Sinus (anatomy)

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A sinus is a sac or cavity in any organ or tissue, or an abnormal cavity or passage caused by the destruction of tissue. In common usage, "sinus" usually refers to the paranasal sinuses, which are air cavities in the cranial bones, especially those near the nose and connecting to it. Most individuals have four paired cavities located in the cranial bone or skull.

Contents

Etymology

Sinus is Latin for "bay", "pocket", "curve", or "bosom". In anatomy, the term is used in various contexts.

The word "sinusitis" is used to indicate that one or more of the membrane linings found in the sinus cavities has become inflamed or infected. It is however distinct from a fistula, which is a tract connecting two epithelial surfaces. If left untreated, infections occurring in the sinus cavities can affect the chest and lungs.

Sinuses in the body

Paranasal sinuses

The four paired sinuses or air cavities can be referred to as:

Function

The function of the sinus cavities within the cranial bone (skull) is not entirely clear. Beliefs about their possible function include: [1]

Sinusitis

If one or more of the paired paranasal sinuses or air cavities becomes inflamed, it leads to an infection called sinusitis. The term "sinusitis" means an inflammation of one or more of the sinus cavities. This inflammation causes an increase in internal pressure within these areas. The pressure is often experienced in the cheek area, eyes, nose, on one side of the head (temple areas), and can result in a severe headache. [2]

When diagnosing a sinus infection, one can identify which sinus cavity the infection is located in by the term given to the cavity. Ethmoiditis refers to an infection in the ethmoid sinus cavity/ies, frontal sinusitis refers to an infection occurring in the frontal sinus cavity/ies, antritis is used to refer to an infection in the maxillary sinus cavity/ies whilst sphenoiditis refers to an infection in the sphenoid sinus cavity/ies.

Classification

Sinusitis can be acute, chronic or recurrent.

  • Acute: Any sinus infection which lasts for a maximum of three weeks can be referred to as acute sinusitis; with the affected individual displaying symptoms such as congestion, post nasal drip, halitosis, a runny nose as well as sinus pressure and pain in the affected areas.
  • Chronic: This infection extends beyond the three-week period and if left untreated can persist for years. Certain causes of chronic sinusitis can be allergies that have been left untreated, bacterial or fungal infections within one or more of the sinus cavities or any allergic disorders which targets and increases the sensitivity of the mucous membrane linings which surround the sinus cavities and nasal passages. Symptoms of chronic sinusitis are debilitating headaches, green colored mucus, severe nasal blockages or congestion and heavy pressure experienced in the cheek, forehead, temple and eye regions.
  • Recurrent: This type of sinus infection is intermittent; a person usually experiences this type of infection numerous times throughout a year with periods of complete relief being experienced for weeks or months between episodes of infection.

Causes

A sinus infection can have a number of causes. Untreated allergies are one of the main contributing factors to the development of sinus infections. A person with a sinus infection often has nasal congestion with thick nasal secretions, fever, and cough (WebMD). Patients can be treated by “reducing the swelling or inflammation in the nasal passages and sinuses, eliminating the infection, promoting drainage from the sinuses, and maintaining open sinuses” (WebMD). Sinusitis can be treated with medications and can also be eliminated by surgery. [3]

Another cause of sinus infections is a result of bacterial invasion within one or more of the sinus cavities. Any bacteria that enter the nasal passages and sinus cavities through the air that is inhaled, are trapped by the mucus secreted by the mucous membranes surrounding these areas. These trapped particles can cause an irritation to these linings resulting in swelling and inflammation. “Bacteria that normally cause acute sinusitis are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis (WebMD). These microorganisms, along with Staphylococcus aureus and some anaerobes (bacteria that live without oxygen), are involved in chronic sinusitis. (WebMD)” Fungi can also cause chronic sinusitis.

Certain abnormalities or trauma related injuries to the nasal cavity can make it difficult for effective drainage of mucus from the sinus cavities. This mucus is then allowed to develop in these areas making the cavity an ideal area in which bacteria can both attach and thrive.

Treatment outlook

Sinusitis or sinus infections usually clear up if treated early and appropriately. [4] Apart from complications, the outlook for acute bacterial sinusitis is good. People may develop chronic sinusitis or have recurrent attacks of acute sinusitis if they suffer with allergies or if they have any “structural or anatomical causes" which predispose them to developing sinus infections.

Viral sinus infections do not, however, respond well to conventional treatments such as antibiotics. When treating fungal sinusitis, an appropriate fungicide is usually administered.

