Medical Science University of Isfahan, Department of Anatomy 1390 1390 Medical Science University of Isfahan, Department of Anatomy Isfahan University of Medical Sciences, Biomedical Sciences Department

من لم یعلم التشریح والنجوم فهو عنّین فی معرفت الله One who do not have the knowledge of Anatomy and Astronomy, will not be able to know God 1390 Medical Science University of Isfahan, Department of Anatomy Figure 12.2b

1390 Medical Science University of Isfahan, Department of Anatomy

Lecture 12 Cerebral hemispheres - Structure - Function - Related structures 1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

General Arrangement of the Cerebrum: Cerebral hemispheres:  derived from the embryological ‘Telencephalon’ (see ‘development’)  underlying white matter (afferent & efferent fibres)  deep nuclear masses = basal ganglia The two cerebral hemispheres are:  Separated by the great longitudinal fissure  Joined by the corpus callosum (nerve fibre system, see later) divided into 4 lobes: Frontal Parietal Temporal Occipital additional structure: Insula (buried deep below the lateral fissure) 1390 Medical Science University of Isfahan, Department of Anatomy

Development of Sulci Sulci appear at predictable points in fetal development with the most prominent sulci (e.g., Sylvian fissure) appearing first. 1390 Medical Science University of Isfahan, Department of Anatomy Source: Ono, 1990

Squirrel monky Cat Rhesus monky Dog Chimpanzee Man 1390 Medical Science University of Isfahan, Department of Anatomy

Cerebral hemispheres Each of them has: 3 poles : 3 Borders : Frontal, Occipital, Temporal 3 Borders : Superior, inferomedial & inferolateral 3 Surfaces : Superolateral, medial & inferior Inferior surface : orbital & tentorial 1390 Medical Science University of Isfahan, Department of Anatomy

Each surface included some suci & gyri Sulcus ----------- A depression or groove in the surface of the cerebrum that helps increase surface area of the cerebrum. Gyrus ------------ An elevated ridge that projects upwards between the sulci of the cerebrum and also helps increase surface area of the cerebrum. 1390 Medical Science University of Isfahan, Department of Anatomy

Defining the lobes central (rolandic) sulcus frontal lobe parietal lobe occipital lobe temporal lobe sylvyan (lateral) sulcus 1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

Sulci of lateral view Lateral sucus: Central sulcus : Anterior horizontal Anterior ascending Posterior Central sulcus : Superior frontal & Inferior frontal sulci Superior & middle temproal gyri 1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

Sulci of medial view Cingulate sulcus Parieto – occipital sulcus Calcarine sulcus 1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

Sulci of inferior view Tentorial portion: Orbital portion Collateral sulcus Fronto - occipital sulcus Orbital portion Oribital sulci 1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

6 1 4 8 Supramarginal 10 3 Angular 2 44 41 17 45 42 1390 Medical Science University of Isfahan, Department of Anatomy

19 18 17 18 19 1390 Medical Science University of Isfahan, Department of Anatomy

Main sulci are formed early in development Fissures are really deep sulci Typically discontinuous sulci: Superior frontal sulcus Inferior frontal sulcus Postcentral sulcus Intraparietal sulcus Superior temporal sulcus Inferior temporal sulcus Cingulate sulcus Precentral sulcus Typically continuous sulci: Interhemispheric fissure Sylvian fissure Parieto-occipital fissure Collateral sulcus Central sulcus Calcarine Sulcus 1390 Medical Science University of Isfahan, Department of Anatomy Source: Ono, 1990

Function of cerebral cortex Cerebral Cortex is: the outer layer of the cerebrum that consists of gray matter which deals with conscious motor action, sensation, memory, communication, reasoning, emotions, intelligence. 1390 Medical Science University of Isfahan, Department of Anatomy

Functions of Cerebral lobes Frontal Lobe ----- controls conscious muscle action, planning for movements, motor memory, voluntary eye movements. Parietal Lobe ----- Controls conscious interpretation of sensation from muscles, tongue and cutaneous areas. Temporal Lobe --- conscious interpretation of auditory and olfactory sensations. Memory of sounds and smells. Occipital Lobe ------- the most posterior lobe of the cerebrum which deals with conscious seeing, eye focus and integrating visual memory with other sensations. 1390 Medical Science University of Isfahan, Department of Anatomy

Insula (Island of Reil) (‘fifth lobe’) Covered by parietal and temporal lobes, not visible from the outside within the lateral fissure It is a component of a functional lobe which is called limbic lobe Limbic lobe is related to emotional and autonomic response to external stimuli 1390 Medical Science University of Isfahan, Department of Anatomy

