Brain Stem Internal

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Nervous system

brain stem

Weihua Yu Department of Anatomy

Chongqing Medical University

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Brain is divide into 6 parts ： telencephalon

diencephalon

cerebellum

brain stem

telencephalon

diencephalon

brain stem

midbrain

pons medulla oblongata

cerebellum

mid brain pons medulla oblongata

procerebrum ： telencephalon and diencephalonmidbrain ： don’t have obvious change

afterbrain

Cerebullar development

Brain

afterbrain ： pons and cerebellum marrowbrain ： medulla oblongata

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1. ventral surface of brain stem

the shape of brain stem

（ 1）medulla oblongata bulbopontine sulcus pyramid decussation of pyramid olive

（ 2） pons basilar part of pons basilar sulcus middle cerebellar peduncle bulbopontine sulcus

（ 3）mid brain cerebral peduncle interpeduncular fossa posterior perforated substance

The external features of brain stem

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There are 9 pairs of cranial nerves on ventral surface of brain stem ： ① the oculomotor nerves links with mid brain, and arise from

interpeduncular fossa ；② there are four pairs of cranial nerves links with pons ： trigeminal nerves （ v ） linked with basilar part of pons

there are abducent nerve （Ⅵ） ,facial nerve （Ⅶ） and vestibulocochlear

nerve （Ⅷ） in the juncture with middle cerebellar peduncle or bulboponti

ne

sulcus from medial to lateral.

③ There are four pairs of cranial nerves linked with medulla oblongata ： gloss

opharyngeal nerve （Ⅸ）， vagus nerve （Ⅹ） and accessory nerve

（Ⅺ） on the dorsal and lateral side of olive from above downward in order. T

he hypoglossal nerve （Ⅻ） leaves medulla oblongata between pyramids of m

edulla oblongata and olive.

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2. Dorsal surface of brain stem

（ 1）medulla oblongata gracile tubercle cuneate tubercle inferior cerebellar peduncle （ restiform body ）

（ 2） pons superior cerebellar peduncle middle cerebellar peduncle（ 3）mid brain superior colliculus inferior colliculus quadrigeminal bodies brachium of superior colliculus brachium of inferior colliculus（ 4） rhomboid fossa sulcus median 、 sulcus limitans 、 striae medullares 、 medial eminence 、 facial colliculus 、 hypoglossal triangle 、 vagal triangle 、 funiculus separans 、 areas postrema 、 vestibular area 、 acoustic tubercle 、locus ceruleus 、 obex

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3. fourth ventricle of cerebrum

superior medullary veluminferior medullary velumtela choroidea of fourth ventricleependymachoroid plexus of fourth ventricle

There are 3 holes on fourth ventricle ： single median aperture of fourth ventricle lies in rhomboid fossa ； paired lateral aperture of fourth ventricle

Communicate with subarachnoid space

medulla oblongata 、 ponsand cerebellum

Similar to diamond shapeThe bottom is rhomboid fossaThe point exposition to vermis

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The internal structure of brain stem

Compared with spinal cord, the internal structure of brain stem appears the following characters ：

（ 1 ） The structure of medulla oblongata’s inferior part is similar to spinal cord. The central canal still remains, but moves to dorsal gradually.

（ 2 ） The gray matter of brain stem don’t continue and form gray column which run lengthwise through the total length of brain stem like that in spinal cord, but get together forming all kinds of nucleus separated with each other.

（ 3 ） The nucleus groups of gray substance of spinal cord all link with spinal nerve basically.

（ 4 ） The reticular structure appeared in the region between gray matter and white matter has sharp expansion area, and more complex in structure, which contains many important nuclear groups of vital center, such as center of heartbeat, blood pressure and respiratory.

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1. Gray matter of brain stem

Nuclei of cranial nerves“non-nuclei of cranial nerves” relay nucleus reticular nucleus

（ 1 ） nuclei of cranial nerves

somatic motor fibervisceral motor fibervisceral sensory fibersomatic sensory fiber

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（ 1 ） general motor nucleus 4 pairs

dominate skeletal muscle（ lingual muscle ，extraocular muscles ）

nucleus of oculomotor nerve

nucleus of trochlear nerve

nucleus of abducent nerve

hypoglossal nucleus

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（ 2 ） special visceral motor nucleus 4 pairs

Dominate the skeletal muscle evolved from branchial arch

masseter muscle 、 muscles 、 soft palate 、 pharyngeal muscle 、 laryngeal muscle

motor nucleus of trigeminal nervefacial nucleusambiguous nucleusaccessory nucleus

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（ 3 ） general visceral motor nucleus ： 4 pairs

Dominate smooth muscle 、 cardiac muscle and glands

accessory nucleus of oculom

otor nerve

superior salivatory nucleus

inferior salivatory nucleus

dorsal nucleus of vagus

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（ 4 ） general visceral sensory nucleus ： 1 pair

receive the sensory fiber of organ and cardiovascular

the lower half of solitary nucleus

（ 5 ） special visceral sensory nucleus

receive taste fibers

the capitular head of solitary nucleus

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（ 6 ） general somatic sensory nucleus ： 1 pair

Receive sensory fiber of skin on head and face and mucosa in oral andnasal cavity

mesencephalic nucleus of trigeminal nerve ：the proprioceptive sense of masseter muscle pontine nucleus of trigeminal nerve ：tactile sense spinal nucleus of trigeminal nerve ：sense of pain and warm

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（ 7 ） special somatic sensory nucleus

vestibular nucleus （ superior nucleus 、 interior 、 lateral nuclear 、 inferior nucleus ） cochlear nucleus dorsal nucleus of cochlear nerve ventral nucleus of cochlear nerve（ anterior nucleus 、 posterior nucleus)

Receive the fiber of auditory or equilibratory sensation.

