Quote of the Week: "I started reading about people of great accomplishment... and it dawned on me suddenly that the person who has the most to do with what happens in your life is you.” -Benjamin Carson Monday February 1, 2016 Do Now: socrative.comsocrative.com Room: 329anatomy Homework:  (Z): Parts of a Neuron  (Z): Organization of the Nervous System  (Z): Sympathetic vs Parasympathetic  (Z): Neuroglia  (Z): Spinal Cord, White & Gray Matter  (Z): Protection of the CNS MS. GALLAGHER’S ANATOMY & PHYSIOLOGY Agenda: Complete & Review “Do Now” Protection of the Central Nervous System Brain surgery Standards: HS-LS1-2

© 2015 Pearson Education, Inc. Protection of the Central Nervous System Scalp and skin Skull and vertebral column Meninges Cerebrospinal fluid (CSF) Blood-brain barrier

Figure 7.17a Meninges of the brain. Skin of scalp Periosteum Bone of skull Periosteal Meningeal Dura mater Arachnoid mater Pia mater Arachnoid villus Blood vessel Falx cerebri (in longitudinal fissure only) Superior sagittal sinus Subdural space Subarachnoid space (a)

© 2015 Pearson Education, Inc. Meninges Dura mater – Tough outermost layer – Double-layered external covering Periosteum—attached to inner surface of the skull Meningeal layer—outer covering of the brain – Folds inward in several areas Falx cerebri Tentorium cerebelli

© 2015 Pearson Education, Inc. Meninges Arachnoid layer – Middle layer – Weblike extensions span the subarachnoid space – Arachnoid villi reabsorb cerebrospinal fluid Pia mater – Internal layer – Clings to the surface of the brain

Figure 7.17b Meninges of the brain. Occipital lobe Tentorium cerebelli Cerebellum Arachnoid mater over medulla oblongata Skull Scalp Superior sagittal sinus Dura mater Transverse sinus Temporal bone (b)

© 2015 Pearson Education, Inc. Cerebrospinal Fluid (CSF) Similar to blood plasma composition Formed by the choroid plexus – Choroid plexuses–capillaries in the ventricles of the brain Forms a watery cushion to protect the brain Circulated in arachnoid space, ventricles, and central canal of the spinal cord

© 2015 Pearson Education, Inc. Cerebrospinal Fluid (CSF) Pathway of Flow 1.CSF is produced by the choroid plexus of each ventricle. 2.CSF flows through the ventricles and into the subarachnoid space via the median and lateral apertures. Some CSF flows through the central canal of the spinal cord. 3.CSF flows through the subarachnoid space. 4.CSF is absorbed into the dural venous sinuses via the arachnoid villi.

Figure 7.18a Ventricles and location of the cerebrospinal fluid. Septum pellucidum Inferior horn Lateral aperture Lateral ventricle Anterior horn Interventricular foramen Third ventricle Cerebral aqueduct Fourth ventricle Central canal (a) Anterior view

Figure 7.18b Ventricles and location of the cerebrospinal fluid. Lateral ventricle Anterior horn Interventricular foramen Third ventricle Cerebral aqueduct Fourth ventricle Central canal Posterior horn Inferior horn Median aperture Lateral aperture (b) Left lateral view

Figure 7.18c Ventricles and location of the cerebrospinal fluid Superior sagittal sinus Choroid plexus Corpus callosum Interventricular foramen Third ventricle Arachnoid villus Subarachnoid space Arachnoid mater Meningeal dura mater Periosteal dura mater Right lateral ventricle (deep to cut) Choroid plexus of fourth ventricle Cerebral aqueduct Lateral aperture Fourth ventricle Median aperture Central canal of spinal cord CSF is produced by the choroid plexus of each ventricle. CSF flows through the ventricles and into the subarachnoid space via the median and lateral apertures. Some CSF flows through the central canal of the spinal cord. CSF flows through the subarachnoid space. CSF is absorbed into the dural venous sinuses via the arachnoid villi. (c) CSF circulation

© 2015 Pearson Education, Inc. Hydrocephalus in a Newborn Hydrocephalus – CSF accumulates and exerts pressure on the brain if not allowed to drain – Possible in an infant because the skull bones have not yet fused – In adults, this situation results in brain damage

Figure 7.19 Hydrocephalus in a newborn.

© 2015 Pearson Education, Inc. Blood-Brain Barrier Includes the least permeable capillaries of the body Excludes many potentially harmful substances Useless as a barrier against some substances – Fats and fat-soluble molecules – Respiratory gases – Alcohol – Nicotine – Anesthesia

© 2015 Pearson Education, Inc. Blood-Brain Barrier Water-soluble items that can travel through barrier: – Water – Glucose – Essential amino acids Items prevented from passing through: – Metabolic wastes – Most drugs – Nonessential amino acids – Potassium ions

Brain Anuerysm An brain aneurysm is a bulging, weak area in the wall of an artery that supplies blood the brain. Two surgical options are: embolization (filling the anuerysm, making it less likely to rupture) surgical clipping (clamping the vessel to cut it off from circulation/decrease pressure) Become a neurosurgeon and perform a surgical clipping