C h a p t e r 15 The Nervous System: The Brain and Cranial Nerves PowerPoint Lecture Slides prepared by Jason LaPres North Harris College Houston, Texas Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Introduction The brain is far more complex than the spinal cord. The brain contains roughly 20 billion neurons. Excitatory and inhibitory interactions among the extensively interconnected neuronal pools ensure that the response can vary to meet changing circumstances.
An Introduction to the Organization of the Brain Figure 15.1 Major Divisions of the Brain
An Introduction to the Organization of the Brain
An Introduction to the Organization of the Brain Figure 15.2a Ventricles of the Brain (Lateral View)
An Introduction to the Organization of the Brain Figure 15.2b Ventricles of the Brain (Lateral View)
An Introduction to the Organization of the Brain Figure 15.2c Ventricles of the Brain (Anterior View)
An Introduction to the Organization of the Brain Figure 15.2d Ventricles of the Brain (Coronal Section)
Protection and Support of the Brain Protection, support, and nourishment of the brain involves: Bones of the skull Cranial meninges Dura mater Arachnoid mater Pia mater Cerebrospinal fluid Blood brain barrier Vessels of the cardiovascular system
Protection and Support of the Brain Figure 15.3a Relationships among the Brain, Cranium, and Meninges (Lateral View)
Protection and Support of the Brain Figure 15.3b Relationships among the Brain, Cranium, and Meninges (Midsagittal View)
Protection and Support of the Brain Figure 15.4a The Cranial Meninges
Protection and Support of the Brain Figure 15.4b The Cranial Meninges
Protection and Support of the Brain Figure 15.4c The Cranial Meninges
Protection and Support of the Brain Figure 15.5 The Choroid Plexus and Blood Brain Barrier
Protection and Support of the Brain Figure 15.6 Circulation of Cerebrospinal Fluid
Protection and Support of the Brain Blood Supply to the Brain Figure 22.13a Arteries of the Neck and Head
Protection and Support of the Brain Blood supply to the brain Figure 22.15a Arteries of the Brain (Inferior View)
Protection and Support of the Brain Blood supply to the brain Figure 22.22a Major Veins of the Head and Neck (Lateral View)
Protection and Support of the Brain Blood Supply to the Brain Figure 22.22b Venous Drainage of the Brain (Inferior view)
Protection and Support of the Brain Figure 15.8 Hydrocephalus This infant has severe hydrocephalus, a condition usually caused by impaired circulation and removal of cerebrospinal fluid. CSF buildup leads to distortion of the brain and enlargement of the cranium.
The Cerebrum The cerebrum is the largest, most superior portion of the human brain. Each cerebral hemisphere receives sensory information from and generates motor commands to the opposite side of the body. The two hemispheres have some functional differences, although anatomically they appear to be identical.
The Cerebrum Figure 15.7a The Cerebral Hemispheres, Part I (Superior View)
The Cerebrum Figure 15.7b The Cerebral Hemispheres, Part I (Anterior View)
The Cerebrum Figure 15.7c The Cerebral Hemispheres, Part I (Posterior View)
The Cerebrum Figure 15.9a The Cerebral Hemispheres, Part II (Lateral View of Intact Brain)
The Cerebrum Figure 15.9b The Cerebral Hemispheres, Part II (The Left Cerebral Hemisphere)
The Cerebrum
The Cerebrum Figure 15.10a The Central White Matter (Lateral View)
The Cerebrum Figure 15.10b The Central White Matter (Anterior View)
The Cerebrum
The Cerebrum Figure 15.11a The Basal Nuclei (Lateral View)
The Cerebrum Figure 15.11b The Basal Nuclei (Horizonatal View, Dissected)
The Cerebrum Figure 15.11d The Basal Nuclei (Frontal Section)
The Cerebrum Figure 15.11c The Basal Nuclei (Horizontal Section)
The Cerebrum Figure 15.11e The Basal Nuclei (Frontal Section)
The Cerebrum
The Cerebrum Figure 15.12a The Limbic System
The Cerebrum Figure 15.12b The Limbic System
The Cerebrum
The Diencephalon The diencephalon connects the cerebrum to the brain stem both structurally and functionally. The functions that occur in the diencephalon are almost exclusively subconscious. Epithalamus controls the circadian rhythm Thalamus relays information Hypothalamus coordinates the nervous and endocrine systems
