最新七科联考系统解剖学解剖脑干PPT文档.ppt

Section 2 脑 Brain,Brain contains almost 98%of bodys neural tissue,average weight about l,400 grams and is composed of an estimated 100 billion neurons.,Although it accounts for only 2%of a persons body weight,brain receives approximately 20%of total resting cardiac output(about 750 2100 ml of blood per minute).,Brain needs a continuous supply of oxygen and nutrients.So a failure of cerebral circulation for as short an interval as 10 seconds causes unconsciousness.,Brain is divided into four principal parts:脑干 Brain stem consists of medulla oblongata,pons and midbrain.Its lower end is continuous with spinal cord.小脑 Cerebellum lies behind pons and medulla oblongata.,间脑 Diencephalon consists primarily of hypothalamusand thalamus;and over it spreads.端脑Telencephalon.,Part 1.脑干 Brain Stem,基本要求 掌握脑干的组成及各部的主要结构；脑神经核的名称、位置、纤维联系、性质和功能；脑干内非脑神经核的名称，位置与性质；脑干内长的上、下行纤维束名称、起始、终止、性,质、各纤维束交叉的部位。熟悉第四脑室的位置、境界，脉络组织、脉络丛的概念。了解网状结构，脑干各代表平面的结构与损伤后的表现。,Brain stem is stalk like part of brain,which connects cerebrum,cerebellum with spinal cord.,Optic tract serves as rostral boundary of brain stem,which separates it from diencephalon.Plane corresponding to level of foramen magnum serves to separate it from spinal cord.,On ventral aspect,two distinct transverse grooves just above superior border and below inferior border of pons demarcatethree parts of brain stem,from below upwards,medulla oblongata,pons and midbrain.,I.脑干的外形 External features I)延髓 Medulla oblongata is most caudal part of brain,stem.Its ventral surface rests upon basilar portion of occipital bone,while its dorsal surface is in large part covered by cerebellum.Fissure and sulci presented in spinal cord extend upwards in medulla oblongata and a series of rootlets of cranial nerves enter or leave through these fissure or sulci.,1.腹侧面 Ventral surface 锥体 Pyramid on each side of anterior median fissure is,an oblongated elevation,contain corticospinal(pyramidal)tract.锥体交叉 Decussation of pyramid formed by crossing fibers of corticospinal tract.前外侧沟 Anterolateral sulcus rootlets of hypoglossal n.(XII)emerge from it.,橄榄 Olive posterolateral to pyramid is an oval elevation,produced by underlying inferior olivary nucleus.橄榄后沟 Retroolivary sulcus rootlets of glossopharyngeal,vagus and accessory n.(IX,X,XI)emerge from it.,2.背侧面 Dorsal surface 1)Lower portion:薄结节 Gracile tubercle produced by underlying gracile nucleus at lower angle of fourth ventricle.楔结节 Cuneate tubercle marks site of cuneate nucleus lateral and adjacent to Gracile tubercle.小脑下脚 Inferior cerebellar peduncle a thick rounded ridge,rostral to,gracileand cuneate tubercles.2)Upper portion:forms lower half of rhomboid fossa.,II)脑桥 Pons interposes between midbrain and medulla oblongata.It rests upon dorsum sellae of sphenoid bone and adjacent basilar part of occipital b.1.Ventral surface 基底部 Basilar part huge,ventral swelling,contain both longitudinal and transverse fibers intermixed with pontine nuclei.基底沟 Basilar sulcus a marked shallow median groove on ventral surface of pons,in which basilar artery is lodged.,延髓脑桥沟 Bulbopontine sulcus from medial to lateral,abducent,facial and vestibulocochlear n.(VI,VII,VIII)appear.小脑中脚 Middle cerebellar peduncle is formed by transverse fibers of basilar part that converge on each side into a compact mass.,三叉神经 Trigeminal n.(V)consisting of a smaller superomedial motor root,and a large inferolateral sensory root,emerges from junction of basilar part and middle cerebellar peduncle.脑桥小脑三角 Pontocerebellar trigone lies junction of medulla,pons and cerebellum.,2.Dorsal surface 小脑上脚 Superior cerebellar peduncle are two prominent along lateral borders of fourth ventricle.前髓帆 Superior medullary velum a thin lamina of,white matter between two superior cerebellar peduncles.