1. Major divisions of the nervous system Central nervous system (CNS) Peripheral nervous system (PNS) Somatic (cerebrospinal) nervous system Visceral (autonomic) nervous system (ANS) - sympathetic division - parasympathetic division Satisfactory criterion for this is found only in the PNS. In the CNS we cannot easily make difference between the somatic and autonomic nervous systems.

2. Cranial cavityVertebral canal dura mater arachnoid mater pia mater external layer of dura mater arachnoid mater pia mater internal layer of dura mater epidural space subdural space subarachnoid space subdural space subarachnoid space No free epidural space!

3. The meninges Three membranes called meninges envelop the nervous system. At the CNS level they are easily recognized as dura mater (pachymeninx), arachnoid mater and pia mater (the last two forming together so-called leptomeninges). At the level of the PNS these membranes continue as the sheaths of peripheral nerves and ganglions. The dura mater is the outermost and thickest of all meninges. It lines the cranial cavity and the vertebral canal and provides support and protection for the nervous system within. It is made of two layers. The external layer serves as the internal periosteum for bones that built the walls of the cranial cavity and vertebral canal. The internal layer may be a separate structure (as it is in the vertebral canal) or may fuse with external layer (as in the cranial cavity). The real space existing in the vertebral canal between the two layers of the spinal dura mater is called epidural (extradural) space and it contains blood vessels and roots of spinal nerves bathed in fatty tissue. The remnants of epidural space in the cranial cavity are only seen as dural sinuses, trigeminal cavity and pituitary cavity. There is no free epidural space in the cranial cavity in a healthy individual. In pathologic condition however, this space may form again when some contents, especially blood flowing out of torn meningeal arteries, will set the two dural layers apart. The internal layer of cranial dura mater in some places makes infoldings that protrude into the cranial cavity and divide it into smaller compartments. These infoldings include the cerebral falx, the tentorium cerebelli and the cerebellar falx. The two falxes are oriented sagittally and they intervene between the hemispheres (cerebral or cerebellar, respectively). The tentorium cerebelli separates the cerebral hemispheres (occipital lobes) from the cerebellum. The tentorium is attached to the grooves of the transverse and superior petrosal venous sinuses and to the posterior and anterior clinoid processes. It divides the cranial cavity into supratentorial and infratentorial compartments. Anteriorly the tentorium is notched to allow the brainstem to pass between the supratentorial and infratentorial compartments. The supratentorial compartment is further partially divided into two halves by the falx cerebri. Each half houses one cerebral hemisphere. Below the cerebral falx the telencephalon impar passes to connect the two hemispheres. The falx cerebelli is not so prominent and it only marginally separates the cerebellar hemispheres. In addition the internal layer of cranial dura roofs the trigeminal cavity and it also passes above the pituitary gland as the so-called sellar diaphragm (diaphragma sellae). The pituitary stalk pierces sellar diaphragm centrally.

4. The meninges - continued The arachnoid mater is a delicate membrane, which lines internal surface of the dura mater. It is pressed to the dura but does not fuse with it. Between the two membranes there is a capillary (hair-like) space moistened with the tissue fluid. This space is called the subdural space or cavity. It can become the true space if something (e.g. blood) will accumulate within. Near the dural sinuses and some veins the arachnoid forms many specialized organs, which serve as the sites of evacuation of the cerebrospinal fluid into the venous blood. These are called arachnoid granulations (granulations of Pacchioni). The pia mater grows together with the tissue of the nervous system. It is very thin but functionally important envelope. It surrounds the vessels, which penetrate the nervous tissue giving them a bit of support. At some places it invaginates deeply in the internal spaces (ventricles) of the brain and takes part in forming the choroid plexuses (the organs which produce the majority of the cerebrospinal fluid). The capacity of the dural envelope is greater than the volume of the nervous system. As pia mater shapes on the nervous system and arachnoid mater shapes on the dura mater, there is quite a distance between them. This space is filled with the cerebrospinal fluid and forms the subarachnoid space or cavity. At some places this space is especially broad and constitutes the subarachnoid cisterns. Through the subarachnoid space tiny fibers of arachnoid mater run, connecting it with pia mater. There are cerebral vessels and roots of cranial nerves suspended in the cerebrospinal fluid in the subarachnoid space.

