Brain: Medial lemniscus
The sensory tract. (Medial lemniscus labeled at center right.)
Coronal section through mid-brain. ("e" is Portion of medial lemniscus, which runs to the lentiform nucleus and insula. "a’" is also the the medial lemniscus.)
Latin	lemniscus medialis
Gray's	subject #188 803
NeuroNames	ancil-736
NeuroLex ID	birnlex_887

The medial lemniscus, also known as Reil's band or Reil's ribbon, is a pathway in the brainstem that carries sensory information from the gracile and cuneate nuclei to the thalamus.

Contents 1 Path 2 Location of the medial lemniscus through the brainstem 3 See also 4 Additional images 5 External links

[edit] Path

After neurons carrying proprioceptive or touch information synapse at the gracile and cuneate nuclei, axons from secondary neurons decussate at the level of the medulla and travel up the brainstem as the medial lemniscus on the contralateral (opposite) side. It is part of the posterior column-medial lemniscus system, which transmits touch, vibration sense, as well as the pathway for proprioception.

The medial lemniscus axons from most of the body synapse at the ventral posterolateral nucleus of the thalamus. The axons transmitting information from the trigeminal nerve synapse at the ventral posteromedial nucleus of the thalamus.

[edit] Location of the medial lemniscus through the brainstem

• The cuneate and gracile nuclei reside at the closed (lower) medulla, so the lemniscus isn't formed at this level. Fibres from these nuclei will pass to the contralateral side of the brainstem, as the internal arcuate fibres.

• At the open medulla (further up the brainstem), the medial lemniscus contains axons from the trigeminal nerve (which supplies the head region), as well as the arms and legs. It sits very close to the midline, at the same orientation of the midline, with head fibres more dorsal (closer to the back), towards the fourth ventricle.

• By mid-pons, the medial lemniscus has rotated. Fibres from the head are medial, fibres from the leg are lateral.

• The orientation in the midbrain is similar to that in the pons.

[edit] See also

• Posterior column-medial lemniscus pathway

[edit] Additional images

Deep dissection of brain-stem. Lateral view.	Deep dissection of brain-stem. Ventral view.	Coronal section of the pons, at its upper part.	Transverse section of mid-brain at level of inferior colliculi.
Scheme showing the course of the fibers of the lemniscus; medial lemniscus in blue, lateral in red.

[edit] External links

• Brainstem at UWisc 04NGNC
• BrainMaps at UCDavis medial lemniscus

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v • d • e Human brain: rhombencephalon, myelencephalon: medulla (TA A14.1.04, GA 9.767) Dorsal Surface Posterior median sulcus · Posterolateral sulcus · Area postrema · Vagal trigone · Hypoglossal trigone · Medial eminence Grey: Cranial nuclei afferent: GVA: VII,IX,X: Solitary/tract/Dorsal respiratory group · SVA: Gustatory nucleus efferent: GSE: XII  · GVE: IX,X,XI: Ambiguus · SVE: X: Dorsal · IX: Inferior salivatory nucleus Grey: other Gracile nucleus · Cuneate nucleus (Accessory cuneate nucleus) White: Sensory/ascending Sensory decussation  · Medial lemniscus · Inferior cerebellar peduncle (Juxtarestiform body) · Ascending dorsal longitudinal fasciculus · MLF, III, IV and VI White: Motor/descending Descending dorsal longitudinal fasciculus · MLF, III, IV and VI Ventral White: Motor/descending Motor decussation · Olivocerebellar tract · Rubro-olivary tract Grey matter Ventral respiratory group · Arcuate nucleus of medulla · Inferior olivary nucleus Surface Anterior median fissure · Antero-lateral sulcus · Olive · Pyramid Grey: Raphe/ reticular Reticular formation (Gigantocellular, Parvocellular, Ventral, Lateral, Paramedian) · Raphe nuclei (Obscurus, Magnus, Pallidus)

v • d • e Human brain, rhombencephalon, metencephalon: pons (TA A14.1.05.101-604, GA 9.785) Dorsal/ (tegmentum) Surface Cerebellopontine angle · Superior medullary velum · Sulcus limitans · Medial eminence · Facial colliculus White: Sensory/ascending Trapezoid body/VIII · Trigeminal lemniscus (Dorsal trigeminal tract, Ventral trigeminal tract) · Medial lemniscus · Lateral lemniscus MLF, III, IV and VI: Vestibulo-oculomotor fibers Anterior trigeminothalamic tract · Central tegmental tract White: Motor/descending ICP (Vestibulocerebellar tract) MLF, III, IV and VI: Vestibulospinal tract (Medial vestibulospinal tract, Lateral vestibulospinal tract) Grey: Cranial nuclei afferent: GSA: Principal V/Spinal V · VIII-c (Dorsal, Anterior)/VIII-v (Lateral, Superior, Medial, Inferior) efferent: SVE: Motor V  · VII · GSE: VI · GVE: VII: Superior salivary nucleus Other grey Apneustic center · Pneumotaxic center (Medial parabrachial nucleus) · Lateral parabrachial nucleus · Superior olivary nucleus · Caerulean nucleus Ventral/ (base) Grey Pontine nuclei White: Motor/descending Corticospinal tract · Corticobulbar tract · Corticopontine fibers MCP (Pontocerebellar fibers) Surface Basilar sulcus Other grey: Raphe/ reticular Reticular formation (Caudal, Oral, Tegmental, Paramedian) · Raphe nuclei (Median)

