Cranial Nerves + Autonomics

Question 1

Function of CN1

Answer 1

Olfactory nerve: special sensory - smell

Question 2

Fxn of CN2

Answer 2

Optic nerve: special sensory - vision

Question 3

Fxn of CN3

Answer 3

Oculomotor n:

• Somatic motor to inferior rectus, superior rectus, inferior oblique, and medial rectus
• Visceral motor to ciliar muscles & sphincter pupillae muscles

Question 4

Fxn of CN4

Answer 4

Trochlear n: motor to superior oblique muscle

Question 5

Fxn of CN5

Answer 5

Trigeminal n.

• Sensory: face, eyes, teeth, sinuses, nasopharynx, oral cavity, nasal cavity, etc…. (most of face)
• Motor:
  
  • Muscles of mastication (medial tperygoid, lateral pterygoid, masseter, temporalis)
  • Mylohyoid
  • Anterior belly of digastric
  • Tensor tympani
  • Tensor veli palatini

Question 6

Fxn of CN6

Answer 6

Abducens n

Motor: external rectus muscle

Question 7

Fxn of CN7

Answer 7

Facial nerve:

• Branchial motor to
  
  • facial muscles
  • stapedius
  • stylohyoid
  • posterior belly of digastric
• Visceral (parasympathetic) motor: secretomotor to
  
  • All salivary glands except parotid gland
  • Mucous glands in oral & nasal cavity
  • Lacrimal gland
• Special sensory - taste (anterior 2/3 of tongue)
• Somatic sensory - part of ext acoustic meatus & deep auricle

Question 8

Fxn of CN8

Answer 8

Vestibulocochlear nerve: special sensory to inner ear- hearing & balance

Question 9

Fxn of CN9

Answer 9

Glossopharyngeal n.

Motor

• Branchial- pharyngeal musculature
• Visceral (parasympathetic) motor - secretomotor to the parotid gland

Sensory

• Visceral - carotid body and sinus
• Special - taste (posterior 1/3 of tongue)
• Somatic - posterior 1/3 of tongue, oropharynx, palatine tonsil, middle ear, pharyngotympanic tube, and mastoid air cells

Question 10

Fxn of CN10

Answer 10

Vagus nerve

Motor: heart, lungs, bronchi, GI tract

Sensory: heart, lungs, bronchi, trachea, larynx, pharynx, GI tract, external ear

Question 11

CN11

Answer 11

Spinal accessory n: motor to SCM & traps

Question 12

Fxn of CN12

Answer 12

Hypoglossal n: motor (GSE) to intrinsic muscles of tongue (hypoglossus, styloglossus, genioglossus)

Question 13

The cranial nerves are numbered according to..

Answer 13

anterior to posterior

Question 14

Foramina through which the cranial nerves exit

Answer 14

Question 15

The trigeminal nerve [V] innervates facial structures derived from which pharyngeal arch?

Answer 15

First

Question 16

The facial nerve [VII] innervates facial structures derived from which pharyngeal arch?

Answer 16

Second arch

Question 17

Fxn of components of CN5

Answer 17

• Ophthalmic nerve [V1] enters the orbit; SENSORY
  
  • Supra orbital & supratrochlear n: upper eyelid, forehead, scalp
  • Infratrochlear n: medial upper eyelid, side of nose, medial angle
  • Lacrimal n: lateral upper eyelid, lateral angle
  • External nasal n: anterior part of nose
• Maxillary nerve [V2]: ​SENSORY​
  
  • Zygomatictemporal branch: small area of temples
  • Zygomaticofacial branch: skin over zygomatic bone
  • Infraorbital nerve: lower eyelid, cheek, side of nose, upper lip
• Mandibular nerve [V3]: MOTOR & SENSORY
  
  • Auriculotemporal n: large area of temples; ext acoustic meatus; ear drum
  • Buccal nerve: cheek
  • Mental nerve: lower lip & chin

Question 18

Sensory innervation of the face and scalp by the three divisions of the trigeminal nerve, the cervical plexus, and cervical dorsal rami.

Answer 18

• Trigeminal branches previously discussed
• Greater occipital (C2 ramus): back of scalp
• Third occipital (C3 ramus): back of neck
• Transverse cervical (C2-3 ramus): side of neck
• Lesser occipital & greater auricular (cervical plexus, C2-3): posterolateral side of head behind ear

Question 19

Branches of the ophthalmic nerve in the orbit and their distribution (green)

Answer 19

Supra orbital & supratrochlear n: upper eyelid, forehead, scalp

Infratrochlear n: medial upper eyelid, side of nose, medial angle

Lacrimal n: lateral upper eyelid, lateral angle

External nasal n: anterior part of nose

Question 20

How does sensory and motor part of the mandibular n enter the infratemporal fossa?

