5 Affected Muscles and Their Actions:
- Orbicularis oculi:
Action: Closes the eye - Frontalis:
Action: Raises the eyebrows - Zygomaticus major:
Action: Draws the corner of the mouth upward and outward (smiling) - Orbicularis oris:
Action: Closes and puckers the lips - Buccinator:
Action: Compresses the cheeks, assists in chewing
Mechanism of Muscle Weakness:
Bell's palsy is caused by inflammation of the facial nerve (cranial nerve VII). When the facial nerve becomes inflamed, it can swell and become compressed within the bony canal it passes through. This compression can disrupt the nerve's ability to send signals to the facial muscles, resulting in weakness or paralysis.
Other Symptoms of Bell's Palsy
1. Difficulty eating or drinking: Due to the weakness of the facial muscles, the patient may have trouble chewing or swallowing.
2. Dry eye: The inability to close the eye completely can cause dryness and irritation.
3. Loss of taste: The facial nerve also carries taste sensation from the front two-thirds of the tongue. Therefore, the patient may experience a loss of taste on the affected side.
4. Hyperacusis: This is a condition where sounds seem louder than normal due to the inability to control the facial muscles that regulate the ear canal.
5. Facial pain or discomfort: The inflammation of the facial nerve can sometimes cause pain or discomfort in the affected area.