v • d • e Human brain: mesencephalon (midbrain) (TA A14.1.06, GA 9.800) Tectum (Dorsal) Surface Corpora quadrigemina: Inferior colliculi (Brachium of inferior colliculus), Superior colliculi (Brachium of superior colliculus) Grey matter Pretectal area White: Sensory/ascending Spinotectal tract · Central tegmental tract White: Motor/descending Tectospinal tract Peduncle (Ventral) Peduncle tegmentum White: Sensory/ascending lemnisci (Medial, Lateral) · Ascending MLF (Vestibulo-oculomotor fibers) · Spinothalamic tract · Anterior trigeminothalamic tract · Dentatothalamic tract White: Motor/descending Rubrospinal tract · Rubro-olivary tract · Descending MLF Grey: cranial nuclei GSA (V: Mesencephalic) - GSE (III: Oculomotor, IV: Trochlear) - GVE (III: Edinger-Westphal) Grey: other Periaqueductal gray/Raphe nuclei (Dorsal raphe nucleus) Ventral tegmental area • Pedunculopontine nucleus • Red nucleus riMLF Ventricular system Cerebral aqueduct Peduncle base White: Motor/descending Cerebral crus: Corticospinal tract · Corticobulbar tract · Corticopontine tract/Frontopontine fibers/Temporopontine fibers Grey: Substantia nigra Pars compacta · Pars reticulata Surface Superior cerebellar peduncles (Decussation of superior cerebellar peduncle) · Interpeduncular fossa

v • d • e Brain and spinal cord: neural tracts and fasciculi Sensory/ascending PCML 1°: Pacinian corpuscle/Meissner's corpuscle → Gracile fasciculus/Cuneate fasciculus → Gracile nucleus/Cuneate nucleus 2°: → sensory decussation/arcuate fibers (Posterior external arcuate fibers, Internal arcuate fibers) → Medial lemniscus/Trigeminal lemniscus → Thalamus (VPL, VPM) 3°: → Posterior limb of internal capsule → Postcentral gyrus Anterolateral/ pain Fast/lateral 1° (Free nerve ending → A delta fiber) → 2° (Anterior white commissure → Lateral and Anterior Spinothalamic tract → Spinal lemniscus → VPL of Thalamus) → 3° (Postcentral gyrus) → 4° (Posterior parietal cortex) 2° (Spinotectal tract → Superior colliculus of Midbrain tectum) Slow/medial 1° (Group C nerve fiber → Spinoreticular tract → Reticular formation) → 2° (MD of Thalamus) → 3° (Cingulate cortex) Motor/descending Pyramidal flexion: Primary motor cortex → Posterior limb of internal capsule → Decussation of pyramids → Corticospinal tract (Lateral, Anterior) → Neuromuscular junction Extrapyramidal flexion: Primary motor cortex → Genu of internal capsule → Corticobulbar tract → Facial motor nucleus → Facial muscles flexion: Red nucleus → Rubrospinal tract extension: Vestibulocerebellum → Vestibular nuclei → Vestibulospinal tract extension: Vestibulocerebellum → Reticular formation → Reticulospinal tract Midbrain tectum → Tectospinal tract → muscles of neck Basal ganglia direct: 1° (Motor cortex → Striatum) → 2° (GPi) → 3° (Lenticular fasciculus/Ansa lenticularis → Thalamic fasciculus → VL of Thalamus) → 4° (Thalamocortical radiations → Supplementary motor area) → 5° (Motor cortex) indirect: 1° (Motor cortex → Striatum) → 2° (GPe) → 3° (Subthalamic fasciculus → Subthalamic nucleus) → 4° (Subthalamic fasciculus → GPi) → 5° (Lenticular fasciculus/Ansa lenticularis → Thalamic fasciculus → VL of Thalamus) → 6° (Thalamocortical radiations → Supplementary motor area) → 7° (Motor cortex) nigrostriatal pathway: Pars compacta → Striatum Bidirectional: Spinocerebellar Unconscious proprioception: Golgi tendon organ → Spinocerebellar (Dorsal/Posterior thoracic nucleus, Cuneocerebellar) → Cerebellum Reflex arc: Ventral - Rostral Brain only Medial longitudinal fasciculus Vestibular nucleus → Vestibulocerebellar tract → Cerebellum Pontine nuclei → Pontocerebellar fibers → Deep cerebellar nuclei Inferior olivary nucleus → Olivocerebellar tract → Cerebellar hemisphere Dentate nucleus → Dentatothalamic tract → Thalamus (VL) see also white matter fibers

v • d • e Nervous system, receptors: somatosensory system (GA 10.1059) Medial lemniscus Touch/mechanoreceptors: Pacinian corpuscles – vibration • Meissner's corpuscles – light touch • Merkel's discs – pressure • Ruffini endings - stretch • Free nerve endings – pain • Hair cells • Baroreceptor Proprioception: Golgi organ – tension/length • Muscle spindle – velocity of change (Intrafusal muscle fiber • Nuclear chain fiber • Nuclear bag fiber) Spinothalamic tract Pain: Nociception and Nociceptors Temperature: Thermoreceptors