The upper airway: nasal cavity, paranasal air sinuses and nasopharynx

Question 1

what is the upper part of the nasopharynx formed by

Answer 1

• the nasal cavity
• the nasopharynx
• the larynx

Question 2

where do the paired nasal cavities lie

Answer 2

medial to the maxillary air sinuses

• separated from the oral cavity below by the palate and from the cranium above by the cribriform plate of the ethmoid bone
• in the midline is the nasal septum which separates the two nasal cavities

Question 3

what do the nasal cavities lead into

Answer 3

Anteriorly, the nasal cavities lead into the vestibules of the nose which open as the nostrils. Posteriorly, the nasal cavities open into the nasopharynx

Question 4

what does the nasolacriminal duct into

Answer 4

he nasolacrimal (tear) duct drains into the inferior meatus

Question 5

what is the walls of the nasal cavities formed by

Answer 5

Medial: the bony nasal septum common to both cavities, formed anteriorly by the perpendicular plate of the ethmoid, which is continued posteriorly by the vomer.

Anteriorly the septum is composed of cartilage

Question 6

what is the septum formed by

Answer 6

Inferior: the floor is formed by the palatine process of the maxilla (anterior) and the horizontal process of the palatine bone (posterior).

Lateral: several bones contribute to the lateral wall. The superior and middle conchae are projections of the ethmoid bone, while the inferior concha is a separate bone overlying the maxilla and palatine bones.

The roof is formed by (in order from anterior to posterior) the nasal and frontal bones, the cribiform plate of the ethmoid and the body of the sphenoid bone.

Question 7

describe the structure of the larynx

Answer 7

• The thyroid cartilage has two flat surfaces (laminae) joined anteriorly to form the laryngeal prominence - Below the thyroid cartilage lies the cricoid cartilage, a modified tracheal cartilage ring.
• The cricoid cartilage is shaped like a signet ring, with a narrow anterior arch and a wide posterior lamina
• Below the cricoid lies the trachea. The cricoid forms synovial joints with the thyroid cartilage. The lamina of the cricoid also articulates with two small pyramid-shaped arytenoid cartilages
• The epiglottis, a leaf-shaped cartilage, is attached in the midline to the inner surface of the thyroid cartilage, and extends upwards and backwards behind the tongue. During swallowing, the epiglottis protects the laryngeal inlet.

The hyoid bone is the uppermost skeletal part of the larynx. It consists of a body with greater and lesser horns.

Between the cricoid and thyroid cartilages in the midline lies the cricothyroid membrane.
Between the arytenoid and thyroid cartilages lies the vocal fold. Above the vocal fold is the vestibular fold.
The thyrohyoid membrane fills the space between the hyoid bone and the top of the thyroid cartilage.

Question 8

what do the intrinsic layrgensl muscles do

Answer 8

• alter the position and tension of the vocal cords therefore changing the sounds
• also active during coughing, swallowing and deep inspiration

Question 9

describe the intrinsic muscles that you should know

Answer 9

cricothyroid, between the cricoid and thyroid cartilages antero-laterally

crico-arytenoids, between the lamina of the cricoid and the arytenoid cartilages

vocalis, lies in the free edge of the vocal fold