Nervous System
THE BRAIN CONTINUED Review
White versus grey matter Ventricles 4 brain regions 4 lobes of cerebral hemispheres 3 layers of cerebrum Cortex Motor Sensory Association White matter tracts Gray matter Brain Regions
4 Adult brain regions 1. Cerebral hemispheres (cerebrum) 2. Diencephalon 3. Cerebellum 4. Brain stem (midbrain, pons, and medulla)
Diencephalon
Three paired structures Thalamus Hypothalamus Epithalamus Encloses the third ventricle Cerebral hemisphere
Septum pellucidum Corpus callosum Interthalamic Fornix adhesion Choroid plexus (intermediate Thalamus mass of (encloses third thalamus) ventricle) Interven- Posterior commissure tricular Pineal gland foramen (part of epithalamus) Anterior Corpora commissure quadrigemina Mid- Hypothalamus Cerebral brain aqueduct Optic chiasma Arbor vitae (of Pituitary gland cerebellum) Mammillary body Fourth ventricle Choroid plexus Pons Cerebellum Medulla oblongata Spinal cord
Figure 12.12 Diencephalon
Thalamus Several nuclei Gateway of the cerebral cortex Major relay station for most sensory impulses
Diencephalon
Thalamus Relay center for cerebral activation Associated with reticular formation Relay center for somatosensory information Except olfaction Coma is associated with thalamic injury Vegetative state = damage to cortical pathways
Refer to diagram on CNS 8 Diencephalon
Hypothalamus Inferior to the thalamus Forms portions of walls of the third ventricle Consists of a number of nuclei
Diencephalon
Hypothalamus Infundibulum Mammillary bodies Responsible for most neurogenic homeostasis of the body
Diencephalon
Hypothalamic function Autonomic control center for many visceral functions Examples Blood pressure, rate and force of heartbeat Regulates body temperature Hunger and G.I tract regulation Center for emotional response Example Tactile sexual response Diencephalon
Hypothalamic Function Water balance and thirst Controls release of hormones by the anterior pituitary and produces posterior pituitary hormones Regulation of sleep-wake cycles Diencephalon
Epithalamus Forms roof of third ventricle Pineal gland, choroid plexus Melatonin We’ll discuss it’s endocrine function later…. Brain Regions
4 Adult brain regions 1. Cerebral hemispheres (cerebrum) 2. Diencephalon 3. Brain stem (midbrain, pons and medulla) 4. Cerebellum
The Brain Stem
Functions Supports most of basic life functions Pathway for fiber tracts Origin for most cranial nerves
The Brain Stem
Midbrain Associated with visual and auditory reflexes Pupillary reflex Cranial nerves III and IV Red nucleus Descending motor pathways involved in voluntary movement
Frontal lobe Olfactory bulb (synapse point of cranial nerve I) Optic chiasma Optic nerve (II) Optic tract Mammillary body Midbrain Pons Temporal lobe Medulla oblongata Cerebellum Spinal cord
Figure 12.14 View (a) Optic chiasma Optic nerve (II)
Diencephalon Crus cerebri of • Thalamus cerebral peduncles • Hypothalamus (midbrain) Thalamus Diencephalon Mammillary body Hypothalamus Oculomotor nerve (III) Midbrain Pons Brainstem Trochlear nerve (IV) Medulla oblongata Trigeminal nerve (V) Middle cerebellar Pons peduncle Facial nerve (VII) Abducens nerve (VI) Vestibulocochlear Glossopharyngeal nerve (IX) nerve (VIII) Hypoglossal nerve (XII) Pyramid Vagus nerve (X) Ventral root of first cervical nerve Accessory nerve (XI) Decussation of pyramids
Spinal cord
(a) Ventral view
Figure 12.15a Crus cerebri of Thalamus cerebral peduncles (midbrain) View (b) Infundibulum Superior colliculus Pituitary gland Inferior colliculus Trochlear nerve (IV) Trigeminal nerve (V) Superior cerebellar peduncle Pons Middle cerebellar peduncle Facial nerve (VII) Inferior cerebellar peduncle Abducens nerve (VI) Vestibulocochlear nerve (VIII) Glossopharyngeal nerve (IX) Olive Hypoglossal nerve (XII) Thalamus Diencephalon Vagus nerve (X) Hypothalamus Accessory nerve (XI) Midbrain Pons Brainstem Medulla oblongata
