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Free STEP1 Exam Braindumps (page: 31)

Page 30 of 213
PDF with 845 Questions

Corneal abrasions produce eye pain and excessive lacrimation. Which cranial nerve innervates the cornea?

  1. fifth (trigeminal)
  2. fourth (trochlea)
  3. second (optic)
  4. sixth (abducens)
  5. third (oculomotor)

Answer(s): A

Explanation:

The ophthalmic division of cranial nerve V (trigeminal) provides general sensory innervations to the eyeball, including the cornea. Cranial nerve II (optic, choice C) carries the visual function of the retina of the eye.
Cranial nerves IV (trochlea, choice B) and VI (abducens, choice D) innervate the superior oblique and lateral rectus muscles, respectively. The innervation of all other extraocular muscles is performed by cranial nerve III (oculomotor, choice E).



The anterior two-thirds of the tongue differ from the posterior one-third of the tongue by its special visceral afferent (SVA; taste) innervation. The perikarya of neurons providing the sensation of taste in the anterior two-thirds of the tongue are found in which of the following?

  1. geniculate ganglion
  2. otic ganglion
  3. pterygopalatine (sphenopalatine) ganglion
  4. submandibular ganglion
  5. trigeminal (gasserian) ganglion

Answer(s): A

Explanation:

SVA (taste) fibers have their perikarya in the geniculate ganglion located in the petrous portion of the temporal bone. These neurons project their axons to the gustatory nucleus in the brainstem. The otic ganglion (choice B) receives preganglionic parasympathetic fibers originating from the inferior salivatory nucleus by way of the ninth cranial (glossopharyngeal) nerve. In turn, it projects postganglionic parasympathetic fibers to the parotid salivary gland. The pterygopalatine (sphenopalatine) ganglion (choice C) is also a parasympathetic ganglion, which receives preganglionic fibers from the superior salivatory nucleus by way of the ninth cranial (glossopharyngeal) nerve. In turn, it sends postganglionic parasympathetic fibers to the lacrimal gland and mucous glands in the nose. The submandibular ganglion (choice D) receives preganglionic parasympathetic fibers from the chorda tympani, a branch of the nervus intermedius which runs with the seventh cranial nerve. It innervates the submandibular and sublingual salivary glands. The trigeminal (gasserian) ganglion (choice E) receives sensations from the face, mucosa, cornea, teeth, gum, palate, and the anterior two- thirds of the tongue. It sends projections to the principal sensory and spinal trigeminal nuclei in the brainstem.



You are concerned that your patient may have compromised function of the mitral valve. The sound of the mitral valve is best heard at which of the following locations?

  1. at the apex in the left fifth intercostals space in the midclavicular line
  2. at the xiphisternal junction
  3. in the fifth intercostal space to the right of the sternum
  4. in the second intercostal space to the left of the sternum
  5. in the second intercostal space to the right of the sternum

Answer(s): A

Explanation:

There is only one point of the heart that can be directly identified on the precordium: the apex. A cardiac impulse may be visible at the apex, and palpation over it confirms the presence of the apex beat. The apex is located in the left fifth intercostal space just medial to the midclavicular line, and is the point where the mitral valve is best heard. None of the heart sounds are best heard at the xiphisternal junction (choice B).
The tricuspid valve is best heard in the fifth intercostal space to the right of the sternum (choice C). The pulmonary valve is best heard in the second intercostal space to the left of the sternum (choice D). The aortic valve is best heard in the second intercostals space to the right of the sternum (choice E).



A 14-year-old female patient complains of a severe sore throat and you use a cotton swab to obtain specimens for a culture. As you lightly touch the pharyngeal wall with the cotton swab, the patient gags. What is the location of neuronal cell bodies innervating pharyngeal constrictor muscles involved in the gag reflex?

  1. abducens nucleus
  2. ambiguus nucleus
  3. dorsal motor nucleus of the vagus
  4. facial nucleus
  5. hypoglossal nucleus

Answer(s): B

Explanation:

Motor innervation of the pharyngeal constrictor muscles is derived from the ambiguous nucleus in the medulla oblongata. These motor fibers reach the constrictor muscles via the vagus nerve. The abducens nucleus (choice A) provides motor innervation to the lateral rectus muscle of the eye. The dorsal motor nucleus of the vagus (choice C) provides preganglionic parasympathetic innervation for the organs of the thorax and abdomen. The facial nucleus (choice D) sends motor innervation to the muscles of facial expression and the stapedius. The hypoglossal nucleus (choice E) innervates the muscles of the tongue.






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