Sinus is Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 for "bay", "pocket", "curve", or "bosom". In anatomy

Anatomy

Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...

, the term is used in various contexts.

A sinus is a sack or cavity in any organ

Organ (anatomy)

In biology, an organ is a collection of tissues joined in structural unit to serve a common function. Usually there is a main tissue and sporadic tissues . The main tissue is the one that is unique for the specific organ. For example, main tissue in the heart is the myocardium, while sporadic are...

 or tissue

Biological tissue

Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...

, or an abnormal cavity or passage caused by the destruction of tissue. In common usage, "sinus" usually refers to the paranasal sinus

Paranasal sinus

Paranasal sinuses are a group of four paired air-filled spaces that surround the nasal cavity , above and between the eyes , and behind the ethmoids...

es, which are air cavities in the cranial bones, especially those near the nose

Human nose

The visible part of the human nose is the protruding part of the face that bears the nostrils. The shape of the nose is determined by the ethmoid bone and the nasal septum, which consists mostly of cartilage and which separates the nostrils...

 and connecting to it. Each individual has four paired cavities located in the cranial bone or skull. These cavities are vitally important for a variety of reasons.

The word "sinusitis" is derived from sinus and 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

Fistula

In medicine, a fistula is an abnormal connection or passageway between two epithelium-lined organs or vessels that normally do not connect. It is generally a disease condition, but a fistula may be surgically created for therapeutic reasons.-Locations:Fistulas can develop in various parts of the...

, which is a tract connecting two epithelialised surfaces. Any untreated infections occurring in the sinus cavities can affect the chest and lungs if left untreated.

Sinuses in the body

• Paranasal sinuses
  • Maxillary
    Maxillary sinus
    The pyramid shaped maxillary sinus is the largest of the paranasal sinuses, and drains into the nose. It is present at birth as rudimentary air cells, and develops throughout childhood.-General characteristics:...
    
    
  • Ethmoid
    Ethmoid sinus
    The ethmoid sinus is each of the two paranasal sinuses within the ethmoid bone, comprising the ethmoidal air cells and filled with air. These are divided into anterior, middle and posterior group. The ethmoidal air cells consist of numerous thin-walled cavities situated in the ethmoidal labyrinth...
    
    
  • Sphenoid
  • Frontal
    Frontal sinus
    Sinuses are mucosa-lined airspaces within the bones of the face and skull. The frontal sinuses, situated behind the superciliary arches, are absent at birth, but are generally fairly well developed between the seventh and eighth years, only reaching their full size after puberty...
    
    
• Subcapsular sinus
  Subcapsular sinus
  The subcapsular sinus is a region within the lymph node immediately deep to the capsule that contains relatively sparse lymphocytes. It thus allows lymph to flow freely through it....
  
  
• Medullary sinuses
• Trabecular sinuses
  Trabecular sinuses
  In the renal cortex, the subcapsular sinus drains to trabecular sinuses. Lymph then flows into the medullary sinuses....
  
  
• Dural venous sinuses
  Dural venous sinuses
  The dural venous sinuses are venous channels found between layers of dura mater in the brain...
  
  
  • Inferior sagittal
    Inferior sagittal sinus
    The inferior sagittal sinus , within the human head, is an area beneath the brain which allows blood to drain outwards posteriorly from the center of the head. It drains to the straight sinus , which connects to the transverse sinuses...
    
    
  • Superior sagittal
    Superior sagittal sinus
    The superior sagittal sinus , within the human head, is an unpaired area along the attached margin of falx cerebri. It allows blood to drain from the lateral aspects of anterior cerebral hemispheres to the confluence of sinuses...
    
    
  • Straight
    Straight sinus
    The straight sinus , within the human head, is an unpaired area beneath the brain which allows blood to drain from the inferior center of the head outwards posteriorly...
    
