The Brainweighs 350 G in the Newborn and 1400 G in the Adult
- The Brainweighs 350 g in the newborn and 1400 g in the adult.
- The brain is classified into six postembryonic divisions:
- Telencephalon
- Diencephalon
- Mesencephalon
- Pons
- medulla oblongata
- cerebellum.
- Telencephalon
- consists of the cerebral hemispheres and the basal ganglia
- The cerebral hemispheres contain the lateral ventricles.
- Cerebral hemispheres consist of six lobes and the olfactory structures
- Frontal lobe contains the following gyri:
- Precentralgyrus - consists of the motor area (area 4).(MCQ)
- Superior frontal gyruscontains the supplementary motor cortex on the medial surface (area 6).
- Middle frontal gyruscontains the frontal eye field (area 8) (MCQ)
- Inferior frontal gyruscontains the Broca speech area in the dominant hemisphere (areas 44 and 45) (MCQ)
- Gyrus rectus and orbital gyriare separated by the olfactory sulcus.
- Anterior paracentral lobule
- is found on the medial surface between the superior frontal gyrus (paracentral sulcus) and the central sulcus.
- represents a continuation of the precentralgyrus on the medial hemispheric surface.
- Parietal lobe contains the following lobules and gyri:
- Postcentralgyrusis the primary somatosensory area of the cerebral cortex (areas 3, 1, and 2).
- Superior parietal lobulecomprisesassociationareasinvolvedinsomatosensoryfunctions(areas5and7)
- Supramarginalgyrusinterrelates somatosensory, auditory, and visual input (area 40)
- Temporal lobecontains the following gyri:
- Transverse temporal gyri of Heschl is the primary auditory areas of the cerebral cortex (areas 41 and 42).
- Superior temporal gyruscontains the Wernicke speech area in the dominant hemisphere (area 22).
- Occipital lobecontains two structures:
- Cuneuscontains the visual cortex (areas 17, 18, and 19).
- Lingual gyrus(medial occipitotemporalgyrus) contains the visual cortex (areas 17, 18, and 19).
- Insular lobe (insula)
- Limbic lobe
- is a C-shaped structure of the medial hemispheric surface
- includes the following structures:
- Paraterminalgyrus and subcallosal area
- Cingulate gyrus
- Parahippocampalgyrus
- Hippocampal formation
- is connected to the hypothalamus and septal area via the fornix.
- includes the following three structures:
- Dentate gyrus
- Hippocampus
- Subiculum
- Olfactory structures
- are found on the orbital surface of the brain and include:
- Olfactory bulb and tract
- Olfactory bulbreceives the olfactory nerve (cranial nerve [CN] I).
- Olfactory trigone and striae
- Anterior perforated substanceis created by penetrating striate arteries
- Diagonal band of Brocainterconnects the amygdaloid nucleus and the septal area.
- Basal ganglia
- are the subcortical nuclei of the telencephalon.
- Caudate nucleus
- Putamen
- Globus pallidus
- Amygdaloid nuclear complex (amygdala)
- What is striatum and lentiform nucleus (MCQ)
- Striatum = Caudate nucleus + Putamen
- lentiform nucleus = Globus pallidus + Putamen
- Lateral ventricles
- areependyma-lined cavities of the cerebral hemispheres.
- containCSF and choroid plexus.
- communicate with the third ventricle via the two interventricular foramina of Monro
- are separated from each other by the septa pellucida.
- Cerebral cortex
- consists of a thin layer or mantle of gray substance.
- is folded into gyri that are separated by sulci.
- White matterincludes the cerebral commissures and the internal capsule
- Cerebral commissures
- interconnect the cerebral hemispheres
- Corpus callosum
- is the largest commissure of the brain.
- interconnects the two hemispheres.
- has four parts: Rostrum, Genu, Body ,Splenium
- Anterior commissure
- interconnects the olfactory bulbs and the middle and inferior temporal lobes.
- Hippocampal commissure (commissure of the fornix)
- Internal capsule
- consists of the white matter
- located between the basal ganglia and the thalamus.
- has three parts:
- Anterior limb
- located between the caudate nucleus and putamen.
