CSD 210 exam 2 (cranial nerves)

CN I

Olfactory

• Class: SVA

• Nuclei: neuro-epithelial cells in the nasal cavity

• CNS Nuclei: olfactory bulb

• Basic Function: smell

• Type: Sensory

A lesion that disrupts the olfactory fibers causes:

Anosmia - partially/fully impaired ability to smell

Hyposmia - reduced sense of smell

Hyperosmia - acute sense of smell

CN II

Optic:

• Class: SSA

• Nuclei: Retina

• Basic Function: Vision

• Type: Sensory

Visual deficits occur when:

A loss of monocular vision occurs before the chaism

Ocular movements are controlled by _______ muscles.

extrinsic

Extrinsic muscles that control ocular movements (7)

1. superior rectus

2. medical rectus (CN III)

3. inferior rectus

4. superior oblique (IV)

5. inferior rectus

6. later rectus (CN VI)

7. (inferior oblique)

CN III

Ocularmotor:

• Class: GSE

• Nuclei: oculomotor nucleus (midbrain)

• Basic Function: Eye movement; maintains open eyelid, regulates…

  • superior rectus

  • inferior rectus

  • medial rectus

  • inferior oblique

• Type: Motor

• Class: GVE

• Nuclei: Edinger-Westphal nucleus (midbrain)

• Basic Function: Reflexive constriction of pupil, accommodation of lens for near vision

• Type: Motor

Damage to CN III causes:

Paralysis of external ocular muscles →

• lateral strabismus - devitation of IPSILATERAL muscle to the LATERAL side

• ptosis - eyelid drooping

• difficulty looking up, down, and medially

CN IV

Trochlear:

• Class: GSE

• Nuclei: trochlear nucleus (midbrain)

• Basic Function: eye movement; regulates superior oblique

• Type: Motor

Damage to CN IV causes:

Paralysis of the superior oblique →

• difficulty looking downward and outward

• eye is fixed with upward medial gaze (remaining muscles are unopposed)

CN VI

Abducens:

• Class: GSE

• Nuclei: abducens nucleus (pons)

• Basic Function: lateral gaze movement, innervates lateral rectus

• Type: Motor

Damage to CN VI causes:

Affected eye turns medially, since the medial rectus muscle is unopposed

CN V

Trigeminal (mixed):

• Class: GSA

• Nuclei: spinal and main sensory nucleus (pons)

• Basic Function: cutaneous proprioceptive sensation from IPSILATERAL side of the face, head, and oral cavity

• Type: sensory

• Class: GSE

• Nuclei: motor nucleus (pons)

• Basic Function: innervations of muscles of mastication (chewing), palatal muscles, middle ear muscles, jaw muscles

• Type: motor

Sensory deficits to CN V

• IPSILATERAL deficits in pain and temperature from the tace, eeth, and anterior 2/3 of the tongue

• damage to peripheral branch → IPSILATERAL loss of sensation in the area of distribution of the nerve

• lost sneezing and blinking reflexes

• trigeminal neuralgia

Motor deficits to CN V

• paralysis or paresis and atrophy of IPSILATERAL masticatory muscles

CN V sensory pathway

Spinal trigeminal pathway - mediates pain and temperature from face

CN VII

Facial (mixed):

• Class: GVE

• Nuclei: superior salivatory nucleus

• Basic Function: secretions from lacrimal, sublingual and submaxillary glands

• Type: motor

• Class: SVA

• Nuclei: nucleus solitarius

• Basic Function: taste from anterior 2/3 of tongue and nasopharynx

• Type: sensory

• Class: SVE

• Nuclei: motor nucleus (pons)

• Basic Function: innervates facial muscles and stapedius muscle

• Type: motor

Damages to CN VII causes:

• paralysis of IPSILATERAL facial muscles

• excessive secretion from the glands

• loss of taste from anterior 2/3 of tongue

taste fibers split off from CN VII in the middle ear as _____ _____.

chorda tympani

Motor deficits to CN VII

• atrophy of ALL muscles of facial expression on IPSILATERAL side of face

• inability to close eyelid due to aatrophy

• drooling on IPSILATERAL side

LNM vs UMN damage

UMN lesion → deficits on LOWER HALF of CONTRALATERAL side

LMN lesion → deficits on IPSILATERAL side

CN VIII

Vestibulocochlear:

• Class: SSA

• Nuclei: vestibular ganglia

• Basic Function:equilibrium and orientation in space

• Type: sensory

• Class: SVA

• Nuclei: cochlear nucleus

• Basic Function: hearing

• Type: sensory

Damage to CN VIII causes:

• disturbances in equilibrium and audition

• vertigo

• dizziness

• nystagmus

• sensorineural hearing loss

CN IX

Glossopharyngeal (mixed):

• Class: GVA

• Nuclei: nucleus solitarius

• Basic Function: general visceral sensations from soft palate, palate arch, poster 1/3 of tongue, gag reflex

• Type: sensory

• Class: SVA

• Nuclei: nucleus solitarius

• Basic Function: transmits taste from posterior 1/3 of tongue

• Type: sensory

• Class: GVE

• Nuclei: inferior salivary nucleus

• Basic Function: regulates secretion from parotid gland

• Type: motor

• Class: SVE

• Nuclei: nucleus ambiguus

• Basic Function: activates pharyngeal muscles for swallowing

• Type: motor

CN X

Vagus (mixed):

• Class: GVA

• Nuclei: nucleus solitarius

• Basic Function: receives general sensation from muscles of pharynx, larynx, thorax, abdomen, and regulates nausea and oxygen intake

• Type: sensory

• Class: SVA

• Nuclei: nucleus solitarius

• Basic Function: mediates taste sensation from posterior pharynx and epiglottis

• Type: sensory

• Class: GVE

• Nuclei: dorsal motor mucleus

• Basic Function: innervates glands, cardiac muscles, muscles of heart, trachea, bronchi, esophagus, stomach, and intestine

• Type: motor

• Class: SVE

• Nuclei: nucleus ambiguus

• Basic Function: controls muscles of larynx, pharynx, soft palate for phonation, swallowing, and resonance

• Type: motor

Damage to CN X cause:

• unilateral lesion of nucleus ambiguus → IPSILATERAL atrophy and paralysis of palatine muscles

• hypernasal speech

• dysphagia - swallowing deficits

• dysphonia - speech deficits

CN XI

Spinal accessory:

• Class: SVE

• Nuclei: spinal accessory nerve

• Basic Function: controls head position by controlling trapezius and sternocledimastoid

• Type: motor

Damage to CN XI causes:

• affect in ability to control head movements

• inability to tilt, forward and backward extension of head, and lateral rotation of head

CN XII

Hypoglossal:

• Class: GSE

• Nuclei: hypoglossal nucleus (pons)

• Basic Function: controls motor movements of tongue

• Type: motor

Damage to CN XII causes:

• IPSILATERAl half of tongue is paralyzed, flaccid, and wrinkles

  • deviation of tongue TOWARD side of lesion

• dysarthia - speech deficit

• dysphagia - swallowing deficit