5. Encephalon - Brain (prosencephalon - forebrain) mesencephalon - midbrain (rhombencephalon - hindbrain) hypothalamus telencephalon cerebral hemispheres diencephalon metencephalon myelencephalon thalamencephalon telencephalon impar cerebellum pons medulla oblongata cerebral peduncles tectum of midbrain Encephalon - Brain cerebrum brainstem cerebellum cerebral hemispheres telencephalon impar diencephalon (not included by some authors) pons midbrain medulla oblongata Major divisions of the brain clinical point of viewontogenetic point of view

6. hypothalamus - includes subthalamus thalamencephalon thalamus epithalamus Diencephalon Mesencephalon tectum of midbrain cerebral peduncles tegmentum cerebral crura Major divisions of the brain - continued

7. Specific sensory pathway: 1) - runs from receptors to cerebral cortex, 2) - conveys only one kind of sensation, 3) - uses as few neurons as possible.

8. Specific sensory pathways Somatosensory pathway of spinothalamic (anterolateral) system Somatosensory pathway of posterior funiculus/medial lemniscus system Olfactory pathway Visual pathway Auditory pathway Gustatory pathway Vestibular pathway Somatosensory pathways of trigeminal system Somatosensory pathways convey information about somatic sensation conveys body movements and position, pressure, vibration and precise touch information from trunk and limbs convey all somatic information from head conveys olfactory information conveys visual infomation conveys gustatory information conveys pain, temperature and imprecise touch information from trunk and limbs conveys head movements and position information conveys auditory information

9. Lateral spinothalamic tract Sensory ganglionic cells are the primary neurons. Their dendrites innervate pain and temperature receptors and convey impulses running in spinal nerve towards the spinal ganglion. In spinal ganglion the somata of these cells are found. Then the impulses are conveyed by axons of sensory ganglionic cells. These small-diameter fibers enter the spinal cord in posterior root and end synapsing with the cells of posterior horn. Posterior horn cells are the secondary neurons. Their axons leave the posterior horn and run through the white commissure toward the contralateral lateral funiculus. Then they bend up and ascend through the whole length of spinal cord and brainstem to reach the thalamus. In the spinal cord they run in anterior part of lateral funiculus. In the brainstem they run through tegmentum (forming the so-called spinal lemniscus). After arriving at thalamic level they end synapsing with the cells in ventral posterior lateral nucleus (VPL). Cells of VPL nucleus of thalamus are the tertiary neurons. Their axons ascend in the posterior limb of internal capsule to get to the cortex. The bundle of these axons forms the sensory radiation. The tertiary neurons end synapsing in the somatosensory cortex. For the trunk and limb regions the cortex is in the posterior part of paracentral lobule (lower limb) and superior (trunk) and middle (upper limb) parts of postcentral gyrus. Lateral spinothalamic tract conveys pain and temperature sensations. It comprises three neurons. Secondary neurons decussate in white commissure of spinal cord. Decussation is called low, for the tract reaches the other side of the nervous system almost at the level at which the primary neurons enter the spinal cord.

10. Lateral spinothalamic tract I neuron II neuron III neuron receptors somatosensory cortex decussation! on the same side on the other side carries pain and temperature information from to cells of ventral posterolateral (VPL) nucleus of thalamus sensory radiation of posterior limb of internal capsule cells of posterior horn of spinal cord lateral funiculus of spinal cord tegmentum of brainstem white commissure of spinal cord cells of spinal ganglion branches of spinal nerve small-diameter fibers of posterior root of spinal nerve

11. Anterior spinothalamic tract Sensory ganglionic cells are the primary neurons. Their dendrites innervate imprecise touch receptors and convey impulses running in spinal nerve towards the spinal ganglion. In spinal ganglion the somata of these cells are found. Then the impulses are conveyed by axons of sensory ganglionic cells. These small-diameter fibers enter the spinal cord in posterior root and end synapsing with the cells of posterior horn. Posterior horn cells are the secondary neurons. Their axons leave the posterior horn and run through the white commissure toward the contralateral anterior funiculus. Then they bend up and ascend through the whole length of spinal cord and brainstem to reach the thalamus. In the spinal cord they run in lateral part of anterior funiculus. In the brainstem they run through tegmentum (adding to the spinal lemniscus). After arriving at thalamic level they end synapsing with the cells in ventral posterior lateral nucleus (VPL). Cells of VPL nucleus of thalamus are the tertiary neurons. Their axons ascend in the posterior limb of internal capsule to get to the cortex. The bundle of these axons forms the sensory radiation. The tertiary neurons end synapsing in the somatosensory cortex. For the trunk and limb regions the cortex is in posterior part of the paracentral lobule (lower limb) and superior (trunk) and middle (upper limb) part of postcentral gyrus. Anterior spinothalamic tract conveys imprecise touch sensations. It comprises three neurons. Secondary neurons decussate in white commissure of spinal cord. Decussation is called low, for the tract reaches the other side of the nervous system almost on the level on which the primary neurons enter the spinal cord.

