Human Anatomy Unit 4 NERVOUS SYSTEM: THE BRAIN

Human Anatomy Unit 4 NERVOUS SYSTEM: THE BRAIN

Major Divisions of the Brain

Terminology Gray ma<er Unmyelinated regions White ma<er Myelinated axons

General Structures of Gray Gyrus (gyri p.) Ma<er (Cortex) folds of the cerebral surface Sulcus (sulci p.) grooves between gyri Fissure deep groove

Ventricles of the Brain Lateral ventricles 2 ventricles shaped like ram horns inferior, medial to cerebral hemispheres Third ventricle surrounded by diencephalon of brain stem Fourth ventricle anterior to cerebellum contains 3 apertures leading to the subarachnoid space (2 lateral and 1 median)

Ventricles of the Brain

Ventricles & Central Canal Cerebral aqueduct canal between third and fourth ventricle Central canal centrally located in the spinal cord Ventricles lined with choroid plexus and ependymal cells cerebrospinal fluid producvon Cerebrospinal fluid circulates throughout ventricles, central canal and subarachnoid space Returns to general circulavon through arachnoid villi at dural sinuses

The Cranial Meninges

Cranial Meninges Dura Mater Tough mother dense connecvve Vssue outer, double layered surrounding the brain outer = periosteal layer inner = meningeal layer (folded in certain locavons as a falx ) openings between the 2 layers are dural sinuses

Cranial Meninges Arachnoid Mater Spidery mother Arachnoid granulavons for return of CSF to general circulavon network of connecvve Vssue

Cranial Meninges Pia Mater Delicate mother indissecvble from surface of the CNS loose connecvve Vssue

Falx Cerebri

Cerebrospinal Fluid Surrounds and bathes exposed surfaces of the CNS FuncVons Prevents fricvon Support RegulaVon of microenvironment Choroid plexus 500 ml/day

CirculaVon of CSF 150 ml in circulavon CSF from lateral ventricles Interventricular foramen > 3 rd ventricle Aqueduct of midbrain From 4 th ventricle enters subarachnoid space Lateral aperture Median aperture 4 th ventricle > central canal Subarachnoid space > arachnoid granulavons

Blood Supply to the Brain Jugular veins Drain the dural sinuses Internal carovd arteries Vertebral arteries

Cerebrum Cerebral hemispheres Leb and right halves Separated by longitudinal fissure Connected in spots by tracts Lobes Contain higher brain centers Nuclei responsible for motor coordinavon and control of memory, emovon and other funcvons

The Cerebral Lobes 5 major divisions in each hemisphere 4 named aber bones under which they lie Frontal Parietal Occipital Temporal 1 on interior Insula

The Cerebral Lobes

Insula Small lobes deep in lateral sulcus beneath temporal lobes FuncVon: memory and interpretavon of taste insula New study suggests that the insula is involved in smoking addiction Naqvi, N.H., et al, 2007. Damage to the insula disrupts addiction to cigarette smoking. Science. V315;531-4.

Motor Areas of the Cerebral Cortex Control voluntary movement Precentral gyrus Primary motor cortex Pyrimidal cells Pathway is corvcospinal tract

Sensory Areas of the Cerebral Conscious awareness of sensavon Primary sensory cortex Postcentral gyrus Collaterals also deliver info to basal nuclei and other centers Visual cortex Auditory cortex Olfactory cortex Gustatory cortex Cortex

AssociaVon Areas of the Cerebral Cortex AssociaVon areas Integrate and store informavon Interpret sensory info Help plan, prepare for and help coordinate motor output Somatosensory associavon area Pre motor cortex

IntegraVve Centers of the Cerebral Cortex Receive, process informavon from many associavon areas Direct complex motor acvvives Complicated analyvcal funcvons

The Central White Ma<er AssociaVon tracts Connect regions of cortex within same hemisphere Commissural tracts Bridges between cerebral hemispheres Ex) corpus callosum ProjecVon tracts Between cerebral cortex, caudal brain, and spinal cord

The Central White Ma<er

Paired, irregular masses of gray ma<er within white ma<er in basal region of cerebral hemispheres Involved in Motor control Learning Components Caudate nucleus Amygdala Putamen & globus pallidus Claustrum Basal Nuclei

The Basal Nuclei

Limbic System Large group of nuclei, inferior to the corpus callosum Responsible for control of emovon, sex drive, aggression, memory consolidavon among other funcvons Hippocampus Responsible for memory consolidavon

Limbic System

Diencephalon in between brain Components Epithalamus Thalamus (right and leb) Hypothalamus FuncVons Relay and switching stavon for certain sensory and motor pathways Control visceral acvvives

Epithalamus Covers 3 rd ventricle Contains choroid plexus and ependymal cells producing CSF and the pineal gland Posterior porvon Pineal gland Melatonin Circadian rhythms Habenular nucleus Relay stavon for limbic system Visceral and emovonal response to odors

Thalamus Clusters of nuclei organized into groups Major relay stavon for sensory informavon Gray ma<er on both sides of third ventricle

Hypothalamus Contains many diverse nuclei controlling body temperature sex drive feeding drinking thirst sensavon pituitary secrevons forms the inferior walls of the third ventricle

Diencephalon

Diencephalon

Brain Stem Connects forebrain (cerebrum, diencephalon) and cerebellum to spinal cord 3 parts Midbrain Pons Medulla oblongata

The Diencephalon and the Brain Stem

The Diencephalon and the Brain Stem

Pons Contains sensory and motor tracts Autonomic respiratory center Pneumotaxic center ApneusVc center origin for many cranial nerves (V VIII)

Medulla Oblongata DecussaVon of pyramids the inferior most region of the brain stem Nuclei controlling addivonal respiratory funcvons, cardiac, vomivng origin of many cranial nerves

Pons and Medulla

The Cerebellum the second largest single structure of the brain Three lobes Anterior Posterior Flocculonodular (small)

Anatomy of the Cerebellum arbor vitae the tree of life white ma<er (axon tracts) of the cerebellum cerebellar cortex folded into many plate like ridges called folia Vermis narrow band of cortex that separates the cerebellar hemispheres

The Cerebellum