Anatomy
Head and Neck
The orbicularis oris muscle is innervated by which of the following nerves:
Answer:
The orbicularis oris muscle is innervated by the facial nerve.Facial Muscles
Anatomy / Head and Neck / Face
Last Updated: 11th April 2019
The facial muscles act as muscles of facial expression, and as sphincters and dilators of the orifices of the face.
The facial muscles are all innervated by the facial nerve (CN VII).
Table: Function of the Facial Muscles
| Muscle | Function |
|---|---|
| Orbicularis oculi | Closes eyelids gentle and forcefully |
| Occipitofrontalis | Raises eyebrows and wrinkles forehead |
| Orbicularis oris | Closes lips and protrudes lips as in whistling |
| Buccinator | Presses cheek against teeth, aids in forceful expulsion of air from distended cheeks |
Orbicularis Oculi
The orbicularis oculi is a large muscle located over the frontal and zygomatic bones and is responsible for closure of the eyelids, both gently (palpebral part) and forcefully as in screwing the eyes up (orbital part).
Occipitofrontalis
The occipitofrontalis is responsible for wrinkling the forehead, raising the eyebrows and drawing the scalp backwards. It has two bellies, the occipital belly originating from the superior nuchal line of the occipital bone and mastoid process of the temporal bone, and the frontal belly originating from the skin of the eyebrows; both heads insert onto the epicranial aponeurosis.
Orbicularis Oris
The orbicularis oris is a complex muscle consisting of fibres that completely encircle the mouth, responsible for closing the lips and protruding the lips (as in whistling).
Buccinator
The buccinator originates from the posterior parts of the maxilla and mandible, deep to the other facial muscles. Its muscle fibres run forwards to blend with those of the orbicularis oris muscle and to insert into the modiolus, which is a small button-shaped nodule of connective tissue at the interface between the muscles of the lips and cheeks on each side. The buccinator is responsible for pressing the cheek against the teeth which helps keeps the cheek taut and aids in mastication by preventing food from accumulating between the teeth and cheek. The muscle also assists in the forceful expulsion of air from the cheeks by compressing the distended cheeks.
![By OpenStax [CC BY 4.0], via Wikimedia Commons](https://primary-cdn.frcemsuccess.com/wp-content/uploads/2016/07/muscles-of-facial-expression2-1024x621.jpg)
Muscles of the Face. (Image by OpenStax [CC BY 4.0], 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 |