The Diencephalon Figure 15.15a Sectional Views of the Brain (Midsagittal Section)
The Diencephalon Figure 15.15b Sectional Views of the Brain (Coronal Section)
The Diencephalon Figure 15.16a The Diencephalon and Brain Stem (Lateral View)
The Diencephalon Figure 15.13a The Thalamus
The Diencephalon Figure 15.13b The Thalamus
The Diencephalon
The Diencephalon Figure 15.14a The Hypothalamus (Midsagittal Section)
The Diencephalon Figure 15.14b The Hypothalamus
The Diencephalon
The Mesencephalon The mesencephalon, or midbrain, is the most superior portion of the brain stem. Nuclei coordinate visual and auditory reflexes. Corpora quadregemina Superior colliculi visual Inferior colliculi auditory Limbic system nuclei Coordinate involuntary movements of skeletal muscles Cerebral peduncles Nerve bundles to and from the brain/spinal cord
The Mesencephalon Figure 15.16a The Diencephalon and Brain Stem (Lateral View)
The Mesencephalon Figure 15.16b The Diencephalon and Brain Stem (Sagittal Section)
The Mesencephalon Figure 15.16c The Diencephalon and Brain Stem (Posterior View)
The Mesencephalon Figure 15.16d The Diencephalon and Brain Stem (Posterior View)
The Mesencephalon Figure 15.17a The Mesencephalon (Transverse Section, Superior View)
The Mesencephalon Figure 15.17b The Mesencephalon (Posterior View)
The Mesencephalon
The Pons The pons mainly functions: As a house for cranial nerve nuclei V, VI, VII, and VIII To help regulate respiration To help coordinate involuntary skeletal muscle movements and muscle tone In relaying information to and from the brain/spinal cord
The Pons Figure 15.18 The Pons
The Pons
The Cerebellum The cerebellum has two primary functions: Adjusts the postural muscles of the body to maintain balance Programs and fine-tunes voluntary and involuntary movements
The Cerebellum Figure 15.19a The Cerebellum (Posterior, Superior Surface)
The Cerebellum Figure 15.19b The Cerebellum (Sagittal Section)
The Cerebellum
The Medulla Oblongata The medulla oblongata physically connects the brain with the spinal cord. It is so important that, if it is severely compromised, the victim will likely die. The medulla oblongata is a relay station, house for cranial nerve nuclei, and most importantly, controls visceral functions like blood pressure, breathing, and heart rate.
The Medulla Oblongata Figure 15.20 The Medulla Oblongata
The Medulla Oblongata
MBrain Animation Review The Brain
The Cranial Nerves Cranial nerves are components of the peripheral nervous system that connect to the brain rather than to the spinal cord. Twelve pairs of cranial nerves Cranial nerves are numbered using Roman numerals Each cranial nerve attaches to the brain near the associated sensory or motor nuclei
The Cranial Nerves Figure 15.21a Origins of the Cranial Nerves
The Cranial Nerves Figure 15.21b Origins of the Cranial Nerves
The Cranial Nerves Figure 15.21c Origins of the Cranial Nerves (Superior View)
The Cranial Nerves
The Cranial Nerves
The Cranial Nerves Olfactory Nerve (N I) Primary function: special sensory (smell) Origin: receptors of olfactory epithelium Passes through: cribriform plate of ethmoid Destination: olfactory bulbs
The Cranial Nerves Figure 15.22 The Olfactory Nerve
The Cranial Nerves The Optic Nerve (N II) Primary function: special sensory (vision) Origin: retina of eye Passes through: optic canal of sphenoid Destination: diencephalon by way of the optic chiasm
The Cranial Nerves Figure 15.23 The Optic Nerve
The Cranial Nerves The Oculomotor Nerve (N III) Primary function: motor, eye movements Origin: mesencephalon Passes through: superior orbital fissure of sphenoid Destination: Somatic motor: superior, inferior, and medial rectus muscles; the inferior oblique muscle; the levator palpebrae superioris muscle Visceral motor: intrinsic eye muscles
The Cranial Nerves Figure 15.24 Cranial Nerves Controlling the Extra-Ocular Muscles
The Cranial Nerves The Trochlear Nerve (N IV) Primary function: motor, eye movements Origin: mesencephalon Passes through: superior orbital fissure of sphenoid Destination: superior oblique muscle
The Cranial Nerves Figure 15.24 Cranial Nerves Controlling the Extra-Ocular Muscles
