organ systems III: cranial nerves

this lecture covered the pathways, functional components, target structures, CNS connections of each of the cranial nerves.
















questions
embryology...
1. all but one of the cranial nerves exit from...
2. after neurulation, the neural tube differentiates into...
3. what separates the alar and basal plates?
4. the 4th ventricle pushes both plates...

cranial nerve classification...
5. GSA
6. GVA
7. SSA
8. SVA
9. GSE
10. GVE
11. SVE

12. describe the arrangement of nuclei for cranial nerves.
13. what are two examples of how a given nucleus can project to or receive from several cranial nerves?
14. describe the orientation of the nuclei with respect to the 4th ventricle.

cranial nerves I, II, III, IV, VI...
15. what is the functional component of the olfactory nerve?
16. where is the primary olfactory cortex?
17. which brain areas are responsible for conscious perception of smell?
18. which brain areas are responsible for association between smell and emotions?
19. describe the course of the optic nerve.
20. what is the functional component of the optic nerve?
21. describe the course of the oculomotor nerve.
22. what are the functional components to the oculomotor nerve?
23. what is the course of the trochlear nerve?
24. what is the functional component of the trochlear nerve?
25. what is the course of the abducens nerve?
26. what is the functional component of the abducens nerve?
27. what are two tests that measure the function of the oculomotor nerve?

trigeminal nerve...
28. what are the courses for the three components of the trigeminal nerve?
29. what are the target structures for the three branches of the trigeminal nerve?
30. where do sensory and motor nulcei from the trigeminal nerve project to?
31. what are the functional components to the trigeminal nerve?
32. what are some tests that measure the function of the trigeminal nerve?

facial nerve...
33. what is the course of the facial nerve?
34. the chorda tympani passes along...
35. what are the visceral nerves of the chorda tympani?
36. what are the functional components to the facial nerve?
37. describe the taste pathway of the facial nerve.
38. what are some tests to gauge proper functioning of the facial nerve?

vestibulocochlear...
39. describe the course of the vestibulocochlear nerve.
40. what are the functional components of the vestibulocochlear nerve?
41. describe the pathway from the auditory system to the CNS via the vestibulocochlear nerve.
42. describe the pathway from the vestibular system to the CNS via the vestibulocochlear nerve.
43. what are the vestibulocochlear nerve tests?

glossopharyngeal, vagus...
44. what is the course of the glossopharyngeal nerve?
45. what is the test for the function of the glossopharyngeal nerve?
46. what are the functional components to the glossopharyngeal nerve?
47. what is the course of the vagus nerve?
48. what are the functional components of the vagus nerve?
49. what are the CNS components/connections from the vagus nerve?
50. what are the tests for vagal functioning?

accessory, hypoglossal...
51. what is the course of the accessory nerve?
52. what is the functional component of the accessory nerve?
53. what is the test for accessory nerve functioning?
54. what is the course of the hypoglossal nerve?
55. what is the functional component of the hypoglossal nerve?
56. what is a test that indicates proper hypoglossal nerve functioning?

answers
1. the ventral side of the brainstem.
2. the dorsal alar and the ventral basal plate.
3. the sulcus limitans.
4. ventrally.

5. general somatic afferent: muscle, connective tissue, skin receptors.
6. general visceral afferent: organs and blood vessel receptors.
7. special somatic afferents: for audition and vision.
8. special visceral afferents: for olfaction and taste.
9. general somatic efferents: control of skeletal muscle.
10. general visceral efferents: smooth and cardiac muscle.
11. special visceral efferents: muscles of face, mastication, larynx, pharynx.

12. nuclei for cranial nerves are arranged in longitudinal columns that are functionally distinct (fit one of the classifications above) and can be connected with multiple cranial nerves.
13. SVA (solitary nucleus) receives from VII, IX, X. SVE (nucleus ambiguus) projects out on IX and X.
14. most of the nuclei line up on the floor of the 4th ventricle except for the SVE and the GSA which migrate ventrally.

