The brainstem

The brain Telencephalon 端脑 Diencephalon间脑 Cerebellum 小脑 Brain stem 脑干

The brain stem Consists of Midbrain Pons Medulla oblongata

Medulla oblongata延髓 Ventral surface Pyramid锥体: contain pyramidal tract (corticospinal tract) Decussation of pyramid锥体交叉: formed by crossing fibers of corticospinal tract Olive橄榄: produced by underlying inferior olivary nucleus Anterolateral sulcus前外侧沟: rootlets of hypoglossal nerve emerge from it Retroolivary sulcus橄榄后沟: rootlets of glossopharyngeal, vagus and accessory nerves emerge from it

Medulla oblongata Dorsal surface Lower portion Gracile tubercle produced by underlying gracile nucleus Cuneate tubercle marks the site of cuneate nucleus Inferior cerebellar peduncle Obex Upper portion: forms the lower half of rhomboid fossa

Pons 脑桥 Ventral surface Basilar part 基底部 Basilar sulcus 基底沟 Bulbopontine sulcus 延髓脑桥沟: from medial to lateral, the abducent, facial and vestibulocochlear nerves appear Middle cerebellar peduncle 小脑中脚 Trigeminal nerve 三叉神经 Pontocerebellar trigone 脑桥小脑三角: the junction of medulla, pons and cerebellum

Pons Dorsal surface Superior cerebellar peduncle Superior medullary velum Trochlear nerve

Midbrain 中脑 Ventral surface Crus cerebri 大脑脚底 Interpeduncular fossa 脚间窝 oculomotor nerves emerge from medial of crus cerebri Posterior perforated substance 后穿质

Midbrain中脑 Dorsal surface Superior colliculus constitute centers for visual reflexes Inferior colliculus associated with auditory pathway Brachium of superior colliculi Brachium of inferior colliculi

Fourth ventricle 第四脑室 Position Central canal →fourth ventricle →mesencephalic aqueduct→third ventricle Position Situated ventral to cerebellum, and dorsal to pons and cranial half of medulla

Boundaries Inferolateral: gracile and cuneate tubercles, inferior cerebellar peduncle Superolateral: superior cerebellar peduncle Lateral recess

Features Median sulcus 正中沟 Sulcus limitans 界沟 Vestibular area前庭区 overlies vestibular nuclei Acoustic tubercle听结节overlying dorsal cochlear nucleus Medial eminence 内侧隆起 Striae medullares 髓纹

Facial colliculus : overlies nucleus of abducent n. and genu of facial nerve Hypoglossal triangle : verlying hypoglossal nucleus Vagal triangle: overlies dorsal nucleus of vagus nerve Funiculus separans Area postrema Locus ceruleus

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 Three apertures Median aperture of fourth ventricle 第四脑室正中孔 Two lateral apertures of fourth ventricle 第四脑室外侧孔

Tela choroidea and choroid plexus

Internal structures Gray matter Cranial nerve nuclei Relay nuclei

General somatic motor nuclei 一般躯体运动核 Nucleus of oculomotor n. Nucleus of trochlear n. Nucleus of abducent n. Nucleus of hypoglossal n.

General somatic motor nuclei Nucleus Site Cranial n. Function Nucleus of Oculomotor n. Midbrain Ⅲ Supreior, inferior,and medial recti, inf. obliquus, levator palpebrae superioris trochlear n. Ⅳ Superior obliquus Nucleus of abducent n. Pons Ⅵ Lateral rectus Nucleus of hypoglossal n. Medulla Ⅻ Muscles of tongue

Special visceral motor nuclei Motor nucleus of trigeminal n Nucleus of facial n. Nucleus ambiguus Accessory nucleus

Special visceral motor nuclei Nucleus Site Cranial n. Function Motor nucleus of trigeminal n. Pons Ⅴ Masticatory muscles Nucleus of facial n. Ⅶ Facial m., platysma, posterior belly of digastric, stylohyoid, stapedius Nucleus ambiguus Medulla Ⅸ,Ⅹ.Ⅺ Skeletal m. of pharynx, larynx and upper part of esophagus Accessory nucleus Medulla-cervical cord Ⅺ Sternocleidomastoid, trapezius

