MDS PREP
The most common site for CSF rhinorrhea
1. frontal bone
2. ethmoid bone
3. tegmen tympani
4. none
Anatomy
Answer: 2
Cerebrospinal fluid (CSF) rhinorrhea occurs when there is a leak of CSF through the nasal cavity, often due to a defect in the skull base. The ethmoid bone is the most common site for such leaks because of its thin structure and proximity to the nasal cavity.
A permanent tooth erupting in the mouth of an 11 years old child is most likely
1. maxillary lateral incisor
2. mandibular second bicuspid
3. maxillary third molar
4. rnandibular central incisor
Dental Anatomy
Answer: 2
A permanent tooth erupting in the mouth of an 11 years old child is most likely mandibular second bicuspid
Tongue is protruded by which of the following muscle
1. Hyoglossus
2. Palatoglossus
3. Myelohyoid
4. Genioglossus
Anatomy
Answer: 4
Tongue is protruded by Genioglossus
The nerve to masseter passes
1. deep to the medial pterygoid muscle
2. posterior to temporomandibular joint
3. superior to zygomatic arch to enter the muscle on its medial surface
4. through the mandibular notch to enter the muscle on its medial surface
Anatomy
Answer: 4
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.
The muscle least related to pterygomandibular raphe is
1. superior pharyngeal constrictor
2.medial pterygoid
3. lateral pterygoid
4.buccinator
Anatomy
Answer: 3
The muscle least related to the pterygomandibular raphe is the lateral
pterygoid. The pterygomandibular raphe primarily connects the superior
pharyngeal constrictor and the buccinator muscles, while the medial and lateral
pterygoid muscles are involved in the movement of the jaw but do not have a
direct attachment to the raphe. Here’s a breakdown of the relationships:
Muscle Relationships to the Pterygomandibular Raphe
Superior Pharyngeal Constrictor:
Attaches to the posterior margin of the pterygomandibular raphe.
Plays a role in swallowing and constricting the pharynx.
Medial Pterygoid:
While not directly attached, it is located near the pterygomandibular
raphe and contributes to jaw movement.
Lateral Pterygoid:
Least related to the pterygomandibular raphe.
Primarily involved in moving the jaw forward and side to side, with
no direct attachment to the raphe.
Buccinator:
Attaches to the anterior margin of the pterygomandibular raphe.
Important for chewing and keeping food between the teeth.
In an average child the mixed dentition period is from
1. 10 years to 25 years
2. 4 yrs to 12 yrs
3. 8 yrs to 17 yrs
4. 6 yrs to 13 years
Dental Anatomy
Answer: 4
In an average child the mixed dentition period is from 6 yrs to 13 y
How many root canals does a madibular first molar normally have
1. 2
2. 3
3. 4
4. 5
Dental Anatomy
Answer: 2
madibular first molar normally have 3 root canals
The average overall length of the permanent maxillary central incisor is
1. 14.5mm
2. 18.0 mm
3. 22.5 mm
4. 30 mm
Dental Anatomy
Answer: 3
The average overall length of the permanent maxillary central incisor is 22.5 mm