Related Research Articles

<span class="mw-page-title-main">Paranasal sinuses</span> Air-filled spaces surrounding the nasal cavity

Paranasal sinuses are a group of four paired air-filled spaces that surround the nasal cavity. The maxillary sinuses are located under the eyes; the frontal sinuses are above the eyes; the ethmoidal sinuses are between the eyes and the sphenoidal sinuses are behind the eyes. The sinuses are named for the facial bones and sphenoid bone in which they are located. Their role is disputed and no function has been confirmed.

<span class="mw-page-title-main">Sinusitis</span> An inflammation of the mucous membrane that lines the sinuses resulting in symptoms

Sinusitis, also known as rhinosinusitis, is an inflammation of the mucous membranes that line the sinuses resulting in symptoms that may include thick nasal mucus, a plugged nose, and facial pain. Other signs and symptoms may include fever, headaches, a poor sense of smell, sore throat, a feeling that phlegm is oozing out from the back of the nose to the throat along with a necessity to clear the throat frequently and frequent attacks of cough.

Sinus may refer to:

<span class="mw-page-title-main">Nasal cavity</span> Large, air-filled space above and behind the nose in the middle of the face

The nasal cavity is a large, air-filled space above and behind the nose in the middle of the face. The nasal septum divides the cavity into two cavities, also known as fossae. Each cavity is the continuation of one of the two nostrils. The nasal cavity is the uppermost part of the respiratory system and provides the nasal passage for inhaled air from the nostrils to the nasopharynx and rest of the respiratory tract.

<span class="mw-page-title-main">Orbit (anatomy)</span> Cavity or socket of the skull in which the eye and its appendages are situated

In anatomy, the orbit is the cavity or socket/hole of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents. In the adult human, the volume of the orbit is 30 millilitres, of which the eye occupies 6.5 ml. The orbital contents comprise the eye, the orbital and retrobulbar fascia, extraocular muscles, cranial nerves II, III, IV, V, and VI, blood vessels, fat, the lacrimal gland with its sac and duct, the eyelids, medial and lateral palpebral ligaments, cheek ligaments, the suspensory ligament, septum, ciliary ganglion and short ciliary nerves.

<span class="mw-page-title-main">Nasal polyp</span> Noncancerous growths within the nose or sinuses

Nasal polyps (NP) are noncancerous growths within the nose or sinuses. Symptoms include trouble breathing through the nose, loss of smell, decreased taste, post nasal drip, and a runny nose. The growths are sac-like, movable, and nontender, though face pain may occasionally occur. They typically occur in both nostrils in those who are affected. Complications may include sinusitis and broadening of the nose.

Catarrh is an inflammation of mucous membranes in one of the airways or cavities of the body, usually with reference to the throat and paranasal sinuses. It can result in a thick exudate of mucus and white blood cells caused by the swelling of the mucous membranes in the head in response to an infection. It is a symptom usually associated with the common cold, pharyngitis, and chesty coughs, but it can also be found in patients with adenoiditis, otitis media, sinusitis or tonsillitis. The phlegm produced by catarrh may either discharge or cause a blockage that may become chronic.

<span class="mw-page-title-main">Nasal irrigation</span> Personal hygiene practice for rinsing out nasal passages

Nasal irrigation is a personal hygiene practice in which the nasal cavity is washed to flush out mucus and debris from the nose and sinuses, in order to enhance nasal breathing. Nasal irrigation can also refer to the use of saline nasal spray or nebulizers to moisten the mucous membranes.

<span class="mw-page-title-main">Rhinorrhea</span> Filling of the nasal cavity with fluid mucus

Rhinorrhea, rhinorrhoea, or informally runny nose is the free discharge of a thin mucus fluid from the nose; it is a common condition. It is a common symptom of allergies or certain viral infections, such as the common cold or COVID-19. It can be a side effect of crying, exposure to cold temperatures, cocaine abuse, or drug withdrawal, such as from methadone or other opioids. Treatment for rhinorrhea may be aimed at reducing symptoms or treating underlying causes. Rhinorrhea usually resolves without intervention, but may require treatment by a doctor if symptoms last more than 10 days or if symptoms are the result of foreign bodies in the nose.

<span class="mw-page-title-main">Aerosinusitis</span> Barotrauma of the sinuses

Aerosinusitis, also called barosinusitis, sinus squeeze or sinus barotrauma is a painful inflammation and sometimes bleeding of the membrane of the paranasal sinus cavities, normally the frontal sinus. It is caused by a difference in air pressures inside and outside the cavities.

<span class="mw-page-title-main">Maxillary sinus</span> Largest of the paranasal sinuses, and drains into the middle meatus of the nose

The pyramid-shaped maxillary sinus is the largest of the paranasal sinuses, located in the maxilla. It drains into the middle meatus of the nose through the semilunar hiatus. It is located to the side of the nasal cavity, and below the orbit.

