2. The physical world is separated by a dimensional gap to the human perception. Humans are “blind” in the sense that they are not capable of conceptualizing the environment around them without a connecting factor to bridge this gap. This connecting factors are the sensory instruments of humans in the form of human organs that capture stimuli from the outside becoming what we call sensations. Through sensations humans are able to live and appreciate and coin the term “world”. Responsible for this phenomenon are the embedded features of the human body that are capable of making connections of the sensation-perception process.

3. Objectives:

4. Predict the effects of a damaged nerve to the life of a human person.

5. Share the appreciation of the significance of the 12 cranial nerve in relation to learning.

6. Construct a schematic diagram on the process of human environment connection starting from the environmental stimuli to the central nervous system.

7. Suggested Materials:

8. Do an internet search and readings about the 12 cranial nerves.

9. Download videos form the internet to facilitate understanding on the nature and functions of the 12 cranial nerves.

10. Read online journals and case studies about the 12 cranial nerve affectation.

12. Direction:

13. Read and understand the contents of this module.

14. Answer the given exercises.

16. Cranial Nerve No. I (Olfactory)

17. The Olfactory Nerve is a sensory nerve responsible for olfaction or simply the sense of smell which occurs in response to airborne molecules called odorants that enter the nasal cavity.

18. The Olfactory nerve is one pair of the nerves. The area in which olfactory nerve arise is situated in the most superior part of the mucous membrane that covers the superior nasal concha. The Olfactory sensory endings are modified epithelial cells and the least specialized of the special senses. The Olfactory nerves connect with the olfactory bulb and the olfactory tract which are components of the part of the brain associated with the sense of smell.

19. Functioning

20. Normal

21. A person with a normally functioning olfactory nerve is able to distinguish and identify the odors with each nostril.

22. Disorder

23. Anosmia is the loss of sense of smell. Total loss of sense of smell may be caused by trauma to the cribriform plate, sinusitis, colds or heavy smoking. Unilateral anosmia (temporary or persistent) may be a result of intracranial neoplasm such as meningioma of the sphenoid compressing the olfactory nerve or bulb.

24. Cranial Nerve No. II (Optic)

25. The Optic nerve is a sensory nerve responsible for vision or the sense of sight. This includes.

26. Optic nerve is one pair of cranial nerves that transmit visual impulses. It consists mainly of coarse myelinated fibers that arise in the retinal ganglionic layer, , traverse the thalamus and connect with the visual cortex. It functions in the perception of light, shade and objects. The optic nerve fibers correspond to a tract of fibers within the brain.

27. Functioning

28. Snellen’s Chart Assessment for Distance Vision

29. Normal

30. The person who has a visual acquity of 20/20 is considered normal.

31. Disorder

32. Myopia (nearsightedness) the axial length of the eyeball is longer than normal, resulting in the image not being focused directly on the retina. This condition can be changed with corrective lenses.

33. Amblyopia is the permanent loss of visual acquity resulting from strabismus that has not been corrected in early childhood or certain medical conditions.

34. Rosenbaum Pocket Vision Screener

35. Normal

36. Until a person is in the late 30s to the late 40s, reading is generally possible at the distance of 14 inches

37. Disorder

38. A person in the age 30-40 who cannot read at 14 inches is considered presbyopic. Younger person may have difficulty in seeing up close because they have hyperopia or farsightedness.

39. The normal aging process causes the lens to harden, decreasing its ability to change shape and therefore focus on near objects.

40. Ishihara Plates for Color Vision

41. Normal

42. The person is able to identify all six Ishihara plates correctly has normal color vision.

43. Disorder

44. Color Blindness or Color Vision Defect is designated as red/green, blue/yellow or complete when the person sees only shades or gray. Defects can result from diseases from the optic nerve, macular degeneration, pathology of the fovea centralis, nutritional deficiency or heredity.

45. Visual Fields

46. Normal

47. The confrontation technique is used to test visual fields of each eye. The visual fields of each eye are divided into quadrants and a stimulus is presented in each quadrant. A normal finding is that a person is able to see that stimulus at about 90° temporarily, 60° nasally, 50° superiorly and 70° inferiorly.

48. Disorder

49. If a person is unable to identify a movement that you perceive, a defect in the visual field is presumed. Defects in the visual field can be associated with tumors or strokes or neurological disease such as glaucoma or retinal detachment.

50. Posterior Segment Structures

51. Funduscopic Assessment requires the use of a direct opthalmoscope to assess the structures in the posterior segment of the eye.

52. Normal

53. Normal findings should reveal red reflex. The optic disk is pinkish orange in color, with yellow white excavated center known as the physiologic cup. Light often produces a glistening “light reflex” from the anterior vessel.

54. Disorder

55. Cataracts can prevent red reflex.

56. Leukocoria or white reflex also referred to as the cat’s eye reflex. The optic disc is pale, there is optic atrophy, edema. The normal hypertensive changes manifest copper wire appearance of the retinal arteries.

57. Retinal Arteriolar Sclerosis occurs as the walls become thickened and obscure portions of the veins lie underneath. Hypertension causes several abnormalities in the posterior eye.

58. Coloboma is a congenital abnormality.

59. Diabetic Retinopathy causes blindness.

60. Macula

61. Normal

62. The macula is a darker, avascular area with a pinpoint reflective center known as the fovea centralis.

63. Disorder

64. The retina is pale with the macular region appearing as cherry red spots. This can be indicative of Tay-Sach’s disease. Sharply defined, small red spots are found in and around the macula. These are pathognomonic of diabetes mellitus.

