NA-9 (Basal Ganglia - Diencephalon) PDF

Basal Ganglia (Nuclei) Basal Ganglia (Nuclei) Basal Ganglia (Nuclei)  Basal Ganglia Definition: Subcortical masses of gray matter, deeply placed inside the cerebral hemisphere, near the base of the brain. Components: a. The caudate nucleus. b. The lenti...

Basal Ganglia (Nuclei) Basal Ganglia (Nuclei) Basal Ganglia (Nuclei)  Basal Ganglia Definition: Subcortical masses of gray matter, deeply placed inside the cerebral hemisphere, near the base of the brain. Components: a. The caudate nucleus. b. The lentiform nucleus. c. The amygdaloid nucleus………….. (a smell center). d. The claustrum ……………………… (unknown function).  Basal Ganglia A. The Caudate Nucleus: - It is an arched nucleus consists of 3 parts: 1. Head. 2. Body. 3. tail. Basal Ganglia  Basal Ganglia A. Caudate nucleus: B. The Lentiform Nucleus: - A biconvex mass consists of 2 parts: 1. A larger darker lateral part; the putamen. 2. A smaller pale medial part; the globus pallidus.  Basal Ganglia A. Caudate nucleus: B. The Lentiform Nucleus: - The 2 parts are separated by a whitish streak. 1. The lateral surface of the nucleus is gently convex and is related to the external capsule which separates it from the claustrum. 2. The medial surface of the nucleus is markedly convex or angulated and is related to the internal capsule which separates the lentiform nucleus from the thalamus and the caudate nucleus except inferiorly where the anterior end of the putamen becomes continuous with the head of caudate and the anterior perforated substance. The lentiform nucleus lies between the internal and external capsules.  Basal Ganglia C. The Amygdaloid Nucleus: - It is a small round mass which lies mostly in the uncus, at the anterior end of the tail of the caudate nucleus. D. The Claustrum: - Is a thin layer of gray matter between the lentiform nucleus and insula with the external capsule in between. - Its function is unknown. Diencephalon Diencephalon Diencephalon  Diencephalon Site: It lies between the lower parts of the two cerebral hemispheres. It lies above the midbrain surrounding the 3rd ventricle. Subdivisions: 5 parts a. Thalamus: It is the largest part and the secretary of the cerebral cortex. All input impulses (except smell) have to stop and synapse 1st in the thalamus before reaching the cerebral cortex. b. Metathalamus: is formed of LGB and MGB that are attached to the lower surface of the posterior part of thalamus. c. Subthalamus: The part which lies immediately above the midbrain. It contains motor nuclei which lie in the extrapyramidal pathway from cortex to lower centers.  Diencephalon a. Thalamus: b. Metathalamus: c. Subthalamus: d. Hypothalamus: Lies in front of the subthalamus; it contains certain autonomic nuclei. e. Epithalamus: Is formed of the 2 habenular nuclei (trigones), the habenular commissure and the pineal body. It is a relay station of smell centres in the cerebral hemisphere to the tegmentum of the midbrain.  Diencephalon Shape and relations: - Diencephalons is wedge-shaped inside the cerebral hemisphere. - The lateral surface: is related to the internal capsule separates it from the lentiform nucleus. - The lower surface: is divided into 3 parts: a. The middle; the largest part; is the subthalamus which lies over the midbrain. b. The anterior part: consists of the hypothalamus and is connected to the pituitary gland. c. The posterior part composed of the metathalamus (medial and lateral geniculate bodies). ‫‪Blood supply of the‬‬ ‫‪brain‬‬ ‫د‪.‬رضا ابراهيم عامر‬ ‫مدرس التشريح وعلم األجنة‬ ‫كلية الطب – جامعة القاهرة‬  Blood systems of the brain 2 Sources ❑ Vertebrobasilar system. ❑ Internal carotid system. Blood systems of the brain  Vertebrobasilar system - the Rt and Lt vertebral arteries unite at the lower border of the pons to form the basilar artery, which ascends in front of the pons in the middle line, at the upper border of pons it divides into 2 posterior cerebral arteries. Vertebrobasilar system Circulus arteriosus of Willis Circulus arteriosus of Willis  Circulus arteriosus of Willis - It is an arterial circle lies in the interpeduncular cistern. - The circle of Willis is formed from: - The six large arteries (paired Rt and Lt) are: 1. Rt. and Lt. anterior cerebral arteries. 2. Rt. and Lt. internal carotid arteries (ICA). 3. Rt. and Lt. posterior cerebral arteries. - The communicating arteries are: i. Posterior communicating arteries (Rt and Lt): connects the ICA with the posterior cerebral artery of its same side. ii. Anterior communicating artery (single): connects the 2 anterior cerebral arteries. Function: - It acts as an important arterial link between the internal carotid and the vertebrobasilar system of the arterial supply of the brain.  Blood supply of different parts of the brain 1. Lateral surface of the cerebral hemisphere: a. Middle cerebral artery supplies the main part. b. Anterior cerebral artery supplies a strip about one inch adjoining the upper border from the frontal pole till the parieto-occipital sulcus. c. Posterior cerebral artery supplies: The occipital lobe and a narrow strip of the temporal lobe adjoining the lower border.  Blood supply of different parts of the brain 2. Medial surface of the cerebral hemisphere: a. Anterior cerebral artery supplies the medial surface from the frontal pole almost to the parieto-occipital sulcus. b. Posterior cerebral artery supplies the area behind this sulcus (occipital lobe). c. Middle cerebral artery supplies the temporal pole  Blood supply of different parts of the brain 3. Tentorial surface of the hemisphere: a. Posterior cerebral artery supplies the main part. b. Middle cerebral artery supplies the temporal pole. 4. Orbital surface of the hemisphere: a. Its medial 1/2: by anterior cerebral artery. b. Its lateral 1/2: by middle cerebral artery.  