33003

The nerve to masseter passes through the mandibular notch to enter the muscle on its medial surface

The nerve to the masseter muscle is the masseteric nerve, which is a branch of the mandibular nerve (CN V3), the largest division of the trigeminal nerve (cranial nerve V). The masseter muscle is one of the muscles of mastication that lifts the lower jaw, contributing to the action of biting and chewing.

The masseteric nerve originates from the anterior division of the mandibular nerve and typically passes:

1. Deep to the medial pterygoid muscle: The medial pterygoid muscle is located in the infratemporal fossa, which is the space deep to the zygomatic arch and medial to the temporomandibular joint (TMJ). The masseteric nerve runs in a deep position relative to the medial pterygoid muscle as it travels towards the masseter muscle. This muscle is involved in the side-to-side movement of the jaw, known as lateral excursion.

2. Posterior to the temporomandibular joint: The TMJ is the articulation between the mandible and the temporal bone of the skull. It is a synovial joint that allows for the hinge movement of the jaw, such as opening and closing the mouth. The masseteric nerve passes behind the TMJ to reach the masseter muscle. This nerve does not actually cross the joint itself but runs in a position posterior to it.

3. Superior to the zygomatic arch: The zygomatic arch is the bony structure that extends from the zygomatic process of the temporal bone to the zygomatic bone of the skull. It forms the prominence of the cheek. The masseteric nerve runs superior to the zygomatic arch to reach the masseter muscle. The arch serves as a landmark for the nerve's course, and the nerve typically does not pass through the arch itself.

4. Through the mandibular notch: This statement is not entirely correct. The masseteric nerve does not pass through the mandibular notch, which is a depression on the medial surface of the ramus of the mandible, but rather it passes above (superior to) the notch. The mandibular notch is the location where the masseteric nerve and the other branches of the mandibular nerve leave the infratemporal fossa and enter the submandibular space to innervate the muscles of mastication, including the masseter. The nerve then runs along the lateral surface of the lateral pterygoid plate and enters the deep surface of the masseter muscle.

In summary, the masseteric nerve passes deep to the medial pterygoid muscle, posterior to the TMJ, and superior to the zygomatic arch. It does not pass through the mandibular notch; instead, it runs superior to it before reaching the masseter muscle. The anatomical pathway of this nerve allows it to effectively innervate the masseter muscle, which is crucial for the function of the muscle in mastication.

22615

Retromolar area should be covered in CD or distal extension RPD in order to derive support from the underlying bone which is resistant to resorption.

75651

This statement is incorrect - sodium perborate can be mixed with water or saline, though hydrogen peroxide is more commonly used. The other statements about walking bleach technique are true.

41176

X-ray films are insensitive to yellow and red light.

15833

Hemiballismus is characterized by violent, flailing movements of the limbs, typically caused by a lesion in the subthalamic nucleus. This damage disrupts the regulatory inhibitory signals to the basal ganglia.

98253

Ormocers have several advantages, including low shrinkage, excellent biocompatibility, and superior resistance to masticatory forces. These properties make them suitable for restorations that resemble natural teeth.

64200

A black line on the gingiva which follows the contour of the margin is due to mercury.

48008

Osmotic fragility is increased in hereditary spherocytosis due to the abnormal shape and membrane stability of red blood cells.

23581

Tubulo-glomerular feedback (TGF) and glomerulo-tubular feedback (GTF) are both important in regulating sodium reabsorption in the kidney tubules. TGF involves the macula densa sensing the sodium chloride concentration in the tubular fluid and adjusting the glomerular filtration rate accordingly, while GTF is the adjustment of tubular sodium reabsorption in response to changes in glomerular filtration rate.

58521

The first sensation of bladder filling occurs at approximately 150 ml, signaling the need to void.