Respiratory system II

Histology 2016-2017
Department of Anatomy &Histology: Dr.Rajaa Ali
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Respiratory System II
PARANASAL SINUSES
? Paranasal sinuses are air-filled spaces in the bones around the nasal cavity.
? There are our pairs o paranasal sinuses—frontal, sphenoidal , ethmoidal and maxillary; they are present in the bones with the corresponding names.
? They open into the nasal cavity.
? They are lined by the respiratory mucosa.
PHARYNX
GENERAL FEATURES
• Pharynx is a fibromuscular tube extending from the base of the skull to the level of the sixth cervical vertebra where it becomes continuous with the oesophagus.
• It lies behind the nasal cavity (nasopharynx), oral cavity (oropharynx) and larynx (laryngopharynx).
STRUCTURE
Pharynx is composed of the following four coats:
1. Mucosa
• This comprises epithelium and lamina propria. The epithelium is pseudostratifi ed ciliated columnar type in the nasopharynx and stratified squamous type in the oropharynx and laryngopharynx.
• Aggregation of lymphatic nodules in the lamina propria of the posterior wall and around the opening of the auditory tube in the nasopharynx results in the formation of pharyngeal and tubal tonsils, respectively.
• The palatine tonsil present in the lateral wall of the oropharynx and the lingual tonsil in the pharyngeal part of tongue, are already dealt with under lymphatic system.