(b) Left lateral view
Figure 12.15b The Brain Stem
Pons Bridge between midbrain and medulla oblongata Connects cerebellum to cerebrum and spinal cord Cranial nerves V- VIII (vestibular branch)
Crus cerebri of Thalamus cerebral peduncles (midbrain) View (b) Infundibulum Superior colliculus Pituitary gland Inferior colliculus Trochlear nerve (IV) Trigeminal nerve (V) Superior cerebellar peduncle Pons Middle cerebellar peduncle Facial nerve (VII) Inferior cerebellar peduncle Abducens nerve (VI) Vestibulocochlear nerve (VIII) Glossopharyngeal nerve (IX) Olive Hypoglossal nerve (XII) Thalamus Diencephalon Vagus nerve (X) Hypothalamus Accessory nerve (XI) Midbrain Pons Brainstem Medulla oblongata
(b) Left lateral view
Figure 12.15b The Brain Stem
Medulla Continuous with spinal cord Passage of motor & sensory impulses between brain & spinal cord Decussation of tracts in pyramids
Commissural Longitudinal fissure (corpus Superior fibers callosum) Lateral ventricle Association Basal nuclei fibers • Caudate • Putamen Corona radiata • Globus Fornix pallidus Internal Thalamus capsule Gray matter Third White matter ventricle Projection Pons fibers Decussation Medulla oblongata of pyramids (a)
Figure 12.10a The Brain Center
Medulla Vital centers Cardiac Vasomotor Respiratory Swallowing Vomiting Cranial nerves VIII (cochlear branch) -XII
Brain Regions
4 Adult brain regions 1. Cerebral hemispheres (cerebrum) 2. Diencephalon 3. Brain stem (midbrain, pons, and medulla) 4. Cerebellum
The Cerebellum
Dorsal to the pons & medulla Subconsciously provides precise timing & appropriate patterns of skeletal muscle contraction Contains both white & gray matter
Anterior lobe Cerebellar cortex Arbor vitae
Cerebellar peduncles Posterior • Superior lobe • Middle Choroid • Inferior plexus of Medulla Flocculonodular fourth oblongata lobe ventricle (b)
Figure 12.17b The Cerebellum
Functions Proprioception Prime mover inhibition and antagonist activation Dysmetria Progression Dysarthria
Functional Brain Systems
Networks of neurons that work together & span wide areas of the brain Limbic system Reticular formation Functional Brain Systems
Limbic system Structures on the medial aspects of cerebral hemispheres and diencephalon Includes parts of the diencephalon and some cerebral structures that encircle the brain stem Septum pellucidum Fiber tracts connecting limbic Diencephalic structures Corpus callosum system structures of the limbic system •Fornix •Anterior thalamic •Anterior commissure nuclei (flanking 3rd ventricle) Cerebral struc- tures of the •Hypothalamus limbic system •Mammillary body •Cingulate gyrus •Septal nuclei •Amygdala •Hippocampus •Dentate gyrus •Parahippocampal gyrus Olfactory bulb
Figure 12.18 Functional Brain Systems
Limbic system Emotional brain Recognizes angry or fearful facial expressions Assesses danger & elicits the fear response Plays a role in expressing emotions via gestures and resolves mental conflict Connection to pre-frontal cortex allows us to “count to ten” Puts emotional responses to odors Example: skunks = smell bad Functional Brain Systems
Reticular formation Broad columns of nuclei along the length of the brain stem Far-flung axonal connections with hypothalamus, thalamus, cerebral cortex, cerebellum & spinal cord Radiations to cerebral cortex
Visual impulses Auditory impulses Reticular formation Ascending general Descending sensory tracts motor projections (touch, pain, temperature) to spinal cord
Figure 12.19 Functional Brain Systems
Functions of the reticular formation 1. Somatic motor control Reticulospinal tract = improves smoothness of movement 2. Autonomic control Respiratory and cardiovascular centers 3. Arousal RAS = filter 4. Pain modulation Can block pain transmission
Questions?
Homework due in Lab PreLab #2 HW #2 – Synapses (page 1 and 2 in HW section)