Cranial Nerve Nuclei - Explain Innervation Targets

Parasympathetic Oculomotor Nucleus
Fiber Type: Visceral Efferent Cranial Nerve: Oculomotor Nerve
Innervation Targets: Smooth muscle of the eyeball: the constrictor pupillary m. and the ciliary m. are innervated. Note: parasympathetic postganglionic neurons are within the ciliary ganglia, located in the orbit.

Oculomotor Nucleus
Fiber Type: Somatic Efferent Cranial Nerve: Oculomotor Nerve
Innervation Targets: Four extrinsic muscles of the eye (dorsal, medial & ventral rectus mm. and the ventral oblique m. Also, the levator palpebrae superioris m. (one of two muscles that elevate the upper eyelid).

Trochlear Nucleus
Fiber Type: Somatic Efferent Cranial Nerve: Trochlear Nerve
Innervation Targets: One extrinsic eye muscle, the dorsal oblique m., which rotates the eye such that the dorsal surface of the eyeball moves toward the nose.

Mesencephalic Trigeminal Nucleus
Fiber Type: General Somatic Afferent Cranial Nerve: Trigeminal Nerve
Innervation Targets: Proprioceptors from the jaw and muscles of mastication. (The nucleus is composed of unipolar cell bodies of primary afferent neurons, located in the CNS rather than in a ganglion.)

Trigeminal Pontine Sensory Nucleus
Fiber Type: General Somatic Afferent Cranial Nerve: Trigeminal Nerve
Innervation Targets: Tactile sensation from the face, particularly discriminative touch involving encapsulated receptors and small receptive fields. Innervated areas of the face include those supplied by ophthalmic, maxillary, & mandibular branches of the trigeminal nerve.

Nucleus of the Spinal Trigeminal Tract
Fiber Type: General Somatic Afferent Cranial Nerve: Trigeminal Nerve
Innervation Targets: Pain and temperature sensation from the face (areas innervated by ophthalmic, maxillary, & mandibular branches of the trigeminal nerve)

Trigeminal Motor Nucleus
Fiber Type: Somatic Efferent (SVE) Cranial Nerve: Trigeminal Nerve (Mandibular Division)
Innervation Targets: Skeletal muscles that move the temporomandibular joint (muscles of mastication). Also, the mylohyoideus and tensor tympani muscles. The innervated muscles are derived from myotomes located in the embryonic first pharyngeal arch.

Abducent Nucleus
Fiber Type: Somatic Efferent Cranial Nerve: Abducent Nerve
Innervation Targets: Two extrinsic muscles of the eye: the lateral rectus m. shifts gaze laterally; the retractor bulbi m. protrudes the third eyelid (by pulling the eyeball caudally into the orbit).

Rostral Salvatory Nucleus
Fiber Type: Visceral Efferent Cranial Nerve: Facial Nerve
Innervation Targets: Nasal glands, the lacrimal gland, and ventral salivary glands: mandibular & sublingual glands. Note: parasympathetic postganglionic neurons are found in two ganglia: pterygopalatine & mandibular ganglia.

Facial Motor Nucleus
Fiber Type: Somatic Efferent (SVE) Cranial Nerve: Facial Nerve
Innervation Targets: Skeletal muscles that produce facial expression (movement of ears, eyelids, lips, & nose). Also, the caudal belly of the digastricus m. and the stapedius m. The innervated muscles are derived from myotomes located in the embryonic second pharyngeal arch.

Caudal Salvatory Nucleus
Fiber Type: Visceral Efferent Cranial Nerve: Glossopharyngeal Nerve
Innervation Targets: Dorsal salivary glands: parotid & zygomatic glands. Note: parasympathetic postganglionic neurons are found in the otic ganglia.

Parasympathetic Nucleus of the Vagus
Fiber Type: Visceral Efferent Cranial Nerve: Vagus Nerve
Innervation Targets: Smooth muscle and glands associated with cervical, thoracic and abdominal viscera (abdominal viscera supplied by celiac & cranial mesenteric arteries). Note: parasympathetic postganglionic neurons are found in terminal ganglia.

Nucleus Ambiguus
Fiber Type: Somatic Efferent (SVE) Cranial Nerves: Glossopharyngeal & Vagus Nerves
Innervation Targets: Skeletal muscles of the larynx, pharynx and esophagus. The innervated muscles are derived from myotomes located in embryonic pharyngeal arches 4-6. (Note: Some axons join the accessory n. for a short distance but then run with the vagus n.)

Hypoglossal Nucleus
Fiber Type: Somatic Efferent Cranial Nerve: Hypoglossal Nerve
Innervation Targets: Intrinsic and extrinsic muscles of the tongue (genioglossus, hyoglossus, & styloglossus mm.) and the geniohyoideus m. Also, the sternohyoideus m. & sternothyroideus m. are innervated by the ansa cervicalis, a loop connecting the hypoglossal n. and C-1 spinal nerve.

Nucleus of the Solitary Tract
Fiber Type: General Visceral Afferent Cranial Nerves: Glossopharyngeal & Vagus Nerves
Innervation Targets: Sensation from pharynx & larynx (gag reflexes) & esophagus. And, afferents from the middle ear and carotid sinus v carotid body. Also: Fiber Type: Special Visceral Afferent Cranial Nerves: Facial, Glossopharyngeal & Vagus Innervation Targets: Taste afferent axons from the tongue & pharynx enter the nucleus rostrally.

Accessory Nucleus
Fiber Type: Somatic Efferent (SVE) Cranial Nerve: Accessory Nerve
Innervation Targets: Four skeletal muscles of the neck: trapezius, omotransversarius, cleidocephalicus, and sternocephalicus (mastoid part).
Note: the accessory nucleus extends nearly the entire length of the cervical spinal cord.