Blood supply of different parts of the brain 5. Corpus callosum: a. Rostrum, genu and body are supplied by anterior cerebral artery. b. Splenium is supplied by posterior cerebral artery.  Circulus arteriosus of Willis 6. Choroid plexuses of the ventricles: a. Lateral ventricle: - Choroid plexus of the central part (body): by the posterior choroidal artery (branch of posterior cerebral artery). - Choroid plexus of the inferior horn: by the anterior choroidal artery (branch of internal carotid artery). b. Third ventricle: posterior choroidal artery. c. Fourth ventricle: posterior inferior cerebellar artery (PICA)(branch of 4th part of vertebral artery).  Circulus arteriosus of Willis 7. Corpus striatum and the internal capsule: a. Anterior part of corpus striatum and anterior part of the anterior limb of the internal capsule are supplied by central branches of the anterior cerebral artery. b. The rest of corpus striatum, posterior part of anterior limb, the genu and the anterior part of the posterior limb of the internal capsule are supplied by central (striate) branches of the middle cerebral artery. c. The posterior part of the posterior limb, the retrolentiform part and the sublentiform part of the internal capsule are supplied by the anterior choroidal branch of ICA.  Circulus arteriosus of Willis 8. Thalamus: Is supplied mainly from posterior cerebral artery: a. Posterior cerebral artery: (terminal branch of basilar artery) through its posterior choroidal branch, medial and lateral central branches. b. Posterior communicating artery: branch from internal carotid artery. c. Anterior choroidal artery supplies the lateral geniculate body (LGB). 9. Hypothalamus: Is supplied from all arteries forming the circle of Willis. 10. The cerebellum: a. The superior surface: is supplied by superior cerebellar branch of basilar artery. b. The inferior surface: is supplied by: i. Posterior inferior cerebellar branch of vertebral artery (supplies the major posterior part). ii. Anterior inferior cerebellar branch of basilar artery supplies a small anterior part.  Circulus arteriosus of Willis 11. The midbrain: - Central branches of posterior cerebral artery (terminal branch of basilar artery) helped by superior cerebellar artery and the posterior communicating artery. 12. The pons: - Anterior part (basis pontis): is supplied by the pontine branches of the basilar artery. - Posterior part (tegmentum): a. In lower pons: by the posterior inferior cerebellar artery. b. In upper pons: by the superior cerebellar artery.  Circulus arteriosus of Willis 13. The medulla oblongata: - It is supplied by branches of the vertebral artery: - Anterolateral surface: is supplied by medullary branches of: a- Anterior spinal artery (medially). b- 4th part of the vertebral artery (laterally). - Posterolateral surface: is supplied by the posterior inferior cerebellar artery. - Gracile and cuneate tracts and nuclei: are supplied by the posterior spinal artery.  Circulus arteriosus of Willis Thalamus: Is supplied mainly from posterior cerebral artery: a- Posterior cerebral artery: (terminal branch of basilar artery) through its posterior choroidal branch, medial and lateral central branches. b- Posterior communicating artery: branch from internal carotid artery. c- Anterior choroidal artery supplies the lateral geniculate body (LGB). 9. Hypothalamus: Is supplied from all arteries forming the circle of Willis. 10. The cerebellum: a- The superior surface: is supplied by superior cerebellar branch of basilar artery. b- The inferior surface: is supplied by: 􀂃 Posterior inferior cerebellar branch of vertebral artery (supplies the major posterior part). 􀂃 Anterior inferior cerebellar branch of basilar artery supplies a small anterior part.  Circulus arteriosus of Willis Thalamus: Is supplied mainly from posterior cerebral artery: a- Posterior cerebral artery: (terminal branch of basilar artery) through its posterior choroidal branch, medial and lateral central branches. b- Posterior communicating artery: branch from internal carotid artery. c- Anterior choroidal artery supplies the lateral geniculate body (LGB). 9. Hypothalamus: Is supplied from all arteries forming the circle of Willis. 10. The cerebellum: a- The superior surface: is supplied by superior cerebellar branch of basilar artery. b- The inferior surface: is supplied by: 􀂃 Posterior inferior cerebellar branch of vertebral artery (supplies the major posterior part). 􀂃 Anterior inferior cerebellar branch of basilar artery supplies a small anterior part.  Circulus arteriosus of Willis Thalamus: Is supplied mainly from posterior cerebral artery: a- Posterior cerebral artery: (terminal branch of basilar artery) through its posterior choroidal branch, medial and lateral central branches. b- Posterior communicating artery: branch from internal carotid artery. c- Anterior choroidal artery supplies the lateral geniculate body (LGB). 9. Hypothalamus: Is supplied from all arteries forming the circle of Willis. 10. The cerebellum: a- The superior surface: is supplied by superior cerebellar branch of basilar artery. b- The inferior surface: is supplied by: 􀂃 Posterior inferior cerebellar branch of vertebral artery (supplies the major posterior part). 􀂃 Anterior inferior cerebellar branch of basilar artery supplies a small anterior part.