University:
Kentucky State University
Course:
BIO 301 | Human Anatomy
Academic year:

2024
Views:

224

Pages:

29
Author:

Nicole Wang

Neuroanatomy 1. cerebrospinal fluid communicates with the subarachnoid space via the………………….. a. 4th ventricle b. 3rd ventricle c. subarachnoid granulations d. choroids plexus e. tela choroidia 2. Regarding the speech centers, chose the correct answer a. It is supplied by Anterior cerebral artery b. Broca’s area is posterior c. Wernicke’s area controls motor response d. Damage to Broca’s area produces motor aphasia e. Damage to Wernicke’s area produces expressive aphasia 3- One of the following is not sharing in the anterior wall of the third ventricle: A- anterior commissure B- optic chiasma C- lamina terminalis D- Anterior column of the fornix E- None of the above The Cerebellum Anterior notch 1ry fissure It is formed of median vermis & 2 cerebellar hemispheres. V It has 2 surfaces: E - Superior surface: facing the midbrain & tentorium R Cerebellar cerebelli . M Cerebellar Hemisphere I Hemisphere - Inferior surface: divided into anterior & posterior S parts. - The surfaces have many parallel folds called folia Posterior It has 2 notches: notch Superior surface - Anterior notch occupied by the brain stem. - Posterior notch (vellecula) occupied by falx Nodule cerebelli. Flocculus The main fissures of the cerebellum: - Primary fissure: separates the anterior & posterior lobes. - Horizontal fissure: Extends between the middle Tonsil cerebellar peduncles . - Posterolateral fissure: Separates the flocculus & nodule from the rest of the cerebellum. - Cerebellar tonsil : on either sides of uvula of inferior vermis - Retrotonsillar fissure : separates tonsil from the Inferior surface Lobes of the cerebellum: (Horizontal division) - Anterior lobe: in front of the primary fissure. Posterior lobe: behind the primary fissure. Flocculo-nodular lobe: Consists of the flocculus & nodule . 1ry Fissure Anterior Lobe Posterior Lobe Paravermis hemispheres Cerebellar nuclei: • Dentate nucleus • Interposed nuclei: Emboliform - Globose • Fastigial "Don't Eat Greasy Food" Arbor vitae In latin “ tree of life” it is the white matter of cerebellum. •It is so called because of the tree like appearance. •It brings sensory and motor sensation to and from cerebellum Vertical subdivisions of the cerebellum 1- vermis (central part on superior and inferior surfaces) represents head, neck, trunk, shoulders and hips). Projects to Fastigeal N 2- Paravemis (lateral to vermis) represents muscles of upper and lower limbs Projects to Globose and Emboliform N 3- Rest of cerebellar hemispheres Project to Dentate N Arbor vitae Fourth ventricle Cerebellar peduncles: Superior cerebellar peduncle (SCP): Connects the cerebellum with the midbrain. Middle cerebellar peduncle (MCP): Connects the cerebellum with the pons. Inferior cerebellar peduncle (ICP): Connects the cerebellum with the medulla oblongata. MCP ICP Cerebellar lobules - Superior view Cerebellar lobules - Superior view Cerebellar Lobules (inferior view) Structure of the cerebellum 2 1- Cerebellar Cortex Outer Molecular Layer (stellate and basket cells) Middle Purkinje Cell Layer (inhibitory to all other cells) Inner Granular Layer Include 2G cells (granule and golgi) Granule cells are the only (excitatory to all other cells). 2- Corpus Medullare (Medullary Center) 3- Deep Cerebellar Nuclei 1 White matter of the cerebellum •Consists of three types of nerve fibres in the white matter A. Mossy fibres (afferent) They end in the granular layer first then purkinje layer (indirect activation of purkinje). B. Climbing fibres (afferent) They end directly in purkinje (direct activation) or molecular layer (olivocerebellar tracts mainly) C- Axons of purkinje cells (efferent) The only axons to leave cerebellar cortex to end in deep cerebellar nuclei (inhibitory). These fibers then projects to brain stem nuclei, thalamus and cerebral cortex. Functional Subdivisions of The Human Cerebellum Archicerebellum (Vestibulo-cerebellum): • Flocculo-Nodular Lobe, Lingual Lobule • It receives afferent Fibres From vestibular apparatus of internal ear Via vestibulo-cerebellar tracts either directly from vestibular ganglia or from vestibular nuclei. • Pyrkinje neurons of each lobe project its inhibitory axons directly to ipsilateral vestibular nuclei Efferent: vestibular nuclei give rise to: • Vestibulospinal tracts to antigravity extensor muscles. • Vestibulo-ocular fibers • Vestibulo-cerebellar • Vestivulo-cortical Function: Equilibrium, Vestibulo-Ocular Reflex (VOR). Paleocerebellum (Spino-cerebelllum): 1- Anterior lobe+ midline vermis (fastigeal N) 2- surrounding paravermis + globose & emboliform nuclei. 