    
  • Occipital
    Occipital sinus
    The occipital sinus is the smallest of the cranial sinuses.It is situated in the attached margin of the falx cerebelli, and is generally single, but occasionally there are two....
    
    
  • Confluence of sinuses
    Confluence of sinuses
    The confluence of sinuses or torcular herophili is the connecting point of the superior sagittal sinus, straight sinus, and occipital sinus. It is found deep to the occipital protuberance of the skull. Blood arriving at this point then proceeds to drain into the left and right transverse sinuses...
    
    
  • Cavernous
  • Superior petrosal
    Superior petrosal sinus
    The superior petrosal sinus is a venous structure located beneath the brain. It receives blood from the cavernous sinus and passes backward and laterally to drain into the transverse sinus....
    
    
  • Inferior petrosal
    Inferior petrosal sinus
    The inferior petrosal sinuses, within the human head, are beneath the brain and allow blood to drain from the center of the head.They drain on either side inferiorly from the cavernous sinus and join with the sigmoid sinus to form the internal jugular vein, which continues inferiorly to drain...
    
    
  • Transverse
    Transverse sinuses
    The transverse sinuses , within the human head, are two areas beneath the brain which allow blood to drain from the back of the head. They run laterally in a groove along the interior surface of the occipital bone...
    
    
  • Sigmoid
• Carotid sinus
  Carotid sinus
  In human anatomy, the carotid sinus is a localized dilation of the internal carotid artery at its origin, the common carotid artery.-Functions:...
  
  
• Renal sinus
  Renal sinus
  The renal sinus is a cavity within the kidney which is occupied by the renal pelvis, renal calyces, blood vessels, nerves and fat....
  
  
• Coronary sinus
  Coronary sinus
  The coronary sinus is a collection of veins joined together to form a large vessel that collects blood from the myocardium of the heart. It is present in all mammals, including humans...
  
  

Sinusitis

If one or more of the paired paranasal sinuses or air cavities becomes inflamed, it leads to an infection called sinusitis

Sinusitis

Sinusitis is inflammation of the paranasal sinuses, which may be due to infection, allergy, or autoimmune issues. Most cases are due to a viral infection and resolve over the course of 10 days...

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

• Ethmoid sinus cavities which are located between the eyes.
• Frontal sinus cavities which can be found above the eyes (more in the forehead region).
• Maxillary sinus cavities are located on either side of the nostrils (cheekbone areas).
• Sphenoid sinuses that are located behind the eyes and lie in the deeper recesses of the skull.

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 spenoiditis refers to an infection in the sphenoid sinus cavity/ies.

The Reason behind Sinus Cavities

The presence of sinus cavities within the cranial bone (skull) is essential for the following reasons:

• Sinus cavities allow for voice resonance (WebMD)
• They help filter and add moisture to any air that is inhaled through the nasal passages. On top of filtering and adding moisture to the air we inhale, they also help in the removal of unwanted particles from the sinus cavities (SinusWars)
• Sinus Cavities provide a means to lighten the overall weight of the skull.

Classification of a Sinus Infection (Sinusitis)

Sinusitis (a sinus infection) can be acute, chronic or recurrent.

• Acute Sinusitis: 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 (SinusWars), a runny nose as well as sinus pressure and pain in the affected areas.

• Chronic Sinusitis: 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 mucus 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. Headaches may also be felt with chronic sinusitis.

• Recurrent Sinusitis: This type of sinus infection is intermittent; a person usually experiences this type of infection numerous times throughout a year with period of complete relief being experienced for weeks or months in-between.

Causes of Sinus Infections

A sinus infection can be caused by a variety of items. 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.
Another cause of sinus infections is a result of bacterial invasions within one or more of the sinus cavities. Any bacteria that enters the nasal passages and sinus cavities through the air that is inhaled gets 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.

Outlook on Sinusitis

Sinusitis or sinus infections usually clear up if treated early and appropriately. Aside from those who develop 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 (SinusWars)” 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.