The Cranial Nerves The Trigeminal Nerve (N V) Primary function: Mixed (sensory and motor) Ophthalmic and maxillary branches sensory Mandibular branch mixed Origin: Ophthalmic branch (sensory): orbital structures, nasal cavity, skin of forehead, superior eyelid, eyebrow, and part of the nose Maxillary branch (sensory): inferior eyelid, upper lip, gums, and teeth; cheek; nose, palate, and part of the pharynx Mandibular branch (mixed): sensory from lower gums, teeth, and lips; palate and tongue (part); motor from motor nuclei of pons
The Cranial Nerves The Trigeminal Nerve (N V) Passes through: Ophthalmic branch through superior orbital fissure Maxillary branch through foramen rotundum Mandibular branch through foramen ovale Destination: Ophthalmic, maxillary, and mandibular branches to sensory nuclei in the pons Mandibular branch also innervates muscles of mastication
The Cranial Nerves Figure 15.25 The Trigeminal Nerve
The Cranial Nerves The Abducens Nerve (N VI) Primary function: motor, eye movements Origin: pons Passes through: superior orbital fissure of sphenoid Destination: lateral rectus muscle
The Cranial Nerves Figure 15.24 Cranial Nerves Controlling the Extra-Ocular Muscles
The Cranial Nerves The Facial Nerve (N VII) Primary function: mixed (sensory and motor) Origin: Sensory from taste receptors on anterior two thirds of tongue Motor from motor nuclei of pons Passes through: internal acoustic meatus of temporal bone, along facial canal to reach stylomastoid foramen Destination: Sensory to sensory nuclei of pons Somatic motor: muscles of facial expression Visceral motor: lacrimal (tear) gland and nasal mucous glands via pterygopalatine ganglion; submandibular and sublingual salivary glands via submandibular ganglion
The Cranial Nerves Figure 15.26a The Facial Nerve
The Cranial Nerves Figure 15.26b The Facial Nerve
The Cranial Nerves The Vestibulocochlear Nerve (N VIII) Primary function: special sensory: balance and equilibrium (vestibular branch) and hearing (cochlear branch) Origin: receptors of the inner ear (vestibule and cochlea) Passes through: internal acoustic meatus of the temporal bone Destination: vestibular and cochlear nuclei of pons and medulla oblongata
The Cranial Nerves Figure 15.27 The Vestibulocochlear Nerve
The Cranial Nerves The Glossopharyngeal Nerve (N IX) Primary function: mixed (sensory and motor) Origin: Sensory from posterior one third of the tongue, part of the pharynx and palate, the carotid arteries of the neck Motor from motor nuclei of medulla oblongata Passes through: jugular foramen between occipital and temporal bones Destination: Sensory fibers to sensory nuclei of medulla oblongata Somatic motor: pharyngeal muscles involved in swallowing Visceral motor: parotid salivary gland, after synapsing in the otic ganglion
The Cranial Nerves Figure 15.28 The Glossopharyngeal Nerve
The Cranial Nerves The Vagus Nerve (N X) Primary function: mixed (sensory and motor) Origin: Visceral sensory from pharynx (part), auricle, external acoustic meatus, diaphragm, and visceral organs in thoracic and abdominopelvic cavities Visceral motor from motor nuclei in the medulla oblongata Passes through: jugular foramen between occipital and temporal bones Destination: Sensory fibers to sensory nuclei and autonomic centers of medulla oblongata Somatic motor to muscles of the palate and pharynx Visceral motor to respiratory, cardiovascular, and digestive organs in the thoracic and abdominal cavities.
The Cranial Nerves Figure 15.29 The Vagus Nerve
The Cranial Nerves The Accessory Nerve (N XI) Primary function: motor Origin: motor nuclei of spinal cord and medulla oblongata Passes through: jugular foramen between occipital and temporal bones Destination: Internal branch innervates voluntary muscles of palate, pharynx, and larynx External branch controls sternocleidomastoid and trapezius muscles
The Cranial Nerves The Hypoglossal Nerve (XII) Primary function: motor, tongue movements Origin: motor nuclei of the medulla oblongata Passes through: hypoglossal canal of occipital bone Destination: muscles of the tongue
The Cranial Nerves Figure 15.30 The Accessory and Hypoglossal Nerves
The Cranial Nerves