The document discusses the central nervous system and cranial nerves. It provides details on the structure and function of the brain, spinal cord, and cranial nerves I-VII. It describes signs and symptoms of damage to different parts of the central nervous system as well as clinical tests to evaluate cranial nerves and localized lesions. Bitemporal hemianopsia is listed as the visual field defect that would result from a pituitary tumor expanding superiorly.

1. Central Nervous System
 DR MAGDI AWAD SASI

2.  Central nervous system (CNS)– includes the
brain and spinal cord
 Peripheral nervous system (PNS)–
composed of the muscles ,NMJ , peripheral
nerves (( cranial and spinal nerves)), roots
and plexuses
 Autonomic system – comprises the
sympathetic and parasympathetic system
(controls smooth muscle action)

4.  Forebrain – cerebrum and diencephalon
 Midbrain – mesencephalon
 Hindbrain – cerebellum,pons and the
medulla oblongata (sometimes called the
brain stem)

5.  Signs of UMN Upper Motor Neuron damage:
 1- Muscle weakness.
 2- Hypertonia ----------spasticity.
 3- Hyperreflexia.( deep tendon reflex) +/- clonus.
 4- Babinski sign
 5- Absent abdominal & cremasteric reflexes
 6- In long standing cases there is wasting( disuse).
 7- Spasticity is hallmark of the UMN disease.
Spasticity is a state of sustained increase in muscle
tension in response to muscle lengthening, in
particular, with passive movements.
 8-Pseudobulbar palsy is hallmark of the UMN
disorder

6.  Signs of LMN lesions
 1.Weakness or paralysis of muscles
 2- Hypotonia
 3- Absent tendon reflexes (Hyporeflexia).
 4- Fasciculation
 5- Absent or flexor planter response
 6- Muscle wasting.

7.  Localization of level of UMNL
 Sites = Brain , Brain stem , Spinal cord
 1- Cortical lesions localized loss of
function e.g. monoplegia, aphasia,
apraxia
 2- Internal capsule ---- hemiplegia
 3- Brain stem lesions ----- crossed
hemiplegia
 4- Spinal cord lesions ------ Ipsi-lateral
weakness.

8.  ((ANTERIOR CIRCULATION))
 Higher Cortical Function
Aphasia, Apraxia , Agnosia
 Cranial Nerves: normal except 7th
&unless
forced eye deviation
 cerebellar Function: normal
 Motor:
 Weakness of face/arm>leg (or vice versa)
 Sensory:
Sensory abnormality of face/arm>leg
 Deep Tendon Reflexes:
Hyper-reflexia Babinski’s reflex

10.  ((POSTERIOR CIRCULATION))
 Higher Cortical Function: normal
 Cranial Nerves:
 III, IV, VI: Diplopia
 V: Decreased facial sensation
 VII: Drooping of nasolabial fold.
 VIII: Deaf and Dizzy
 IX, X, XII: Dysarthria and Dysphagia
 XI: Decreased strength in neck and shoulders
 Cerebellar Function: usually normal
 Motor: hemi-paresis ( crossed)
 Sensory: hemi-dysesthesias ( crossed).
 Deep Tendon Reflexes: hemi-hyper-reflexia.
 Pathologic Reflexes: Babinski’s reflex

11. CEREBELLUM
 Higher Cortical Function: normal
 Cranial Nerves: usually normal
 Cerebellar Function:
 Nystagmus
 Flaccid dysarthria
 Motor:
 Normal bulk and strength with ipsilateral hemi-hypotonia
 Intention tremor
 Axial instability with dysmetria
 Sensory: Normal
 Deep Tendon Reflexes: Normal
 Pathologic Reflexes: Normal
 (plantar flexing to plantar stimulation

12.  ((SPINAL CORD LESION))
 Higher Cortical Function: normal
 Cranial Nerves: normal
 Cerebellar Function: normal
 Motor:
 weakness (extensors worse than flexors) below the lesion
 Hypertonia below the lesion with spasticity
 Sensory:
 horizontal level usually lower than the lesion, poorly
localizing , may be somewhat asymmetric
 Deep Tendon Reflexes:
 Hyper-reflexia below the level, possibly clonus
 Pathologic Reflexes:
 loss of superficial reflexes (abdominal, cremasteric, anal
wink)
 Babinski’s reflex

