middle part of Larynx: T T T
- It extends from vestibular folds to vocal folds. The gap between the vocal folds is
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known as “Rima Glottitis”. A small recess between the vestibular and vocal fold is
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known as the sinus of larynx. From it a small diverticulum passes upward called
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saccule of larynx.
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iii. Lower part of larynx: T T T
- It extends from vocal folds to the lower border of cricoid cartilage.
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