Cerebral cortex Sensory Area of the Cerebral Cortex -- Located in areas posterior to the central sulcus. Receives and interprets conscious sensory impulses. The postcentral gyrus of the parietal lobe is a key ridge of gray matter that allows a person to judge the source of sensory stimuli. Motor Area of the Cerebral Cortex --- Located in areas anterior to the central sulcus. Plans and initiates impulses for conscious motor movements. The precentral gyrus of the frontal lobe is an another key ridge of gray matter that allows a person to operate specific areas of the body. Associatiopn Area of Cerebral cortex 1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

Cytoarchitecture of cerebral cortex 1390 Medical Science University of Isfahan, Department of Anatomy

Cytostructure of cerebral cortex 1 – Molecular layer 2 – External granular layer 3 – External pyramidal layer 4 - Internal granular layer 5 – Internal pyramidal layer 6 – Multiform layer 1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

Cytoarichitecture of cerebral cortex based on Brodmann divisioions Brodmann area Location Function 17 Banks of cal.sul Primary visual c 18, 19 Medial aspect of occipital lobe Secondary visual cortex 3,1,2 Postcentral gyr. primary somato. 4 Precentral gyr. Primary motor 6 Sup&middle f.g. Premotore cort. 44,45 Inf. front. gyirus Speech 41,42 Sup. tem .gyr. Auditory cortex 1390 Medical Science University of Isfahan, Department of Anatomy

Primary Motor Cortex 1390 Medical Science University of Isfahan, Department of Anatomy

Somatic Sensory Cortex 1390 Medical Science University of Isfahan, Department of Anatomy

6 1 4 8 Supramarginal 10 3 Angular 2 22 44 41 42 17 45 1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

Right vs. Left hemisphere Lateralisation: asymmetrical distribution of function, emerges during fetal development Example: Hand preferences General distribution of functions: Right hemisphere: Non-verbal perceptual tasks, visual & spatial perception Left hemisphere: Language & analytic functions 1390 Medical Science University of Isfahan, Department of Anatomy

* 1390 Medical Science University of Isfahan, Department of Anatomy

Ventricles ----------------------- Hollow spaces in the brain which store cerebral spinal fluid ( CSF ) for support, protection and circulation of extracellular fluid (ECF). Cerebral Spinal Fluid ( CSF ) - A specialized extracellular fluid produced by choroid plexus which bathes, supports and protects the interior of the brain and spinal cord. Choroid Plexus ------------------ A cluster of specialized capillaries enclosed by specialized cells that line the brain ventricles. These circulatory bodies produce cerebral spinal fluid ( CSF ). 1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

Four Ventricles Lined by ependymal cells CSF filled chambers Communicating with central canal of spinal cord Lined by ependymal cells 1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

Function of Brain Structures Continued Sensory Area of the Cerebral Cortex -- Located in areas posterior to the central sulcus. Receives and interprets conscious sensory impulses. The postcentral gyrus of the parietal lobe is a key ridge of gray matter that allows a person to judge the source of sensory stimuli. Motor Area of the Cerebral Cortex --- Located in areas anterior to the central sulcus. Plans and initiates impulses for conscious motor movements. The precentral gyrus of the frontal lobe is a another key ridge of gray matter that allows a person to operate specific areas of the body. 1390 Medical Science University of Isfahan, Department of Anatomy

Brain Structure Functions Continued Association Areas ----- Regions of the cerebral cortex that analyze, recognize and act on sensory input and communicate with the motor areas. Examples include the visual and auditory association areas. 1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

The localisation of language functions in the human brain 1390 Medical Science University of Isfahan, Department of Anatomy

Speech Wernicke’s area: Sensory speech Broca’s area: Motor speech Speech area normally in left cerebral cortex Wernicke’s area: Sensory speech Broca’s area: Motor speech Aphasia: Absent or defective speech or language comprehension 1) Broca’s aphasia (expressive aphasia, motor aphasia) 2) Wernicke’s aphasia (no comprehension & failure to convey meaning 1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

How to speak in response to seeing a word or hearing it. 1390 Medical Science University of Isfahan, Department of Anatomy Figure 9-23: Cerebral processing of spoken and visual language

Brain white mater Association fibers: Commissural fibers: Short association fasciculus Long association: Superior long association fasciculus Inferior long association fascculus Uncinate (frontotemporal) fasciculus Commissural fibers: Corpus callosum Fornix Anterior commisure Posterior commisure Projection fibers Ascending Descending 1390 Medical Science University of Isfahan, Department of Anatomy

Cortical white matter: links with other brain structures 1) Projection fibres: between cortex and subcortical structures Fibres form: corona radiata (fan-like arrangement), converge and concentrate to form the internal capsule 2) Commissural fibres: inter-hemispheric connection Main system: Corpus callosum (CC) Anterior commissure: connects temporal fields Hippocampal commissure (Fornix) 3) Association fibres: intra-cortical connections short, U-fibres arching beneath adjacent sulci long, travel through white matter 1390 Medical Science University of Isfahan, Department of Anatomy

Red: projection fibres Green: commissural fibres Blue: association fibres 1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy

1390 Medical Science University of Isfahan, Department of Anatomy