Neurosurgery notes/Anatomy/Brainstem/Cranial nerve nuclei

Cranial nerve nuclei

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General

  • Organized into Longitudinal Columns
    • 10/12 cranial nerves have their nuclei in the brain-stem.
      • Cranial nerves I and II are the exceptions.
  • Difference between spinal cord and brainstem sensory and motor nuclei orientation
    • Brainstem
      • Motor nuclei: Medial columns
      • Sensory nuclei: Lateral columns
    • Spinal cord
      • Motor efferents: ventrally orientated
      • Sensory afferents: dorsal orientated
    • During development
        • Alar plates of developing neural tube:
          • Give rise to sensory afferents
        Embryonic Development - The Central Nervous system
        • This orientation is kept in the spinal cord but in the brainstem this organization is changed: the lateral spread of the fourth ventricle causes the dorsal alar plate to rotate laterally in relation to the ventral basal plate.
      • Basal plates of the developing neural tube: give rise to motor efferents
          • GSA General somatic afferent
          • GSE General somatic efferent
          • GVA General visceral afferent
          • GVE General visceral efferent
          • SSA Special somatic afferent
          • SVA Special visceral afferent
          • SVE Special visceral efferent
          • SL Sulcus limitans
          notion image

Components of cranial and spinal nerves

Medial
Lateral
G
G
S
Sulcus
S
G
S
G
S
V
V
Limitants
V
V
S
S
E
E
E
A
A
A
A
  • Medial to lateral in the brainstem and spinal cord
  • GSA General somatic afferent
  • GSE General somatic efferent
  • GVA General visceral afferent
  • GVE General visceral efferent
  • SSA Special somatic afferent
  • SVA Special visceral afferent
  • SVE Special visceral efferent
  • SL Sulcus limitans
 
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Medial Columns Contain 3 Types of Motor Nuclei

  • Column 1: Somatic motor nuclei
  • Visceral motor nuclei.
    • Two types of visceral motor nuclei are distinguished on the basis of the two types of muscles their neurons innervate
      • Column 2: Striated muscle derived from primitive branchial arches
      • Column 3: Smooth muscle associated with viscera and glands.
Column 1: Somatic motor
  • Not continuous longitudinally,
  • Location
    • Immediately adjacent to the midline
    • Just below the floor of the ventricular system.
  • Contains nuclei composed of neurons that innervate the striated muscles of the head and neck derived from embryonic myotomes
    • Extraocular muscles
    • Muscles of the tongue
Rostrocaudal order:
  • Oculomotor nucleus (III)
    • Innervate
      • Inferior oblique
      • Superior rectus
      • Inferior rectus
      • Medial rectus
      • Levator palpebrae superioris.
    • Location
      • In the midbrain
      • At the level of the superior colliculus,
      • Ventral to the cerebral aqueduct.
  • Trochlear nucleus (IV)
    • Innervate
      • Superior oblique
    • Located
      • Midbrain
      • At the level of the inferior colliculus,
      • Ventral to the cerebral aqueduct.
  • Abducens nucleus (VI)
    • Innervate
      • Lateral rectus muscle.
    • Located
      • Pons,
      • Ventral to the floor of the fourth ventricle.
  • Hypoglossal nucleus (XII)
    • Innervate the muscles of the tongue.
    • Located
      • Medulla
      • Ventral to the floor of the fourth ventricle.
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Column 2: Visceral striated muscle
  • Located
    • Lateral and ventral to column 1.
  • Contains nuclei composed of neurons that innervate the striated muscles of the head and neck derived from the branchial arches
In rostrocaudal order:
Motor nucleus of the trigeminal nerve (V)
  • Special visceral efferent fibres
  • Arise from the motor nucleus of the nerve located at the level of upper pons
  • Innervate the muscles of mastication
  • Located in the pons.
  • Facial motor nucleus (VII)
    • Innervate the muscles of facial expression.
    • Located in the pons.
  • Nucleus ambiguus (IX and X)
    • Innervate the muscles of the larynx and pharynx responsible for speech and swallowing.
    • The nucleus ambiguus, so-called because of its unclear borders in histological sections, Located in the medulla.
  • Nucleus of the spinal accessory nerve (XI)
    • Innervate the sternocleidomastoid and trapezius muscles.
    • Location: extends from the medulla into the cervical regions of the spinal cord.
MOTOR NUCLEUS OF TRIGEMINAL NERVE FACIAL MOTOR NUCLEUS NUCLEUS AUBIGUUS X) NtELEUS OF THE SPINAL ACCESSORY NERVE
Column 3: Visceral smooth muscle
  • Located immediately lateral to column 1.
  • Contains nuclei of preganglionic parasympathetic neurons that innervate the smooth muscles and glands of the head and neck, as well as the thoracic and parts of the abdominal viscera.
Rostrocaudal order:
  • Edinger-Westphal nucleus (III)
    • Located in midbrain
    • Terminate in the ciliary ganglion.
      • Contains postganglionic neurons that travel in the short ciliary nerve to innervate
        • Pupillary constrictor
        • Ciliary muscles → lens
        • Superior tarsal (Müller's) muscle
  • Superior and inferior salivatory nuclei (VII and IX, respectively)
    • Located in the medulla
    • Superior salivatory nucleus:
      • Preganglionic parasympathetic neurons that are projected in the CN7 to terminate in the
        • Submandibular ganglion
          • Contains post-ganglionic neurons that innervate the
            • Sublingual glands
            • Submandibular glands,
        • Pterygopalatine (sphenopalatine) ganglia.
          • Contains postganglionic neurons that innervate the lacrimal gland.
    • Inferior salivatory nucleus:
      • Preganglionic parasympathetic neurons that are projected in the CN9 to terminate in the
        • Otic ganglion.
          • Contains postganglionic neurons that innervate the parotid gland.
  • Dorsal motor nucleus of the vagus (X)
    • Innervate the heart, lungs, and gastrointestinal tract.
    • Located in medulla.
EOINGER.WEST PHAL NUCLEUS 4) SUPER OR SAuvATORY NUCLEUS INFERIOR SALIVATORY NUCLEUS DORSAL MOTOR NUCLEUS OF THE VAGUS (X)