滑车神经 Trochlear n.(IV)emerge from superior medullary velum.3.菱形窝 Rhomboid fossa is floor of fourth ventricle and is rhomboidal in shape.It is formed by posterior surface of both pons and open part of medulla oblongata.,Its boundaries are superior cerebellar peduncles,inferior cerebellar peduncles,and cuneate and gracile tubercles from above downwards.,Of the four angles to rhomboid fossa,two are laterally placed;caudal angle of rhomboid fossa is continuous with central canal in closed part of medulla oblongata,rostral angle with mesencephalic aqueduct of midbrain.髓纹 Striae medullares divide rhomboid fossa into pontine and medullary parts.,正中沟 Median sulcus divide rhomboid fossa into symmetrical halves.内侧隆起 Medial eminence a ridge on each side of median sulcus.界沟 Sulcus limitans bound medial eminence laterally.,蓝斑 Locus ceruleus adjacent to top of sulcus limitans there is a depression that presents bluish-grey in colour.面神经丘 Facial colliculus is a rounded swelling at middle of medial eminence and overlies nucleus of abducent n.and genu of facial nerve.,舌下神经三角 Hypoglossal triangle is a medial triangular area on each side of median sulcus verlying hypoglossal nucleus.迷走神经三角 Vagal triangle is a lateral triangular area on each side of median sulcus and overlies dorsal nucleus of vagus n.,前庭区 Vestibular area is a triangular field lateral to sulcus limitans and overlies vestibular nuclei.听结节 Acoustic tubercle lies lateral angle of vestibular area overlying dorsal cochlear nucleus.,4.第四脑室Fourth ventricle 1)Position:Situated ventral to cerebellum,and dorsal to pons and cranial half of medulla.,2)Boundaries:Inferolateral:gracile and cuneate tubercles,inferior cerebellar peduncle;Superolateral:superior cerebellar peduncle;Roof:Anterior part formed by superior cerebellar peduncle and superior medullary velum;,Posterior part formed by inferior medullary velum and choroid plexus of fourth ventricle;Floor:rhomboid fossa.There are three apertures,one median aperture(正中孔)and two lateral apertures(外侧孔)of fourth ventricle,opening into subarachnoid space.,III)中脑 Midbrain is shortest part of brain stem.It connects pons and cerebellum with cerebrum.1.Ventral surface,大脑脚 Cerebral peduncle a pair of longitudinal columns.0n transverse sections,it is semilunar in shape and termed crus cerebri(大脑脚底),which consists of descending fibers from cerebral cortex.,Pyramidal tract occupies middle 3/5;Frontopontine tract occupies medial l/5,and Corticopontine tract from temporal,parietal and occipital lobes occupies lateral l/5 of crus cerebri.,脚间窝 Interpeduncular fossa a deep depression bounded by cerebral peduncles,oculomotor nerves(III)emerge from medial of crus cerebri.中脑水管Mesencephalic aqueduct passes through midbrain and serves to connect third ventricle above with fourth ventricle below.,2.Dorsal surface 上丘 Superior colliculus two rounded eminences constitute centers for visual reflexes.下丘 Inferior colliculus two rounded eminences,associated with auditory pathway.,上丘臂 Brachium of superior colliculi a ridge between superior colliculus and lateral geniculate body.下丘臂 Brachium of inferior colliculi a ridge between inferior colliculus and medial geniculate body.,Position of Cranial nerves emerge from Brain stem,12 pairs Cranial Nerves connected to brain,II.脑干的内部结构 Internal structure Internal structure of brain stem comprises Gray matter(cranial nerve nuclei,non-cranial nerve nuclei),White matter(ascending and descending pathways),and Reticular formation.I)灰质 Gray matter,1.