Internal Capsule & Basal Nuclei 8th Lecture PDF

Internal capsule (Projection fibers) By Dr. Mariam Atef Lecturer of Anatomy  From Thalamus From cerebral cortex (Thalamic radiation) to lower centers to the cerebral cortex e.g.: Pyramidal tract Internal capsule Definiti...

Internal capsule (Projection fibers) By Dr. Mariam Atef Lecturer of Anatomy  From Thalamus From cerebral cortex (Thalamic radiation) to lower centers to the cerebral cortex e.g.: Pyramidal tract Internal capsule Definition: ◦It is a broad lamina of white matter made up of projection fibres. ◦It is so called because it forms an internal capsule to the lentiform nucleus. In horizontal section : it appears V shaped that looks laterally. Relations: ◦Medially: Head of caudate & thalamus. ◦Laterally: Lentiform nucleus. In Horizontal section, it has a wide V-shaped appearance  Parts ◦ Anterior limb ◦ Genu ◦ posterior limb ◦ Retrolentiform ◦ sublentiform  Descending tracts: Ascending tracts: Anterior -Anterior thalamic radiation Fronto pontine fibres. limb  *Descending tracts: *Ascending tracts: -Cortico–bulbar ---------------- Genu: ( nuclear) fibres:  *Descending tracts: *Ascending tracts: -Cortico–spinal fibres: Somatosensory from -Fronto–pontine fibres. thalamus to main Posterior sensory area limb: (superior thalamic radiation)  Descending tracts: Ascending tracts: Retro- -Posterior thalamic radiation: Optic -Parieto-pontine & radiation lentiform -Occipito–pontine fibres  Descending tracts: Ascending tracts: Sub- -Inferior thalamic (auditory) -Temporo–pontine fibres. lentiform radiation Blood supply of the internal capsule: Anterior part of anterior limb: Anterior Cerebral Artery Posterior part of anterior limb, genu and anterior part of posterior limb: Middle Cerebral A Posterior part of posterior limb, retrolentiform and sublentiform part: Anterior choroidal artery Basal nuclei By Dr. Mariam Atef Lecturer of Anatomy  Ganglia nucleus Collection of nerve cells Collection of nerve cells Outside CNS inside the CNS 1) Definition: Collection of nerve cells body (=gray matter) deeply placed in cerebral hemisphere 2) Components : a) Caudate N. corpus striatum b) Lentiform N. (extrapyramidal motor nuclei) c) Amygdaloid N (smell center) d) Claustrum (unknown function)  II- lentiform 2 parts : Large lateral dark : putamen (+ caudate =neostriatum) Small pale medial : globus pallidus  II- lentiform Shape: biconvex 2 surfaces: 1) Medially : anterior limb of internal capsule separates it from head of caudate, posterior limb of internal capsule separates it from thalamus 2) Laterally : related to external capsule separates it from claustrum Lentiform N. has 2 surfaces, related to 2 capsules and formed of 2 parts (Golbus pallidus and putamen) III.Amygdaloid nucleus It is a small rounded mass which lie mostly in the uncus of temporal lobe. At the ant. end of tail of caudate nucleus. it is considered a Smell center  IV. Claustrum Thin sheet of gray matter between the lentiform nucleus and insula with the external capsule inbetween. Related laterally to the extreme capsule separating it from the insula. Unknown function Horizontal section of the 2 cerebral hemispheres  MCQ’S 1- The corticobulbar fibers pass through the following part of internal capsule: A. Anterior limb. B. Genu. C. Posterior limb. D. Retrolentiform. E. Sublentiform. 2- The anterior commissure mainly connects the right and left: A. Temporal poles. B. Frontal poles. C. Occipital poles. D. Parietal lobes. E. None of the above 3-The projection fibers of the cerebral hemisphere: A.Contain fibers from the thalamus to the cerebral cortex. B.Contain fibers from the cerebral cortex to the lower limb. C.All its fibers pass in the internal capsule. D.All of the above. E. None of the above.