DEMO III Cerebral Cortex and Basal Nuclei Ali

DEMO – III (Cerebral Cortex and Basal Nuclei) Ali Jassim Alhashli Year IV – Unit VIII - CNS

STATION – 1 (Cerebral Cortex) • There are two cerebral hemispheres (right and left) which are connected to each other by corpus callosum. • Areas which are bulging up are gyri while those which project down are sulci. Fissures areas which project deeply down. There are 3 main fissures: – Great longitudinal fissure: which is dividing the 2 cerebral hemispheres. – Transverse fissure: which is separating cerebrum from cerebellum. – Lateral fissure (of Sylvian): which is dividing temporal lobe from frontal and parietal lobes.

STATION – 1 (Cerebral Cortex) • • • Folds of dura matter: – Falx cerebri: between the two cerebral hemispheres. – Tentorium cerebelli: separating forebrain from hindbrain (pons + medulla + cerebellum). – Diaphragma sellae: covering the pituitary gland has a hole allowing the passage of pituitary stalk. Central sulcus: sulcus it is the landmark between motor area (pre-central gyrus) and sensory area (postcentral gyrus). Lobes of the brain: – Frontal lobe. – Parietal lobe. – Temporal lobe. – Occipital lobe. Note: insula (which is hidden) is considered as a 5 th lobe.

STATION – 1 (Cerebral Cortex) • Frontal lobe (motor function): – Functions in: memory, emotions, personality, decision making and reasoning. – Primary motor cortex: involved in controlling movements of the body. – Broca’s area: ability to speak. This area is linked to Wernicke’s area which enables us to understand speech. – Olfactory bulb (cranial nerve I): responsible for smell sensation. – Note: to minimize permanent damage to the brain during surgery → it is done in non-dominant hemisphere.

STATION – 1 (Cerebral Cortex) • Parietal lobe: – Functioning mainly in spatial awareness and proprioception. – Parietal lobe is divided into the following regions: • Primary somatosensory cortex: processing of tactile and proprioceptive information. • Somatosensory association cortex: integration of sensations relative to body position and orientation in space. • Primary gustatory cortex: interpretation of the sensation of taste.

STATION – 1 (Cerebral Cortex) • Occipital lobe: – Function: processing, integration and interpretation of visual stimuli. – It is divided into 2 regions: • Primary visual cortex: which is responsible for recognition of size, color, light, motion, dimensions… etc. • Visual association area: interpreting information acquired through primary visual cortex.

STATION – 1 (Cerebral Cortex) • Temporal lobe: divided into the following regions: – Primary auditory cortex: hearing. – Primary olfactory cortex: smell. – Wernicke’s area: language comprehension.

STATION – 2 (Radiology) • • Cerebrum is composed of 4 lobes: – Frontal. – Parietal. – Temporal. – Occipital. Brainstem is composed of: – Midbrain. – Pons. – Medulla. Hindbrain is composed of: – Pons. – Medulla. – Cerebellum. CNS is covered by meninges: – Dura matter: the outermost covering. – Arachenoid: notice that subarachenoid space contains CSF and cerebral vessels. – Pia matter: innermost covering.

STATION – 2 (Radiology) • Ventricular system: – Lateral ventricle: which is composed of 3 horns: • Anterior horn: extending to frontal lobe. • Posterior horn: extending to occipital lobe. • Lateral/inferior horn: extending to temporal lobe. – CSF will move from lateral ventricle to the 3 rd ventricle (which is present between the 2 thalami) through foramen of MONRO. – From the 3 rd ventricle, CSF will move to the 4 th ventricle through cerebral aqueduct (which is present in the midbrain). – From the 4 th ventricle, CSF will exit to subarachenoid space through foramen LUSCHKA and foramen MEGENDIE.

STATION – 2 (Radiology) • • (1): cerebrum (2): corpus callosum (3): ventricles (4): midbrain (5): pons (6): cerebellum (7): medulla

STATION – 2 (Radiology)

STATION – 2 (Radiology)

STATION – 2 (Radiology)

STATION – 2 (Radiology)

STATION – 2 (Radiology) • • • (1): lateral ventricle. (2): caudate nucleus. (3): putamen. (4): pallidum. (5): temporal lobe (right side). (6): lateral fissure (of Sylvian).

STATION – 3 (Arterial Supply of Brain) • • The arterial supply of the brain is composed of: – Carotid system. – Vertebrobasilar system. Carotid system: – It is the anterior system which is supplying the brain. – Originating from internal carotid arteries. – Entering the cranium (skull) through carotid canal. – Passing in cavernous sinus. – And eventually providing its branches: • Anterior cerebral arteries (ACA) which are connected to each other by anterior communicating artery. • Middle cerebral arteries (MCA) which are connected to posterior cerebral arteries PCA (from vertebrobasilar system) by posterior communicating arteries.

STATION – 3 (Arterial Supply of Brain)

STATION – 3 (Arterial Supply of Brain) • Vertebrobasilar system: – It is the posterior system which is supplying the brain. – Vertebral arteries (which are arising from subclavian arteries) will pass through foramina transversaria of cervical vertebrae. – Then they will enter the cranium (skull) through foramen magnum. – Where the 2 vertebral arteries (right and left) will unite to form the basilar artery (which will run in basilar groove/ sulcus of pons). – Branches of vestibular system: • Anterior spinal artery: formed by contributions from the 2 vertebral arteries. • PICA (Posterior Inferior Cerebellar Arteries): arising from vertebral arteries. • AICA (Anterior Inferior Cerebellar Arteries): arising from basilar arteries. • Labrinthine arteries: going to inner ear. • Superior cerebellar arteries. • Posterior cerebral arteries.

STATION – 3 (Arterial Supply of Brain)

STATION – 3 (Arterial Supply of Brain) • Blood supply of cerebral cortex: – Anterior cerebral arteries: supplying the medial part of frontal and parietal lobes. In addition, it is supplying corpus callosum. – Middle cerebral arteries: supplying most of the lateral part of frontal, parietal and temporal lobes. An important branch is latera lenticulostriatal artery which is supplying the basal ganglia and posterior limb of internal capsule (notice that medial lenticulostriatal artery is a branch from anterior cerebral artery and it supplies anterior limb of internal capsule). – Posterior cerebral arteries: supplying the area of occipital lobe and the midbrain.

STATION – 4 (Arterial Supply of Spinal Cord)

STATION – 4 (Arterial Supply of Spinal Cord)

STATION – 4 (Arterial Supply of Spinal Cord) 1. 2. 3. 4. Dorsal column is spared. Lower motor neuron manifestations at the level of the lesion. Upper motor neuron manifestations below the level of the lesion. Bilateral loss of pain and temperature 2 -3 segments below the level of the lesion. 5. Bilateral loss of crude touch 3 -4 segments below the level of the lesion. 6. Bilateral dystaxia.

STATION – 5 (Case discussion) Similar stations will not be included in my DEMO notes because they are useless !

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