Answer 20

• Sensory portion drops between the tensor veli palatini & upper head of lateral pterygoid muscle
  
  • All branches of V3 originate in the infratemporal fossa.
• The small motor root of the trigeminal nerve [V] passes through the foramen ovale and joins the sensory part

Question 21

Name all the branches of the mandibular nerve and the nerve types

Answer 21

• Meningeal branch - sensory
• Nerve to medial pterygoid - motor
• Anterior trunk - mostly motor
  
  • Buccal (sensory*)
  • Masseteric
  • Deep temporal
  • Nerve to lateral pterygoid
• Posterior trunk - mostly sensory
  
  • Auriculotemporal
  • Lingual
  • Inferior alveolar
    
    • Gives n. to mylohyoid (motor*)

Question 22

Meningeal branch of V3 supplies sensory innervation to

Answer 22

• Dura mater of middle cranial fossa
• Mastoid cells that communicate with middle ear

Question 23

N to medial pterygoid supplies motor to

Answer 23

deep surface of the medial pterygoid muscle

Question 24

The auriculotemporal nerve carries what fiber types and to where?

Answer 24

• Postganglionic parasympathetic and sympathetic GVE’s to the parotid gland
• Sensory GSA’s to the
  
  • temporomandibular joint
  • skin of auricle
  • scalp

Question 25

What is the lingual nerve's main function?

Answer 25

Sensory branch that carries general sensation from the anterior 2/3 of the tongue

Question 26

Relationship between lingual nerve (from V3) & chorda tympani (from CN7)

Answer 26

The **lingual n** (carries general sensation from anterior 2/3 of tongue) is joined high in the infratemporal fossa by the **chorda tympani** (carries taste from same area). Chorda tympani's preganglionic parasympathetic fibers go through the **submandibular ganglion**, which hangs off the lingual n in the floor of the oral cavity. Then, it either reenters the lingual n to run with it, or it goes straight to glands.

Question 27

Describe the **inferior alveolar nerve's** fxns

Answer 27

* Mostly sensory, but has one motor branch: **nerve to mylohyoid** innervates the mylohyoid muscle and anterior belly of digastric * Innervates lots of teeth before dividing into terminal branches: * **Mental nerve**: innervates lower lip & skin * **Incisive branch**: innervates canine & incisor teeth

Question 28

Course of facial nerve

Answer 28

1. Starts in the **pons** with a **large motor root** and a small **sensory root** 2. The roots leave through the **internal acoustic meatus,** and enter the **facial canal** where they 1. Fuse 2. Form the **geniculate ganglion** 3. Give rise to the greater petrosal n, n. to stapedius, and chorda tympani. 3. Leave the canal via the **stylomastoid foramen** right behind the temporal bone's styloid process. 4. Gives off the first extracranial branch: the **posterior auricular nerve**, which gives motor innervation to the **posterior belly of the digastric** muscle and the **stylohyoid** muscle. 5. Main trunk goes to **parotid gland**, where it doesn't inervate it, but terminates into 5 branches (TZBMC) that innervate facial expression muscles 1. Temporal, Zygomatic, Buccal, Marignal mandibular, cervical

Question 29

Course of glossopharyngeal nerve

Answer 29

1. **Medulla oblongata** 2. **Jugular foramen,** gives off **tympanic nerve** 1. **Superior** and **inferior/petrous** **ganglia** right outside contain the cell bodies of the sensory fibers 3. Down the neck, anterolateral to internal carotid artery 1. Gives off motor branches to the **stylopharyngeus**​ **muscle** 2. Gives rise to **carotid sinus nerve** that gives sensation to carotid sinus and body 4. Enter the pharynx and divide into **lingual, tonsil, and pharyngeal branches.**

Question 30

Course of **hypoglossal n**

Answer 30

1. **Medulla oblongata** 2. Runs across posterior cranial fossa in the subarachnoid space 3. **Hypoglossal canal** 4. Travels in a sheath with branch from the **cervical plexus** that conducts fibers from C1/C2 spinal nerve roots 5. Goes down to the **mandible**, crossing the **int & ext carotid arteries** 6. **Tongue** : hyloglossus, styloglossus, and genioglossus muscles

Question 31

Innervation of parotid gland

Answer 31

* Sensory - **auriculotemporal** * Parasympathetic innervation (increase salivation) * **Glossopharyngeal n \> otic ganglion \> auriculotemporal n** * Sympathetic innervation (decrease salivation): **superior cervical ganglion**