General visceral motor nuclei 一般内脏运动核 Accessory oculomotor nucleus 动眼神经副核 Superior salivatory nucleus 上泌涎核 Inferior salivertory nucleus 下泌涎核 Dorsal nucleus of vagus n. 迷走神经背核

General visceral motor nuclei Nucleus Site Cranial n. Function Accessory oculomotor nucleus Midbrain Ⅲ Sphincter pupillae and ciliary m. Superior salivatory nucleus Pons Ⅶ Submandibular, sublingual and lacrimal glands Inferior salivertory nucleus Medulla Ⅸ Parotid gland Dorsal nucleus of vagus n. medulla Ⅹ Many cervical, thoracic and abdominal viscera

Visceral sensory nuclei ( general and special ) Nucleus of solitary tract 孤束核

Visceral sensory nuclei ( general and special ) Nucleus Site Cranial n. Function Nucleus of solitary tract Medulla Ⅶ,Ⅸ,Ⅹ Taste and visceral sensation

General somatic sensory nuclei Mesencephalic nucleus of trigeminal n. 三叉神经中脑核 Pontine nucleus of trigeminal n. 三叉神经脑桥核 Spinal nucleus of trigeminal n. 三叉神经脊束核

General somatic sensory nuclei Nucleus Site Cranial n. Function Mesencephalic nucleus of trigeminal n. Midbrain Ⅴ Proprioception of head Pontine nucleus of trigeminal n. Pons Tactile sensation of head Spinal nucleus of trigeminal n. Medulla Pain and temperature sense of head

Special somatic sensory nuclei Cochlear nuclei 蜗神经核 Vestibular nuclei 前庭神经核

Special somatic sensory nuclei Nucleus Site Cranial n. Function Cochlear nuclei Pons and medulla Ⅷ Sense of hearing Vestibular nuclei Sense of equilibrium

Relay nuclei 传导中继核 Gracile nucleus 薄束核 Cuneate nucleus 楔束核 Inferior olivary nucleus 下橄榄核 Superior olivery nucleus 上橄榄核 Pontine nucleus 脑桥核 Nucleus of inferior colliculus下丘核 Gray matter layers of superior colliculus 上丘灰质层 Red nucleus 红核 Substantia nigra 黑质 Pretectal area 顶盖前区

Non-cranial nerve nuclei Nucleus Site Gracile nucleus Medulla (underneath gracile tubercle) Cuneate nucleus Medulla (underneath cuneate tubercle) Superior olivery nucleus Pons Pontine nucleus pons Nucleus of inferior colliculus Midbrain Gray matter layers of superior colliculus Red nucleus Substantia nigra Pretectal area

White matter Ascending tracts Medial lemniscus 内侧丘系 Spinal lemniscus脊髓丘系 Trigeminal lemniscus 三叉丘系 Lateral lemniscus外侧丘系

Medial lemniscus 内侧丘系

Spinal lemniscus 脊髓丘系

Trigeminal lemniscus 三叉丘系

Descending tracts Corticospinal tract 皮质脊髓束 Rubrospinal tract 红核脊髓束 Tectospinal tract 顶盖脊髓束 Vestibulospinal tract 前庭脊髓束 Reticulospinal tract 网状脊髓束

Lateral lemniscus 外侧丘系

Reticular formation of brain stem Ascending reticular activating system (ARAS) 上行网状激动系统 Motor central and vital centres Reticulospinal tract Cardiovascular center and respiratory center Serotonergic rapheal nuclei

The characters of internal structure of brain stem

Medulla oblongata Lower part (closed part) Two decussations– Decussations of medial lemniscus Decussations of pyramid

Medulla oblongata Upper part (open part) Appearance of inferior olivary nuculeus and inferior cerebellar peduncle Enlargement of central canal to form the fourth ventricle floor

Pons Tegmentum of pons 脑桥被盖directed upward continuation of medulla oblongata Basilar part 基底部 contain both longitudinal and transverse fibers intermixed with pontine nuclei

Midbrain Rectum of midbrain中脑顶盖: includes superior and inferior colliculi Cerebral peduncle 大脑脚 Tegmentum 被盖: contain ascending tracts, central gray matter, recticular formation and so on Substentia nigra 黑质 Crus cerebri 大脑脚底: Pyramidal tract锥体束－ middle three-fifths of the crus: Frontopontine tract额桥束 medial one-fifth: pariatotempopontine tract 顶颞桥束lateral one-fifth