Cranial Nerves Flashcards
Describe CN I (Olfactory Nerve)
- Special Sensory
- Only Sensory
- Part of Telencephalon, NOT a true cranial nerve
- True Olfactory fibers run from olfactory epithelium in nasal cavity thru cribiform plate and innervated the olfactory bulb
Describe CN II (Optic Nerve)
- Special Sensory
- Only sensory
- Part of diencephalon, NOT a true cranial nerve
- Some fibers cross, others do not, at the optic chiasm
- fibers then run in the optic track
- Leaves the orbit via the optic canal
What nerves control Ocular muscles?
CN III, IV, VI
What is CN III called and what does it do?
- Oculomotor Nerve
- All ocular muscles except lateral rectus and superior oblique
What is CN IV called and what muscle does it control?
- Trochlear Nerve
- Only the superior oblique
- Only cranial nerve that emerges dorsally out of the brain stem
- Only cranial nerve that crosses (Axons on left side arise from cell body on right side)
What is CN VI called and what muscle does it control?
- Abducens
- Only controls lateral rectus
Name all the muscles innervated by Oculomotor Nerve
- superior rectus
- inferior rectus
- Medial rectus
- inferior oblique
- Levator palpebrae superioris (upper eyelid)
- Pupillary constrictors
- pupillary sphincter
- ciliary muscle
What is CN V called
Trigeminal nerve
Describe the trigeminal nerve
- Emerges in the middle of the pons
- Trigeminal ganglion
3 Branches:
- V1: ophthalmic
- V2: maxillary
- V3: mandibular
What does trigeminal nerve innervate?
- Muscles of mastication
- Oral floor muscles
- tensor tympani (middle ear)
- tensor veil palatini (pharyngeal)
- sensation of face, forehead, tongue
- branches of other cranial nerves also join up with CN V
List the general sensory functions for CN V
- Skin of the face
- Nasal mucosa
- Anterior 2/3 of the tongue
List the general motor functions for CN V
Muscles of Mastication:
- Temporalis
- Masseter
- Medial pterygoid
- Lateral pterygoid
Who are the visceral hitchhikers with CN V?
- Branches of CN VII used V2 and V3 nerves to get to the glands in the face
- CN IX uses V3/post. Auricular to get to parotid gland
Where does CN V1 emerge and what branches does it give off?
-Superior Orbital Fissure Branches: 1. Frontal N. 2. Nasociliary N. 3. Lacrimal N. (Sensory only)
Where does CN V2 emerge and what does it branch into?
Foramen Rotundum
Branches:
- Posterior, Middle, Anterior Superior Alveolar Nerves
- Infraorbital nerve
- Zygomatic Nerve
Where does CN V3 emerge and what does it branch to?
Foramen Ovale
Branches:
- Auriculotemporal n.
- Buccal nerve
- Masseteric branch
- Deep Temporal branch
- Pterygoid branches
- Masseteric branches
- Inferior alveolar nerve
- Lingual nerve
Describe the Lingual nerve
- Runs medial to mandible
- General Sensory
- mucosa 2/3 tongue and floor of mouth
- Chorda Tympani (branch of CN VII) Runs with it
Where does Chorda Tympani run and what does it do?
- Branch of CN VII
- Runs with Lingual Nerve
- Innervates glands (submandibular, sublingual, small ones)
- Taste for anterior 2/3 of tongue
Where would you find inferior alveolar and what does it do?
- Branch of V3
- runs within mandible, enters mandibular foramen
MOTOR:
- mylohyoid
- Anterior belly digastric
SENSORY:
- Pulp of the teeth
- Mental nerve (skin and lip)
What does CV VI do?
Abduction of the eye that it innervates (right side, right eye–other eye is doing adduction)
What are the different divisions to remember of CN VII (Facial Nerve)?
- Muscles of Facial Expression
- Greater Petrosal Nerve
- Chorda Tympani Nerve
- Nerve to Stapedius
**Major branch of CN VII comes out through parotid gland
What are the 5 branches of facial nerve pertaining to facial expression?
- Temporal
- Zygomatic
- Buccal
- Cervical
- Posterior Auricular
- Mandibular Branches (sit between Zygomatic and Cervical)
What is the Greater Petrosal Nerve and what does it do?