65. Cranial Nerve No. III (Occulomotor)

66. Occulomotor nerve is the nerve responsible for the extraoccular movement or the four of the six extrinsic muscles and upper eyelid; and the puppilary constriction and the control of the lens shape.

68. The trochlear nerve is either of the smallest of the cranial nerves, essential for eye movement and muscle sensitivity.

69. Functioning

70. Normal

71. Both eyes should move smoothly and symmetrically in each of the six fields of gaze and converge on the held object as it moves towards the nose. A few bits of nystagmus with extreme lateral gaze can be normal

72. Disorder

73. Trochlear nerve damage is manifested by the inability of the eye to move downward when deviated inward.

74. Traumaic Opthalmoplegia can damage the extraoccular muscles or nerves

75. Extraoccular Muscle Palsy may be caused by Herpes Zoster, Syphlis , Scarlet Fever, Whooping Cough or botulism infections.

76. Parasellar Minengiomas or tumors in the sphenoid sinus may impinge on the wall of the cavernous sinus and involve one or more cranial nerves.

77. Cranial Nerve No. V (Trigeminal)

78. The Trigeminal nerve is both motor and sensory in nature. It is responsible for the sensation of face, scalp, cornea, oral and nasal mucous membrane and the teeth. Its motor functions are to muscles of mastication of chewing. It has the greatest general sensory distribution of all the sensory nerves and it is the only nerve supplying the sensory information to the brain to the skin of the face. Injections of anesthetic administration carried through branches of the trigeminal nerve from the teeth.

79. Functioning

80. Normal

81. The temporalis and Masseter muscles should be equally strong on palpation. The joint should not deviate and should be equally strong side-to-side movement against resistance. The value and bulk of muscles should be bilaterally equal. Sensation to light touch, superficial pain and temperature should be present on the sensory distribution areas of the trigeminal nerve. The corneal reflex should case bilateral blinking of eyes.

82. Disorder

83. Lesions of the trigeminal nerve may give rise to either reduced sensory perception or facial pain.

84. Trigeminal Neuralgia (Tic Douloureux) characterized by brief paroxysmal, unilateral facial pain along the distribution of the trigeminal nerve. The pain can be provoked by touch or movement of the face such as in tooths brushing, yawning chewing or talking.

85. Post Thereptic Neuralgia is found most often in the elderly. Characterized by continuous pain which is constant stabbing, burning ache.

86. Tetanus is characterized by tonic spasms interfering with muscles that open the jaw (trismus). Dysphagia and spasms of the pharyngeal muscles are also observed in tetanus.

87. Cranial Nerve No. VI (Abducent/Abducens)

88. The Abducent or abducent nerve is a motor nerve responsible for the lateral eye movement. It is either of the pair of the 6th cranial nerve. It makes the eye turn outward. The term abducens relates to the tern abduct which means to move away from the central axis of the body.

89. Functioning

90. Normal

91. The normal manifestation of the abducent nerve is the same as the normal findings of the Trochlear nerve (CN VI)

92. Corneal light reflex (Herschberg Test) must result where the reflected light (light reflex) should have been symmetrically in the center of each cornea.

93. Cover-uncover test is normal if the eyes are in alignment, there will be no movement in the other eye.

94. Disorder

95. There id discrepancy in the placement of one of the light reflections.

96. Strabismus or topia is the condition where one eye is constantly deviated.

97. Estropia is an inward turning of the eye.

98. Exoptropia is the outward turning of the eye.

99. Phoria is the misalignment of an eye. This condition is a mild weakness elicited by the cover-uncover etst and has two forms: Esophoria: nasal or inward drift and exophoria, a temporal or outward drift.

100. Truamatic Opthalmoplegia amy cause damage to the extraocular muscles.

101. Extaocular Muscle palsy and Nystagmus occurs late after the onset of increased intracranial pressure.

102. Parasellar meningiomas or tumors.

103. Skew deviation is the deviation of one eye down and the other up.

104. Cranial Nerve No. VII (Facial)

105. The Facial nerve is both a sensory and a motor nerve. The sensory function of the facial nerve is responsible for the taste on the posterior 1/3 of the tongue. The motor function of the facial nerve is responsible to muscles of facial expression, eye closure labial speech and salivary and tear glands.

106. The nerves arise from the brain stem at the base of the pons and divide in front of the ear into six branches, innervating the scalp, forehead eyelids, muscles of the facial expression, cheeks and jaws

107. Functioning

108. Normal

109. Normal findings of he motor function of the facial nerve include symmetry between the right and the left sides of the face as well as the upper and the lower portions of the face at rest and while executing facial movements. There should be an absence of abnormal muscle movement.

110. The normal sensation would be accurate perceptions of sweet, sour, salty, bitter tastes.

111. Disorder

112. Bell’s Palsy (idiopathic facial palsy) characterized by complete paralysis of the facial muscles on the involved side. The affected side of the face is smooth, the eye cannot close, the eyebrows droop, the labiofacial fold is gone and the mouth may droop. Loss of sensation of taste in the anterior two thirds of the tongue may occur.

113. Supranuclear facial palsy is the paralysis of the lower one third to two thirds of the face; the upper portion of the face is spared.

114. Ageusia (loss of taste), hypogeusia (diminution of taste)

115. Cranial Nerve No. VIII (Vestibulocochlear/Acoustic)

116. Vestibulocochlear or the acoustic nerve is responsible for hearing and balance. It is either of the pair of cranial nerves composed of fibers from the cochlear and the vestibular nerve in the inner ear, conveying impulses of both the sense of hearing and the sense of balance.

117. Functioning