What Are Paranasal Sinuses?

Paranasal sinuses (parannasal sinuses), also known as paranasal sinuses or sinuses, are the general term for air-containing cavities in the skull bones (frontal bone, sphenoid bone, maxillary bone, and ethmoid bone) around the nasal cavity. Resonate with pronunciation. There are four pairs of left and right sinuses, which are called frontal sinus, maxillary sinus, sphenoid sinus, and ethmoid sinus.

Chinese name: Paranasal sinuses
Foreign name: parannasal sinuses

Also known as: Paranasal or sinuses
Frontal sinus: Deep in frontal bone arch

Overview of Paranasal Sinus :

1. Also known as paranasal sinuses, are some air-containing cavities in the bone wall around the nasal cavity, the inner surface is covered with mucous membranes, and the nasal cavity is opened through small holes. Paranasal sinuses include frontal sinus, maxillary sinus, sphenoid sinus, and ethmoid sinus. The paranasal sinuses warm the air and resonate with pronunciation.

2. Inflammation of the paranasal sinus mucosa, of which maxillary sinusitis is the most common, because the opening of the maxillary sinus is in the upper part of the nasal cavity, so the exudate is easily retained.

3. The paranasal sinuses have a very close local relationship with the cranial cavity and the orbit. When the paranasal sinus is inflamed, it often leads to intracranial and orbital complications.

Paranasal sinus opening

1. Frontal sinus (frontal sinus): located in the frontal arch deep, opening in the middle nasal funnel.

2. Maxillary sinus (maxillary sinus): located in the body of the maxilla, opening in the middle nasal canal.

3 Sphenoid sinus: located in the sphenoid bone, opening in the sphenoid crypt.

4 Ethmoid sinus: located in the upper ethmoid labyrinth, and divided into anterior, middle and posterior ethmoid sinus. The anterior and middle ethmoid sinuses open in the middle nasal passage, and the posterior ethmoid sinus open in the upper nasal passage.

The paranasal sinuses are lined with mucous membranes, which are continuous with the nasal mucosa. They are ciliated columnar respiratory epithelium, which contains goblet cells and glands. The direction of movement of the sinus mucosa cilia is toward the natural sinus ostium, which is conducive to the discharge of endocrine secretions.

Inflammation of the nasal mucosa can often spread to the paranasal sinuses and cause sinusitis. If the inflammation spreads to the maxillary sinus, due to the large volume of the maxillary sinus, the opening position is high and small, the natural drainage is not smooth, and it is easy to become chronic inflammation and prolonged.

The role of paranasal sinuses

Mainly resonate with pronunciation. In addition, the paranasal sinuses are rich in blood vessels that help regulate the temperature and humidity of the inhaled air. There is also a role in reducing cranial weight.

Imaging examination of paranasal sinuses and nasal cavity

X-ray, CT and MRI imaging techniques play an important role in the diagnosis and treatment of nasal cavity and sinus diseases. In clinical practice, CT scans are often the imaging method of choice for nasal and sinus disorders. High-resolution coronary CT images can better show anatomical variations and sinusitis. Using MRI to detect sinus gas exchange is worthy of further research. According to the imaging findings and the clinic, a more accurate diagnosis can be made for most nasal and sinus diseases.

Paranasal sinus indications

1. External nasal diseases Understand external nasal tumors, fractures and trauma.

2. Nasal cavity Understand the condition of nasal cavity mass and foreign body.

3. Sinus understand the sinus inflammation, tumor, foreign body, fracture, anatomy, etc.

4, nasal septum to understand the nasal septum deformity, affecting nasal ventilation and sinus drainage.

Paranasal sinus contraindications

1. Those with cachexia or excessively weak constitution.

2. For patients with hypertension, check for stimuli that may induce cerebral hemorrhage.

3. Patients with intellectual disability cannot understand and cooperate with the examination.

4. Others who cannot tolerate the test, such as patients with mental illness.

Paranasal sinus operation method

(A) X-ray standard projection position of the nose and sinuses

1, occipital position

Also known as Fahrenheit and nasal condyle, you can observe the maxillary sinus, ethmoid chamber, frontal sinus and facial bone. Because the head was tilted back when shooting, the maxillary sinus on the X-ray film was slightly smaller than the real thing.

