a. Chief Sensory Nucleus
b. Nucleus of Spinal Tract of Trigeminal Nerve
c. Nucleus of Mesencephalic Tract of Spinal Nerve
d. Dorsal Vagal Nucleus
Answer
c. Nucleus of Mesencephalic Tract of Spinal Nerve
Reference
Gray’s Anatomy 38th Edition Page 1237
QTDF
Gray
Gray
Quality
Thinker
Status
New
Discussion
Ä The
trigeminal, the largest cranial nerve, is the sensory supply to the
face, the greater part of the scalp, the teeth, the oral and nasal
cavities, the dura mater and the cerebral blood vessels. It gives the
motor supply to the masticatory muscles, and the anterior belly of
digastric and mylohyoid, and contains proprioceptive nerve fibres from
the masticatory and probably the extraocular and facial muscles
Expanation
a. Chief Sensory Nucleus is concerned with Tactile sensation.
b. Nucleus of Spinal Tract of Trigeminal Nerve is concerned with Pain and Temperature Sensation.
c. Nucleus of Mesencephalic Tract of Spinal Nerve is concerned with proprioception
d. Dorsal
Vagal Nucleus is a General Visceral Efferent Nucleus which innervates
glands of the head, the sphincter pupillae and ciliary muscles, and the
thoracic and abdominal viscera.
Comments
Ä Masseter is supplied by a branch of the anterior trunk of the mandibular nerve.
Tips
Other
ascending fibres enter the mesencephalic nucleus, a column of unipolar
cells, whose peripheral branches may convey proprioceptive impulses from
the masticatory muscles; it is also stated that similar impulses reach
it from the teeth and from the facial and ocular muscles. Its neurons
are unique in being the only primary sensory neurons with somata in the
CNS. It is the relay for the only supraspinal monosynaptic reflex,
namely the 'jaw-jerk'. If, however, the primary proprioceptive neurons
of extraocular muscles are in fact situated in their motor nerves or in
the trigeminal ganglion, some mesencephalic trigeminal neurons may be
'secondary' in status. Small multipolar cells, possibly interneurons,
occur near the unipolar neurons.
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