Lecture 14- Cranial Nerves II

Somatic Motor CNs (4)

Trochlear nerve (CN IV), Abducens nerve (CN VI), Accessory nerve (CN XI), Hypoglossal nerve (CN XII)

CN IV Trochlear nerve locations

• Superior Orbital Fissure

• Superior Oblique Muscle

CN VI Abducens nerve locations

• Superior Orbital Fissure

• Lateral Rectus Muscle

CN XI accessory nerve locations

• Jugular Foramen

• Sternocleidomastoid & Trapezius Muscles

CN XII Hypoglossal nerve locations

• Hypoglossal Canal

• Tongue Muscles

The accessory nerve provides somatic motor innervation for what muscles

The trapezius and sternocleidomastoid muscles

Accessory nerve (CN XI) 2 roots

Cranial - medulla oblongata, Spinal - spinal cord C1-C5

Accessory nerve (CN XI) 2 branches

Cranial - accessory to vagus (CN X), and Spinal - trapezius - sternocleidomastoid

Spinal root

Enters cranium via foramen magnum

Spinal branch

Exits cranium via jugular foramen

The hypoglossal nerve (CN XII) provides somatic motor innervation to which muscles

intrinsic tongue muscles and most extrinsic tongue muscles

Hypoglossal Nerve (XII) somatic motor innervation extrinsic tongue muscle EXCEPTION

Palatoglossus

The hypoglossal nerve exits the cranium through the

hypoglossal canal

The trochlear nerve provides somatic motor innervation to which muscle

the superior oblique muscle of the eye

The trochlear nerve exits the cranium through the

superior orbital fissure

The abducens nerve provides somatic motor innervation to which muscle

the lateral rectus muscle of the eye

The abducens nerve exits the cranium through the

superior orbital fissure

The oculomotor nerve provides somatic motor innervation to what muscles

most eye orbit muscles and parasympathetic innervation to the eye smooth muscles.

oculomotor nerve provides somatic motor innervation muscles list (5)

Levator palpebrae superioris, Superior rectus, Inferior rectus, Medial rectus, Inferior oblique

oculomotor nerve provides somatic motor innervation muscles EXCEPTIONS (2)

Superior oblique and lateral rectus

oculomotor nerve provides parasympathetic innervation to which muscles (2)

Ciliary muscle (shapes lens) and constrictor pupillae (constricts pupil)

The oculomotor nerve exits the cranium through the

superior orbital fissure

Levator palpebrae superioris function

opens upper eyelid

Ptosis of the eye is a

somatic motor symptom

What is a symptom of oculomotor nerve palsy related to pupillary reflexes?

Lack of direct and consensual pupillary reflexes

What happens to the accommodation reflex in oculomotor nerve palsy?

Lack of accommodation reflex

A lack of eye abduction is what kind of symptom

somatic motor

Lateral rectus muscle function

eye abduction

The trigeminal (CN V) carries somatic sensory signals from the

face

The trigeminal (CN V) carries somatic motor signals to

masticatory muscles

Trigeminal nerve (CN V) somatic sensory (face) list (9)

• Eyeball

• Skin of nose

• Skin of forehead

• Maxillary teeth

• Skin of cheeks

• Mandibular teeth

• Skin of lower jaw

• Oral mucosa

• Tongue ant 2/3 (not taste)

Trigeminal nerve (CN V) somatic motor muscles

masticatory muscles

Trigeminal Nerve Divisions (3)

Ophthalmic (V1): upper face

Maxillary (V2): upper jaw

Mandibular (V3): lower jaw

Trigeminal Nerve Division Foramina

1. Ophthalmic (V1): Superior orbital fissure

2. Maxillary (V2): Foramen rotundum

3. Mandibular (V3): Foramen oval

The ophthalmic division (CN V1) carries somatic sensory signals from the

Upper face (eyeball, skin of nose, skin of forehead)

The ophthalmic division pathway:

Leave cranium via Superior Orbital Fissure

Exits orbit via Supraorbital Notch

The maxillary division (CN V2) carries somatic sensory signals from the

upper jaw and cheeks (maxillary teeth and skin of cheeks)

The Maxillary division pathway:

Leave cranium via Foramen Rotundum

Exits maxilla via Infraorbital Foramen

Supraorbital notch for

ophthalmic division

Infraorbital foramen for

maxillary divison

The mandibular division (CN V) carries somatic sensory signals from the

lower jaw; (Mandibular teeth, skin of lower jaw, oral mucosa, tongue anterior 2/3 (not taste)

