The Cerebellum

Position

Lies above and behind the medullar and pons and occupies posterior cranial fossa

Cerebellum

External features

Consists of two cerebellar hemisphere united in the midline by the vermis

External features

Three peduncles Inferior cerebellar peduncle

－ connect with medulla and with spinal cord, contain both afferent and efferent fibers

Middle cerebellar peduncle － connect with pons, contain afferent fibers

Superior cerebellar peduncle － connect with midbrain, contain mostly efferent fibers

External features

Tonsil of cerebellum two elevated masses on inferior surface of hemispheral portion just nearby foramen magnum

Lobs Two deep fissures

Primary fissure

Posterolateral fissure

Three lobs

Flocculonodular lobe 叶 floccul

us and nodule

Anterior lobe

Posterior lobe

Corpus of cerebellar

Lobs

Primary fissure

Posterolateral fissureFlocculonodular lobe

Anterior lobe

Posterior lobe

corpus of cerebellar

Internal structures Gray matter Cerebellar cortex Cerebellar nuclei

Dentate nucleus Fastigial nucleus Interposed nucleus

Emboliform nucleus Globose nucleus

White matter － medullary center

Internal structures

Cerebellar cortex

Dentate nucleus

Fastigial nucleus

Globose nucleus

Emboliform nucleus

medullary center

Three functional divisions Vestibulocerebellum

Archicerebellum Flocculonodular lobe

Spinocerebellum Paleocerebellum Vermis and intermediate

zone Cerebrocerebellum

Neocerebellum Lateral zone Flocculonodular lobe

Verm

is In

termed

iate zo

ne

Lateral

zon

e

Connections and function of cerebellum

Vestibulocerebellum Connections

Afferents: receive input from vestibular nuclei and primary vestibular

Efferents: projects to the vestibular nucleus → vestibulospinal tract and medial longitudinal fasciculus → motor neurons of anterior horn

Function: involved in eye movements and maintain balance

Connections and function of cerebellum

Spinocerebellum Connnection

Afferents: receive somatic sensory information via spinocerebellar tracts

Efferents: Vermis projects to the fastigial nucleus → vestibular nucl

ei and reticular formation → vestibulospinal tract and reticulospinal tract → motor neurons of anterior horn

Intermediate zone projects to the interposed nuclei Contralateral red nucleus → rubrospinal tract →motor neurons of

anterior horn Contralateral VI →cerebral cortex→ coticospinal tract→motor ne

urons of anterior horn

Function: play an important role in control of muscle tone and coordination of muscle movement on the same side of the body

Connections and function of cerebellum

Cerebrocerebellum Connection

Afferents: receives input from the cerebral cortex via a relay in pontine nuclei

Efferents: projects to dentate nucleus → VI → primary motor cortex → corticospinal tract → motor neurons of anterior horn

Function: participates in planning movements

小脑的分叶和功能 前庭小脑－古小脑 － 绒球小结叶 维持身体姿势平衡和协调眼球运动 脊髓小脑－旧小脑 包括蚓垂、蚓锥体和前叶 控制运动中的肢体远端肌的肌张力和协调 大脑小脑－新小脑 : 协调肢体的随意运动，使运动更精确

小脑损伤的临床表现 小脑是运动的重要调节中枢，有大量的传入和传出联系。大脑皮

质发向肌肉的运动信息和执行运动时来自肌肉和关节等的信息，都可传入小脑。小脑经常对这两种传来的神经冲动进行整合，并通过传出纤维调整和纠正各有关肌肉的运动，使随意运动保持协调。此外，小脑在维持身体平衡上也起着重要作用。它接受来自前庭器官的信息，通过传出联系，改变躯体不同部分肌肉的张力，使肌体在重力作用下，作加速或旋转运动时保持姿势平衡。此外，据研究，小脑对内脏机能活动也有一定作用。小脑损伤引起的功能障碍是同侧性的。小脑受损伤后功能障碍主要表现为：肌张力低下，肌肉弛缓，如出现小腿呈钟摆样反射；随意运动发生障碍，表现为运动的速度、范围、力量和方向不准确，如步态失调，动作笨拙；平衡障碍，如躯体不易维持直立姿势，而向受损侧倾斜；植物性神经系统功能障碍，如尿失禁。

The Diencephalon

Position Position: Lies between midbrian and cerebrum, almost

entirely surrounded by cerebral hemisphere

Subdivision Doral thalamus Metathalamus Epithalamus Subthalamus Hypothalamus

Dorsal thalamusExternal features A large egg-shaped nucle

us mass, Anterior end called anterio

r thalamic tubercle, Posterior end called pulvin

ar Right and left portion of th

alamus are joined by interthalamic adhesion

Floor － hypothalamic sulcus

Classification of nuclei of dorsal thalamus

Three nuclear group － divided by internal medullary lamina

Anterior nuclear group Medial nuclear group Lateral nuclear group

Med. nuclear group

Ant. nuclear group Dorsal tier

internal medullary lamina

Ventral anterior

Ventral intermediate

Ventral posterolateral (VPL)

