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11、Cranial nerve & External features of brain stem Cranial nerve Key Points of Learning · Name · Components · Passing through · Peripheral distribution · Central connection · Function Ⅰ olfactory Ⅱ optic Ⅲ occulomotor Ⅳ trochlear Ⅴ trigeminal Ⅵ abducent Ⅶ facial Ⅷ vestibulocochlear Ⅸ glossophryngeal Ⅹ vagus Ⅺ accessory Ⅻ hypoglossal Conposition of cranial nerve 1. General somatic motor (GSM) 2. General visceral motor (GVM) 3. Special visceral motor (SVM) 4. General somatic sensory (GSS) 5. Special somatic sensory (SSS) 6. General visceral sensory (GVS) 7. Special visceral sensory (SVS) Every pair of CN has not all of the above components. General somatic motor (GSM) General visceral motor (GVM) supplies cardiac muscle, smooth muscles and glands. Special visceral motor (SVM, Branchial motor) supplies striated muscles of face, pharynx and larynx. General somatic sensory (GSS) Special somatic sensory (SSS) receives position and balance. General visceral sensory (GVS) receives visceral sensation from vessels and viscera Special visceral sensory (SVS) receives smell and taste. Pure sensory CN · olfactory n. · optic n. · vestibulocochlear n. 1.Olfactory nerve CN I · Pure sensory (SVS) -- smell · Olfactory bulb of telencephalon端脑 · enters cranial cavity through foramina in cribriform plate · Distributes to mucosa of superior part of lateral and septal walls of nasal cavity. 2.optic n.(Ⅱ) · pure sensory (SSS)-- sight · Connects with optic chiasma of diancephlon. · enters cranial cavity through optic canal. · Distributes to retina of eyeball · optic tract optic nerve, chiasma, optic tract？ 3. vestibulocochlear(Ⅷ) conveys impulses from inner ear. sense of position terminates in vestibular N, sense of hearing in cochlear N · Pure sensory (SSS) · Internal acoustic meatus → internal ear · Vestibular nerve is responsible for equilibrium · Cochlear nerve is responsible for hearing Pure motor CN · oculomotor n. · trochlear n. · abducens n. · accessory n. · hypoglossal nerve 1. oculomotor n.(GSM and GVM)( Ⅲ) · Midbrain · Superior orbital fissure · Superior division--superior rectus & levator palpebrae superioris提上睑肌 · Inferior division supplies inferior & medial rectus, & inferior oblique. · GVM fibers—parasympathetic, synapse in ciliary ganglion, postganglionic fibers supply ciliary muscle睫状肌 and sphincter pupillae瞳孔括约肌. 2. Trochlear N(Ⅳ) · Pure motor (GSM) ; midbrain ; Superior orbital fissure ; Superior oblique m 3.Abducens N(Ⅵ) · Pure motor (GSM) ; Pons ; Superior orbital fissure · Lateral rectus m 4.accessory n.( Ⅺ) · Two roots · Pure motor · Medulla & spinal cord · Jugular foramen · Cranial root--joins X · Spinal root--sternocleidomastoid & trapezius 5.Hypoglossal n. (Ⅻ) · Pure motor (GSM) · Medulla · Hypoglossal canal · supply extrinsic and intrinsic muscles of tongue. Mixed CN · trigeminal n. · facial n. · glossopharyngeal n. · vagus n. 1.Trigeminal nerve V · pons · Has three divisions: ophthalmic, maxillary,and mandibular nerve · Has both sensory and motor components (general somatic sensory and general somatic motor) . · It is the main sensory nerve for head and face. · Its motor nerve innervates the muscles of mastication Three divisions: Ophthalmic--Superior orbital fissure into orbital cavity Maxillary-foramen rotundum into pteygopalatine Mandibular –foramen ovale Trigeminal nerve –ophthalmic N (sensory) · superior orbital fissure · Lacrimal nerve to lacrimal gland. · Frontal nerve to forehead · Nasociliary nerve鼻睫神经 to eyeball, part of nasal cavity, and skin of dorsum of nose from root to top. Trigeminal nerve –maxillary N(sensory) · foramen rotundum, pterygopalatine fossa, inferior orbital fissure, sulcus, canal and foramen · to part of nasal cavity, maxilla, upper teeth, and skin between eye and mouth · zygomatic, pterygopalatine, superior alveolar Trigeminal nerve –Mandibular n.