Chewing muscles helps in chewing are temporalis, medial pterygoid, lateral pterygoid, and masseter g. Swallowing muscles help in swallowing are suprahyoid and muscles (pharynx is pulled upward and forward) the stylopharyngeus, salpinopharyngeus, palatopharyngeus and thyroid muscles h. Nodding the head “yes i. Shaking the head “no” j. Tilting the head to look up toward the sky k. Tilt the head to the side (bring the ear to the shoulder) 3. Bell’s Palsy results from damage to the facial nerves. If innervation to the facial nerves ceased, which muscles would be affected? Which actions of the face would be affected?
The Correct Answer and Explanation is:
Correct Answer
If innervation from the facial nerve (Cranial Nerve VII) ceased due to a condition like Bell’s Palsy, the muscles of facial expression would be affected. This would impact actions such as smiling, frowning, raising the eyebrows, closing the eye, wrinkling the nose, and pursing the lips.
Explanation
Bell’s Palsy is a condition characterized by the acute paralysis or significant weakness of the muscles on one side of the face. This occurs due to inflammation or damage to the facial nerve (Cranial Nerve VII), which is the primary motor nerve responsible for innervating the muscles of facial expression. It is crucial to distinguish these from the muscles of mastication (chewing), such as the masseter and temporalis, which are controlled by the trigeminal nerve (Cranial Nerve V) and would remain unaffected.
The muscles affected by facial nerve paralysis are numerous and control nearly all movements of the face. Key muscles include:
- Frontalis: Responsible for raising the eyebrows and wrinkling the forehead.
- Orbicularis Oculi: A circular muscle surrounding the eye that is essential for closing the eyelid.
- Zygomaticus Major and Minor: The primary “smiling” muscles, which elevate the corners of the mouth.
- Orbicularis Oris: A circular muscle around the mouth used for pursing the lips, whistling, and closing the mouth.
- Buccinator: The cheek muscle that keeps food between the teeth during chewing and helps with actions like blowing.
- Platysma: A broad sheet of muscle in the neck that tenses the skin.
Consequently, the loss of innervation to these muscles leads to a range of debilitating functional deficits on the affected side. An individual would be unable to raise their eyebrow, wrinkle their forehead, or close their eye completely, which can lead to eye dryness and damage. The corner of the mouth would droop, resulting in an asymmetrical smile and difficulty retaining food or liquids in the mouth, often causing drooling. The inability to purse the lips affects actions like drinking from a straw or whistling. The face often appears flat and expressionless on the paralyzed side.thumb_upthumb_down