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According to the nature and function, 6 functional columns arrange longitudinally in brain stem according to the following laws ：

In the gray matter of the bottom of fourth ventricle of cerebrum, the motor nucleus and columns are interior to sulcus limitans ， while the sensory nucleus and columns lie lateral to sulcus limitans ； from median line to two sides are general somatic motor column, general visceral motor column, general and special visceral sensory column and special somatic sensory column. Special visceral column and general somatic sensory column are ventrolateral to gray matter of pavimentum ventriculi, or in reticular structure.

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2 、 non-nuclei of cranial nerves

1 ） medulla oblongata（ 1 ） gracile nucleus cuneate nucleus （ medial lemniscus ）

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（ 2 ） inferior olivary nucleus ： participate in the controlling of cerebellum on motor olivocerebellar tract→inferior cerebellar peduncle enter into cerebellum（ 3 ） accessory cuneate nucleus cuneocerebellar tract→inferior cerebellar peduncle enter into cerebellum

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2 ） Pons

（ 1 ） superior olivary nucleus enter into lateral lemniscus and participate in tone localization

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（ 2 ） nuclei of ponspontocerebellar fibers→middle cerebellar peduncle enter into cerebellumThe relay station of these fibers connects cerebral cortex with cerebellum cortex.

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（ 3 ） nucleus of lateral lemniscuslateral lemniscus

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（ 1 ） inferior colliculus receive the termination of lateral lemniscus ，auditory reflex center（ 2 ） superior colliculus visual reflex center ， tectospinal tract emited from superior colliculus red nucleus, eyes and horns of a cattle cow

3 ） mid brain

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（ 3 ） pretectal area lies in the symphyses of mid brain with diencephalon, an area between commissura posterior and superior colliculus

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（ 4 ） red nucleus ： receive the projection of dentate body of cerebellum receive the corticocerebral projection send out fibers to spinal cord — rubrospinal tract send out fibers to inferior olivary nucleus（ 5 ） substantia nigra produce dopamine→ neostriatum（ 6 ） ventral tegmental area the deep surface of interpeduncular fossa contains dopamine neurons, which participates in the regulation of voluntary movements

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white matter fiber bundles long preceding fiber bundles

long descending fiber bundles

1 、 long preceding fiber bundles

medial lemniscus

spinal lemniscus

trigeminal lemniscus

lateral lemniscus

anterior spinocerebellar tract

posterior spinocerebellar tract

medial longitudinal fasciculus

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1 ） medial lemniscus→nucleus ventralis posterolateralis thalami

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1 ） medial lemniscus

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1） medial lemniscus

The sensory conductive pathway

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2 ） spinothalamic tract （ spinal lemniscus ）→ nucleus ventralis posterolateralis thalami

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2 ） spinothalamic tract （ spinal lemniscus ）

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3 ） spinal lemniscus →nucleus ventralis posteromedialis thalami

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3 ） trigeminal lemniscus

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3 ） trigeminal lemniscus

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3） trigeminal lemniscus

the conductive pathway

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4 ） lateral lemniscus

arises from the auditory fibers of superior olivary nucleus on two sides and dorsal cochlear nucleus as well as ventral cochlear nucleus of opposite side. The lateral lemniscus turns upward on the lateral superior olivary nucleus and forms lateral lemniscus→inferior colliculus→medial geniculate body

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4） lateral lemniscus

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trapezoid bodyThe auditory fibers of superior olivary nucleus and ventral cochlear nucleus runs transversely in the inferior middle part of pons, then crosses above median line and forms trapezoid body. Some trapezoid body fibers turn upward and join lateral lemniscus.


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4） lateral lemniscus

the conductive pathway

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5 ） posterior spinocerebellar tract

anterior spinocerebellar tract→ascending

via superior cerebellar peduncle →enter in

to cerebellum

posterior spinocerebellar tract→ inferior cerebe

llar peduncle →enter into cerebellum

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preceding fiber→extraocular muscles motor nucleus

descending fiber→cervical cord segment→intermedial zone and medial part of anterior horn

6 ） medical longitudinal fasciculus

these fibers derived from vestibular nucleus go upward and downward along median line.

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pyramidal tract

rubrospinal tract

tectospinal tract

vestibulospinal tract

reticulospinal tract

2 、 long descending fiber bundle

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1 ） pyramidal tract

corticonuclear tract

corticospinal tract

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corticospinal tract

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corticospinal tract

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corticospinal tract

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corticospinal tract

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1） pyramidal tract corticonuclear tractcorticospinal tract

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2 ） tectospinal tract

3 ） rubrospinal tract

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4 ） vestibulospinal tract

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3 、 reticular formation of brain stem

There are lots of pericaryon in central region of brain stem. The fibers arranged in a cross pattern, which constitutes reticular formation of brain stem.

the main nucleus groups of reticular formation of brain stem

1 ） the nuclear groups project to cerebellum2 ） raphe nuclei groups3 ） the reacting region of medial nucleus4 ） the reception region of lateral nuclear group

Brain Stem Internal

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