(mixed)五个分支 · Buccal nerve to cheek · Lingual nerve to anterior 2/3 mucosa of tongue · Inferior alveolar nerve to mandible, lower teeth, and chin · Auriculotemporal nerve to parotid gland and temporal region · SVM fibers supply muscles of mastication, tensor veli palatini腭帆张肌 , and tensor tempani骨膜张肌, etc. 2.Facial nerve attaches to brain stem: pons(Ⅶ) · Mixed (SVM, GVM, SVS) Pons → internal acoustic meatus→canal of facial nerve→stylomastoid foramen → parotid gland · SVM fibers supply muscles of facial expression & stapedius镫骨肌 · GVM fibers synapse ①in pterygo-palatine ganglion to supply lacrimal gland; ②in submandibular ganglion to submandibular & sublingual gland · SVS fibers receive taste from anterior 2/3 of tongue facial n in the internal auditory meatus, canal, through the stylomastioid foramen Ⅶ Facial nerve distributes to expression muscles (SVM) Temporal Zygomatic Buccal Mandibular Cervical Facial nerveⅦ distributes (chorda tympaniSVSunite lingual n of VGVS) to mucous of tongue taste recieve taste from anterior 2/3 of tongue 舌的感觉：前2/3由面神经鼓索支（SVS）和三叉神经下颌支发出的舌神经（GVS）支配 后1/3由舌咽神经支配（SVS&GVS） 舌的运动：由舌下神经支配同时舌根部还有迷走神经分支支配 3..glossopharyngeal n. (Ⅸ) · Mixed; medulla; · jugular foramen · GVS fibers to carotid sinus(baroreceptors ) and body(chemoreceptors) , oropharynx, and posterior 1/3 of tongue · SVS fibers receive taste from posterior 1/3 of tongue · SVM fibers supply stylopharyngeus · GVM fibers synapse in otic ganglion耳神经节to supply the parotid gland glossopharyngeal n. (Ⅸ)distributes to pharyngeal muscle, parotid salivary gland 4..The vagus nerve (Ⅹ)in the neck, thorax, and abdomen Mixed(4 fibors); medulla→ jugular foramen → carotid sheath → on the side of mediastinum → esophgeal plexus → esophgeal hiatus → anterior and posterior vagal trunks Parasympathetic fibers in the vagus nerve · Parasympathetic fibers originate from the dorsal motor nucleus of vagus. · They are distributed widely throughout the respiratory,gastrointestinal system and cardiovascular. · GVM The afferent fibers of vagus n. 1.receptor for general sensation in tympanic membrane, external autitory meatus, and part of the concha of the external ear. 2. receptor for general viscera sensation are distributed widely throughout the mucous membrane of the respiratory,gastrointestinal system and internal layer of the cardiovascular. 3.chemoreceptors are distributed in aortic bodies and baroreceptors in the aortic arch GVS (above the left colic flexure), GSS (dura mater, auricle, skin of posterior external acoustic meatus) motor fibers in the vagus nerve innervates to the muscles of larynx and pharynx through the superior laryngeal nerves and the recurrent nerves--SVM Brachomotor fibers arise from the nucleus ambiguus of the medulla It innervates the muscles of soft palate, pharynx, larynx, and upper part of esophagus SUMMARIZE Nerves of eye Nervers of tongue nervers of pharynx …… 经眶上裂的神经和血管 · 动眼神经 · 滑车神经 · 展神经 · 三叉神经眼支（眼神经） · 上眼静脉 经内耳门的结构 · 面神经 · 位听神经（前庭蜗神经） · 迷路动脉 经颈静脉孔的神经和血管 · 舌咽神经 · 迷走神经 · 副神经 · 颈内静脉 经海绵窦和海绵窦外侧壁的结构 · 动眼神经 · 滑车神经 · 展神经 · 三叉神经眼支（眼神经） · 三叉神经上颌支 · 颈内动脉 二 Brain Stem External structure · Ventral view · Dorsal view · Midbrain · Pons · Medulla oblongata Ventral aspect of medulla · Hypoglossal nerve · Postolivary sulcus · Glossopharyngeal nerve · Vagus nerve · Accessory nerve · Anterior median fissure · Pyramid · Decussation of pyramid · Olive · Preolivary sulcus Ventral surface of medulla · It is divided into symmetrical right and left half by the anterior median fissure · pyramid is located beside the anterior median fissure; the olives is lateral to pyramid. The preolivary sulcus is anterior to olives and postolivary sulcus is posterior to olives. · roots of the cranial Ⅻ (hypoglossal N ) exits in preolivary sulcus · roots of the Ⅸ( glossopharyngeal N ),Ⅹ ( vagus N ),and Ⅺ ( accessory N)ⅡⅣ exit in postolivary sulcus. · At the lower end (junction between the medulla and