Lateral columns contain 3 types of sensory nuclei

  • Unlike most motor nuclei, whose axons are carried in a single corresponding cranial nerve, each sensory nucleus receives input from several different cranial nerves.
Trigeminal sensory nucleus
  • Comprises 3 distinct nuclei:
    • Mesencephalic nucleus
      • Proprioceptive
      • Midbrain
    • Main sensory nucleus
      • Light touch
      • Pons
    • Spinal trigeminal tract nucleus
      • Pain and temperature
      • Pons + medulla
      • Contains
        • Pars Oralis
          • Hypoglossal nucleus to motor nucleus
        • Pars interpolaris
          • Obex to hypoglossal nucleus
        • Pars Caudalis
          • C2/3 to obex
          • An extension of the dorsal root entry zone and substantia gelatinosa of the trigeminal system into the lower medullary and high cervical regions
  • Receive input from
    • Trigeminal (V)
    • Facial (VII)
    • Glossopharyngeal (IX)
    • Vagus (X)
      • Headache, Facial Pain, and Disorders of Facial Sensation - ScienceDirect
TRIGEMINAL SENSORY NUCLEUS MEDIATES PROPRIOCEPTION (MESENCEPHAuC). LIGHT TOUCH (MAIN SENSORY). ANO PAIN AND TEMPERATURE SENSATION (SPINAL TRIGEMINAL) FOR FACE ANO HEAD Nuc•Eus "Gus SPNAL wc LEOS
notion image
Vestibular and cochlear nuclei
  • Extends from the rostral medulla into the pons
  • Receiving input from fibers of the vestibulocochlear nerve (VIII).
 