14. Cranial Nerves
DR MAGDI AWAD SASI

15.  1. NAME
 2. NUCLEUS
 3. FUNCTION
 4. HOW TO EXAME
 5. DEFECT
 INFECTION ISCHEMIA INFLAMMATION
 TUMOUR T2RY TB
 DEGENERATIVE

16. Olfactory Nerve I
 Sense of smell
 Damage causes impaired sense of smell

17.  Test with alcowipes, coffee .
 Unilateral anosmia may be significant
 Bilateral anosmia: commonest cause viral
 Classical pathology:olfactory groove
meningioma
 Basal skull fractures another potential cause
(unilateral or bilateral)

18. Optic Nerve II
 Provides vision
 Damage causes blindness in visual field

19.  Visual acuity
 Visual fields to confrontation
 Colour vision
 Light reflex
 Pupillary reflexes (II and III)
 Fundoscopy (papilloedema, optic atrophy,
retinitis pigmentosa)

20. VISUAL ACUITY
 CORRECTED (ie brain not lens)
 Each eye separately
 Snellen charts for distance and near vision
reading charts for near vision
 If unable, finger counting, hand movements,
perception of light

21. VISUAL FIELDS
 Often forgotten but very important
 First do a bilateral screening test: will uncover
the majority of significant visual field defects
immediately
 Go on to check each eye separately, ask
about scotomata
 Mention checking for blind spot enlargement

24. COMMON FIELD DEFECTS
 HOMONOMOUS HEMIANOPIA: lesion
posterior to the optic chiasm (eg posterior
cerebral artery territory infarction)
 BITEMPORAL HEMIANOPIA: lesion at the
optic chiasm (eg pituitary tumour)
 BLINDNESS ONE EYE: lesion in eye, retina
or optic nerve

25. PUPILLARY RESPONSES
 Light reflex is the clinically significant one
 Afferent limb = II, efferent limb = III
 Look at pupillary sizes
 Direct and consensual response
 Look for afferent pupillary defect (optic nerve
lesion)

26.  One large pupil: IIIrd nerve palsy, iris problem
(eg traumatic midriasis), unilateral dilator eye
drops
 Small pupil: Horner’s syndrome, Argyll-
Roberston pupil (small, irregular, reacts to
accommodation but not to light)
 Bilateral small pupils: drugs (opiates), pontine
lesion (haemorrhage

27. HORNER’S SYNDROME
 Oculosympathetic paralysis
 A good lateralising sign but a poor localising
sign
 Ptosis, miosis and sometimes unilateral
anhydrosis of face
 Look especially at neck, supraclavicular
fossa and hand (Pancoast’s tumour)

28. . A patient who has been exhibiting various
endocrine abnormalities has an MRI scan of the
head. This scan reveals a small tumor of the
pituitary gland. As this tumor expands superiorly
what visual field defect will this patient exhibit?
A. Left or right monocular blindness
B. Binasal hemianopsia
C. Left or right homonymous hemianopsia
D. Bitemporal hemianopsia

31. Eye movements (III, IV and VI)
 III: OCULOMOTOR NERVE: all
extraocular muscles,Except SO & LR ,
 Also carries parasympathetic (constrictor)
fibres to pupil, and
 Fibres to levator palpebrae superioris

32.  Look at eyes in primary position of gaze
 IIIrd nerve palsy: ptosis ,eye often ‘down and out’
 VI nerve palsy: often eyes convergent
(unopposed medial rectus)
 Look at pupils
 Look for ptosis

33. Oculomotor Nerve III
 Somatic and Autonomic motor function
 Eye movement (Superior, inferior, medial rectus muscles and inferior
oblique muscle), opening of eyelid (levator palpebrae superioris),
constriction of pupil (circular muscle), focusing (ciliary muscle and
accomodation)