Pillow forehead

Also known as the Coriolis and nasal frontal positions, the frontal sinus is mainly observed. Because the frontal sinus is almost in direct contact with the film, it is rarely deformed, which is good for observing the frontal sinus orbit. Because the rock bone overlaps with the maxillary sinus at this position, the maxillary sinus cannot be observed. If liquid is suspected in the forehead and sieve booth, the standing or sitting position should be taken when the photo is taken.

3.Side position

Examination of the frontal sinus, sphenoid sinus, and their anterior and posterior depths is good. The maxillary sinus and ethmoid sinus can also be displayed, but the projections on both sides overlap.

4, top position

Also known as the skull base, skull axis or Hertz. According to the X-ray direction of the projection, it is divided into parietal position and parietal position, which is also the ear foramen position. The bones of the skull base, nasopharyngeal cavity, sphenoid sinus, middle cranial fossa, external auditory canal, and eustachian tube are mainly observed. The condyles on both sides are shown in front of the external auditory canal and do not overlap the external auditory canal.

5. Decrease angle

Also known as Welin position and semi-axial position of the skull base, the posterior wall of the maxillary sinus can be observed well, and the arcs of the posterior wall of the maxillary sinus and the side wall of the orbit are clearly displayed.

6.Sinus lateral position

The depth of frontal sinus, ethmoid chamber, maxillary sinus, and orbital lesions were clearly displayed, and the nasopharynx and soft palate were observed satisfactorily. The bilateral maxillary sinuses overlapped, so the observation was not satisfactory.

7.Sinus left and right oblique position

Also known as Rhese, Goalwin or Hodgson, the posterior ethmoidal chamber and optic nerve foramen can be displayed in the orbit. According to statistics, only 45% of the sides of the optic foramen are symmetrical, 40% of them are 10% different in size on both sides, and the remaining 15% are 25% different on both sides.

8.Sinus modified oblique position

Also known as Johnson and Dutt, the display site is similar to the oblique position. The advantage is that the orbital floor and the ethmoidal chamber can be avoided from overlapping, and the complete ethmoidal orbital plate can be observed.

9, hard palate bite

Observation of nasal vestibular cysts and palatal odontogenic cysts is a method to display the hard palate and nasal vestibular frontal images.

10.Opening pillow position

The main observation is the sphenoid sinus. The position is the same as that of the occipital condyle, except that the mouth is opened when the photo is taken.

(B) CT examination of the nose and sinuses

The coronal plane scan is used as the basic position, and the vertical line of the orbital line is generally used as the reference. The orbital line is the horizontal line from the outer ear hole to the outer corner of the eye, referred to as the OM line. Routinely scan layer by layer from the front 2cm before the external ear hole. The planar scan showed that the sinus-oral-nasal complex was the most accurate, and the anatomical structure displayed was basically consistent with that seen by functional nasal endoscopy.

Whether the sinus-oral-nasal complex can be clearly shown is related to three factors: scan angle: the patient takes a prone position, the neck is overextended, and the coronary surface is scanned from the front edge of the frontal sinus to the front edge of the ethmoid and perpendicular to the orbital line. Scanning layer thickness and layer distance: 3mm layer thickness and 3mm layer distance are the best, and the excellent rate of sinus-nasal-nasal complex display can reach 100%; Apply high-resolution bone algorithm, window width 2000 2500Hu, The window level is 100 300Hu, which can display the changes of bone and soft tissue at the same time, and generally does not need enhanced scanning. The horizontal scan showed better ethmoid sinus air cells and sphenoethmoid crypts. Scan in parallel with the orbital line. Generally, the CT scan thickness of the sinuses does not exceed 5mm.

(Three) MRI examination of the nose and sinuses

Because MRI can directly multi-plane imaging and has good soft tissue resolution, it can accurately show the range of lesions, and can also identify some lesions, especially tumors and inflammation. The emptiness effect of MRI can directly display blood vessels, and reflects the phenomenon of vascular increase in tumors, such as paraganglioma and aneurysms and other vascular diseases. The amalgam in the teeth and the cortical bone of the skull base often form artifacts on the CT image and affect the examination. MRI does not have this disadvantage. The biggest disadvantage of MRI in nasal and sinus examinations is that it can not detect fine bone changes such as bone hyperplasia, erosion and calcification