MDS PREP
If a 4th root canal is present in a maxillary 1st molar, it will likely be located in which of the following roots?
1) Mesiolingual
2) Mesiobuccal
3) Distolingual
4) Distofacial
Dental Anatomy Answer: 2
Well over 50% of maxillary 1st molars have two canals in the mesiobuccal root. Some authors cite the number as high as 90%.
There are usually 3 roots and 4 canals in a maxillary 1st molar.
The fourth canal, the mesiolingual canal, is also referred to as: the accessory mesiobuccal canal, mesiocentric, mesiopalatal canal or MB2.
It is usually tough to find MB2 through clinical inspection and it is not obvious on a radiograph. A dentist should expect it is present before beginning a root canal on the first maxillary molar.
The palatine bone articulates with all of the following except
1.sphenoid
2. ethmoid
3. zygomatic
4. vomer
Anatomy Answer: 2
The palatine bone articulates with all of the following except a.sphenoid b. ethmoid c. zygomatic d. maxilla
The auriculotemporal nerve carries some fibers which are .
1. motor to masseter muscle
2. secretory to parotid gland
3. afferent from the carotid body
4. sensory to lining of tympanic cavity
Anatomy
Answer: 4
The auriculotemporal nerve carries some fibers which are sensory to lining of tympanic cavity
The largest resting membrane potential is observed in
1. skeletal muscle
2. smooth muscle
3. equal in both
4. -120 mv in resting smooth muscle
Anatomy
Answer: 1
The largest resting membrane potential is observed in skeletal muscle.
Resting membrane potential (RMP) is the electrical potential difference across
the membrane of a cell when it is not undergoing an action potential or a
similar excitation. It is crucial for the functioning of excitable cells, such
as neurons and muscle cells, as it is the basis for the transmission of
electrical signals. The RMP is primarily determined by the concentration
gradients of ions across the cell membrane and the permeability of the membrane
to those ions.
In skeletal muscle cells, the resting membrane potential is typically around -90
millivolts (mV). This relatively high negative value is due to the higher
concentration of potassium ions (K+) inside the cell compared to the outside,
and the lower concentration of sodium ions (Na+) inside the cell compared to the
outside. The cell membrane is more permeable to K+ than to Na+ at rest, which
allows K+ to leak out through potassium channels and sets up the resting
membrane potential.
Smooth muscle cells, on the other hand, have a resting membrane potential that
is generally less negative than that of skeletal muscle cells. The typical RMP
in smooth muscle cells ranges from -40 to -70 mV, which is closer to the
threshold for depolarization and makes these cells more responsive to stimuli
that could cause contraction. The difference in RMP between smooth and skeletal
muscle is due to variations in ion channel expression and the activity of ion
pumps, which control the ionic composition of the intracellular and
extracellular environments.
To summarize:
1. Skeletal muscle cells have a resting membrane potential of approximately -90
mV.
2. Smooth muscle cells have a resting membrane potential that is generally more
positive than skeletal muscle cells, typically ranging from -40 to -70 mV.
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
The muscle assisting in mastication but not supplied by mandibular nerve is
1.masseter 2.buccinator
3.mylohyoid 4.tensor veli palatine
Anatomy
Answer: 4
The muscle assisting in mastication but not supplied by mandibular nerve is tensor veli palatine
The parasympathetic fibers to pterygopalatine ganglion come from
1. maxillary nerve
2. mandibular nerve
3. deep petrosal nerve
4. greater petrosal nerve
Anatomy
Answer: 4
The parasympathetic fibers to pterygopalatine ganglion come from greater petrosal nerve
A mandibular primate space is usually found in the primary dentition between
1. first and second molars
2. central and lateral incisors
3. lateral incisor and canine
4. canine and first molar
Dental Anatomy
Answer: 4
A mandibular primate space is usually found in the primary dentition between canine and first molar