Ventral posteromedial (VPM )

Pulvinar

Medial geniculate body (MGN)

Lateral geniculate body (LGN) Ventral posterior nucleus (VP)

Subdivision Principal Nuclei Common abbreviation

Ant. nuclear group

Med. nuclear group

Lat. nuclear group

Dorsal tier Lateral dorsal LD

Lateral posterior LP

Pulvinar

Ventral tier Ventral anterior VA

Ventral intermediate VI

Ventral posterior VP

Ventral posterolateral VPL

Ventral posteromedial VPM

Functional subdivisionNonspecific relay nuclei － receive afferents from rh

inencephalon and reticular formation of brain stem, project mainly to hypothalamus and corpus striatum

Midline nucleus group Intralaminar nuclear group Thalamic reticular nucleusAssociation nuclei － receive input from many conv

erging sours and in turn project widely to the association areas of cerebral cortex

Anterior nuclear group Medial nuclear group Dorsal tier of lateral nuclear group

Special relay nuclei Vent. anterior nucleus (VA) Vent. intermediate nucleus (VI) Receiving dentate nucleus, globus pallidus and substantia nigra to m

otor cortex

Vent. posteromedial nucleus (VPM) － receives trigeminal lemniscus and teste fibers

Vent. posterolateral nucleus (VPL) － receives medial lemniscus and spinal lemniscus

Projects to first somatic sensory area via central thalamic radiation

Metathalamus

Lateral geniculate body (LGN)

Medial geniculate body (MGN)

Metathalamus

Metathalamus Medial geniculate body

(MGN) Relay station of audition Receive fibers from inferio

r colliculus Projects to auditory area vi

a acoustic radiation Lateral geniculate body

(LGN) Relay station of vision Receive fibers from optic t

ract Projects to visual area via

optic radiation

EpithalamusIncludes Thalamic medullary s

tria Habenular trigone Habenular commissur

e Pineal body posterior commissure

HypothalamusPosition － lies ventral to thalamus

Boundaries Superiorly: hypothalamic sulcus

Inferiorly: optic chiasma

tuber cinereum

Infundibulum

mamillary body

Anterior: lamina terminalis Posterior: continues with midbrai

n tegmentum

Subthalamus 底丘脑

Transition zone between diencephalons and tegmentum of midbrain

Contain subthalamic nucleus( 底丘脑核 ), parts of red nucleus and substantia nigra

Subdivisions Preoptic region 视前区 Supraoptic region 视上区 Tuberal region 结节区 Mamillary region 乳头体区

Important nuclei Supraoptic region 视上区

Supraoptic nucleus 视上核－ produce antidiuretic hormone 抗利尿激素 (ADH ， vasopressin 加压素 )

Paraventricular nucleus 室旁核－ produce oxytocin 催产素 Tuberal region 结节区

Infundibular nucleus 漏斗核 Ventromedial nucleus 腹内侧核 Dorsomedial nucleus 背内侧核

Mamillary region 乳头体区 Mamillary nucleus 乳头体核 Posterior hypothalamic nucleus 下丘脑后核

Paraventricular nucleus

Supraoptic nucleus

Mamillary nucleus

arcuate nucleus

Paraventriculohypophyeal tract

Supraopticohypophyseal tract

infundibulum

posterior lobe of hypophysisanterior lobe of hypophsis

tuberoinfundibular tract

Hypothalamus --connection

Connects with limbic system Connects with brainstem and spinal cord Connects with dorsal thalamus Connects with hypophysis

Hypothalamus --connection Supraoptic nucleus →supraoptic nucleus (A

DH) →supraopticohypophyseal tract →posterior l

obe of hypophysis

Paraventricular nucleus → paraventicular n

ucleus (oxytocin) →paraventriculohypophyseal t

ract→posterior lobe of hypophysis

Paraventricular nucleus

Paraventriculohypophyseal tract

Supraoptic nucleus

Supraopticohypophyseal trac

posterior lobe of hypophysis

Inferior hypophyseal a.

Hypophyseal v.

Tuberoinfundibular tract

Median eminence

Portal v.

Superior hypophyseal a.

Hypophyseal v.anterior lobe

Parvicellular neurons in the arcuate nucleus and nearby region of the walls of the third ventricle secrete releasing and inhibiting hormones → tuberoinfundibular tract →portal vein of hypophsis → anterior lobe of hypophsis

Hypothalamus

Function Regulates functions of neuroendocrine system Autonomic nervous system

Third ventricle Position: a narrow ventricle c

left lies within diencephalons Boundaries

Roof: choroids plexus Floor: optic chiasma, tuber cinereu

m, infundibulum and mamillary body

Anterior: lamina terminalis Posterior: continuous with mesenc

ephalic aqueduct Lateral wall: dorsal thalamus and h

ypothalamus

Communication Third ventricle →mesencephalic aqueduct

→ fourth ventricle