脑神经核 Nuclei of cranial n.Almost all cranial nerve nuclei are located in brain stem except first two cranial nuclei,which are evaginations of brain itself.,Functional composition of lower 10 cranial nerve can best be analyzed by referring development of nuclei.There are 7 characters of nuclei of cranial n.in brain stem.They are:一般躯体运动核 General somatic motor nuclei,特殊内脏运动核 Special visceral motor nuclei,一般内脏运动核 General visceral motor nuclei,内脏感觉核 Visceral,sensory nuclei(general and special 一般和特殊内脏感觉),一般躯体感觉核 General somatic sensory nuclei,特殊躯体感觉核 Special somatic sensory nuclei.,1)一般躯体运动核 General somatic motor nuclei innervate striated muscles that are derived from somites and are involved movement of tongue and eyeballs.They are located closed to median plane and include oculomotor,trochlear,abducens and hypoglossal nuclei.,动眼神经核 Oculomotor nucleus is located ventromedially to central grey matter at level of superior colliculus.Their efferent fibers form oculomotor n.and emerge from medial of crus cerebri to supply most of extraocular muscles except lateral rectus and superior obloquies.,滑车神经核 Trochlear nucleus lies in ventral region of central grey matter close to midline at level of inferior colliculus.Its outgoing fibers pass laterally and dorsally round central grey matter.,They reach cranial end of superior medullary velum,decussating with those of opposite side and become unique cranial nerve,which emerges from dorsal surface of brain stem to supply superior obloquies.,展神经核 Abducent nucleus lies deeply in facial colliculus.Fibers course ventrally and inferiorly,passing through basilar part of pons and emerging from medial end of Bulbopontine sulcus to supply lateral rectus.,舌下神经核 Hypoglossal nucleus lies under hypoglossal triangle.Fibers run ventrolaterally,finally emerging between pyramid and olive to become rootlets of hypoglossal n.to supply muscles of tongue.,舌下神经性交叉瘫 Alternating hypoglossal hemiplegia A relatively small lesion in ventral part of medulla oblongata may therefore impair both corticospinal tract and hypoglossal n.causing a characteristic crossed paralysis.Muscles of tongue are paralyzed on same side as lesion,but muscles of limbs are paralyzed on opposite side of lesion.,一般躯体运动核 General somatic motor nuclei,2)特殊内脏运动核 Special visceral motor nuclei innervate muscles that are derived from brachial arches and include motor nucleus of trigeminal n.,facial nucleus,nucleus ambiguus and spinal accessory nucleus.,三叉神经运动核 Motor nucleus of trigeminal n.lies in reticular formation of pons,deep to lateral part of floor of fourth ventricle.Motor root of trigeminal n.arises from this nucleus and emerges from junction of basilar part and middle cerebellar peduncle.,面神经核 Nucleus of facial n.situated at ventrolateral part of reticular formation of pons.Upper portion of nucleus receives fibers from corticonuclear tract of both sides and innervates occipitofrontalis and,orbicularis oculi,while lower portion receives fibers from corticonuclear tract of opposite side only and innervates muscles of lower part of face.Efferent fibers of facial nucleus wind upper pole of nucleus of abducent n.to form genu of facial n.Finally,they emerge from Bulbopontine sulcus.,疑核 Nucleus ambiguus is placed deeply in reticular formation of medulla oblongata.It provides special visceral efferent fibers for glossopharyngeal,vagus and accessory nerves.rootlets of these nerves leave medulla oblongata by passing through posterolateral sulcus.,副神经核 Spinal accessory nucleus In corresponding to spinal roots of accessory n.,it may be located in grey matter as low as level of fifth cervical segment of spinal cord and gives rise to efferent fibers emerging from Retroolivary sulcus to supply sternocleidomastoid and trapizus.,特殊内脏运动核 Special visceral motor nuclei,General somatic&Special visceral motor nuclei,3)一般内脏运动核 General visceral motor nuclei are parasympathetic preganglionic neurons that provide autonomic innervations of smooth m.and glands