Anatomy
Head and Neck
Regarding the paranasal sinuses, which of the following statements is INCORRECT:
Answer:
The sphenoidal sinuses open onto the sphenoethmoidal recess of the nasal cavity.Paranasal Sinuses
Anatomy / Head and Neck / Nose and Paranasal Region
Last Updated: 11th April 2019
There are four paired paranasal air sinuses - the ethmoidal cells and the sphenoidal, maxillary and frontal sinuses - named according to the bone in which the sinus is found. The paranasal sinuses develop as outgrowths from the nasal cavities and erode into the surrounding bones.
Location
All of the paranasal sinuses are lined by respiratory mucosa, open into the nasal cavities and are innervated by branches of the trigeminal nerve.
- The frontal sinuses are the most superior of the sinuses and drain onto the middle meatus of the lateral wall.
- The maxillary sinuses are the largest of the paranasal sinuses and drain onto the middle meatus of the lateral wall.
- The ethmoidal cells drain into the superior or middle meatus.
- The sphenoidal sinuses open into the sphenoethmoidal recess of the nasal cavity.
![By OpenStax College [CC BY 3.0], via Wikimedia Commons](https://primary-cdn.frcemsuccess.com/wp-content/uploads/2016/07/724_Paranasal_Sinuses.jpg)
Paranasal Sinuses. (Image by OpenStax College [CC BY 3.0], via Wikimedia Commons)
Developmental Staging
The maxillary sinus is the first sinus to develop and is filled with fluid at birth and undergoes two phases of growth during years 0 - 3 and again at 6 - 12 years.
The frontal sinus is the last sinus to pneumatise; it is formed by the upward movement of anterior ethmoid cells after age 2, growth increases at age 6 and continues until late teenage years.
The sphenoid sinus starts to pneumatise at around 2 years of age and reaches its full size by the late teenage years.
The ethmoid sinuses are present at birth and develop rapidly, continuing to grow and pneumatise until the age of 12.
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