spinal cord) can be seen the decussation of pyramid. The ventral surface of the pons · It is convex and is continuous laterally with the cerebellum by large paired middle cerebellum peduncle · There is sulcus in the ventral surface of pons which is called basilar sulcus in which the basilar artery lies. · The ventral surface of pons is closely associated with four cranial nerves Ⅴ,Ⅵ,Ⅶ,Ⅷ. · The trigeminal nerve Ⅴ, is located between the pons and middle cerebelum peduncle. It consists of a large sensory root and small motor root. · The Ⅵ( abducens N ),Ⅶ (facial N),Ⅷ ( vestibolocochlear N) exit the sulcus between the pons and medulla from the medial to lateral. · The Ⅶ (facial N) consists of a large motor root & a small sensory root is called intermediate N. Ventral view of midbrain · Massive crural cerebri · interpeduncular fossa · oculomotor nerve emerging between the crura cerebri. · Floor of the fossa is called posterior perforated substance due to the many blood vessels perforate the midbrain. midbrain is smallest & least differentiated brain stem segments. Dorsal surfaces of the pons and medulla · Boundary · Lateral recess/aperture · Median sulcus · Aqueduct 水管 very important structure on the dorsal surfaces of the pons and medulla is rhomboid-shaped fossa. Boundaries of rhomboid-shaped are superior ,middle cerebellar peduncles, and inferior cerebellar peduncle. widest part of the fossa is immediately inferior to the middle cerebellar peduncles. In this region there is a lateral recess on each side. The rhomboid-shaped is divided by median sulcus into symmetrical halves. · stria medullaris run from the region of lateral recess toward the midline. · divides the rhomboid-shaped fossa into upper portion(pons) & lower(medulla). · sulcus limitans divided each half into a medial eminence and a lateral region known as the vestibular area. · vestibular nuclei lie beneath the vestibular area. · Medial to the sulcus limitans is motor area. · facial colliculus lies in the medial eminence just superior to stria medullaris. · abducens nucleus lie beneath the facial colliculus. · hypoglossal triangle lie within the medial eminence just inferior to stria medullaris. · dorsa vagus motor nucleus lie beneath vagus motor dorsal triangle. The dorsal surface of the medulla consists of · gracilis tubercle The nuclei gracilis lie beneath it. It is relay nuclei of the fasciculis gracilis . · cuneate tubercle The nuclei cuneatus lie beneath it. It is relay nuclei of the fasciculis cuneatus fasciculus gracilis and fasciculus cuneatus ascending ipsilaterally and terminate upon the relay nuclei, namely the nucleus gracilis and nucleus cuneatus. trigeminal tubercle (tuberclulum cinereum 灰结节) It is continuous with the posterior horn of spinal cord. The dorsa surface of mid brain · Four rounded eminences, arranged in pairs, are called superior and inferior colliculi. Quadrigemina corpora · Colliculi form the roof or tectum of the midbrain · The superior colliculi, lateral geniculate body膝状体, optic system · The inferior colliculi, medial geniculate body, auditory pathway · Cranial nerve Ⅳ ( trochlear nerve ) emerges from the midbrain just inferior to inferior colliculi and round the crural cerebri to ventral surface. 12、Internal structures of brain stem · grey matter · white matter · reticular formation Review the external structures of brain stem 1. Important marks · Pyramids underlying – pyramidal (corticospinal tract) · Decussation of pyramids— · Olive– within inferior olivary nucleus · Gracile tubercle- fasciculus gracilis and nucleus · Cuneate tubercle – fasciculus cuneatus and nucleus cuneatus · Convex of pon – transverse pontine fiber --- pontocerebellar fibers – middle cerebellar peduncle · Facial colliculus –abducens nucleus and fibers of facial nerve 2. CN III ~ XII attachment to brain stem Development of spinal cord & brain stem？ Internal structures in spinal cord Asecending tracts: Fasciculus gracilis & cuneatus Spinothalamic Descending tracts: Corticospinal tract Intersegmental tract： Fasciculus proprius Central canal 3 nulei column Anterior, posterior,and lateral or intermediolateral horn Internal structures in brain stem · Central canal –expend to form Ⅳventricle · 7 nulei column: Somatic motor Special visceral motor General visceral motor General visceral sensory Special visceral sensory General Somatic sensory Special somatic sensory Grey matter · Nuclei CN connected to cranial nerves · relay nuclei of ascending & descending tract ( NON cranial nuclei )- Nucleus of ascending and descending tract at different level of the brain stem Extrapyramidal system：Red nucleus,black matter,inferior salivatory Reticular nuclei？ Cranial nerve nuclei ⑴ Motor somatic motor nuclei · Oculomotor nuclei-- at the level of the superior colliculus of midbarin · Trochlear nuclei-- at the level of the inferior colliculus of the midbarin · Abducens nuclei-- at the of caudal pons lie beneath the fascial colliculus · Hypoglossal nuclei-- at the rostral (cephalic) medulla lie beneath the hypoglossal trigone. Ⅲ, Ⅳ, Ⅵ, Ⅻ cranial nerve nuclei near the median plane. Special visceral motor nuclei · Trigeminal motor nuclei-- at midpons，Ⅴ，m of mastication · Facial nuclei-- at the caudal pons ，Ⅶ, facial expression · Accessory spinal nuclei-- at the caudal medulla and C1-C6 segment of the spinal cord. SCM,Trapezius · Ambiguus nuclei疑核-- at the rostral medulla，Ⅸ, Ⅹ, Ⅺ, pharygo-larygeal m General visceral motor nuclei · Accessory oculomotor nuclei (E-W/ Edinger-Westphal nucleus) -- at the level of superior colliculus of minbrain, just dorsal-medial to the Oculomotor nuclei, ciliary ganglion睫状神经节 · Superior & inferior salivatory nuclei-- at the caudal of pons Superior salivatory nuclei(pons) →Ⅶ →submandebular gland,sublingualis gland and lacrimal gland Inferior salivatory nuclei(medulla) →Ⅸ →otic ganglion耳神经节 → parotic gland · Dorsal motor vagus nuclei-- at the rostral medulla just lie beneath the vagus trigone→Ⅹ （2）Sensor General somatic sensory nuclei · Trigeminal nuclei : Chief sensory · pontine nucleus (deep) · mesencephalic nucleus (touching,) · spinal nucleus (pain,temperature) Special somatic sensory nuclei Vestibular nuclei from midpons to rostral medulla just lie beneath the vestibular area. Cochlear nuclei between the pons and medulla just lie beneath the lateral recess of rhomboid fossa. General visceral sensory nuclei--Solitary nucleus(孤束核) Rostral to mid medulla (Ⅸ, Ⅹ) Special visceral sensory nuclei (taste) Solitary nucleus : Rostral to mid medulla (Ⅶ, Ⅸ) Solitary nucleus including gustatory味觉的 portion and general portion Cranial nerve nuclei and their CN？ Relay nuclei of ascending & descending tract( NON cranial nuclei ) · ① Nucleus Gracilis & Nucleus Cuneatus · ②Inferior olivary nucleus 下橄榄核 · ③Pontine nucleus （脑）桥核 · ④Superior & inferior collicus nuclei 上丘核，reflection nuclei of the optic 下丘核, relay nucleus of auditory · ⑤Red nucleus 红核 at the level of superior collicus · ⑥Substantia nigra 黑质 in the midbrain, concerned with extrapyramidal system White matter · ascending & descending tracts · Fibers take part in reflex The tracts The brain stem contains numerous ascending and descending fiber tracts. 1. Some of these pass throughout its whole length, having their origin in the spinal cord or cerebral hemisphere. 2. Respectively; others have their origin or termination within brain stem nuclei. Certain of these nuclei receive fibers from , or send fibers into, cranial nerves. ten of which (III---XII) attach to the surface of the brain stem. These are known as the cranial nerve nuclei. 