- Genu
- located between the anterior and posterior limbs.
- containscorticobulbar fibers
- Posterior limb
- located between the thalamus and lentiform nucleus
- Contains corticospinal fibers.
- Diencephalon
- is located between interventricular foramen and the posterior commissure.
- receives the optic nerve (CN II).
- consists of the epithalamus, thalamus, hypothalamus, subthalamus, and the third ventricleand associated structures.
- Epithalamus
- Pineal body (epiphysis cerebri)
- Habenulartrigone
- Medullary stria of the thalamus
- Posterior commissure
- mediates the consensual reaction of the pupillary light reflex.
- Telachoroidea and choroid plexus of the third ventricle
- Thalamus
- consists of the following surface structures:
- Pulvinar
- Metathalamus
- Medial geniculate body (auditory system)
- Lateral geniculate body (visual system)
- Hypothalamus
- Optic chiasm
- Mamillary body
- Infundibulum
- Tuber cinereum
- Subthalamus (ventral thalamus)
- Subthalamic nucleus
- Zonaincerta and fields of Forel
- Third ventricle and associated structures
- Lamina terminalisresults from closure of the anterior neuropore.
- Telachoroidea
- Choroid plexus
- Interventricular foramen of Monro
- interconnects the lateral ventricle and the third ventricle.
- Optic recess
- Infundibular recess g. Suprapineal recess
- Pineal recess
- Mesencephalon (midbrain)
- contains the cerebral aqueduct, which interconnects the third and fourth ventricles.
- Ventral surface
- Cerebral peduncle
- Interpeduncular fossa
- Oculomotor nerve (CN III)
- Posterior perforated substanceis created by penetrating branches of the posterior cerebral and posterior communicating arteries.
- Dorsal surface
- Superior colliculus (visual system)(MCQ)
- Brachium of the superior colliculus
- Inferior colliculus (auditory system)(MCQ)
- Brachium of the inferior colliculus
- Trochlear nerve (CN IV)
- is the only cranial nerve to exit the brainstem from the dorsal aspect.
- Pons
- Ventral surface
- Base of the pons
- Cranial nerves (MCQ)
- Trigeminal nerve (CN V)
- Abducent nerve (CN VI)
- Facial nerve (CN VII)
- Vestibulocochlear nerve (CN VIII)
- Dorsal surface (rhomboid fossa)
- Locus ceruleus
- contains the largest collection of norepinephrinergic neurons in the CNS. (MCQ)
- Facial colliculus
- contains the abducent nucleus and internal genu of the facial nerve.
- Sulcus limitans(MCQ)
- separates the alar plate from the basal plate.
- Striaemedullares of the rhomboid fossa
- divide the rhomboid fossa into the superior pontine portion and the inferior medullary portion.
- Medulla oblongata (myelencephalon)
- Ventral surface
- Pyramidcontains the corticospinal tract.
- Olive contains the inferior olivary nucleus.(MCQ)
- Cranial nerves
- Glossopharyngeal nerve (CN IX)
- Vagal nerve (CN X)
- Accessory nerve (CN XI)
- Hypoglossal nerve (CN XII)
- Dorsal surface
- Gracile tubercle
- Cuneate tubercle
- Rhomboid fossa
- Striaemedullares of the rhomboid fossa
- Vagal trigone
- Hypoglossal trigone
- Sulcus limitans
- Area postrema (vomiting center) (MCQ)
- Cerebellum
- is located in the posterior cranial fossa.
- is attached to the brainstem by three cerebellar peduncles.
- forms the roof of the fourth ventricle.
- is separated from the occipital and temporal lobes by the tentorium cerebelli.
- consists of folia and fissures on its surface.
- contains the following surface structures
- Hemispheresmade up of two lateral lobes.
- Vermisis a midline structure.
- Tonsil
- may herniate, with increased intracranial pressure, through the foramen magnum.
- Superior cerebellar peduncle connects the cerebellum to the pons and midbrain.
- Middle cerebellar peduncleconnects the cerebellum to the pons.
- Inferior cerebellar peduncleconnects the cerebellum to the medulla.
- Anterior lobe
- Posterior lobe
- Flocculonodular lobe