Anatomy
Central Nervous System
Which of the following best describes the function of the cerebral aqueduct:
Answer:
The third ventricle is connected to the fourth ventricle by the cerebral aqueduct.Cerebral Ventricles
Anatomy / Central Nervous System
Last Updated: 11th April 2019
The ventricles are a set of communicating cavities within the brain that are responsible for the production, transport and removal of cerebrospinal fluid (CSF), which bathes the central nervous system.
In total there are four ventricles; right and left lateral ventricles, the third ventricle and the fourth ventricle. In cross sectional radiology, the midline cavities (third and fourth ventricles and the aqueduct) are symmetrical, but the lateral ventricles (the cavities of the hemispheres) are not.
Lateral Ventricles
The lateral ventricles are C-shaped cavities located within their respective hemispheres of the cerebrum. They are divided into a body, an anterior horn (projecting into the frontal lobe), an inferior horn (projecting into the temporal lobe) and a posterior horn (projecting into the occipital lobe). The lateral ventricles are connected to the third ventricle by the interventricular foramen (of Monro).
Third Ventricle
The third ventricle is a slit-like space in the sagittal plane, situated between the right and left thalamus and superior to the hypothalamus. The third ventricle is connected to the fourth ventricle by the cerebral aqueduct.
Fourth Ventricle
The fourth ventricle lies within the brainstem, at the junction between the pons and the medulla oblongata.
Ventricular System of the Brain. (Image by BruceBlaus (Own work) [CC BY 3.0 , via Wikimedia Commons)
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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 |
