White Fibres and Basal Ganglia PDF

Dr ZN Tshabalala  Gray’s Clinical Neuroanatomy - White matter link (Pages 276 –277, 304 -307) - Basal ganglia link (Pages 247 –256) Gray’s Anatomy for students - Pages e49 (Electronic version on ClinicalKey Student) Osmosis videos - White fibres link - Basal ganglia link Complete Anatom...

Dr ZN Tshabalala  Gray’s Clinical Neuroanatomy - White matter link (Pages 276 –277, 304 -307) - Basal ganglia link (Pages 247 –256) Gray’s Anatomy for students - Pages e49 (Electronic version on ClinicalKey Student) Osmosis videos - White fibres link - Basal ganglia link Complete Anatomy Identify and describe the commissural and projection tracts Commissures Anterior commissure Posterior commissure Corpus callosum Projection fibres Internal capsule and its relationship to the Basal Ganglia Association fibres Identify and describe the basal nuclei with regards to their position and relationships Caudate nucleus Globus pallidus Putamen Claustrum By the end of the session you should be able to … Identify and describe white fibre bundles according to their: Type Function Location Identify and describe the basal nuclei according to their: Location Relationship to surrounding structures  Association fibres Link areas in the same hemisphere Short fibres link adjacent gyri - Possibly in the same lobe Long fibres link different lobes with each other - Uncinate and fronto-occipital fasciculi - Superior and inferior longitudinal fasciculi - Cingulum  Association fibres Uncinate fasciculus - Connects Broca’s area and orbital gyri with the temporal lobe Cingulum connects rostrum to temporal lobe Superior and inferior longitudinal fasciculi - Superior connects frontal and occipital lobes - Inferior connects occipital and temporal lobes Fronto-occipital fasciculus connects frontal and occipital lobes - Lateral to the caudate nucleus and superior longitudinal fasciculus  Commissural fibres Course across the midline - Link corresponding areas between cerebral hemispheres Examples - Corpus callosum - Anterior and posterior commissure - Habenular commissure - Commissure of the fornix  Commissural fibres Course across the midline - Link corresponding areas between cerebral hemispheres Examples - Corpus callosum - Anterior and posterior commissure - Habenular commissure - Commissure of the fornix  Corpus callosum Links cerebral cortices between two hemispheres Forms the roof of the lateral ventricles Rostrum is located anterioinferiorly Genu is the most anterior part Body (Trunk) arches posteriorly - It is convex superiorly Splenium is the most posterior part - Overhangs the pineal gland  Corpus callosum Minor forceps - Anterior extensions of the genu - Connect medial and lateral front lobe surfaces Major forceps - Posterior extensions of the splenium - Courses between the occipital lobes Tapetum - Lateral projections of the splenium and body  Anterior commissure It is embedded within the lamina terminalis Forms the anterior border of the third ventricle Connects amygdala and temporal lobes Important for the olfactory pathway Posterior commissure Contains fibres from the thalamus and superior colliculus Important for language processing pathways  Habenular commissure Located anterior to the pineal gland Connects the habenular nuclei Commissure of the fornix Connects the left and right hippocampus Fibres of the fornix terminate in the thalamus and mammillary bodies  Projection fibres Link cerebral cortex to lower levels - Of the brain and spinal cord Its fibres are in the internal capsule  Projection fibres Internal capsule In a horizontal section - Anterior limb is in lateral to caudate nucleus - Genu lies between caudate nucleus and thalamus - Posterior limb is lateral to the thalamus Lentiform nucleus lies lateral to the internal capsule  General Collection of gray matter structures - Responsible for posture and voluntary movements Nuclei connect to thalamus, cortex, neighbouring basal nuclei Nuclei in each cerebral hemisphere - Putamen, caudate, nucleus accumbens and globus pallidus - Nuclei are together referred to as the corpus striatum Subthalamic nucleus lies in the diencephalon Substantia nigra lies in the rostral midbrain  Lentiform nucleus Collective name for the globus pallidus and putamen Has a wedge-like shape (Horizontal section) Putamen Forms the outermost part of the lentiform nucleus Separated from globus pallidus via lateral medullary lamina Putamen located where di- and telencephalon fuse  Lentiform nucleus Collective name for the globus pallidus and putamen Has a wedge-like shape Globus pallidus Divided into medial (GPi) and lateral (GPe) parts Separated by the medial medullary lamina Globus pallidus has a pale appearance - As a result of large number of myelinated fibres  Caudate nucleus Found in the walls of the lateral ventricle Grows into a C-shape with lateral ventricle development It has an enlarged head bulging into the anterior horn Body Body lies in lateral wall of the lateral ventricle Head Slender tail borders on the inferior horn Tail is continuous with the amygdala in the temporal lobe - Amygdala is continuous with the putamen Amyg  Subthalamic nucleus Nucleus is enveloped in white matter - Located between medial part of cerebral peduncle and the thalamus Substantia nigra It is made up of a dorsal and reticular part Compact part contains closely packed neurons Reticular part contains loosely packed neurons - Near the cerebral peduncle  Claustrum Plate of gray matter lateral to the lentiform nucleus Separated from the putamen by the external capsule