The paranasal sinuses are air-filled cavities located within the frontal, maxillary, ethmoid, and sphenoid bones. They are lined with mucous membranes and communicate with the nasal cavity through small openings. The sinuses help produce and drain mucus, act as resonators for the voice, and help reduce the weight of the skull. The document then proceeds to describe the specific anatomical details of each type of paranasal sinus.

1. Paranasal sinuses
Dr. Mohammad Mahmoud Mosaed

2. Paranasal sinuses
• The paranasal sinuses are cavities
found in the interior of the maxilla,
frontal, sphenoid, and ethmoid bones
• They are lined with mucoperiosteum and
filled with air
• They communicate with the nasal cavity
through relatively small apertures

4.  The mucus produced by the mucous
membrane is moved into the nose by
ciliary action of the columnar cells
 Drainage of the mucus is also achieved
by the siphon action created during the
blowing of the nose

5. 1. the sinuses act as resonators to the voice
 When the apertures of the sinuses are
blocked or they become filled with fluid,
the quality of the voice is markedly
changed
2. They also reduce the weight of the skull

6.  The maxillary sinus is pyramidal in shape with its apex directed
laterally and base directed medially
 Site located within the body of the maxilla
 The roof is formed by the floor of the orbit and contains
infraorbital canal with its contents,
 The floor is formed by alveolar process of the maxilla and is
related to the roots of the premolars and molar teeth
 The maxillary sinus opens into the middle meatus of the nose
through the hiatus semilunaris, the opening lies in the
anterosuperior part of the base
 Nerve supply infraorbital and superior alveolar nerves
 Lymphatic drainage submandibular lymph node

9.  The two frontal sinuses are contained within the frontal
bone
 They are separated from each other by a bony septum
 Each sinus is roughly triangular, extending upward
above the medial end of the eyebrow and backward
into the medial part of the roof of the orbit
 The sinus opens in the infundibulum of the middle
meatus of the nose by the frontonasal duct
 Nerve supply supraorbital and anterior ethmoidal
 Lymphatic drainage submandibular lymph node
 Venous drainage superior ophthalmic vein

10.  The two sphenoidal sinuses lie within the body of the
sphenoid bone
 Each sinus opens into the sphenoethmoidal recess
above the superior concha
 Nerve supply posterior ethmoidal nerve
 Arterial supply posterior ethmoidal artery
 Lymphatic drainage retropharyngeal lymph node
 Relations
 Superiorly pituitary fossa
 Inferiorly roof of the nasopharynx
 Laterally cavernous sinus
 Posteriorly posterior cranial fossa

12.  The ethmoidal sinuses are anterior, middle, and
posterior and they are contained within the ethmoid
bone between the nose and the orbit
 The anterior sinuses open into the infundibulum
 The middle sinuses open into the middle meatus, on
or above the bulla ethmoidalis
 The posterior sinuses open into the superior meatus
 Nerve supply anterior and posterior ethmoidal
nerves and lateral posterior superior nasal nerve
 Lymphatic drainage submandibular and
retropharyngeal lymph node