<span class="mw-page-title-main">Ethmoid sinus</span> Air-filled space near the nasal cavity

The ethmoid sinuses or ethmoid air cells of the ethmoid bone are one of the four paired paranasal sinuses. Unlike the other three pairs of paranasal sinuses which consist of one or two large cavities, the ethmoidal sinuses entail a number of small air-filled cavities. The cells are located within the lateral mass (labyrinth) of each ethmoid bone and are variable in both size and number. The cells are grouped into anterior, middle, and posterior groups; the groups differ in their drainage modalities, though all ultimately drain into either the superior or the middle nasal meatus of the lateral wall of the nasal cavity.

<span class="mw-page-title-main">Cranial cavity</span> Space inside the skull formed by eight cranial bones known as the neurocranium

The cranial cavity, also known as intracranial space, is the space within the skull that accommodates the brain. The skull minus the mandible is called the cranium. The cavity is formed by eight cranial bones known as the neurocranium that in humans includes the skull cap and forms the protective case around the brain. The remainder of the skull is called the facial skeleton. Meninges are protective membranes that surround the brain to minimize damage to the brain in the case of head trauma. Meningitis is the inflammation of meninges caused by bacterial or viral infections.

<span class="mw-page-title-main">Frontal sinus</span> Airspace below ridge of eyebrow in humam anatomy

The frontal sinuses are one of the four pairs of paranasal sinuses that are situated behind the brow ridges. Sinuses are mucosa-lined airspaces within the bones of the face and skull. Each opens into the anterior part of the corresponding middle nasal meatus of the nose through the frontonasal duct which traverses the anterior part of the labyrinth of the ethmoid. These structures then open into the semilunar hiatus in the middle meatus.

<span class="mw-page-title-main">Cavernous sinus thrombosis</span> Medical condition

Cavernous sinus thrombosis (CST) is the formation of a blood clot within the cavernous sinus, a cavity at the base of the brain which drains deoxygenated blood from the brain back to the heart. This is a rare disorder and can be of two types–septic cavernous thrombosis and aseptic cavernous thrombosis. The most common form is septic cavernous sinus thrombosis. The cause is usually from a spreading infection in the nose, sinuses, ears, or teeth. Staphylococcus aureus and Streptococcus are often the associated bacteria.

<span class="mw-page-title-main">Functional endoscopic sinus surgery</span> Surgery to enlarge the paranasal sinus drainage pathways

Functional endoscopic sinus surgery (FESS) is a procedure that is used to treat sinusitis and other conditions that affect the sinuses. Sinusitis is an inflammation of the sinuses that can cause symptoms such as congestion, headaches, and difficulty breathing through the nose.

<span class="mw-page-title-main">Human nose</span> Feature of the human face

The human nose is the first organ of the respiratory system. It is also the principal organ in the olfactory system. The shape of the nose is determined by the nasal bones and the nasal cartilages, including the nasal septum which separates the nostrils and divides the nasal cavity into two.

<span class="mw-page-title-main">Respiratory system of the horse</span> Biological system by which a horse circulates air for the purpose of gaseous exchange

The respiratory system of the horse is the biological system by which a horse circulates air for the purpose of gaseous exchange.

<span class="mw-page-title-main">Fungal sinusitis</span> Inflammation of the paranasal sinuses due to fungal infection

Fungal sinusitis or fungal rhinosinusitis is the inflammation of the lining mucosa of the paranasal sinuses due to a fungal infection. It occurs in people with reduced immunity. The maxillary sinus is the most commonly involved. Fungi responsible for fungal sinusitis are Aspergillus fumigatus (90%), Aspergillus flavus, and Aspergillus niger. Fungal sinusitis occurs most commonly in middle-aged populations. Diabetes mellitus is the most common risk factor involved.

<span class="mw-page-title-main">Oroantral fistula</span> Medical condition

Oroantral fistula (OAF) is an epithelialised oroantral communication (OAC). OAC refers to an abnormal connection between the oral cavity and antrum. The creation of an OAC is most commonly due to the extraction of a maxillary (upper) tooth closely related to the antral floor. A small OAC may heal spontaneously but a larger OAC would require surgical closure to prevent the development of persistent OAF and chronic sinusitis.

References

  1. Cappello, Zachary J.; Minutello, Katrina; Dublin, Arthur B. (August 12, 2020). Anatomy, Head and Neck, Nose Paranasal Sinuses. StatPearls Publishing. PMID   29763001 via PubMed.
  2. "Sinusitis (sinus infection)". nhs.uk. 8 January 2018.
  3. "Newcastle Hospitals - Functional Endoscopic Sinus Surgery". www.newcastle-hospitals.org.uk.
  4. "Antibiotics should not be used to treat the majority of sinus infections, NICE says | News and features | News". NICE. 27 October 2017.
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