CNs 5, 7, 9, 10 - Pharnygeal Arch Set - Sensory
CNs 5, 7, 9, 10 - pharyngeal arch set - Sensory
Pharyngeal Arch Set
- It comprises CNs 5, 7, 9, 10, derived from the pharyngeal (aka branchial) arches.
- They have special sensory and sensory autonomic functions.
Entrance of Cranial Nerves into the Brainstem
- CN 5, the trigeminal nerve
- Enters the mid/lower pons.
- CN 7, the facial nerve
- Enters at the pontomedullary junction.
- CN 9, the glossopharyngeal nerve
- Enters the medulla laterally
- CN 10, the vagus nerve
- Enters the medulla laterally.
midbrain
- The mesencephalic trigeminal nucleus of CN 5 lies laterally
- CN 5 exits the brainstem at the level of the pons.
pons
- The principal sensory nucleus of CN 5 lies laterally
- Its lateral path through the brainstem and exit is in the upper pons: it has both motor and sensory roots.
- Note that we ignore the mesencephalic nucleus and spinal trigeminal nucleus extensions into the pons, for simplicity (we'll see their heights in the sagittal diagram).
medulla
- The solitary tract nucleus of CNs 7, 9, and 10 lies medially.
- Lateral to it, lies the spinal trigeminal nucleus, CN 5, and lateral to it, lies the spinal trigeminal tract where nerve fibers descend through the brainstem alongside the nucleus.
- Nerve fibers of CNs 7, 9, and 10 enter the medulla laterally through the post-olivary sulcus to enter the cerebellomedullary cistern.
CN 5, the trigeminal nerve
Function
- Provides facial sensation
Nuclei Anatomy
- Mesencephalic trigeminal nucleus of CN 5 extends through the midbrain into the pons.
- Principal sensory nucleus of CN 5 lies in the mid-pons.
- Spinal trigeminal nucleus extends from the pons through the medulla.
Surrounding Structures
- We include the trigeminal ganglion, which resides in Meckel's cave.
- Anterior to it, lies the cavernous sinus.
Foramina
- The trigeminal nerve divisions cross through the following 3 foramina:
- 5[1] enters via the superior orbital fissure
- 5[2] enters via foramen rotundum
- 5[3] enters via foramen ovale
- They join at the trigeminal ganglion and then enter the brainstem and parse into their central nuclear destinations.
- 5[1] is the ophthalmic division
- 5[2] is the maxillary division
- 5[3] is the mandibular division
CN 7, 9, 10, the solitary tract nucleus
- It spans the height of the medulla, and receives innervation from:
- CN 7 (the facial nerve)
- CN 9 (the glossopharyngeal nerve)
- CN 10 (the vagus nerve).
CN 7
- CN 7 passes through the internal acoustic meatus, enters the brainstem at the pontomedullary junction, to innervate the solitary tract nucleus.
- It provides taste sensation from the ant. 2/3 of the tongue.
CNs 9 & 10
- CNs 9 & 10 enter the medulla directly through the jugular foramen.
- CN 9 functions in salivation, swallow, and cardio-pulmonary function.
- CN 10 functions in gut motility, swallow, and cardio-pulmonary function.
Spinal Trigeminal Nucleus Innervation
- CNs 7, 9, and 10 all also innervate the spinal trigeminal nucleus with sensory coverage of the outer ear.