1）Descending tracts 1. Pyramidal tract includes the corticospinal tract and the corticonuclear tract. It arises from the motor area, descends through the internal capsule, and then enters the brain stem. It locates the intermediate three fifths of the basis of cerebral peduncle of the midbrain, the basilar part of the pons (dispersed被分散 by the transverse fibers that pontine nucleus given off), and the pyramid of the medulla oblongata. (1) The corticonuclear tract gives rise to collaterals *to the bilateral两侧的 oculomotor, trochlear, abducens, trigeminal motor, ambiguous, accessory nuclei and superior part of the facial nucleus, and **to the contralateral 对侧的hypoglossal nucleus (in medulla oblongata) and inferior part of the facial nucleus (in pons). ***These nuclei give off fibers that consist of the relevant 相应的cranial nerves and supply the muscles of the head-face. · terminate to opposite hypoglossal nuclei · Decussation 应用 图解 Corticonuclear tract conveys motor impulses from motor area of cortex to their termination motor nucleus of CN. (2) The corticospinal tract Descends through the pyramid of the medulla oblongata. At the pyramidal decussation of the caudal part of the medulla oblongata, The greater90% part of the tract crosses to the opposite side to form the pyramidal decussation and is continued as the lateral corticospinal tract in the lateral funiculus of the spinal cord, as the lateral corticospinal tract. and ends to the motor cells of the anterior horn. The smaller part is continued as the anterior corticospinal tract (uncrossed fibers, at the brain stem) directly into the anterior funiculus of the same side, and ends to the bilateral motor nucleus of the anterior horns. called the anterior corticospinal tract. The anterior corticospinal tract is generally believed to exist above the level of the mid-thoracic segments. Corticospinal tract conveys motor impulses from motor area of cortex to their termination anterior horn of spinal cord (one time relay–synapse) 2. Extrapyramidal system to their termination motor nucleus of CN and anterior horn of spinal cord much more than one time relay --synapses. ---To regulate muscular tension 3.Medial longitudinal fasciculus The medial longitudinal fasciculus interconnects the oculomotor, trochlear, abducens, Edinger-Westphal, vestibular, reticular and spinal accessory nuclei, coordinating conjugate eye movements and associated movements of the head and neck. 2)Ascending tract (1) Medial lemnisci conveys general somatic impulses of the proprioceptive which are mediated by receptors developed in the muscles, ligaments and joints The fasciculus gracilis (fibers derived from the segments of the below the level of the 5th thoracic segment) and fasciculus cuneatus are synapse with (end in) the gracile and cuneate nuclei separately. The fibers of nuclei sweep ventrally round the central grey matter as the internal arcuate fibers, and take part in the decussation of the lemniscus. Thereafter, as the medial lemnisci, they ascend on each side through the medulla oblongata (at the posterior to the pyramidal tract, both sides of the midline, between the inferior olivary nucleuses), pons (posterior to the pyramidal tract), midbrain (posterior to the substantia nigra, lateroposterior to red nucleus), and end in the ventroposterior lateral nucleus of the thalamus. Its function is that transmits deep sensory and discriminating tactile sense of the opposite side of the trunk and limbs. The deep sensation includes posture姿势, movement, vibration振动 and pressure. (2) the trigeminal lemniscus--conveys impulses of exteroceptive (light touch, pain, pressure,and heat,cold sense) from the opposite side of trigeminal nucleus that the peripheral process distribute to face and head, which are mediated by receptors developed in the skin. The sensory root of the trigeminal nerve (the central processes of the neurons in the trigeminal ganglion) enters the pons. The descending fibers, known as trigeminal spinal tract, terminate in the spinal nucleus of the trigeminal nerve concerning with pain and thermal热, and the others end in pontine nucleus o