34.  Fibers extend from the ventral midbrain, pass
through the superior orbital fissure, and go to the
extrinsic eye muscles
 Functions in raising the eyelid, directing the
eyeball, constricting the iris, and controlling lens
shape
 The latter 2 functions are parasympathetically
controlled
 Parasympathetic cell bodies are in the ciliary
ganglia

35.  Damage causes
1. Drooping eyelid ((ptosis))
2. Dilated pupil
3. Double vision
4. Difficulty focusing and inability to move
eye in certain directions
5. Down and out {{eye}}

37. Trochlear Nerve IV
 Eye movement (superior oblique muscle)
 Damage causes double vision and inability to
rotate eye inferolaterally

38. Abducens Nerve VI
 Provides eye movement (lateral rectus m.)
 Damage results in inability to rotate eye
laterally and at rest eye rotates medially

41.  Diagnosing complete 6th cranial nerve palsies is easy,
but determining their etiology can be more challenging.
Excluding increased intracranial pressure and
papilledema (by looking for retinal venous pulsations
during funduscopy) is important. MRI or CT can help
exclude intracranial mass lesions, hydrocephalus, and
direct nerve compression by lesions in the orbit,
cavernous sinus, and base of the skull. Lumbar puncture
determines the CSF opening pressure and can detect
leptomeningeal inflammatory, infectious, or neoplastic
infiltrates entrapping the 6th nerve. A collagen vascular
screen helps exclude a vasculopathic process. In many
cases, 6th nerve palsies resolve once the primary
disorder is treated.

42. Trigeminal Nerve V

43.  MOTOR
 SENSORY
 REFLEX
 3 SENSATIONS + 3 BRANCHES
 3 MUSCLES FUNCTIONS
 MASTICATIONS

44.  Most important function is sensory
 Ophthalmic, maxillary and mandibular divisions
 Test with light touch and pinprick in all 3
divisions, comparing each side
 Corneal reflexes (afferent limb V, efferent limb
VII)
 Know something about trigeminal neuralgia
(examination is normal in these cases)

45.  Ophthalmic branch – sensations from nasal
cavity, skin of forehead, upper eyelid, eyebrow,
nose
 Maxillary branch – sensations from lower eyelid,
upper lips and gums, teeth of the maxilla, cheek,
nose, palate, pharynx
 Mandibular branch – sensations from teeth of
the mandible, lower gums and lips, palate,
tongue. Motor function of temporalis and
masseter muscles.
 Damage produces loss of sensation and
impaired chewing

46.  Ophthalmic (V1)
 Maxillary (V2)
 Mandibular (V3)
 Fibers run from the face to the pons via the
superior orbital fissure (V1), the foramen
rotundum (V2), and the foramen ovale (V3)
 Conveys sensory impulses from various areas of
the face (V1) and (V2), and supplies motor fibers
(V3) for mastication
 Tic douloureux or trigeminal neuralgia
- Most excruciating pain known (?)
- Caused by inflammation of nerve

48. Facial Nerve VII

50.  Motor - facial expressions
 Autonomic Motor - salivary and lacrimal
glands, mucous membranes of nasal and
palatine mucosa
 Sensory - taste on anterior 2/3’s of tongue
 Damage produces sagging facial muscles
and disturbed sense of taste (no sweet
and salty)

51.  DIFFERENTIATE AN UPPER MOTOR
NEURON FROM A LOWER MOTOR
NEURON LESION
 Upper motor neuron lesion: milder, spares
the forehead, no Bell’s phenomenon

52. Branches of Facial Nerve
Clinical test: Test anterior 2/3’s of tongue with
substances such as sugar, salt,; test response of tear
glands to ammonia fumes; test motor functions by
asking subject to close eyes, smile, whistle, frown, raise
eyebrows, etc.

53.  Upper facial territory is supplied by bilateral motor
cortices
 Lower facial territory is supplied only by contralateral
motor cortex
 Therefore, unilateral central lesions spare upper face
 Lesions distal to geniculate ganglion
 Mostly motor abnormalities
 Lesions proximal to geniculate ganglion
 Motor, gustatory & autonomic abnormalities

55. Bell's Palsy
 Unilateral facial paralysis of sudden onset
 Unknown cause.
 The mechanism presumably involves
swelling of the nerve due to immune or
viral disease, with ischemia and
compression of the facial nerve in the
narrow confines of its course through the
temporal bone.

