Brain and Cranial Nerves PDF

Brain and Cranial Nerves Part I: The Brain  Brain Surface Structure Gyrus: ridges on brain surface Sulcus: grooves between gyri Fissures: deep sulci between gyri  Organization of Neural Tissue in the Brain Gray Matter: Cell bodies, dendrites, and unmyelinated axons of neurons...

Brain and Cranial Nerves Part I: The Brain  Brain Surface Structure Gyrus: ridges on brain surface Sulcus: grooves between gyri Fissures: deep sulci between gyri  Organization of Neural Tissue in the Brain Gray Matter: Cell bodies, dendrites, and unmyelinated axons of neurons White Matter: myelinated axons of neurons – Color is based on color of myelin  Neuronal Tracts Tracts: axons in the white matter are grouped into bundles Tracts are classified according to the direction in which they run – Association Fibers: Connect different parts of the same hemisphere – Commissural Fibers: Connect corresponding areas of the two hemispheres – Projection Fibers: Link cerebral cortex to lower brain regions and spinal cord  Regions of the Brain 1. Cerebrum 2. Diencephalon 3. Brainstem 4. Cerebellum  Cerebrum Cerebrum: principal part of the brain located in the front area of the skull Location of conscious thoughts and intellectual activity Contains 2 cerebral hemispheres divided by the longitudinal fissure.  Layers of the Cerebrum Cerebral Cortex: superficial layer of cerebrum – Composed of gray matter Cerebral Medulla: deep layer of cerebrum – Composed of white matter  Cerebrum Corpus Callosum: bundle of axons that connect the right and left cerebral hemispheres  Cerebrum Each hemisphere has 5 lobes: frontal, parietal, occipital, temporal, insula – Central Sulcus divides the frontal and parietal lobes – Lateral Sulcus divides the frontal/parietal lobes from the temporal lobe  Cerebrum: Frontal Lobe The most anterior lobe of the brain. Functions – Voluntary motor functions – Decision making and planning – Personality  Cerebrum: Frontal Lobe Important Areas: Precentral Gyrus: – Gyrus immediately anterior to the central sulcus – Location of the primary motor cortex: controls majority of motor function. Broca’s Area: – Controls muscles used for speech – Only present on one side (usually left)  Cerebrum: Parietal Lobe Lobe posterior to the central sulcus. Functions – General sensory information for touch, pain, temperature  Cerebrum: Parietal Lobe Important Areas: Postcentral Gyrus – Gyrus immediately posterior to central sulcus – Contains primary somatosensory cortex – Processes touch, pain, and temperature. Wernicke’s Area: – Comprehension of written/spoken language. – Partially in the temporal lobe Primary Motor and Somatosensory Cortexes  Cerebrum: Temporal Lobe Lobe inferior to frontal and parietal lobes. Functions: – Primary auditory perception – Olfaction – Emotional association  Cerebrum: Occipital Lobe Posterior-most lobe. Functions: – Process visual information – Stores visual memory  Cerebrum: Insula Located deep to the lateral sulcus Function – Memory and interpretation of taste  Regions of the Brain 1. Cerebrum 2. Diencephalon 3. Brainstem 4. Cerebellum  Diencephalon Contains 3 Regions: – Epithalamus, Thalamus, Hypothalamus  Thalamus Function: – relay both motor and sensory information to and from the cerebrum Contains specific nuclei for various functions  Epithalamus Epithalmus is the structure behind the thalamus. Contains the Pineal Gland – Secretes melatonin for circadian rhythm  Hypothalamus The Hypothalamus is the region anterior/inferior to the thalamus Contains many nuclei with a variety of functions including appetite, and temperature. – Important for maintaining homeostasis.  Hypothalamus Connects the nervous system to the endocrine system through the pituitary gland – Pituitary gland hangs from the hypothalamus by the infundibulum – Hypothalamus controls the secretion of hormones Pituitary hormones control several other hormone glands  Limbic System The Limbic System is a group of structures on the cerebrum and diencephalon. Our “emotional brain” – Allows us to generate emotions – Connects emotions to senses.  Regions of the Brain 1. Cerebrum 2. Diencephalon 3. Brainstem 4. Cerebellum  Brainstem 3 Regions: – Midbrain – Pons – Medulla Oblongata  Brainstem: Midbrain Midbrain: Superior- most portion of brainstem  Brainstem: Midbrain Internal Structures: Cerebral Aqueduct – Connects 3rd and 4th ventricles – Central Midbrain  Brainstem: Midbrain Posterior Structures: Corpora quadrigemina: consists of the paired superior colliculi and inferior colliculi. – Superior colliculus: Visual reflex centers. Track moving objects Movement of eyes and head in response to visual stimulus – Inferior Colliculus: auditory reflex center Movement of body in respond to sound  Brainstem: Pons Middle portion of the brainstem. Acts as a respiratory center for the body. – Controls the skeletal muscles used for breathing – Works with the medulla oblongata  Brainstem: Medulla Oblongata Most inferior portion of brainstem – Continuous with spinal cord  Brainstem: Medulla Oblongata The medulla oblongata contains multiple vital centers: – Cardiac Center: regulate heart rate and strength of contraction – Vasomotor Center: regulate blood vessel diameter – Respiratory Center: rate of respiration (works with Pons)  Regions of the Brain 1. Cerebrum 2. Diencephalon 3. Brainstem 4. Cerebellum  Cerebellum Second largest part of the brain Contains two cerebellar hemispheres – Both hemispheres connected by Vermis  Cerebellum Functions: – Fine tune skeletal movements – Provides feedback to cerebrum – Maintain equilibrium and posture  Cerebellum Effects of alcohol on cerebellum – Loss of gait Can’t walk straight or smoothly – Loss of balance and posture Can’t stand on one foot – Inability to detect proprioceptive information. Can’t close eyes and touch nose.  Cerebellum The cerebellum contains white and gray matter organized similarly to the cerebrum. – Cerebellar Cortex: Outer gray matter – Arbor Vitae: inner white matter Looks like a tree (“arbor”)