Neuroscience Introduction Course PDF

2. Blood Supply of Spinal Cord: Spinal cord is supplied by spinal and radicular arteries. The venous blood is drained by vertebral plexuses of veins. b. Cerebro-Spinal Fluid (CSF): clear fluid found in cavities of the CNS which are ventricles of brain, sub-arachnoid space and cen...

2. Blood Supply of Spinal Cord: Spinal cord is supplied by spinal and radicular arteries. The venous blood is drained by vertebral plexuses of veins. b. Cerebro-Spinal Fluid (CSF): clear fluid found in cavities of the CNS which are ventricles of brain, sub-arachnoid space and central canal of the spinal cord. B. Peripheral Nervous System a. Cranial Nerves: They are 12 pairs (I to XII), which are connected to the brain. All arise from brain stem except olfactory (from nose) and optic (from retina): 1. Olfactory Nerve: this is the first cranial nerve (I). It is pure sensory nerve. It carries the information of the sense of smell. It may regenerate after injury. Its injury causes loss of smell. 2. Optic Nerve: this is the second cranial nerve (II). It is pure sensory nerve. It carries the information of the sense of vision from the retina to the brain. It never regenerates after injury. It is considered as part of the brain as it is covered by meninges and surrounded by CSF. It is the mirror of the brain. Its injury causes loss of vision (blindness). 3. Occulomotor Nerve: the third cranial nerve (III) is a motor nerve that supplies all muscles of the eye except the superior oblique and lateral rectus muscles. Its injury causes ophthalmoplegia. It contains autonomic fibers. 4. Trochlear Nerve: the fourth cranial nerve (IV) is a motor nerve that supplies one muscle of the eye the superior oblique which moves the eye downwards and lateral. Its injury causes vertical squint and may be double vision. 5. Trigeminal Nerve: the fifth cranial nerve is a mixed nerve. Its sensory part receives general sensation from the face and the anterior 2/3 of the tongue. It supplies all muscles of mastication (chewing). It contains autonomic fibers to the salivary glands in the mouth and lacrimal gland. It has three large branches: Ophthalmic, Maxillary and Mandibular. Irritation of trigeminal nerve causes Trigeminal Neuralgia which is sever pain in the area of distribution of the nerve. 8 6. Abducent Nerve: the sixth cranial nerve (VI) is a motor nerve that supplies one muscle of the eye the lateral rectus which moves the eye laterally. Its injury causes lateral squint and may be double vision. 7. Facial Nerve: the seventh cranial nerve (VII) is a mixed nerve. Its sensory part receives taste sensation from the anterior 2/3 of the tongue. Its motor part supplies all muscles of expression (face). It contains autonomic fibers to the parasympathetic ganglia of the head and neck. Injury of the facial nerve causes Facial Palsy. 8. Vestibulo-cochlear Nerve: the eighth cranial nerve (VIII), transmits sound and equilibrium (balance) information from the inner ear to the brain. Damage of this nerve may cause: hearing loss, vertigo, loss of equilibrium, motion sickness, nystagmus and tinnitus. 9. Glossopharyngeal Nerve: the ninth cranial nerve (IX) is a mixed nerve. It contains general sensory fibers from the posterior one third of the tongue, external ear and upper pharynx. It contains special sensory fibers that receive taste from the posterior one third of the tongue (bitter and sour taste). It contains motor fibers to the stylopharyngeus muscle of the pharynx which helps swallowing. It contains autonomic parasympathetic fibers to the parotid salivary gland. It contains afferent visceral fibers from carotid sins and aortic bodies (baroceptors and chemceptors) which adjust blood pressure and blood pH respectively. Damage to the nerve causes loss of bitter and sour tastes and impaired swallowing. Irritation of the nerve causes Glossopharyngeal Neuralgia which is sever pain in the ear, back of the tongue, upper pharynx and throat. The pain is precipitated by chewing, coughing, laughing and swallowing. 10. Vagus Nerve: the tenth cranial nerve (X). This is a mixed nerve. It is considered as a very important parasympathetic source to control heart rate, gastrointestinal movement, respiratory passages and sweating. It contains general sensory fibers from the most posterior part of the tongue and skin behind the auricle. It receives taste from the most posterior part of the tongue. It contains motor fibers to the larynx to produce sounds and speech. It contains 9  afferent visceral fibers from carotid sins and aortic bodies (baroceptors and chemceptors) to adjust blood pressure and blood pH respectively. Irritation of vagus may cause bradycardia and even cardiac arrest. Vagal triggering areas are the carotid bulb in the neck, epigastrium and testicles. A blow to vagal trigger zone may cause cardiac arrest. 11. Accessory Nerve: the eleventh cranial nerve (XI). Is a pure motor nerve. It has spinal and cranial parts and supplies two important muscles: trapezius and sternomastoid. Its injury affects sternomastoid and upper trapezius. 12. Hypoglossal Nerve: (XII) this is the motor nerve of the tongue. When injuried the tongue points to the affected nerve (Explain). b. Spinal Nerves: 1. Distribution: There are 31 pairs of spinal nerves are distributed as follows: i. 8 cervical nerves: in the cervical region. ii. 12 thoracic nerves in the thoracic region. iii. 5 lumbar nerves in the lumbar region. iv. 5 sacral nerves in the sacral region. v. 1 coccygeal nerve in the coccygeal region. 2. Formation: Each spinal nerve except C1 and coccygeal nerves arise by 2 roots: i. Ventral Root: motor (efferent): it contains: a) Motor axons of the anterior horn cells to supply the skeletal muscles. b) Autonomic axons of lateral horn cells (T1 to L2 and S2 to S4) to viscera. ii. Dorsal Root: sensory (afferent). It shows: a) Dorsal root ganglion which contains pseudounipolar cells. b) The 2 roots unite at intervertebral foramen to form spinal nerve trunk. 3. Branches (Divisions): nerve trunk divides immediately into 2 primary rami: i. Anterior (Ventral) Primary Ramus (larger in size): It runs anteriorly and may join each other to form plexuses. It is attached to sympathetic ganglion by 2 rami communicants: white ramus (myelinated) and gray ramus (unmyelinated). ii. Posterior (Dorsal) Primary Ramus (smaller in size): 10