What are the sinuses?
Air containing cavities
What are the functions of the sinuses?
- Serve as a resonating chamber for the voice
- Decrease the weight of the skull (air)
- Help warm and moisten inhaled air
- Shock absorbers in trauma
- Possibly control the immune system
What are the 4 sinuses?
Frontal, ethmoid, sphenoid of the cranium and maxillary bone of the face
Which is the largest of all the sinuses?
Maxillary
How many maxillary sinuses are there?
2 paired of varying size but are usually symmetric
What is the general shape of the maxillary sinuses?
Pyramid shape with 3 walls
Where are the maxillary sinuses located?
In each maxilla
What is the second largest sinus?
Frontal sinuses
How many frontal sinuses are there and were are they located?
Two, paired and located in the frontal bone
What is the general form of the frontal sinuses?
Vary great in size and may be absent
Where do the frontal sinuses sometimes extend?
Into the orbital plates
Where are the ethmoid sinuses located?
Within the lateral masses of the labrynth of the ethmoid bone
What are the ethmoid sinuses composed of?
Varying number of air cells divided into 3 main groups: anterior, middle and posterior
What do the ethmoid sinuses communicate with?
Sphenoid sinuses and nasal cavity
Where are the sphenoid sinuses located?
Occupy the sphenoid bone
How many sphenoid sinues are there?
Usually one, and never more than two
Where do the sphenoid sinuses lie?
Immedieately below the sella turcica
How are the views of the sinuses performed?
All must be performed erect
What are the projections used for the sinuses?
- Lateral
- PA Axial (Caldwell)
- Pareitalacanthial (Waters)
- Pareitalacanthial: (Waters - Open Mouth)
- SMV
What is the evaluation criteria for the lateral sinuses?
- All four sinus groups, with sphenoid best demonstrated
- No rotation or tilt of sinuses demonstrated by (Sella turcica in profile, superimposed orbital roofs and mandibular rami)
- soft tissue, bony trabecular detail and air-fluid levels
Which sinuses are best demonstrated in the PA Axial sinus projection?
Frontal and anterior ethmoidal sinuses
What is the evaluation criteria for PA Axial Sinuses?
- Fontal sinuses lying above the frontonasal suture and anterior ethmoidal air cells above the petrous ridges
- No rotation or tilt demonstrated by: equal distance between lateral border of skull and orbits and symmetric petrous ridges
- Petrous ridges lying in lower third of orbit
What is the evaluation criterial for the Parietoacantioal Projection (Waters) Sinuses?
- Petrous pyramids immediately inferior to floor of maxillary sinuses
- No rotation demonstrated by equal distance between lateral border of skull and lateral orbit and symmetric orbits and maxillary sinues
- Maxillary sinuses
What is the evaluation criteria for Pareitalacanthial: (Waters - Open Mouth) Sinuses?
- Petrous pyramids immediately inferior to floor of maxillary sinuses
- No rotation demonstrated by equal distance between lateral border of skull orbits and symmetric orbits/sinues
- Maxillary sinuses
- Sphenoid sinueses projected through open mouth