in head,neck and so on.They include EW nucleus,superior and inferior salivatory nucleus and dorsal nucleus of vagus n.,动眼神经副核 Accessory oculomotor nucleus(Edinger-Westphal nucleus)is situated dorsally to oculomotor nucleus.Their efferent fibers travel in oculomotor n.to relay in ciliary ganglion,subsequently in short ciliary n.to innervate ciliary muscle and sphincter pupillae.,上泌涎核 Superior salivatory nucleus lies in pons and sends preganglionic parasympathetic fibers into facial n.,which controls secretion of lacrimal,submandibular and sublingual glands.,下泌涎核 Inferior salivertory nucleus lies in medulla oblongata and sends preganglionic parasympathetic fibers into glossopharyngeal n.to controls secretion of parotid gland.,迷走神经背核 Dorsal nucleus of vagus n.lies under vagus triangle and gives rise to preganglionic parasympathetic fibers,which innervate thoracic visceral organs and a large number of abdominal visceral organs via vagus n.,一般内脏运动核 General visceral motor nuclei,45)内脏感觉核 Visceral sensory nuclei consist of just one nucleus,孤束核 Nucleus of solitary tract,which is an elongated sensory nucleus in medulla.It receives visceral afferent fibers consisting of primary afferent fibers from facial,glossopharyngeal and vagus n.,In fact,Nucleus of solitary tract is shared by these three cranial n.Some authors consider upper end of this nucleus as Special visceral sensory nucleus(特殊内脏感觉核),while lower end of this nucleus as General visceral sensory nucleus(一般内脏感觉核).,内脏感觉核 Visceral sensory nuclei(general and special),6)一般躯体感觉核 General somatic sensory nuclei receive and relay sensory stimuli from skin and mucosa of most of head:spinal nucleus,pontine nucleus and mensecephalic nucleus of trigeminal n.,三叉神经中脑核 Mesencephalic nucleus of trigeminal n.is located in lateral margin of floor of fourth ventricle.It extends upwards to enter lateral portion of periaqueductal grey matter of midbrain.It is concerned with conduction of proprioceptive impulse from trigeminal n.,三叉神经脑桥核 Pontine nucleus of trigeminal n.lies on lateral side of motor nucleus and extends inferiorly and continues with spinal nucleus.Pontine nucleus receives primary afferent fibers of trigeminal n.Functionally,it relates to conduction of tactile and pressure impulses.,三叉神经脊束核 Spinal nucleus of trigeminal n.is directly continuous with substantia gelatinosa of dorsal grey column of spinal cord and lies on medial side of spinal tract of trigeminal n.,Spinal nucleus receives primary afferent fibers of trigeminal n.Functionally,it relates to conduction of pain and thermal impulses from skin,mucous membrane,cornea;conjunctiva and meninges through branches of trigeminal n.,一般躯体感觉核 General somatic sensory nuclei,7)特殊躯体感觉核 Special somatic sensory nuclei include four vestibular and two cochlear nuclei that receive stimuli via vestibulocochlear n.蜗神经核 Cochlear nuclei composed of dorsal cochlear nucleus and ventral cochlear nucleus.Two nuclei receive afferent fibers from cochlear ganglion through cochlear nerve that enter cerebellopontine angle.,前庭神经核 Vestibular nuclei is made up of medial,inferior,lateral and superior vestibular nuclei in Vestibular area.,Major afferent fibers of complex originate from vestibular ganglion and cerebellum;efferent fibers of complex project extensively to spinal cord through vestibulospinal tract,to cerebellum through vestibulocrerebellar tract,to nuclei of oculomotor,trochlear,abducent,accessory nerve and cervical anterior grey column cells through medial longitudinal fasciculus.,特殊躯体感觉核 Special somatic sensory nuclei,2.非脑神经核 Non-cranial nerve nuclei(传导中继核 Relay nuclei)薄束核与楔束核 Gracile and Cuneate nucleus are located in lower medulla oblongata,deep to gracile and cuneate tubercle.Axons emerge from nuclei as inter