Unit 4 Nervous System Lab 2 Human Brain

Unit 4: Nervous System Lab 2: Human Brain Structures Jessica Radke-Snead, RD, MS Bio 241 Anatomy & Physiology

Review from Lab 1 • On your own, review: – Cerebral meninges – Organization of tissue in brain – Skull and muscle review (designated in your lab guides)

Lab 2 Objectives • What you need to work on today: – Primary and secondary embryonic structures – External and internal anatomy of spinal cord – Lobes – Grooves – Ridges – Surface and internal anatomy – Functional areas – Structures associated with CSF – Cranial Nerves—location, function if you have time

BEFORE Lab 3 next week • By next lab, please have a working knowledge of: – Cranial nerves: number, name, location, type and function – Spinal nerves: nerves, plexus and arising nerves – Nerve functions: nerves, motor and/or sensory – Skull and muscle review (designated in your lab guides)

Organization of tissue in the brain • White matter includes: – Myelin sheath – Nerve fibers – Neuroglia nuclei • Gray matter includes: – Motor neuron cell bodies – Nerve fibers – Neuroglia

Neurulation: Development of the Neural Tube • ~Day 18, embryonic ectoderm thickens to form a neural plate, which eventually gives rise to the CNS • ~Day 20, neural plate forms the neural groove with neural folds on each side

Neurulation Continued • ~Day 21, neural folds fuse to form the ___ – Closure begins in the __ of the embryon and progresses toward ___. • On which days to the cephalic and caudal ends close? • The lumen of the neural tube develops into what? • __ ___ cells, formed from some ectoderm cells, become sensory neurons, sympathetic neurons, Schwann cells, etc.

Primary Structures of the CNS Week 4

Secondary Vesicles • Prosencephalon divides into: – ___ Cerebral hemispheres (lateral outgrowths), cerebral cortex, basal ganglia, hippocampus, amygdala – ___ Retinas (optic vesicles), thalamus, hypothalamus • ___ Tectum and tegmentum • Rhombencephalon divides into: – ___ Pons and cerebellum – ___ Medulla oblongata

Secondary Structures of the CNS Week 5

Major landmarks of the brain • 3 major portions: – Cerebrum, which contains the cerebral hemispheres • Marked by gyri and separated by sulci • Separated by the longitudinal fissure • Connected by corpus callosum – Cerebellum • Contains ~50% of the brain’s neurons • Marked by gyri, sulci and fissures – Brainstem • • Diencephalon* Midbrain Pons Medulla oblongata

Cerebral Hemisphere Lobes, Grooves and Ridges

Anatomy of the brain • Cerebral peduncles – Anchor the cerebrum to the brainstem – Corticospinal tracts pass through the peduncles to the medulla • Tegmentum: main mass of the midbrain – Collaborates in fine motor control • Tectum – Corpora quadrigemina • Superior colliculi: visual attention (blinking, focusing, pupillary dilation/constriction) • Inferior colliculi: receive signals from the inner ear and relay them to other parts of the brain, ie thalamus

Midbrain Surface Anatomy

Cerebral Hemisphere Surface Anatomy: Inferior View

Cerebrum Olfactory Bulb Olfactory Tract Mammillary Body Cerebral Peduncle Pons I Olfactory (fibers) II Optic III Oculomotor IV Trochlear (not shown) V Trigeminal (cut) VI Abducens VII Facial VIII Vestibulocochlear IX Glossopharyngeal X Vagus XI Accessory Cerebellar Peduncle XII Hypoglossal (cut) Cerebellum Medulla Oblongata

Anatomy of the brain • Medulla oblongata – Contains sensory nuclei that receive input from the taste buds, pharynx and viscera of the thoracic and abdominal cavities – Some motor nuclei • Cardiac center: regulates HR and force of beat • Vasomotor center: adjusts BV diameter • Respiratory centers: regulate the rate and depth of breathing • Pons – Contains nuclei that relay signals from the cerebrum to the cerebellum – Contains nuclei involved with sleep, hearing, equilibrium, taste, eye movements, facial expressions, facial sensation, respiration, swallowing, bladder control and posture

