The substantia nigra is located in which of the following regions of the brain:
The brainstem comprises the midbrain, the pons and the medulla. It extends from the tentorial aperture to the level of C1. The medulla passes out of the cranial cavity via the foramen magnum and becomes the spinal cord as C1 roots emerge. The cells of the brainstem are predominantly clumped into nuclei.
The midbrain lies predominantly within the posterior cranial fossa. The aperture in the tentorium cerebelli lies on its dorsal surface.
The midbrain receives its blood supply from the posterior cerebral and superior cerebellar arteries (ex-basilar).
Dopaminergic cells sit within the midbrain within the substantia nigra; loss of dopaminergic neurons is the basis of Parkinson’s disease.
The pons receives its blood supply from pontine branches of the basilar artery. The pons houses nuclei of the trigeminal nerve, the abducens nerve, the facial nerve and the vestibulocochlear nerve. This knowledge allows prediction of the clinical effects of a pontine haemorrhage:
The medulla oblongata is the upward continuation of the spinal cord. It receives its blood supply from the posterior inferior cerebellar arteries and branches of the vertebral and basilar arteries.
Lateral medullary syndrome results from occlusion of the intracranial portion of the vertebral artery (most commonly) or of the posterior inferior cerebellar artery (PICA). The resultant structures affected are the:
Medial medullary syndrome results from occlusion of small perforating branches from the vertebral or proximal basilar artery such as the anterior spinal artery. The resultant structures affected are the:
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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 |