15. olfactory bulb for smell.
16. medial temporal lobe.
17. thalamus and cortex.
18. amygdala and entorhinal cortex.
19. optic nerve projects information from retina to thalamus, which projects to visual and association cortices.
20. the lateral geniculate nucleus (SSA)
21. from the midbrain to the cavernous sinus, through the superior orbital fissure to the extraocular muscles.
22. oculomotor nucleus (GSE) involved in external eye movements. edinger westfal nucleus (GVE) involved in parasympathetic constriction of pupil in response to incoming light.
23. posterior midbrain, cavernous sinus, superior orbital fissure.
24. trochlear nucleus (GSE)-- innervates superior oblique.
25. pons, cavernous sinus, superior orbital fissure.
26. abducens nucleus (GSE)-- innervates lateral rectus.
27. equal ocular motion test measures the somatic aspect and the pupils equal round reactive to light test measures the parasympathetic function of the oculomotor nerve.

28. V1: pons, cavernous sinus, SOF. V2: pons, cavernous sinus, foramen rotundum. V3: pons, foramen ovale.
29. V1: orbital cavity, upper face, eyes sensory innervation. V2: palate, nasal cavity, middle face innervation. V3: oral cavity sensory innervation and mastication muscles motor innervation.
30. thalamus (and from there to face area in primary somatosensory cortex) for sensory, and muscles for motor.
31. the primary sensory nuclei (GSA) which receives discriminative touch, the mesencephalic (GSA) which receives proprioceptive input, the spinal trigeminal tract (GSA), which receives pain and temperature input, and the motor nucleus (SVE) which innervates
32. somatosensory tests (sharp or dull sensations), clenching jaw (to test masticating muscle function), and the corneal blink test (irritation causes eye closure via V and VII reflex loop).

33. pons, internal acoustic meatus, stylomastoid foramen.
34. the interior of the tympanic membrane.
35. parasympathetic branches which innervate the submandibular and sublingual glands. special visceral afferent branches receive visceral input from the anterio 2/3 of the tongue via the lingual nerve.
36. the motor nucleus (SVE) which innervates the muscles of facial expression and the stapedius, the salivatory nucleus (GVE) which innervates nasal, lacrimal, and palatine glands via the pterygopalatine ganglion and the submandibular and sublingual glands via the submandibular ganglion. also, the solitary nucleus (SVA) receives taste input from the anterior 2/3 of the tongue via the lingual nerve, and the spinal trigeminal nucleus (GSA) which receives somatosensory input from the ear.
37. solitary nucleus (SVA) receives visceral sensory information from tongue from VII, IX, X, which then projects to the VPM nucleus of the thalamus, and then to the cortex in the insula.
38. facial muscle tests: various facial expressions.

39. vestibular apparatus / cochlea through the internal auditory meatus to the nuclei in the medulla.
40. cochlear and vestibular nuclei (SSA) for hearing and balance.
41. cochlear nuclei in medulla to superior olive to inferior colliculus to primary auditory cortex and association cortices.
42. vestibular nuclei, cerebellum, III, IV, VI, spinal cord.
43. conductive vs. sensorineural defect tests; humming/tuning forks

44. medulla, jugular foramen, descends neck.
45. the gag reflex.
46. the nucleus ambiguus (SVE), inferior salivatory nucleus (GVE), solitary nucleus (SVA and GVA), spinal trigeminal nucleus (GSA).
47. medulla, jugular foramen, down into pharynx/larynx/lungs/GI/kidney, etc.
48. nucleus ambiguus (SVE) for motor innervation of pharynx/larynx, dorsal vagal nucleus (GVE) for parasympathetic innervation of lung, GI, kidney, solitary nucleus (SVA) for taste from epiglottis/palate and (GVA) afferents from viscera and blood vessels, and spinal trigeminal nucleus (GSA) for sensory from ear.
49. GVA from solitary nucleus relayed to hypothalamus, reticular formation, limbic system for homeostatic organ regulation, memory, emotion. SVA from solitary nucleus projected to thalamus and gustatory cortex. GSA from spinal trigeminal nucleus projects somatosensory input from ear to thalamus and somatosensory cortex.
50. raising the tongue to the roof of the mouth, deviated palate, and gag reflex.

51. medulla, jugular foramen, into neck.
52. accessory nucleus (SVE) for motor innervation of SCM and trapezius.
53. shrugging the shoulders, resisting pressure on forehead, chin
54. medulla, hypoglossal canal, oral cavity.
55. hypoglossal nucleus (GSE) for motor innervation of tongue.
56. deviation of tongue.