Longitudinal Fissure Contains the ACA and Falx Cerebri Superior Frontal Sulcus Precentral Sulcus Central Sulcus PostCentral Sulcus Superior Frontal Gyrus Middle Frontal Gyrus Precentral Gyrus Primary Motor Cortex - BA 4 Postcentral Gyrus Primary Somatosensory Cortex BA 3,1,2 Connected to Broca’s via Arcuate fasciculus Middle Frontal Gyrus Precentral Central Sulcus Postcentral Wernicke’s Area Speech Comprehension Gyrus Gyrus BA - 22,39,40 Supramarginal Gyrus Inferior Frontal Sulcus Pars orbitalis Angular Gyrus Pars opercularis Pars triangularis BA 44 BA 45 Inferior Frontal Gyrus Pars Opercularis + Pars triangularis = Broca’s Area Damage —> Broca’s Aphasia (“Telegraph Style Speech”) Lateral Sulcus a.k.a Sylvian fissure Contains the MCA Primary Auditory Cortex BA 41/42 Superior Temporal Gyrus Contains Primary Auditory Cortex - BA 41,42 Superior Temporal Sulcus Middle Temporal Gyrus Lateral Sulcus Inferior Temporal Gyrus Connects posterior frontal lobes, parietal lobes, + ant. temporal lobes Genu of the Corpus Callosum Body of the Corpus Callosum Cingulate Gyrus Anterior nucleus of the thalamus projects here via internal capsule. Cingulate Sulcus Marginal Sulcus Splenium of the Corpus Callosum Connects Occipital Lobes Connects Anterior Frontal Lobes Septum Pellucidum Cingulate Gyrus: Receives axons from anterior nucleus of the thalamus via the internal capsule. Divides lateral ventricles Fornix Connects Hippocampus to Mammillary Bodies, Part of Papez Circuit Outputs fibers to the hippocampus and cortex via the cingulum bundle. Primary Motor Cortex for the leg Supplied by the ACA Paracentral Lobule anterior Central Sulcus Paracentral Lobule posterior Primary Somatosensory cortex for the leg + genitals - Supplied by the ACA Marginal Sulcus Parieto-occipital Sulcus Contains the PCA Cuneus Inferior C/L Visual Field - BA 17 Lesion produces C/L inferior quadrantanopia Supplied by PCA Receives input from parietal optic radiation. Superior C/L Visual Field - Lesion Produces C/L Superior Quadrantanopia - Supplied by PCA Receives input from Meyer’s Loop (Temporal Optic Radiation) Lingual Gyrus Calcarine Sulcus Olfactory Bulb From telencephalon - Adult neurogenesis Mitral cells (2nd order neurons) are main output - Synapses in Glomeruli - Sends axons to olfactory tract Olfactory Trigone Site where medial and lateral olfactory stria separate. One goes to piriform cortex and the other goes through the anterior commissure to the other primary olfactory cortex. Olfactory Tract Uncus Contains the Amygdala Parahippocampal Gyrus Contains the Hippocampus. Hippocampus receives axons from entorhinal cortex and cingulum bindle via the parahippocampal gyrus. Affected by Alzheimer’s. Affects Semantic Memory. Lateral Olfactory Pathway - axons project to IPSILATERAL primary olfactory cortex, amygdala, entorhinal cortex Medial olfactory Pathway - axons project IPSILATERALLY to the basal limbic structures (e.g. medial septal nucleus) and others arise from the CONTRALATERAL anterior olfactory nucleus (via ant. commissure) Adult neurogenesis in the Dentate region. Supplied by Internal Choroidal Artery. Septum Pellucidum 3rd From Diencephalon Ventricle (space) Stria Medullaris Thalami Contains Cholinergic neurons from basal forebrain nuclei to habenula Genu of Corpus Collusum Habenular Nuc. Cerebral Aqueduct Fornix From Mesencephalon, w/in midbrain (space) Anterior Commissure 4th Ventricle (space) Interventricular Foramen (Foramen of Monro) Hypothalamus From Rhombencephalon (Metencephalon + Mylencephalon) Mammillary Body Basal Forebrain Nuclei to Habenular Nucleus via Stria Medularis Thalami - Cholinergic Neurons (ACh) Interthalamic adhesion Thalamus Hypothalamic sulcus Anterior commissure Pineal gland Connects olfactory nuclei, anterior temporal lobes, and amygdala Secretes Melatonin. Regulated by the Suprachiasmatic