12. Anterior spinothalamic tract I neuron II neuron III neuron receptors somatosensory cortex decussation! on the same side on the other side carries imprecise touch information from to cells of ventral posterolateral (VPL) nucleus of thalamus sensory radiation of posterior limb of internal capsule cells of posterior horn of spinal cord anterior funiculus of spinal cord tegmentum of brainstem white commissure of spinal cord cells of spinal ganglion branches of spinal nerve small-diameter fibers of posterior root of spinal nerve

13. Ascending tracts of posterior funiculus Sensory ganglionic cells are the primary neurons. Their dendrites innervate receptors of many kinds of discriminative sensations (limb position and movement, pressure, vibration, precise touch) and convey impulses running in spinal nerve towards the spinal ganglion. In spinal ganglion the somata of these cells are found. Then the impulses are conveyed by axons of sensory ganglionic cells. These large-diameter fibers enter the spinal cord in posterior root and reach posterior funiculus. In posterior funiculus they bend up and ascend through the spinal cord to reach the medulla. Fibers from lower part of the body form gracile fasciculus, fibers from upper part - cuneate fasciculus. In medulla the fibers end synapsing with cells of gracile or cuneate nucleus, respectively. Cells of gracile and cuneate nuclei are the secondary neurons. Their axons cross the midline in lemniscal decussation and then ascend in the brainstem tegmentum, forming the medial lemniscus. They run through the whole length of brainstem to reach the thalamus. After arriving at thalamic level they end synapsing with the cells in ventral posterior lateral nucleus (VPL). Cells of VPL nucleus of thalamus are the tertiary neurons. Their axons ascend in the posterior limb of internal capsule (adding to the sensory radiation) to get to the cortex. The tertiary neurons end synapsing in the somatosensory cortex. For the trunk and limb regions the cortex is in posterior part of the paracentral lobule (lower limb) and superior (trunk) and middle (upper limb) part of postcentral gyrus. Ascending tracts of posterior funiculus convey discriminative kinds of sensations. They comprise three neurons. Secondary neurons decussate in lemniscal decussation. Decussation is called high, for the tracts reach the other side of the nervous system on the level of medulla, which is high above the level of primary neurons entrance.

14. Ascending tracts of posterior funiculus I neuron II neuron III neuron receptors somatosensory cortex decussation! on the same side on the other side carry discriminative information from to cells of ventral posterolateral (VPL) nucleus of thalamus sensory radiation of posterior limb of internal capsule cells of gracile and cuneate nuclei medial lemniscus in tegmentum of brainstem lemniscal decussation fascicles of posterior funiculus of spinal cord cells of spinal ganglion branches of spinal nerve large-diameter fibers of posterior root of spinal nerve

15. Trigeminothalamic tracts I neuron II neuron III neuron receptors somatosensory cortex decussation! on the same side on the other side carry somatosensory information from to cells of ventral posteromedial (VPM) nucleus of thalamus sensory radiation of posterior limb of internal capsule cells of sensory nuclei of trigeminal nerve tegmentum of brainstem cells of sensory ganglions of cranial nerves branches of cranial nerves roots of cranial nerves

16. Gustatory pathway I neuron II neuron III neuron receptors gustatory cortex decussation! on the same side on the other side carries taste information from to cells of sensory ganglions of cranial nerves branches of cranial nerves roots of cranial nerves cells of upper part of solitary nucleus tegmentum of brainstem cells of ventral posteromedial (VPM) nucleus of thalamus along with sensory radiation of posterior limb of internal capsule

17. Visual pathway I neuron II neuron III neuron visual cortex partial decussation! to intraretinal pathway rods and cones carries visual information from bipolar cells of retina IV neuron ganglion cells of retina optic chiasma optic nerve cells of lateral geniculate nucleus (LGN) of thalamus optic radiation of posterior limb of internal capsule optic tract

18. Partial decussation of visual pathway optic nerve optic chiasma optic tract lateral geniculate body optic radiation visual cortex visual field retina optical apparatus of the eye 1 2 3 1 - blindness of left eye 2 - hemianopia heteronyma (bitemporalis) 3 - hemianopia homonyma (right) site of lession visual field defects LR

19. Auditory pathway I neuron II neuron III neuron auditory cortex partial decussation! to on the same side receptors carries auditory information from IV neuron bipolar cells of spiral ganglion lateral lemniscus cells of cochlear nuclei trapezoid body root of vestibulocochlear nerve branches of cochlear part of vestibulocochlear nerve cells of different nuclei of brainstem cells of medial geniculate nucleus (MGN) of thalamus acoustic radiation of sublentiform part of internal capsule brachium of inferior colliculus lateral lemniscus partial decussation! on both sides

