Overview of Cranial Nerves

In this lecture, we reviewed the 12 cranial nerves, focusing on their functions and classifications as sensory or motor nerves.

Classification

• Sensory Nerves: Shown in blue
• Motor Nerves: Shown in red
• Mixed Nerves: Both sensory and motor functions

Cranial Nerves Breakdown

Cranial Nerve I: Olfactory Nerve

• Type: Sensory
• Function: Receives smell senses from the nasal cavity and sends them to the brain
• Pathway: Travels through the ethmoid bone and lays upon the cribriform plate

Cranial Nerve II: Optic Nerve

• Type: Sensory
• Function: Receives visual information from the retina and transmits it to the brain

Cranial Nerve III: Oculomotor Nerve

• Type: Motor
• Function: Supplies most eye muscles (inferior oblique, superior rectus, inferior rectus, medial rectus), innervates ciliary muscles (role in accommodation)
• Originates from: Midbrain

Cranial Nerve IV: Trochlear Nerve

• Type: Motor
• Function: Supplies the superior oblique muscle of the eye
• Originates from: Midbrain

Cranial Nerve V: Trigeminal Nerve

• Type: Mixed
• Function:
  • Sensory: Facial sensation
    • V1: Ophthalmic nerve
    • V2: Maxillary nerve
    • V3: Mandibular nerve
  • Motor: Muscles of mastication (temporal, masseter, lateral, and medial pterygoid muscles)
  • Originates from: Pons and midbrain

Cranial Nerve VI: Abducens Nerve

• Type: Motor
• Function: Abducts the eye (lateral rectus muscle)
• Originates from: Pons

Cranial Nerve VII: Facial Nerve

• Type: Mixed
• Function:
  • Motor: Muscles of facial expression (frontalis, orbicularis oculi, orbicularis oris), secretory glands (sublingual, submandibular, lacrimal glands) excluding the parotid gland
  • Special Sensory: Taste for anterior two-thirds of the tongue
  • Originates from: Pons
  • Note: Passes through but does not innervate the parotid gland

Cranial Nerve VIII: Vestibulocochlear Nerve

• Type: Sensory
• Function: Hearing and balance
• Components: Vestibular nerve (balance), Cochlear nerve (hearing)
• Originates from: Pons

Cranial Nerve IX: Glossopharyngeal Nerve

• Type: Mixed
• Function:
  • Motor: Parotid gland
  • Sensory: Taste for posterior one third of the tongue, sensory for the pharynx (gag reflex)
• Originates from: Medulla

Cranial Nerve X: Vagus Nerve

• Type: Mixed
• Function: Motor and sensory for organs (heart, lungs, digestive system), stimulates rest and digest response
• Originates from: Medulla

Cranial Nerve XI: Spinal Accessory Nerve

• Type: Motor
• Function: Supplies the SCM (Sternocleidomastoid) and trapezius muscles
• Originates from: Medulla

Cranial Nerve XII: Hypoglossal Nerve

• Type: Motor
• Function: Movement of the tongue
• Originates from: Medulla

Conclusion

• The lecture provided an overview of the 12 cranial nerves, emphasizing their primary functions and neural pathways. Each nerve may have additional roles beyond what's covered here.