Nucleus. Posterior commissure Communication between pretectal nuclei for pupillary light reflex. Lesion results in light-near dissociation. Hypothalamus Mammillary body Receives input from hippocampus via fornix. Output to anterior nucleus of thalamus via mammillothalamic tract. Composed of Emboliform + Globose Nuclei - Connects to Paleocerebellum (spinocerebellum) - intermediate zone Interposed Nuclei Dentate Involved with the Pontocerebellum (Neocerebellum) - lateral zone APPENDICULAR ATAXIA - Consists of most of the cerebellar cortex - Coordinates movements - Main input is from the sensory + motor cortices Folia Medial Lemniscus Inferior Cerebellar Peduncle Interpeduncular fossa CN I Optic N - SSA CN III Oculomotor N GSE - Oculomotor Nucleus GVE - Edinger Westphal Trigeminal N. - GSA - Chief Sensory Nucleus of V (Face Touch) - GSA - Spinal Nucleus of V (Face Pain/Temp) - GSA - Mesencephalic Nucleus (Jaw Proprioception) - BE - Motor Nucleus of V (M. of Mastication) CN V Trochlear N. GSE - Trochlear Nucleus -UP + IN; Head tilt AWAY -Trouble descending stairs CN IV Abducens N. - Abducens Nucleus CN VI GSE Lesion -> head turn to affected side. Inferior pontine sulcus CN VII CN VIII Vestibulocochlear N. - SSA - Vestibular + Cochlear Nuclei (many) CN VII - Facial N. - BE - Facial Nucleus - GVE - Superior Salivary Nucleus - GSA - Chief Sensory Nucleus of V - GSA - Spinal Nucleus of V - SVA - Nucleus Solitarius Glossopharyngeal n. BE - Nucleus Ambiguus SVA - Nucleus Solitarius GVE - Inf. Salivatory Nucleus GSA - Chief Sensory Nucleus of V GSA - Spinal Nucleus of V CN XII Inferior Olivary Nucleus - Motor intentions to cerebellum on “Climbing Fibers” - Synapse on Purkinje Cells and DCN - Inferior Cerebellar Peduncle Olive Pyramid Contains Corticospinal Tract Anterior median fissure Contains Anterior Spinal Artery Decussation of the pyramids Hypoglossal N. - GSE - Hypoglossal nucleus - Lesion -> Ipsilateral tongue deviation CN IX CN X Uvula away from side of lesion. Vagus N. SVA - Rostral Nucleus Solitarius GVA - Caudal Nucleus Solitarius BE - Nucleus Ambiguus GSA - Chief Sensory Nucleus of V GSA - Spinal Nucleus of V GVE - Dorsal Motor Nucleus CN XI Spinal Accessory N. BE - Accessory Nucleus Visual Reflexes Origination of tectospinal tract. Lesion results in Parinaud Syndrome. Superior colliculus Inferior colliculus Audition Receives fibers from Superior Olivary Nucleus via lateral lemniscus. Sends fibers to Medial geniculate nucleus via brachium of the inferior colliculus. CN IV Superior Cerebellar peduncle Contains 2nd order axons of Anterior spinocerebellar tract from Spinal Border Cells. DISTAL LOWER LIMB. Facial colliculus Middle Cerebellar Peduncle Contains fibers of facial nerve and ABDUCENS NUCLEUS (GSE). Inferior Cerebellar peduncle Vagal trigone Contains Dorsal Motor Nucleus (GVE) Parasympathetic Just a landmark. Obex Gracile tubercle Contains Nucleus Gracilis Posterior median sulcus Contains Hypoglossal nucleus (GSE). Hypoglossal trigone Cuneate tubercle Contains Nucleus Cuneatus. - Touch, vibration, pressure, proprioception from C1-T6. - Contains 2nd order neurons of Medial lemniscus tract. Receives input from DRG. These cells axons go via IAF to ML to VPL. Medulla, caudal Also contains axons of the Dorsal spinocerebellar tract from Clarke’s Nucleus heading to inferior cerebellar peduncle. Fasciculus Gracilus Nucleus gracilis GSA - Touch - T7 + Below Also contains axons of cuneocerebellar tract. Fasciculus Cuneatus GSA - Touch - C1-T6 GSA - Touch - T7 + Below Nucleus cuneatus GSA - Touch - C1-T6 Spinal Tract of V GSA - Pain/ Temp from Face Spinal Nucleus of V GSA - Pain/ Temp from Face -2nd order fibers leave, decussate, and ascend to VPM via trigeminothalamic tract Pyramidal Decussation Rostral lesion results in bilateral paresis of upper limbs. Caudal Lesion results in bilateral