Anatomy
Head and Neck
Regarding the blood supply of the scalp, which of the following statements is INCORRECT:
Answer:
The scalp has an extremely rich blood supply which it receives from branches of the external carotid artery and the internal carotid artery (via its ophthalmic branch). Veins draining the scalp follow the arterial pattern and the posterior auricular vein communicates with the sigmoid sinus via the mastoid emissary vein; in this way infections of the ear or mastoid can spread intracranially.Blood Supply of Scalp
Anatomy / Head and Neck / Scalp
Last Updated: 11th April 2019
Arterial Supply
The arterial supply of the scalp is from branches of the external carotid artery or the ophthalmic artery (branch of the internal carotid artery) which form a rich anastomosing network.
The scalp has an extremely rich blood supply, so lacerations of the scalp tend to bleed profusely. Scalp bleeding is predominantly arterial, firstly because in the erect position venous pressure is extremely low and secondly because the vessels do not retract and close when lacerated because the dense connective tissue in which they are found holds them open.
Arterial Supply of the Scalp. (Image by Internet Archive Book Images [No restrictions], via Wikimedia Commons)
Venous Drainage
Veins draining the scalp follow the arterial pattern. The posterior auricular vein drains the area of the scalp posterior to the ear. The sigmoid sinus is connected with the exterior by the mastoid emissary vein which joins the posterior auricular vein. In this way infections of the ear or mastoid may spread intracranially.
Venous Drainage of the Scalp. (Image by Henry Vandyke Carter [Public domain], 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 |