56. Symptoms of Bell’s Palsy
--Symptoms usually start suddenly, and range from mild to severe. They may
include:
 Twitching in face
 Weakness in face
 Face feels stiff or pulled to one side
 Droopy eyelid or corner of mouth
 Drooling due to inability to control facial muscles
 Facial Paralysis of one side of the face, makes it hard to close one eye
 Change in facial expression (for example, grimacing)
 Dry eye or mouth
 Loss of sense of taste
 Difficulty with eating and drinking
 Pain behind or in front of the ear, may occur 1-2 days before muscle
weakness
 Sensitivity to sound (hyperacusis) on the side of the face affected
 Headache
--These symptoms of Bell's palsy usually begin suddenly and reach their peak
within 48 hours

58.  The affected side becomes flat and
expressionless, but patients may complain
instead about the seemingly twisted intact side.
 In severe cases, the palpebral fissure widens,
and the eye does not close.
 The patient may complain of a numb or heavy
feeling in the face, but no sensory loss is
demonstrable. A proximal lesion may affect
salivation, taste, and lacrimation and may cause
hyperacusis.

59.  Weakness of the entire half of the face
distinguishes Bell's palsy from supranuclear
lesions (eg, stroke, cerebral tumor), in which the
weakness is partial, affecting the frontalis and
orbicularis oculi less than the muscles in the
lower part of the face. Bell's palsy must be
differentiated from unilateral facial weakness
due to other disorders of the facial nerve or its
nucleus, chiefly geniculate herpes (Ramsay
Hunt's syndrome), middle ear or mastoid
infections, sarcoidosis, Lyme disease, petrous
bone fractures, carcinomatous or leukemic
nerve invasion, chronic meningeal infections,
and cerebellopontine angle or glomus jugulare
tumors

60. A 24 y. o. woman presents to her physician with an
inability to close her right eye. Physical exam reveals
weakness of the right orbicularis oculi. Which of the
following symptoms would likely also be present?
A. Double vision
B. Inability to feel the face
C. Inability to chew
D. Hyperacusis
E. Inability to shrug the shoulder

61. 61
A 49 year old woman is in a motor vehicle accident and sustains a
closed head injury. A CT scan does not show any intracranial
hemorrhage but reveals a small tumor at the cerebellopontine angle
of the brain. Which of the following nerves is most likely to be
affected by this tumor?
A. Facial nerve
B. Glossopharyngeal nerve
C. Abducens nerve
D. Trigeminal nerve
E. Vagus nerve

62. Vestibulocochlear Nerve VIII
 Special Sensory
 Provides hearing (cochlear branch) and sense of
balance (vestibular branch)
 Damage produces deafness, dizziness, nausea,
loss of balance and nystagmus

63.  For clinical examination purposes, forget the
vestibular element
 Check hearing approximately in each ear
 If reduced, determine whether conductive
(BC >AC) or sensorineural (AC>BC)
deafness

65. GLOSSOPHARYNGEAL (IX) AND
VAGUS (X)
 Tested together
 Speech, palate, cough, swallow, (gag reflex)
 Bulbar palsy: bilateral LMN lesions of IX and
X: poor palatal movement, nasal speech,
nasal regurgitation of fluids
 Pseudobulbar palsy: bilateral UMN lesions:
‘hot potato’ speech, no nasal regurgitation,
additional frontal lobe signs

66. Glossopharyngeal Nerve IX
 Somatic motor – Swallowing and voice production via pharyngeal
muscles
 Autonomic motor - salivation, gagging, control of BP and respiration
 Sensations from posterior 1/3 of tongue including taste
 Sensations from baroreceptors and chemoreceptors
 Damage results in loss of bitter and sour taste and impaired swallowing,
blood pressure anomalies (with CN X).