paresis of lower limbs. Accessory Nucleus CN XI - GSE Medulla, caudal Nucleus gracilis Cuneocerebellar Pathway-muscle spindle+GTO from upper limb+ neck 1st order soma = DRG - Fibers travel in fasciculus cuneatus 2nd order soma - Lateral (External) Cuneate Nucleus in caudal medulla. Fibers travel rostrally via cuneocerebellar tract through the inferior cerebellar peduncle to the cerebellum. Nucleus cuneatus Accessory (external/ lateral) cuneate nucleus Hypoglossal CN XII - GSE nucleus lesion results in tongue Protrusion deviation to same side. Spinal Nucleus of V GSA Pain - From face - Axons from CN V, VII, IX, X Nucleus Ambiguus A GSA - Pain/Touch from C/L body T BE - Voluntary Motor for CN IX, X L Corticospinal axons GSE from PMC to LMNs in ventral horn. Pyramid Spinothalamic tract Inferior olivary nucleus Medial lemniscus Medulla, rostral Tectospinal Tract superior colliculus to superior spinal cord (Lamina VI, VII, VIII) Medial Vestibular Nucleus GSE for CN XII Hypoglossal nucleus 4th ventricle MLF Solitary tract GVE - Visceral Motor Lesion -> I/L INO, Abducens Nuc. to Oculomotor Axons from CN VII, IX, X. - SVA (rostral, taste) + GVA (caudal, carotid body + sinus) Dorsal Motor Nucleus Afferent from CN VII - Involved in VOR Nucleus Solitarius From CN VII, IX, X. - SVA (rostral, taste) + GVA (caudal, carotid body + sinus) Fibers from rostral NS to Gustatory cortex on Insula. Mossy fiber axons of dorsal spinocerebellar tract (from Clarke’s Column) + cuneocerebellar tract (from external cuneate nucleus) - Supplied by PICA Inferior Cerebellar Peduncle A T Nucleus Ambiguus L BE for CN IX, X Corticospinal Axons Spinothalamic tract GSA Pain/Temp From Nucleus Proprius (Lamina V) to VPL of Thalamus Inferior olivary nucleus Neurons project from here to the cerebellum as climbing fibers. Pyramid Medial lemniscus GSA Touch from Nucleus Cuneatus + Nucleus Gracilis to VPL of Thalamus Medial Vestibulospinal Tract - medial + lateral inferior vestibular nuclei → Cervical cord (lamina VII + VIII) - partial cross in medulla Rotation + lifting of head + rotation of shoulder blade. Changes in posture + balance. Primarily inhibit MNs innervating extensors + neurons serving muscles of back + neck. Pons Lateral Vestibular Nucleus Medial Vestibular Nucleus Facial Colliculus to lateral Abducens GSE rectus via CN Nucleus VI. Superior Cerebellar Peduncle Contains Axons from Anterior Spinocerebellar tract (distal lower limb) Central tegmental tract Ascending axonal fibers from the rostral nucleus solitarius to the VPM. Middle Cerebellar Peduncle BE Axons for Motor to Muscles of facial expression + stapedius via CN VII - Bell’s Palsy L T Facial Nucleus Corticospinal Axons A Descending axonal fibers from Red nucleus to inferior olivary nucleus. Spinothalamic Tract Medial lemniscus Pons Main Sensory Nucleus of V GSA Touch from face + mouth via CN V, VII, IX, X L T BE to muscles of mastication + tensor tympani via CN V3 Medial lemniscus Lesion results in I/L jaw deviation upon opening. Motor Nucleus of V A Spinothalamic Tract Corticospinal Axons Pons, rostral Spinothalamic tract Medial lemniscus L T A Middle Cerebellar peduncle Corticospinal Axons Pontocerebellar fibers Associated with the Corticospinal Tract and synapse within the Dentate Nucleus. Lesion results in APPENDICULAR ATAXIA. Associated with middle cerebellar peduncle. Pons-midbrain junction Inferior colliculus Input bilaterally from superior olivary nucleus via lateral lemniscus. Output the medial geniculate Periaqueductal Grey Connects superior olivary nucleus to inferior colliculus. Lateral Lemniscus Medial Longitudinal Fasciculus Spinothalamic tract L T A Medial lemniscus Superior colliculus Cerebral Aqueduct Midbrain, caudal Origin of Tectospinal Tract. Innervates C/L Sup. Oblique w/ GSE via CN IV Brachium of inferior colliculus Trochlear Nucleus Periaqueductal