All Nuclei of the CNS

Neuroanatomy

Nucleus gracilis

• Located in the medulla oblongata (posterior column);

• relays fine touch and proprioception from the lower limbs;

• forms the medial lemniscus after decussation to the thalamus (VPL)

Nucleus cuneatus

• Located in the medulla oblongata (posterior column);

• relays fine touch and proprioception from the upper limbs;

• forms the medial lemniscus to the thalamus (VPL)

Inferior olivary nucleus

• Located in the medulla oblongata (tegmentum);

• coordinates motor activity and learning;

• sends olivocerebellar fibers to the contralateral cerebellar cortex

Vestibular nuclei

• Located in the pons and medulla (floor of the fourth ventricle);

• maintain balance, posture, and eye coordination;

• connect via vestibulospinal and vestibulocerebellar tracts

Cochlear nuclei

• Located at the junction of pons and medulla;

• relay auditory information from the cochlea;

• project via trapezoid body to superior olivary nucleus and lateral lemniscus

Pontine nuclei

• Located in the basis pontis of the pons;

• relay motor information from the cerebral cortex to the cerebellum through corticopontine and pontocerebellar fibers

Superior olivary nucleus

• Located in the pons (tegmentum);

• processes binaural auditory input for sound localization;

• part of trapezoid body and lateral lemniscus pathway

Red nucleus

• Located in the midbrain (tegmentum);

• controls motor coordination and muscle tone;

• connects via cerebellorubral and rubrospinal tracts

Substantia nigra

• Located in the midbrain (basis pedunculi);

• produces dopamine for motor control;

• part of the nigrostriatal pathway to the striatum

Superior colliculus nucleus

• Located in the midbrain (tectum);

• mediates visual reflexes and eye–head coordination;

• origin of the tectospinal tract

Inferior colliculus nucleus

• Located in the midbrain (tectum);

• processes auditory reflexes and sound localization;

• projects to the medial geniculate body

Dentate nucleus

• Located in the lateral cerebellar hemisphere;

• coordinates planning, initiation, and precise control of voluntary movements;

• projects via the dentatothalamic and dentatorubral tracts

Emboliform nucleus

• Located in the intermediate cerebellar hemisphere;

• regulates limb movements and muscle tone;

• sends output through the interposed nuclei pathways to the red nucleus

Globose nucleus

• Located medial to the emboliform nucleus in the intermediate zone;

• controls proximal limb movements;

• connects to the red nucleus via the cerebellorubral tract

Fastigial nucleus

• Located in the vermis (medial cerebellum);

• maintains posture, balance, and eye movements;

• connects via vestibulocerebellar and reticulocerebellar tracts

Reticular formation nuclei

• Located throughout the brainstem;

• regulate arousal, pain, and autonomic functions;

• connected via reticulospinal and reticulocerebellar tracts

Ventral posterior lateral nucleus (VPL)

• Located in the thalamus (lateral group);

• relays sensory input from the body to the somatosensory cortex;

• receives spinothalamic and medial lemniscus fibers

Ventral posterior medial nucleus (VPM)

• Located in the thalamus (lateral group);

• relays sensory input from the face to the somatosensory cortex;

• receives trigeminal lemniscus fibers

Lateral geniculate body (LGB)

• Located in the thalamus (metathalamus);

• visual relay nucleus;

• receives optic tract and projects to the visual cortex

Medial geniculate body (MGB)

• Located in the thalamus (metathalamus);

• auditory relay nucleus;

• receives inferior colliculus input and projects to the auditory cortex

Anterior thalamic nuclei

• Located in the thalamus (anterior group);

• relay limbic information for emotion and memory;

• connected via the mammillothalamic tract to the cingulate cortex

Mediodorsal thalamic nucleus

• Located in the thalamus (medial group);

• involved in emotion and cognition;

• connects to frontal and cingulate cortices

Pulvinar nucleus

• Located in the thalamus (posterior-lateral group);

• integrates sensory information and attention;

• projects to the parietal cortex

Subthalamic nucleus

• Located in the subthalamus;

• modulates motor activity of the basal ganglia;

• connected to the globus pallidus via the subthalamic fasciculus

Habenular nuclei

• Located in the epithalamus;

• process reward and emotional responses;

• connected via the habenulointerpeduncular tract

Preoptic nucleus

• Located in the anterior hypothalamic area;

• regulates body temperature by promoting heat loss through vasodilation and sweating;

• part of the thermoregulatory center

Supraoptic nucleus

• Located in the hypothalamus (anterior region);

• produces vasopressin (ADH);

• sends axons through the hypothalamo-hypophyseal tract to the posterior pituitary

Paraventricular nucleus

• Located in the hypothalamus (anterior region);

• produces oxytocin and releasing hormones;

• connected via the hypothalamo-hypophyseal tract

Suprachiasmatic nucleus

• Located above the optic chiasm;

• serves as the circadian rhythm pacemaker;

• receives direct retinal input for synchronization of biological clocks

Anterior hypothalamic nucleus

• Located anteriorly near the preoptic area;

• promotes heat dissipation and activates parasympathetic responses during elevated body temperature

Arcuate nucleus

• Located in the hypothalamus (tuberal region);

• regulates pituitary hormone secretion;

