Anatomy
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Head and Neck
A 35 year old patient presents to ED with palpitations. ECG demonstrates a regular narrow-complex tachycardia. He has no adverse features. You are going to attempt carotid sinus massage. At which of the following levels should you apply pressure:
Answer:
At the level of the superior margin of the thyroid cartilage (C4), the carotid arteries split into the external and internal carotid arteries. This bifurcation occurs in an anatomical area known as the carotid triangle. The carotid sinus is a dilated portion of the common carotid and internal carotid arteries containing baroreceptors. For carotid sinus massage the patient is placed in the supine position with the neck extended (i.e. raising the chin away from the chest) to maximise access to the carotid artery. The carotid sinus is usually located inferior to the angle of the mandible at the level of the thyroid cartilage near the arterial impulse. Pressure is applied to one carotid sinus for 5 to 10 seconds. Although pulsatile pressure via vigorous circular motion may be more effective, steady pressure is recommended because it may be more reproducible. If the expected response is not obtained, the procedure is repeated on the other side after a one- to two-minute delay.Neck Triangles
Anatomy / Head and Neck / Neck
Last Updated: 20th April 2020
The trapezius and sternocleidomastoid divide the neck into anterior and posterior triangles on each side.
Anterior Triangle
Each anterior triangle is bounded:
- medially by the median vertical line of the neck
- laterally by the anterior margin of the sternocleidomastoid muscle
- superiorly by the inferior margin of the mandible
The contents of the anterior triangle include muscles, nerves, arteries, veins and lymph nodes:
- Muscles
- Suprahyoid muscles
- Infrahyoid muscles
- Nerves
- Facial nerve
- Glossopharyngeal nerve
- Vagus nerve
- Accessory nerve
- Hypoglossal nerve
- Arteries
- Common carotid artery bifurcates into the external and internal carotid artery
- Veins
- Internal jugular vein
- Lymph nodes
Posterior Triangle
Each posterior triangle is bounded:
- anteriorly by the posterior margin of the sternocleidomastoid
- posteriorly by the anterior margin of the trapezius
- basally by the middle one-third of the clavicle
- apically by the occipital bone
![By Olek Remesz (wiki-pl: Orem, commons: Orem) Modified by user:madhero88 (original image File:Musculi coli base.svg) [CC BY 3.0], via Wikimedia Commons](https://mrcemsuccess.com/wp-content/uploads/2016/07/neck-triangles.png)
Anterior and Posterior Triangles of the Neck. (Image by Olek Remesz (wiki-pl: Orem, commons: Orem) Modified by user:madhero88 (original image File:Musculi coli base.svg) [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 |