Grey Spinothalamic Tract Connects Inferior Colliculus and MGN. Medial Longitudinal Fasciculus Medial Lemniscus L T A Corticospinal Axons Superior Cerebellar Peduncle Substantia Nigra Midbrain, caudal Superior colliculus Cerebral aqueduct Periaqueductal Grey Oculomotor nucleus Contains Occulomotor nucleus (GSE) + EdingerWestphal Nucleus (GVE- Para). Spinothalamic tract Medial lemniscus L T Corticospinal Axons A Black because of production of MELANIN. Substantia nigra Nigrostriatal Dopaminergic Neurons to Striatum originate in Pars Compacta. SNc DEGENERATED in PARKINSON’S DISEASE. Pars Reticularis receives Glutamatergic (Excitatory) neurons from the Subthalamic Nucleus and sends GABAergic (Inhibitory) neurons to the Thalamus. Pars Reticularis receives GABAergic neurons from Striatum. Cerebral peduncle (Crus Cerebri) Origin of rubrospinal tract. Lesion above results in decorticate rigidity. Lesion at or below results in decerebrate rigidity. Involved in proximal flexor musculature. Midbrain, rostral Red Nucleus LGN Corticospinal Axons Within Cerebral Peduncle Mammillothalamic Tract Connects mammillary Bodies to anterior nucleus of thalamus. 3rd Ventricle Fornix Connects Hippocampus to mammillary bodies Optic Tract Rubrospinal tract = red nucleus to cervical cord (Lamina V-VIII) - Ventral tegmental decussation in MIDBRAIN. Facilitates motor neurons that innervate flexor muscles. Functionally parallel to corticospinal tract. Pineal Gland Containing Brain Sand. Secretes melatonin. Cirvumventricular organ. Part of epithalamus. Regulated by suprachiasmatic nucleus. Sensation from face (trigeminothalamic + facial nucleus) VPM Sensation from body. ML + spinothalamic tracts. Projects to primary somatosensory cortex. VPL Internal capsule, posterior limb Left Right Dorsal (posterior) root Sensory! Posterior median sulcus Posteriolateral sulcus Posterior intermediate sulcus Left Posterior median sulcus Dorsal (posterior) root Fasciculus gracilis GSA Touch - T7 + below Fasciculus cuneatus GSA - touch C1-T6 dermatomes Right Left Right Ventral (anterior) root Anterior median fissure Contains Anterior Spinal Artery Anterior median fissure Right Left Ventral (anterior) root Conus medullaris L1/L2 Ends at L1/L2 Cauda equina Filum terminale Composed of Pia. Fasciculus gracilis Sacral Cord Contained within Lumbar Vertebrae!!! Te Posterior Median Sulcus Lateral corticospinal tract Spinothalamic tract Anterior median fissure Lumbar Cord Fasciculus gracilis Posteromarginal Nucleus Lamina I Lateral corticospinal tract Substantia gelatinosa Lamina II Lesion Results in Spastic Paralysis Lumbar enlargement Spinothalamic tract Lesion to Ventral horn results in Flaccid Paralysis. Spinal border cells (2nd order neuron of anterior spinocerebellar tract) live here. Anterior median fissure Thoracic Cord Fasciculus gracilis Nucleus Posteromarginalis Lateral corticospinal tract Substantia Gelatinosa Intermediolateral cell column Lateral horn Contains Sympathetic Preganglionic Somas (B-fibers) in intermediolateral cell column. L Found at Spinal Levels T1-L2. T A Spinothalamic tract Central Canal Enlargement results in syringomeylia. Primarily affects the C5 dermatome. Clarke s (Column) nucleus 2nd order neurons in the Posterior Spinocerebellar Tract. Located in Lamina VII from T1-S2 Receives input from DRGs in fasciculus gracilis Cervical Cord Fasciculus gracilis Fasciculus cuneatus Substantia gelatinosa Posteromarginal Nucleus Lateral corticospinal tract Cervical enlargement Spinothalamic tract Contains Lower Motor Neurons for brachial plexus. Both A-alpha motor neurons (extrafusal fibers) and Agamma motor neurons (intrafusal fibers). C5-T1 Anterior median fissure Anterior White Commissure Contains Spinothalamic 2nd order axons. First Affected in Syringomelia. Contains Anterior Spinal Artery from vertebral artery. Ophthalmic