Anatomy
Head and Neck
Regarding the larynx, which of the following statements is INCORRECT:
Answer:
The cricoid cartilage is the most inferior of the laryngeal cartilages and completely encircles the airway. The thyroid cartilage articulates with the hyoid bone superiorly.Larynx Structure
Anatomy / Head and Neck / Larynx
Last Updated: 11th April 2019
The skeletal framework of the larynx is formed from three large unpaired cartilages (cricoid, thyroid, and epiglottis), three smaller paired cartilages (arytenoid, corniculate and cuneiform), joints, ligaments and membranes.
![Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://mrcemsuccess.com/wp-content/uploads/2016/07/larynx3.png)
Structure of the Larynx (Posterior View). (Image by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
Cartilages
The cricoid cartilage is the most inferior of the laryngeal cartilages and completely encircles the airway. The cricoid cartilage articulates with the base of the arytenoid cartilages superiorly (forming the cricoarytenoid joint) and the inferior horns of the thyroid cartilage posterolaterally (forming the cricothyroid joint).
The thyroid cartilage is the largest of the laryngeal cartilages. The thyroid cartilage articulates with the cricoid cartilage inferiorly and the hyoid bone superiorly.
The epiglottis is attached to the posterior aspect of the thyroid cartilage and projects posterosuperiorly. The upper margin of the epiglottis is behind the pharyngeal part of the tongue.
The two arytenoid cartilages articulate inferiorly with the cricoid cartilage and superiorly with the corniculate cartilages.
![Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://mrcemsuccess.com/wp-content/uploads/2016/07/larynx2.png)
Laryngeal Cartilages. (Image by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
Joints
The cricothyroid and cricoarytenoid joints are the main laryngeal joints allowing normal function.
Movements at the cricoarytenoid joints abduct and adduct the vocal ligaments.
Movements at the cricothyroid joint enable the thyroid cartilage to move forward and tilt downwards on the cricoid cartilage which effectively lengthens and puts tension on the vocal ligaments.
Cricothyroid Membrane
The cricothyroid membrane (conus elasticus) is attached to the arch of the cricoid cartilage and extends superiorly to end in a free upper margin within the space enclosed by the thyroid cartilage. This upper free margin attaches on each side anteriorly to the thyroid cartilage and posteriorly to the vocal processes of the arytenoid cartilage. The free margin between these two points is thickened to form the vocal ligament which is under the vocal fold of the larynx.
The cricothyroid membrane is also thickened anteriorly in the midline to form the distinct median cricothyroid ligament, which spans the distance between the arch of the cricoid cartilage and the thyroid cartilage up to the attachments of the vocal ligaments. In emergency situations, when the airway is blocked above the level of the vocal folds, the median cricothyroid ligament can be perforated to establish an airway (cricothyrotomy).
![By Olek Remesz (wiki-pl: Orem, commons: Orem) [CC BY-SA 2.5-2.0-1.0], via Wikimedia Commons](https://mrcemsuccess.com/wp-content/uploads/2016/07/larynx-1024x887.png)
Structure of the Larynx (Anterior View). (Image by Olek Remesz (wiki-pl: Orem, commons: Orem) [CC BY-SA 2.5-2.0-1.0], via Wikimedia Commons)
Laryngeal Inlet
![Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://mrcemsuccess.com/wp-content/uploads/2016/07/larynx4.png)
Laryngoscopic View of Interior of Larynx. (Image by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
Entrance to Larynx (Posterior View). (Image by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
Report A Problem
Is there something wrong with this question? Let us know and we’ll fix it as soon as possible.
Loading Form...
- 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 |