Anatomy of the brain • Thalamus – 2 thalami joined by a narrow intermediate mass – Most sensory input and other info going to the cerebrum passes through it thalami filter it – Key role in motor control: relays signals from the cerebellum to the cerebrum and provides feedback loops – Role in memory and emotional functions (limbic system)

Anatomy of the brain • Hypothalamus – Between optic chiasm and mammillary bodies, forms floor of the 3 rd ventricle – Major control center of the ANS and endocrine system • Hormone secretion • Autonomic effects: HR, BP, GI secretion and motility, pupillary diameter – Role in homeostatic regulation of most organs of the body • Thermoregulation: monitors blood temperature (shiver, sweat, vasodilation, vasoconstriction) • Food/water intake: hunger and satiety communication, osmolarity of blood to signal thirst – Sleep and circadian rhythms – Memory – Emotional behavior

Anatomy of the brain • Mammillary bodies – Relay signals from the limbic system to the thalamus • Pituitary gland (Hypophysis) – Attached to hypothalamus via infundibulum (sella turcica) – Secretes numerous hormones, most of which regulate the activities of other glands • Pineal gland – Produces melatonin and serotonin – Timing and onset of puberty

Anatomy of the brain • Fornix – Axons in the brain that carry signals from the hippocampus to the hypothalamus • Septum pellucidum – Thin membrane separating the anterior horns of the left and right lateral ventricles of the brain • Corpus callosum – Thick band of nerve fibers that divides the cerebrum into left and right hemispheres

Internal Anatomy of the Brain Fornix Septum Pellucidum Corpus Callosum Int Mass of Thalamus Corpora Quadrigemina Arbor Vitae (white matter) Folia (gray matter)

Internal Anatomy of the Brain

Midbrain Internal Anatomy

Cerebellum and Brain Stem

Functional areas of the brain • Primary cortex – Detects basic dimensions of sensory information • Association cortex – Area outside the primary cortex that detects more complex dimensions of sensory information

Functional areas of the brain • Primary somatosensory area – Somesthetic fibers decussate on way to thalamus – Right postcentral gyrus receives signals from left side, and vice versa • Somatosensory association area (parietal lobe) – Awareness of positions in our limbs – Location of touch or pain – Shape, weight and texture (something held in hand) • Primary visual area – Basic formation of visuals • Visual association area (occipital lobe) – Spatial perception – Recognition of familiar objects

Functional areas of the brain • Primary motor area – Neurons send signals to the brainstem and spinal cord that ultimately result in muscle contractions • Motor association area – Plan our behavior – Neurons compile a program for the degree and sequence of muscle contractions and send to: • Primary auditory area – Processes sound • Auditory association area ( temporal lobe) – Remember the name of a piece of music – Identify a person by their voice

Functional areas of the brain

Structures involved with CSF • 3 purposes of CSF: – Buoyancy: brain remains suspended in CSF – Protection: typically prevents brain from striking the cranium – Chemical stability: rinses metabolic wastes from the CNS and regulates chemical environment • High glycine: disrupts temp and BP control • High p. H: dizziness and fainting • Meninges of the brain Dura mater includes a periosteal and meningeal layer (continues to vertebral canal) • Dural sinuses: spaces that collect blood that has circulated through the brain – Superior sagittal sinus – Transverse sinus

• Heart and lungs Arterial blood: 1. Lateral ventricle’s choroid plexus Lateral Ventricle a. Through interventricular foramina 2. 3 rd Ventricle’s choroid plexus 3 rd Ventricle a. Through cerebral aqueduct 3. 4 th Ventricle’s choroid plexus 4 th Ventricle a. Through lateral and median aperatures 4. Arachnoid villi of dural venous sinuses superior sagittal sinus 5. Venous blood Return blood to heart

Structures involved with CSF 1 1 a 3 3 a 2 2 a 3 a 4: Arachnoid villi of dural venous sinuses Venous blood

Cranial Nerves (by #) 1 2 34 6 12 11 5 7 8 9 10