Artery Occlusion results in ipsilateral anopia. Anterior Cerebral Artery Occlusion results in loss of voluntary motor and sensation to contralateral lower limb + genitals. Middle Cerebral Artery Occlusion results in loss of voluntary motor + sensation Anterior Choroidal Artery Anterior Communicating Artery Aneurysm results in bitemporal hemianopia. Posterior Communicating Artery Internal Carotid System Vertebral Artery System Posterior Cerebral Superior Alternating / Weber’s / Medial Artery Midbrain Syndrome - unilateral damage to the ventral region of the midbrain caused by occlusion of the PCA / Basilar Arteries. Results in superior alternating hemiplegia (ipsilateral oculomotor n. palsy + contralateral hemiplegia). If lateral tegmental areas are involved as well, it results in the addition of ataxia and is called Benedikt’s syndrome. Superior Cerebellar Frequently the cause of trigeminal neuralgia. Artery Occlusion results in ATAXIA. Anterior Inferior Cerebellar Artery (AICA) Basilar Artery Occlusion results in LATERAL PONTINE SYNDROME. Posterior Inferior Cerebellar Artery (PICA) Vertebral Artery Occlusion results in Lateral Medullary Syndrome - (Wallenberg’s Syndrome) Anterior Spinal Artery Occlusion results in medial medullary syndrome (inferior alternating syndrome). Anterior Cerebral Artery Occlusion results in loss of voluntary motor + sensation to contralateral lower limb. Internal Carotid Artery Middle Cerebral Artery Occlusion results in loss of sensation + voluntary motor to contralateral upper limb + face. Middle Cerebral Artery Anterior Cerebral Artery Internal Carotid Artery Posterior Cerebral Artery Superior Cerebellar Artery Basilar Artery Vertebral Artery Posterior Cerebral Artery Occlusion results in Superior Alternating (Weber’s) Syndrome Superior Cerebellar Artery Basilar Artery Vertebral Artery Posterior Cerebral Artery Occlusion results in Superior Alternating (Weber’s) Syndrome Superior Cerebellar Artery Basilar Artery Vertebral Artery Occlusion -> Superior Alternating (Weber’s) Syndrome Posterior Cerebral Artery AICA Occlusion results in Lateral Pontine Syndrome. Superior Cerebellar Artery Basilar Artery PICA Occlusion results in Lateral Medullary (Wallenberg’s) Syndrome. Vertebral Artery Contains ACA. Afferent From Anterior Nucleus of Thalamus. Efferent to cortex and parahippocampal gyrus via cingulum bundle. Cingulate gyrus Cingulum Bundle Efferents from cingulate gyrus. Fibers to parahippocampal gyrus. Longitudinal fissure Corpus callosum Body Septum pellucidum Corona radiata Lateral ventricle, anterior horn Caudate nucleus Huntington’s Disease will have degeneration of MEDIUM SPINY NEURONS in the Caudate. Part of the Striatum. Associated with Association cortex. Internal capsule, anterior limb Contains Corticofugal and thalamocortical fibers. Putamen Part of Striatum with Caudate and part of lentiform nucleus with globus pallidus. Associated with SENSORYMOTOR cortex. Caudate nucleus Cingulate gyrus Internal capsule, anterior limb Corticofugal fibers. Lateral ventricle, body Putamen External capsule Extreme capsule Lateral Sulcus Insula Claustrum Globus Pallidus, externum Inhibitory input from striatum + GABA inhibitory output on subthalamic nuclei Globus Pallidus, internum Inhib by striatum, excited by STN, inhibits Thalamus. T Hypothalamus Amygdala 3rd ventricle A subcortical Structure. Receives input from olfactory tract. Communicates via anterior commissure. Lesion -> Kluver-Bucy Syndrome. Connected to the hypothalamus via STRIA TERMINALIS. Cingulate gyrus Hippocampus to mammillary bodies. Fornix Caudate nucleus Internal capsule, posterior limb Mammilothalamic Tract Mammillary Bodies to Ant. Nucleus of thalamus. Part of Circuit of Papez. External capsule Extreme capsule Putamen Globus Pallidus, externum Insula Claustrum Globus Pallidus, internum