The mandibular division (CN V) carries somatic motor to

masticatory muscles

Mandibular division pathway:

Leaves cranium via Foramen Ovale

Enters mandible via Mandibular Foramen

Exits mandible via Mental Foramen

Mandibular foramen

into mandible

Mental foramen

out of mandible

The mandibular division (CN V) carries somatic motor signals

Masticatory muscles (Temporalis, masseter, lateral pterygoid, medial pterygoid)

The facial nerve (CN VII) special carries special sensory and parasympathetic signals to

oral cavity

The facial nerve (CN VII) carries somatic motor signals to

facial expression muscles

Facial nerve (CN VII) special sensory

Taste (anterior 2/3)

Facial nerve (CN VII) parasympathetic innervation targets

• Lacrimal Gland

• 2/3 Salivary Glands

- Submandibular

- Sublingual

What is the target of the Greater Petrosal branch of the Facial Nerve (CN VII)?

Lacrimal Gland (Parasympathetic)

What are the targets of the Maxillary (V2) branch of the Facial Nerve (CN VII)?

Salivary Glands (Parasympathetic) and Taste (Special Sense)

What is the function of the Facial Nerve (CN VII)?

Facial Expression (somatic motor)

The facial nerve (CN VII) enters the skull via the

Internal acoustic meatus

Where does the Greater Petrosal nerve exit?

Hiatus of facial canal to foramen lacerum

Where does the Chorda Tympani nerve exit?

Petrotympanic Fissure

Where does the Facial Nerve exit?

Stylomastoid Foramen

Greater Petrosal Branch Pathway

1. Hiatus of facial canal

2. Foramen lacerum

3. Pterygopalatine ganglion

4. Parallel to V2

5. Lacrimal Gland

The lacrimal gland secretes

tear fluid

Chorda Tympani Branch Pathway

1. Petrotympanic fissure

2. Parallel to V3

Chorda Tympani parasympathetic innervation

• Submandibular ganglion

• Submandibular & Sublingual Glands

Chorda Tympani special sense

Taste to anterior 2/3 of tongue

The submandibular and sublingual glands are innervated by the

Chorda Tympani branch of CN VII

Facial Nerve (CN VII) Branch pathway

1. Stylomastoid Foramen

2. Five Branches

3. Facial Expression Muscles

What is another name for Facial Paralysis?

Bell's Palsy

What is the cause of Facial Paralysis?

Inflammation of the facial nerve at the stylomastoid foramen

What is a symptom of Facial Paralysis related to muscle tone?

Loss of muscle tone

What happens to the Lower Orbicularis Oculi in Facial Paralysis?

It falls away from the eye

What is a symptom of Facial Paralysis related to the mouth?

Weakening of Orbicularis Oris

What is a symptom of Facial Paralysis that affects the eye?

Dry cornea

What is a symptom of Facial Paralysis related to saliva?

Saliva dribbling

What is a symptom of Facial Paralysis during chewing?

Food accumulation

Glossopharyngeal Nerve (CN IX) somatic sensory target

Pharynx and posterior 1/3 of tongue

Glossopharyngeal Nerve (CN IX) special sensory target

Taste (posterior 1/3)

Glossopharyngeal Nerve (CN IX) visceral afferent target

• Carotid body - blood chemoreceptor

• Carotid sinus - blood pressure

Glossopharyngeal Nerve (CN IX) somatic motor target

stylopharyngeus

Glossopharyngeal Nerve (CN IX) parasympathetic target

parotid gland (Salivary)

Glossopharyngeal (CN IX) Nerve Branch Foramina Targets

1. Tympanic - Foramen Ovale

2. Glossopharyngeal - Jugular Foramen

Tympanic Branch pathway:

1. Foramen Ovale

2. Otic ganglion

3. Parotid Gland (parasymp.)

The glossopharyngeal branchpasses through the ____ and innervates all except ____

1- jugular formen 2- parasympathetic

Vagus Nerve (CN X) somatic sensory target

external auditory meatus

Vagus Nerve (CN X) special sensory target

taste (epiglottis)

Vagus Nerve (CN X) visceral afferent targets (2)

1) Tracheobronchial tree 2) Viscera -abdomen, -thorax

Vagus Nerve (CN X) somatic motor targets (2)

Pharyngeal constrictors, larynx

Vagus Nerve (CN X) parasympathetic targets (3)

Heart, abdominal organs, tracheobronchial tree

The vagus nerve passes leavesthe cranium via the

jugular foramen

Postganglionic fibers of cranial nerves run

parallel to branches of the trigeminal, expect for those from the Vagus nerve