68. 68
A physician is performing a cranial nerve exam on a patient.
While testing the gag reflex it is noted that when the left side of the
pharyngeal mucosa is touched, the patient gags and his uvula
deviates to the left. When the right side is touched, the patient
does not gag. Which of the following is the most likely location of
his lesion?
A. Left glossopharyngeal and vagus nerves
B. Right glossopharyngeal and vagus nerves
C. Right glossopharyngeal nerve only
D. Right vagus nerve only
E. Left glossopharyngeal nerve only

69. Vagus Nerve X
 Sensations from skin at back of ear,
external acoustic meatus, part of
tympanic membrane, larynx, trachea,
espophagus, thoracic and abdominal
viscera
 Sensations from bararoceptors and
chemoreceptors
 Special sensory – taste from
epiglottis and pharynx
 Somatic motor – Swallowing and
voice production via pharyngeal
muscles
 Autonomic motor – smooth muscle of
abdominal viscera, visceral glands
secretions, relaxation of airways, and
normal or decreased heart rate.
 Damage causes hoarseness or loss
of voice, impaired swallowing, GI
dysfunction, blood pressure
anomalies (with CN IX), fatal if both
are cut

70.  Dyspnea
 Dysphagia
 Dysphonia
 Dysarthria
 Emotional liability if UMN
 Total destruction incompatible with life

71. ACCESSORY NERVE (XI)
 Cranial and spinal roots
 Cranial roots: sternocleidomastoid (note
direction of head turn)
 Spinal roots: trapezius (shoulder shrug)

72. Accessory Nerve IX
 Swallowing, head, neck and shoulder movement via trapezius
and sternocleidomastoid and pharyngeal muscles
 Damage causes impaired head, neck, shoulder movement

74.  It is purely motor. It has two roots, CRANIAL& SPINAL.
The spinal root arises from the anterior horn
cells of the upper 5 cervical segments, &it enter
the skull through foramen magnum.
 These fibers are joined by the cranial root which arises
from the caudal part of the nucleus ambigus & together
they leave the skull through the jugular foramen with the
vagus.
 In the jugular foramen the cranial root fibers join the
vagus to be distributed along with fibers of the vagus to
the pharynx and larynx.
 This part of the nerve cannot be tested separately. The
spinal part supplies the sternomastoid and upper part of
the trapeziuz.

75. Hypoglossal Nerve XII
 Tongue movements for speech, food
manipulation and swallowing
 If both are damaged – can’t protrude tongue
 If one side is damaged – tongue deviates towards
injured side

76. HYPOGLOSSAL NERVE
 Movement of the tongue
 Look for wasting and fasiculation of the
tongue
 Deviation of tongue on protrusion
 Tongue movements including power

77.  Fibers arise from the medulla and exit the
skull via the hypoglossal canal
 Innervates both extrinsic and intrinsic
muscles of the tongue, which contribute to
swallowing and speech
 If damaged, difficulties in speech and
swallowing; inability to protrude tongue

78. Function of the Cranial Nerves
Olfactory (I) Smell
Optic (II) Vision
Oculomotor (III) Eye movement (Inf Rec/Med
Rec/ Sup Rec/Inf Oblique);
Focusing (Iris and Lens)
Trochlear (IV) Eye movement (Sup Oblique)

79. Function of the Cranial Nerves
Trigeminal (V) Chewing, sensation of scalp,
face, teeth (Not tongue)
Somatosensory information
(touch, pain) from the face and
head; muscles for chewing.
Abducens (VI) Eye Movement (Lat Rectus)

80. Function of the Cranial Nerves
Facial (VII) Taste (anterior 2/3 of tongue);
Somatosensory information
from ear; Controls muscles
used in facial expression.
Vestibulocochlear
(VIII)
Vestibular branch: Posture,
balance, equilibrium
Cochlear branch: Hearing
Glossopharyngeal
(IX)
Taste (posterior 1/3 of
tongue); Somatosensory
information from tongue,
tonsil, pharynx; Controls some
muscles used in swallowing.

81. Function of the Cranial Nerves
Vagus (X) Sensory, motor and autonomic
functions of viscera (glands,
digestion, heart rate)
Accessory (XI) Swallowing and head
movement (Trapezius and
SCM = Sternocleidomastoid
muscle)
Hypoglossal (XII) Controls muscles of tongue

82.  THANKS FOR PATIENCE