• projects through the tuberoinfundibular pathway

Ventromedial nucleus

• Located in the hypothalamus (tuberal region);

• acts as the satiety center inhibiting feeding;

• connected via the medial forebrain bundle

Dorsomedial nucleus

• Located in the tuberal region;

• integrates autonomic and emotional behavior;

• influences circadian and feeding responses

Posterior hypothalamic nucleus

• Located in the posterior hypothalamic area;

• promotes heat conservation and sympathetic activation during cold exposure;

• associated with arousal and wakefulness

Mammillary nucleus

• Located in the hypothalamus (posterior region);

• involved in memory and limbic relay;

• projects via the mammillothalamic tract to the anterior thalamus

Caudate nucleus

• Located in the telencephalon (basal nuclei);

• controls movement and cognition;

• receives corticostriatal and nigrostriatal inputs

Putamen

• Located in the telencephalon (basal nuclei);

• regulates learned movement patterns;

• receives corticostriatal fibers

Globus pallidus

• Located in the telencephalon (basal nuclei, internal and external segments);

• regulates voluntary movement via pallidothalamic fibers to VA/VL thalamic nuclei

Nucleus accumbens

• Located in the telencephalon (ventral striatum);

• mediates reward, motivation, and reinforcement;

• receives mesolimbic dopaminergic input

Amygdaloid nucleus

• Located in the telencephalon (temporal lobe, limbic system);

• controls emotion and behavior;

• connected via stria terminalis and ventral amygdalofugal pathway

Claustrum

• Located in the telencephalon (between insula and putamen);

• integrates multisensory information;

• connected with cortical association areas

Olfactory (I)

• Nucleus: Olfactory bulb and tract

• Location: Telencephalon (base of frontal lobe)

• Function: Smell perception

• Type: Sensory

Optic (II)

• Nucleus: Lateral geniculate body

• Location: Diencephalon (thalamus)

• Function: Visual relay to occipital cortex

• Type: Sensory

Oculomotor (III)

• Nucleus: Oculomotor nucleus, Edinger–Westphal nucleus

• Location: Midbrain at the level of superior colliculus

• Function:

  • Oculomotor nucleus: motor control of extraocular muscles (SR, IR, MR, IO)

  • Edinger–Westphal nucleus: parasympathetic control for pupil constriction and lens accommodation

• Type: Motor + Parasympathetic

Trochlear (IV)

• Nucleus: Trochlear nucleus

• Location: Midbrain at the level of inferior colliculus (dorsal aspect)

• Function: Innervates superior oblique muscle (eye depression and intorsion)

• Type: Motor

Trigeminal (V)

• Nuclei:

  • Motor nucleus of V – controls muscles of mastication

  • Principal (chief) sensory nucleus – touch and pressure from face

  • Spinal nucleus of V – pain and temperature from face

  • Mesencephalic nucleus of V – proprioception from jaw muscles

• Location: Pons and medulla (extends into midbrain)

• Type: Sensory + Motor

Abducens (VI)

• Nucleus: Abducens nucleus

• Location: Pons (floor of 4th ventricle)

• Function: Innervates lateral rectus muscle for eye abduction

• Type: Motor

Facial (VII)

• Nuclei:

  • Facial motor nucleus – muscles of facial expression

  • Superior salivatory nucleus – parasympathetic to submandibular, sublingual, lacrimal glands

  • Nucleus tractus solitarius (NTS, rostral part) – taste from anterior 2/3 of tongue

• Location: Pons

• Type: Motor + Sensory + Parasympathetic

Vestibulocochlear (VIII)

• Nuclei:

  • Vestibular nuclei (superior, inferior, medial, lateral) – balance and head position

  • Cochlear nuclei (anterior and posterior) – auditory information

• Location: Pons–medulla junction

• Type: Sensory

Glossopharyngeal (IX)

• Nuclei:

  • Nucleus ambiguus – motor to stylopharyngeus muscle

  • Inferior salivatory nucleus – parasympathetic to parotid gland

  • Nucleus tractus solitarius (NTS, middle part) – taste and visceral sensation from posterior 1/3 of tongue

  • Spinal nucleus of V – pain and temperature from ear and pharynx

• Location: Medulla oblongata

• Type: Motor + Sensory + Parasympathetic

Vagus (X)

• Nuclei:

  • Dorsal motor nucleus of vagus – parasympathetic control of thoracic and abdominal viscera

  • Nucleus ambiguus – motor to pharynx and larynx

  • Nucleus tractus solitarius (NTS, caudal part) – visceral sensory input

  • Spinal nucleus of V – somatic sensory from ear and meninges

• Location: Medulla oblongata

• Type: Motor + Sensory + Parasympathetic

Accessory (XI)

• Nucleus: Spinal accessory nucleus (C1–C5 ventral horn), cranial root from nucleus ambiguus

• Location: Cervical spinal cord and medulla

• Function: Sternocleidomastoid and trapezius control (spinal part); pharyngeal and laryngeal muscles (cranial part)

• Type: Motor

Hypoglossal (XII)

• Nucleus: Hypoglossal nucleus

• Location: Medulla oblongata (floor of 4th ventricle)

• Function: Tongue muscle movement (intrinsic and extrinsic)

• Type: Motor