VESTIBULOCOCHLEAR NUCLEUS MEOIATES HEARING EQUILIBRIUM, ANO POSITION SENSATION AT THE HEAD ANO NECK
Solitary nucleus
  • Located in the medulla
  • Receives general and special visceral afferents carried in the (these CN enter the solitary nucleus via the solitary tract)
    • Facial (VII) - cranial part of the Solitary nucleus
    • Glossopharyngeal (IX) - middle part
    • Vagus (X) - Caudal part
  • These nerves mediate taste sensation as well as general visceral sensations of the heart, lungs, and GI tract.
  • Cell bodies of these visceral afferents
    • Located in sensory ganglia outside the brainstem;
    • Has central connections with the
      • Thalamus (taste sensation)
      • Reticular formation
      • Limbic system of the forebrain
      • See Taste
SOLITARY NUCLEUS MEDIATES TASTE SENSATION AND GENERAL VISCERAL SENSATION OF THE LUNGS, HEART. AND GASTROINTESTINAL TRACT
Gag reflex
  • Afferent: CN9 → solitary nucleus
  • Intermediate neurons:
    • Solitary projections to the nucleus ambiguus are largely bilateral
  • Efferent: Nucleus ambiguus → CN9/10
Vomiting centre
  • Nucleus tractus solitarius in the medulla receives:
    • Chemoreceptor trigger zone (CTZ, located within area postrema (pronounce “puke”-strema) in 4th ventricle)--
      • CTZ and adjacent vomiting center nuclei receive input through 5 major receptors:
        • Histamine (H1),
        • Muscarinic (M1),
        • Neurokinin (NK-1),
        • Dopamine (D2 ),
        • Serotonin (5-HT3).
      • 5-HT3, D2, and NK-1 antagonists
        • Treatment chemotherapy-induced vomiting.
      • H1 and M1 antagonists
        • Treatment motion sickness;
      • H1 antagonists
        • Treatment hyperemesis gravidarum.
    • GI tract (via CN10),
    • Vestibular system,
    • CNS.
      • Review of Blood Supply to SolNu and SolTr
      Structures
      Arteries
      SolNu and Tr in inferior cerebellar
      Caudal medulla, anterior spinal; rostral medulla, posterior inferior cerebellar
      Ascending Fibers in Pons
      Long circumferential branches of basilar and branches of superior cerebellar
      VPM
      Thalamogeniculate branches of posterior cerebral
      Posterior Limb of IC
      Lateral striate branches of middle cerebral
notion image
AmyNu: Amygdaloid nucleus (complex); CardResp: Cardiorespiratory portion (caudal) of solitary nucleus; GustNu: Gustatory nucleus (rostral portion of solitary nucleus); GVA: General visceral afferent; HyNu: Hypoglossal nucleus; HyTh: Hypothalamus; InfVNu: Inferior (or spinal) vestibular nucleus; MVNu: Medial vestibular nucleus; NuAm: Nucleus ambiguus; PBNu: Parabrachial nuclei; RB: Restiform body; SalNu: Salivatory nuclei; SolTr & Nu: Solitary tract and nuclei; SVA: Special visceral afferent; Tr: Tract; VA: Visceral afferent; VPM: Ventral posteromedial nucleus of thalamus; 1: Geniculate ganglion of facial; 2: Inferior ganglion of glossopharyngeal; 3: Inferior ganglion of vagus; 4: Dorsal motor vagal nucleus
      Image

Olivary nucleus

  • Are marked oval eminences
  • Located on the anterolateral surface of the medulla
    • At the inferior olivary nucleus, a cross-section shows fibers of the hypoglossal nerve separating it from the corticospinal tract running within the pyramids.
A diagram of the human body AI-generated content may be incorrect.
 
  • The olive consists of two parts:
    • Inferior olivary nucleus (or 'complex'),
      • Which is a part of the olivo-cerebellar system
        • Involved in cerebellar motor-learning and function.
      • Divided to 3 main nuclei:
        • Principle olivary nucleus
          • Aka: primary olivary nucleus
          • Consist of the major laminar structure.
        • Medial accessory olivary nucleus
          • Lies between the primary olivary nucleus and the pyramid,
          • Forms a curved lamina, the concavity of which is directed laterally.
        • Posterior accessory olivary nucleus
          • Aka: dorsal accessory olivary nucleus
          • Smallest
          • Appears on transverse section as a curved lamina behind the primary olivary nucleus.
    • Superior olivary nucleus
      • Considered
        • Part of the pons
        • Part of the auditory system,
          • Aiding the perception of sound.
      • BAER 3rd wave