Nervous System - Brain

*Composed of:
1-Central Nervous System {CNS}: brain and spinal cord
2-Peripheral Nervous System {PNS}: nerves and ganglia(groups of cell bodies)
*Nerves: afferent {sensory}, efferent {motor} & mixed ( both)
*Nerves: somatic{voluntary}& autonomic {involuntary}
*Autonomic Nervous System (ANS): sympathetic and parasympathetic

*Connective tissue membranes surrounding brain & spinal cord
1- Dura mater: outer layer
2- Arachnoid: middle layer
3- Pia mater: inner layer
*The brain is continuous with the spinal cord at the foramen magnum( large opening in the occipital bone)

*Largest part
*Divided into two cerebral hemispheres by a longitudinal fissure
*The two cerebral hemispheres are connected by white fibers called “corpus callosum”
*Its surface has convolutions {gyri}, separated by grooves {sulci}
*Each hemisphere has 5 lobes
frontal, parietal, temporal, occipital & insula}
*The outer portion of cerebrum is thin layer of gray matter {cerebral cortex}
*The main bulk of cerebrum is white matter(under cerebral cortex)

*Separated from parietal lobe by central sulcus
*Separated from temporal lobe by lateral sulcus
*Has precentral gyrus (movements)

*Separated from temporal lobe by lateral sulcus
*Has postcentral gyrus (sensation)
Temporal Lobe: Functions in hearing & smell
Occipital Lobe: Functions in vision
Insula: Deep to lateral sulcus

*2nd largest part
*Divided into two cerebellar hemispheres (connected by vermis)
*Outer surface has folia or folds (gray matter) surrounding the internal, white matter (arbor vitae)
*Functions of cerebellum:
1-Skeletal muscle coordination
2-Posture
3-Balance (equilibrium)

*A- Thalamus:
Main part of the diencephalon
*B- Hypothalamus:
Connected to the pituitary gland by the infundibulum
Regulates visceral activities, emotions, body temperature & endocrine functions
*C- Epithalamus:
Connected to pineal gland (secretes melatonin which regulates day-night cycles, circadian rhythm)

*A- Midbrain: upper part
*B- Pons: middle part
*C- Medulla: lower part
Continuous with spinal cord inferiorly
Includes cardiac, vasomotor, & respiratory centers

*Four cavities lined with ependymal cells which produce CSF
Two Lateral Ventricles:
*In cerebrum, separated by septum pellucidum
*Connected to 3rd ventricle by interventricular foramina
Third Ventricle:
*Connected to 4th ventricle by cerebral aqueduct
Fourth Ventricle
*Sickle-shaped space
*Merges with the central canal of the spinal cord

*Clear liquid surrounding CNS
*Formed in ventricles by ependymal cells lining the choroid plexus
*Circulates in subarachnoid space
*The amount of CSF within the brain at any given moment is approximately 130 ml.

- Sensory Function
- Somatic Motor Function
- Parasympathetic Motor (Autonomic Function)

I {1} (Olfactory)
II {2} (Optic)
III {3} (Oculomotor)
IV {4} (Trochlear)
V {5} (Trigeminal)
VI {6} (Abducens)
VII {7} (Facial)
VIII {8} (Vestibulochlear)
IX {9} (Glossopharyngeal)
X {10} (Vagus)
XI {11} (Accessory)
XII {12} (Hypoglossal)

I {1} (Olfactory): Olfaction (smell)
II {2}(Optic): Vision
VIII {8} (Vestibulochlear): Hearing (cochlear branch); equilibrium (vestibular branch)

III {3} (Oculomotor): Four extrinsic eye muscles (medial rectus, superior rectus, inferior rectus, inferior oblique); levator palpebrae superioris muscle (elevates eyelid)
IV {4} (Trochlear): Superior oblique extrinsic eye muscle
VI {6} (Abducens): Lateral rectus extrinsic eye muscle
XI {11} (Accessory): Trapezius muscle, sternocleidomastoid muscle
XII {12} (Hypoglossal): Intrinsic and extrinsic tongue muscles

V {5} (Trigeminal): Sensory - General sensory from the anterior scalp, nasal cavity, nasopharynx, entire face, most of the oral cavity, teeth, anterior two-thirds of tongue; part of the auricle of the ear; meninges Motor - Muscles of mastication, mylohyoid, digastric (anterior belly), tensor tympani tensor veli palatini
VII {7} (Facial): Sensory: Taste from anterior two-thirds of tongue Motor - Muscles of facial expression, digastric (posterior belly), stylohyoid, stapedius
IX {9] (Glossopharyngeal): Sensory - General sensory and taste from posterior one-third of the tongue, general sensory from part of the pharynx, visceral sensory from carotid bodies Motor - One pharyngeal muscle (stylopharyngeus)
X {10} (Vagus): Sensory - Visceral sensory information from the heart, lungs, and most abdominal organs. General sensory information from external acoustic meatus, tympanic, membrane, part of pharynx, laryngopharynx, and larynx Motor - Most pharyngeal muscles; all laryngeal muscles

VII {7} (Facial): Increases secretion from the lacrimal gland of the eye, submandibular, and sublingual salivary glands
IX {9} (Glossopharyngeal): Increases secretion from parotid salivary gland
X {10} (Vagus): Innervates smooth muscles and glands of the heart, lungs, larynx, trachea, and most abdominal organs