1- Vermal zone of the spinocerebellum Purkinje neurons of each hemivermis projects inhibitory axons to ipsilateral fastigeal nuclei. Afferent : venteral and dorsal spinocerebellar, olivo-cerebellar and cuneocerellar tracts. Projects to fastigeal N Fastigeal N gives bilateral excitatory fibers to the medial mtotor system that controls axial and porximal limb muscles through: Efferent: Fasigeo-Vestibulo-spinal (ipsilateral and contralateral vestibular nuclei) Fastigeo- Reticulo-spinal (Ipsilateral and contralateral RF) Anterior cortico-spinal (ipsilateral and contralateral VL nucleus of thalamus which project to trunk part of area 4. (cerebello-fastigeo-thalamo-cortico-spinal) Function: Regulate muscle tone of axial and proximal limb muscles 2- para-vermal zone of spinocerebellum Function: it is concerned with muscle tone (mainly flexors) and regulation of voluntary movements of the distal muscles. It receives afferent proprio-ceptive impulses from Ms.& tendons Via spino-cerebellar tracts (dorsal & ventral), olivo-cerebellar and cuneorebellar Project to Globose-Emboliform N •it sends efferent to lateral motor pathway : Contralateral VL nuclei of thalamus which project to precenteral gyrus (distal limbs area) from which lateral corticospinal fibers arise (control distal limb muscles) Cerebello-Globose- Embliform- thalamocortical-spinal pathway Contralateral red nucleus of midbrain (controlling distal limb muscles) Cerebello-Globose-Emboliform-Rubral-spinal pathway Neocerebellum (cere bellum) It includes the most 2-cerebellar hemispheres + dendate nuclei. It receives afferent impulses from the cerebral cortex+pons Via cerebro-ponto- cerebellar pathway which project to dentate N. it sends efferents to contralateral red nucleus that projects to Ventro lateral nucleus of thalamus (VL). Function: 1- controls voluntary movements, planning of sequence of intended movements (even before execution of motor activity) i.e anticipation 2- Regulation of force and timing Of Movement. 3- Learning new complex movements The whole pathway Cortico-ponto-cerebellarDentato-rubro-thalamo-cortical Fibres entering and leaving through cerebellar peduncles Superior cerebellar peduncle (major efferent) Fibres entering the cerebellum Ventral spino-cerebellar tract Trigimino-cerebellar from Mesencephalic nucleus Tecto-cerebellar fibres Fibres leaving the cerebellum Cerebello-rubral fibres (Globose-Emboliform-rubral) Cerebello-thalamic fibres (Dentato-thalamo-cortical) Cerebello-reticular fibres (Fastigeal nucleus) Middle cerebellar peduncle (afferent Pontocerebellar fibres (cortico-ponto-cerebellum) to dentate nucleus) Inferior cerebellar peduncle (afferent) Fibres entering cerebellum (restiform body) Posterior spino cerebellar tract Cuneo-cerebellar tract Olivo-cerebellar fibres Reticulo-cerebellar Vestibulo-cerebellar fibres Trigemino-cerebellar fibres Anterior external arcuate fibers Fibres Leaving the cerebellum (juxta-restiform body) Cerebello-olivary fibres Cerebello (Fastigio)-vestibular fibres Cerebello (Fastigio)- reticular fibres Blood Supply of the Cerebellum It is supplied by 3 cerebellar arteries • Superior cerebellar artery: from the basilar artery • Anterior inferior cerebellar artery: from the basilar artery • Posterior inferior cerebellar artery: from the vertebral artery Basal ganglia and cerebellum Cerebellum and basal nuclei are the 2 major subcortical centers which affect cortical activity Both receive input from cortex Both projet output to the cortex via the thalamus Cerebellm Basal ganglia Receive cortico-ponto-cerebellar from contralateral cerebral cortex Receives cortico-striate fibres from ipsilateral cerebral cortex Projects to VL nucleus of the contralateral thalamus projects directly to areas 4,6 Projects to VA nucleus of the ipsilateral thalamus which projects first to SMA then to areas 4,6 Controls movement of the ipsilateral half of the body Controls movement of the contralateral half of the body Cerebellar lesion Syndromes • • • • • • • Ataxia: incoordination of movement decomposition of movement dysmetria, past-pointing dysartheria dysdiadochokinesia rebound phenomenon of Holmes gait ataxia, truncal ataxia Intention Tremor Hypotonia, Nystagmus Archicerebellar Lesion: Medulloblastoma (see later) Paleocerebellar Lesion: gait Disturbance, tested by heel shin test Neocerebellar Lesion: hypotonia, upper Limb ataxia , tremor, dysmetria. Tested by finger to nose test. Cerebellar Medulloblastoma Cerebellar tumors on vermis •Truncal Ataxia •Frequent Falling The child in this picture: - would not try to stand unsupported •would not let go of the bed rail if she was stood on the floor.

Neuroanatomy

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