Hippocampus Lateral ventricle, NMDA receptors are hekka important for LTP here. CA1 region of hippocampus is the most vulnerable to Pons inferior horn amyloid plaque formation in AD. Hypothalamus (specifically Anterior nucleus Receives input from mammillary bodies via mammillothalamic tract the mamillary body of the thalamus and outputs to cingulate gyrus. Cingulate gyrus Internal capsule, posterior limb Corona radiata Lateral sulcus Putamen Insula Dorsomedial Nucleus of the Thalamus Limbic system relay circuit Hippocampus Bilateral Ablation will cause anterograde amnesia. Allocortex (3 layers) Pons Lateral ventricle, inferior horn Substantia Nigra Pars Compacta Degenerated in Parkinson’s disease. Longitudinal fissure Fornix Thalamus Caudate Lateral sulcus Hippocampus Cerebral aqueduct Connects the 3rd + 4th Ventricles. Occlusion here would cause noncommunicating hydrocephalus. Lateral ventricle, inferior horn Middle cerebellar peduncle Medulla Longitudinal fissure Cingulate Gyrus Corona radiata Corpus callosum Cingulate Gyrus Longitudinal fissure Genu of the corpus callosum Connects anterior frontal lobes Caudate nucleus Cingulate gyrus Internal capsule, Fornix anterior limb Globus pallidus Putamen Genu of Corpus Callosum External capsule Corticobulbar fibers Insula Claustrum Internal capsule, posterior limb Extreme capsule Corticospinal + sensory fibers. Dorsomedial Nucleus of the Thalamus Relaying information from hypothalamus, hippocampus, amygdala, to frontal + cingulate cortex Thalamus Splenium of the corpus callosum Connects occipital lobes. Lateral ventricle, posterior horn 3rd ventricle Hypothalamus 3rd ventricle Mammillary Body Hippocampus Crus cerebri a.k.a Cerebral peduncle Hippocampus Cerebral aqueduct Receives input from the inferior colliculus via the brachium of the inferior colliculus. Output to I/L primary auditory cortex (BA 41,42). Medial geniculate nucleus Lateral geniculate nucleus Receives input from the optic tract. Carries information from the C/L visual field. Lesion results in C/L homonymous hemianopia. Output to primary visual cortex (BA 17) via optic radiation. Parietal radiation to cuneus carrying inferior C/L visual field. Temporal Radiation (Meyer’s Loop) carries C/L superior visual field. Ending of Optic Tract (retinal ganglion cells end here). Thalamic relay of visual information. Organized into layers depending on eye of origin + type of retinal ganglion cell axon: 2 magnocellular layers: input from M-ganglion cells “where pathway” 4 parvocellular layers: input from P-ganglion cells “what pathway” Internal capsule, posterior limb Anterior Commissure Connects amygdala, olfactory nuclei, anterior temporal lobes. Medial geniculate nucleus Internal capsule, posterior limb Optic radiations Lateral geniculate nucleus Lesion results in C/L homonymous hemianopia. Hippocampus Superior colliculus Origin of tectospinal tract. Medial geniculate nucleus of tectospinal tract. Receives input Superior colliculus Origin from the optic tract. Receives input from the inferior colliculus via the brachium of the inferior colliculus. Output to primary auditory cortex via the ACOUSTIC RADIATION. Brachium of inferior colliculus Connects inferior colliculus to the medial geniculate nucleus. Lateral geniculate nucleus Inferior colliculus Receives input from superior olivary nucleus via the lateral lemniscus. Sends output to the medial geniculate nucleus via the brachium of the inferior colliculus. Incomplete damage -> Marcus Gunn pupil (afferent pupil). Optic nerve results in bitemporal hemianopsia. Optic chiasm Lesion Decussation of temporal visual fields. Optic tract Lesion results in C/L homonymous hemianopsia. Lateral geniculate nucleus Lesion results in C/L homonymous hemianopsia. Medial geniculate nucleus Origin of medial vestibulospinal tract. Medial vestibular nucleus