- Branch of CN VII
- Innervates Lacrimal and Nasal Glands
**runs with CN V2
Chorda Tympani Nerve. What is it and what does it do?
- Branch of CN VII
- Providing autonomics/Innervates submandibular, sublingual glands
- Taste for anterior 2/3 of tongue
**runs with lingual nerve (branch of V3)
What is the Nerve to Stapedius and what does it do?
- Branch of CN VII
- Innervates the Stapedius muscle (tiny muscle in middle ear)
**It has branches that innervate the Stylohyoid and posterior belly of Digastric
T/F CN VII innervates all the glands in the face.
FALSE
It innervates all the glands except for the one it runs through: Parotid Gland
What is CN VIII called and what does it do?
-Vestibulochochlear Nerve
- Vestibular senses (proprioception/balance)
- Sense of Hearing
-Special sensory nerve only but 2 different modalities
What are the Motor Functions of CN IX (Glossopharyngeal)?
- Pharyngeal Constrictors
- Stylopharyngeus
- Parotid Gland
What are the Sensory functions of CN IX?
- Posterior tongue (taste and touch)
- Posterior oral pharynx
- Mucosa-middle ear
- Skin: external ear, canal
- tympanic membrane
What are special sensory functions of CN IX?
- Taste: posterior 1/3 of tongue
- Chemo- /Baro- receptors in carotid sinus
What are the sensory functions for Vagus nerve?
- Viscera in abdomen and thorax
- Laryngopharynx and larynx
- Taste: epiglottis
- ear and external acoustic meatus
- posterior cranial fossa: dura
What are the motor functions of the Vagus nerve ( CN X )?
- Pharyngeal constrictors (with CN IX)
- Laryngeal Muscles
What muscle does the Trochlear nerve control?
Superior oblique only
Where does CN IV pass through?
Superior orbital fissure
What are two unique traits of CN IV that make it different from every other cranial nerve?
- Contralateral symptoms in nuclear lesion, while still ipsilateral in nerve lesion
- this is because the axons cross before going out
- Only CN to emerge from dorsal surface
What is the muscle controlled by Abducens nerve?
Lateral rectus
What are the points of attachment for the Temporalis?
Temporal line (inferior I think) on parietal bone
Coronoid process of mandible
What are the attachment points of the masseter?
SUPERFICIAL PORTION OF MASSETER:
-maxillary process of the zygomatic bone and anterior 2/3 of inferior border of zygomatic arch
DEEP PORTION:
-deep and medial surface of zygomatic arch
Both portions go down to the angle and ramus of the mandible
What are the attachment points for the lateral pterygoid?
Goes from Greater wing of sphenoid and pterygoid plate to the condyloid process of the mandible
What are the attachment points for the medial pterygoid?
Origin:
Deep head:
-medial side of lateral pterygoid plate behind upper teeth
Superficial head:
-pyramidal process of palatine bone and maxillary tuberosity
Insertion:
Medial angle of the mandible
What are the motor functions of the Glossopharyngeal nerve (CN IX)?
- Pharyngeal constrictors
- Stylopharyngeus
- Parotid Gland
What are the sensory functions of CN IX?
- Posterior tongue
- Posterior oral pharynx
- Mucosa: middle ear
- Skin: external ear, canal
- Tympanic Membrane
What are the special sensory functions of CN IX?
- Taste: posterior 1/3 of the tongue
- Chemo and Baro receptors : carotid sinus, plexus
What are the special senses of the Vagus nerve?
- Pressure receptors: aortic arch
- Chemreceptors: aortic body
What 2 muscles does the spinal accessory nerve innervate?
- SCM
2. Trapezius
What motor deficits would be associated with CN XI impingement?
Anything that would be a function of SCM or Trapezius.
- Lifting shoulder
- Rotating head
T/F Hypoglossal nerve (CN XII) has both motor and sensory function
FALSE–only Motor
What muscles are controlled by CN XII?
Tongue muscles
What Foramen does CN XII exit through?
Hypoglossal canal
Which Cranial nerves are only sensory?
- CN I
- CN II
- CN VIII
Which Cranial Nerves are only motor?
- CN III
- CN IV
- CN VI
- CN XI
- CN XII
Which cranial nerves can serve both sensory and motor functions?
- CN V
- CN VII
- CN IX
- CN X
T/F CN VIII is the most Lateral/dorsal nerve and is therefore sensory
True