20. Olfactory pathway I neuron II neuron receptors olfactory cortex on the same side carries smell information from to olfactory receptor cells in mucous membrane of nasal cavity olfactory cilia olfactory nerve mitral cells of olfactory bulb olfactory tract lateral olfactory stria ! Olfactory pathway has two neurons only does not pass through thalamus does not cross the midline

21. Cortical areas Association cortical areas - exchange information mainly with other cortical areas and also with many lower centers Projection areas - get information mainly from one lower center or send information mainly to one lower center, are interconnected with projection thalamic nuclei Motor area Unimodal association areas - deal with one functional modality only Multimodal association areas - deal with many functional modalities Sensory areas Somatosensory (somaesthetic) area Olfactory area Gustatory area Auditory area Visual area Vestibular area Complexes of areas dealing with one functional modality = projection area + unimodal association area

22. Sensory areas Projection somatosensory area - postcentral gyrus and posterior part of paracentral lobule Olfactory complex Auditory complex Visual complex Somatosensory complex Projection visual area - calcarine sulcus and adjacent parts of cuneus and lingual gyrus Association visual area - around (except anteriorly) the projection visual area extending into the temporal and parietal lobes Projection auditory area - transverse temporal gyri and middle part of superior temporal gyrus Association auditory area - superior temporal gyrus around the projection auditory area Projection olfactory area - uncus Association olfactory area - enthorhinal area Association somatosensory area - superior parietal lobule Association unimodal areas - probably in superior parietal lobule Projection gustatory area - opercular part of postcentral gyrus Projection vestibular area - probably lower part of postcentral gyrus

23. Motor areas Primary projection motor area - precentral gyrus and anterior part of paracentral lobule Motor complex Posterior association area - opercular part of the postcentral gyrus, inferior parietal lobule, posterior parts of superior and middle temporal gyri Sensory (posterior) speech area (Wernicke’s area) - unpaired, only in dominant hemisphere - supramarginal and angular gyri and posterior parts of superior and middle temporal gyri Association motor area - middle and posterior parts of frontal gyri on the superolateral surface Supplementary projection motor area - posterior part of medial frontal gyrus Frontal eye field - middle part of middle frontal gyrus Motor (anterior) speech area (Broca’s area) - unpaired, only in dominant hemisphere- triangular and opercular parts of inferior frontal gyrus Multimodal association areas Anterior association area - anterior parts of frontal gyri and inferior surface of frontal lobe Medial association area - cingulate and parahippocampal gyri

24. Pyramidal motor system comprises two neurons Lower motor neuron - motor cells of anterior horn of spinal cord or cells of motor nuclei of cranial nerves Upper motor neuron - cells of primary motor cortex is functionaly connected with voluntary movements Pyramidal motor tracts Corticospinal tracts - related to the striated muscles innervated by spinal nerves Lateral corticospinal tract Anterior corticospinal tract Corticonuclear tracts - related to the striated muscles innervated by cranial nerves

25. Lateral corticospinal tract I neuron II neuron muscles motor cortex decussation! carries motor information from to cells of paracentral lobule and superior and middle parts of precentral gyrus corona radiata of internal capsule longitudinal fascicles of pons cerebral crus pyramidal decussation pyramid motor cells of anterior horn of spinal cord branches of spinal nerves anterior root of spinal nerve anterior part of posterior limb of internal capsule lateral funiculus of spinal cord

26. Anterior corticospinal tract I neuron II neuron muscles motor cortex decussation! carries motor information from to cells of paracentral lobule and superior and middle parts of precentral gyrus corona radiata of internal capsule longitudinal fascicles of pons cerebral crus white commissure pyramid motor cells of anterior horn of spinal cord branches of spinal nerves anterior root of spinal nerve anterior part of posterior limb of internal capsule anterior funiculus of spinal cord

27. Corticonuclear tracts I neuron II neuron muscles motor cortex partial decussation! carry motor information from to cells of lower part of precentral gyrus corona radiata of internal capsule (longitudinal fascicles of pons) cerebral crus tegmentum of brainstem cells of motor nuclei of cranial nerves roots and branches of cranial nerves genu of internal capsule

28. Corticonuclear tract is „duplicated” for most motor nuclei of cranial nerves, with the exception of the lower part of motor facial nucleus and hypoglossal nucleus. Motor nuclei of cranial nerves except the two mentioned above receive crossed and uncrossed cortical fibers. Lower part of facial motor nucleus and hypoglossal nucleus receive only crossed cortical fibers.