just the vestibular nuclei Medial longitudinal fasciculus Cochlear nuclei Lesion here results in I/L sensorineural hearing loss. Lesion results in I/L internuclear opthalmoplegia. i.e. inability to adduct the ipsilateral eye. Tectospinal Tract Originates in superior colliculus. Medial Vestibulospinal Tract medial + lateral inferior vestibular nuclei → Cervical cord (lamina VII + VIII) - partial cross in medulla Rotation + lifting of head + rotation of shoulder blade. Changes in posture + balance. Primarily inhibit MNs innervating extensors + neurons serving muscles of back + neck. Medial vestibular nucleus Lateral vestibular nucleus Lateral Vestibulospinal Tract Lateral vestibular nucleus of medulla to all levels (Lamina VII, VIII) - NO DECUSSATION. Facilitates 𝛂 + 𝛄-motor neurons that innervate extensor muscles. Maintains posture, modulated by activation of vestibular apparatus or cerebellum. May inhibit some flexor motor neurons, but they mainly facilitate spinal reflexes via their excitatory influence on spinal motor neurons innervating extensors. Extensor response of lower limbs in both decerebrate + decorticate rigidity. Superior olivary nucleus Receives auditory info from cochlear nucleus and outputs to inferior colliculus via the lateral lemniscus. Performs LOCALIZATION of SOUND. GSE to lateral rectus via CN VI. Input from Paramedian Pontine Reticular Formation. Output to C/L Oculomotor nucleus via MLF. Abducens nucleus Lesion causes I/L internuclear opthalmoplegia. Connects C/L Abducens nucleus with I/L oculomotor nucleus. Medial longitudinal fasciculus Origin of tectospinal tract. Superior colliculus GVE for pupillary light reflex to sphincter puppillae and to ciliary muscle for accomodation via CN III (oculomotor) and ciliary ganglion. Edinger-Westphal nucleus Receives input from Inferior colliculus via brachium of the inferior colliculus. Output to primary auditory cortex (BA 41,42) (caudal superior temporal gyrus). Medial geniculate nucleus Oculomotor nucleus GSE to eye muscles. CN III. Lateral geniculate nucleus Medial longitudinal fasciculus Lesion results in bitemporal hemianopia. Optic chiasm Parieto-occipital sulcus Contains the PCA. Processes the C/L inferior visual field. Receives input from parietal stream of optic radiation. Cuneus Lesion results in I/L anopia. left superior quedrantanopia Optic nerve Lingual gyrus Calcarine sulcus Processes C/L Superior visual field. Receives input from Meyer’s Loop (Temporal stream of optic radiation). Olfactory Bulb Olfactory Tract Olfactory Trigone Uncus Parahippocampal Gyrus Periallocortex (4-5 layers). Mammillary Body Cingulate Gyrus Cingulate cortex is Periallocortex (4-5 layers). Fornix Cingulum Bundle Fibers from cingulate cortex to parahippocampal cortex and on to entorhinal cortex and hippocampus. Hippocampus Outputs to mammillary bodies via the fornix. Degenerates (particularly CA1) in Alzheimer’s due to accumulation of betaamyloid plaques derived from amyloid precursor protein. A site of adult neurogenesis. Fornix Uncus Anterior Commissure Amygdala Communication between amygdalae, anterior temporal lobes, + olfactory nuclei. Fornix Dorsomedial Nucleus of the Thalamus Hippocampus Cingulate Gyrus Fornix Hippocampus Fornix Hippocampus Splenium of Corpus Callosum Carries communication between the occipital Posterior Horn of Lateral Ventricle Hippocampus Cingulate Gyrus Fornix Carries fibers from the hippocampus to the mammillary bodies from the hippocampus. Bilateral lesion will result in minor anterograde memory disturbance. Receives input from the anterior nucleus of the thalamus and sends output to the cortex and parahippocampal gyrus via the cingulum bundle. Anterior Nucleus of the Thalamus Receives input from the mammilary bodies via the mammilothalamic tract and projects to the cingulate cortex via the internal capsule.
