CN V

Question 1

What CN contribute to the trigeminal nucleus?

Answer 1

V, VII, IX, X

Question 2

What are the subdivisions of the trigeminal sensory nucleus? (sensory afferent nuclei)

Answer 2

Mesencephalic nucleus Chief Spinal trigeminal

Question 3

Mesencephalic nucleus? What CN is it a component of? Location? Function?

Answer 3

• CN V
• Midbrain
• Proprioceptive input (mechanoreceptors) from joints, muscles of mastication, teeth and peridontium
• Sensory limb of jaw jerk reflex, force of bite
• Projects to motor nucleus of V

Question 4

Chief (main, pontine, primary, principle) trigeminal sensory nucleus? What CN is it a component of? Location? Function?

Answer 4

• Pons
• Lateral to motor nucleus
• 2 point discrimination or discriminative touch and pressure sensations from face, scalp, oral cavity, nasal cavity, and dura

Question 5

Spinal trigeminal (descending) nucleus? What CN is it a component of? Location? Function?

Answer 5

• CN V
• Spinal cord to ponns
• Continuation of chief sensory
• Pain and temperature sensations from face

Question 6

CN V Course and Distribution

Answer 6

• Largest CN
• Anterior pons
  
  • Small motor root and large sensory root
• Posterior cranial fossa
• Apex of petrous part of temporal bone in middle cranial fossa
• Sensory root forms the trigeminal ganglion
• V1, V2, V3 branch from the ganglion
  
  • V1 - only sensory; cavernous sinus, superior orbital fissure
  • V2 - only sensory; cavernous sinus, foramen rotundum
  • V3 - motor and sensory; foramen ovale

Question 7

What is the primary function of V1?

Answer 7

GSA

Sensation - forehead, scalp, eyelids, nose, eye (sclera, cornea, conjunctiva), and mucus membrane of nasal cavity and sinuses (frontal, ethmoid, sphenoid)

Question 8

What nerves does V1 divide into?

Answer 8

• Frontal n.
• Lacrimal n.
• Nasociliary n.

Question 9

What does the frontal n. divide into?

Answer 9

• Supraorbital n.
• Supratrochlear n.

Question 10

What does the lacrimal n. divide into?

Answer 10

Nothing, it’s just lacrimal

Question 11

What does the nasociliary n. divide into?

Answer 11

• Posterior ethmoid n.
• Anterior ethmoid n.
  
  • External nasal n.
• Infratrochlear n.
• Long ciliary nn. (2-4 branches)
• Short ciliary nn. (8-12 branches) via ciliary ganglion

Question 12

Supraorbital n. functions

Answer 12

Sensory

Frontal sinus and skin superior to lateral orbit, including lateral upper eyelid

Question 13

Supratrochlear n. functions

Answer 13

Sensory

Frontal sinus and skin superior to medial orbit, including medial upper eyelid

Question 14

Lacrimal n. functions

Answer 14

Sensory: Conjunctiva, lacrimal gland, skin of upper eyelid

Parasympathetic: Communicates with zygomatic n. of V2, VII hitch hikers, parasympathetic from pterygopalatine ganglion to lacrimal gland

Question 15

Posterior ethmoid n. functions

Answer 15

Sensory

Ethmoid and spehnoid sinuses

Question 16

Anterior ethmoid n. functions

Answer 16

Ethmoid sinus and nasal cavity

Question 17

External nasal n. functions

Answer 17

Sensory

Skin at apex of nose

Question 18

Infratrochlear n. functions

Answer 18

Sensory

Conjunctiva, lacrimal structures and skin of bridge of nose and eyelids

Question 19

Long ciliary nn. functions

Answer 19

sensory

Sclera and cornea

Question 20

Short ciliary nn. functions

Answer 20

Sensory: Ciliary body and iris

Parasympathetic: III hitch hikers, parasympathetic from ciliary ganglion to ciliary body and iris

Question 21

Ciliary ganglion: Sensory, parasympathetic, sympathetic innervation

Answer 21

Sensory: V1, nasociliary

Parasympathetic: III (EW nucleus)

Sympathetic: T1-T2

Question 22

Long vs. Short ciliary nn.

Answer 22

• Long ciliary - inn. sclera and cornea
  
  • Sympathetic (superior cervical ganglion) hitch hikers
• Short ciliary - ciliary body and iris
  
  • Parasympathetic (EW nucleus) hitch hikers
  • Sympathetic (superior cervical ganglion)