29. Thalamic nuclei - anatomical classification Median nuclei Medial nucleus (medialis dorsalis nucleus) Anterior nucleus Lateral nucleus Reticular nucleus Dorsal nucleus Metathalamus Ventral nucleus lateral dorsal nucleus lateral posterior nucleus pulvinar lateral geniculate body medial geniculate body ventral anterior nucleus ventral lateral nucleus ventral posterior nucleus posterior nuclei ventral posterior medial nucleus ventral posterior lateral nucleus ventral posterior inferior nucleus Intralaminary nuclei

30. Thalamic nuclei - functional classification Association nuclei - nucleus receives their main subcortical input from other thalamic nuclei Sensory nuclei - nucleus is involved in sensory function Relay nuclei - nucleus receives a major non-thalamic subcortical input Nonspecific nuclei - nuclear connections with the cerebral cortex are not of topographically reciprocal type Specific nuclei - nucleus has precise topographical projection to a limited region of the ipsilateral cortex and this cortical region projects back topographically upon the nucleus Limbic nuclei - nucleus is involved in limbic function Motor nuclei - nucleus is involved in motor function

31. Sensory thalamic nuclei spinothalamic tracts, medial lemniscus trigeminothalamic tracts, gustatory pathway optic tract brachium of inferior colliculus ventral posterior lateral (VPL) nucleus ventral posterior medial (VPM) nucleus lateral geniculate nucleus (LGN) medial geniculate nucleus (MGN) somatosensory cortex (trunk and limbs areas) somatosensory cortex (head area) visual cortex auditory cortex Motor thalamic nuclei globus pallidus, substantia nigra (cerebellum) ventral anterior (VA) nucleus premotor cortex cerebellum (globus pallidus, substantia nigra) ventral lateral (VL) nucleus motor cortex

32. Limbic thalamic nuclei amygdaloid body part of medialis dorsalis (MD) nucleus orbitofrontal cortex mamillary bodyanterior nucleus (Ant)cingulate cortex Association thalamic nuclei other thalamic nuclei, visual pathway collaterals other thalamic nuclei other thalamic nuclei, hypothalamus pulvinar (Pul) lateral posterior (LP) nucleus part of medialis dorsalis (MD) nucleus parietal, occipital and temporal association cortex medial temporal and prefrontal association cortices parietal association cortex

33. Hypothalamic nuclei optic region supra-optic nucleus paraventricular nucleus tuberal region infundibular nucleus mamillary region mamillary nuclei pre-optic area lateral region subthalamus

34. tuberal region infundibular nucleus - secretes hormones which control the function of anterior lobe of pituitary gland mamillary region mamillary nuclei - take their part in Papez’s circuit, which is related to memory functions Function of better known hypothalamic nuclei optic region supra-optic nucleus - secretes vasopressin (antidiuretic hormone, ADH) paraventricular nucleus - secretes oxytocine pre-optic region belongs to the telencephalon on embryological grounds, secretes factors controling pituitary production of gonadotropins, demonstrates sexual dimorphism subthalamus subthalamic nucleus - belongs to the motor extrapyramidal system

35. Nuclei of cranial nerves projection of telencephalon, no nucleiI, olfactory nerve projection of diencephalon, no nucleiII, optic nerve III, oculomotor nerve IV, trochlear nerve True cranial nerves mesencephalic tegmentum at the level of superior colliculus P - accessory oculomotor nucleus (Westphal-Edinger nucleus) M - oculomotor nucleus mesencephalic tegmentum at the level of inferior colliculus M - trochlear nucleus M - motor nucleus S - sensory nucleus P - parasympathetic nucleus

36. VII, facial nerve V, trigeminal nerve VI, abducent nerve M - abducent nucleustegmentum of lower pons M - trigeminal motor nucleusmidlevel of pontine tegmentum S - mesencephalic nucleus tegmentum in upper pons and mesencephalon S - spinal nucleus tegmentum in lower pons, medulla and cervical spinal cord S - pontine nucleusmidlevel of pontine tegmentum M - facial motor nucleustegmentum of lower pons S - sensory nuclei of trigeminal nerve as described above S - upper (gustatory) part of solitary nucleus tegmentum of lower pons P - superior salivatory nucleustegmentum of lower pons

37. IX, glossopharyngeal nerve VIII, vestibular part of vestibulocochlear nerve VIII, cochlear part of vestibulocochlear nerve tegmentum of lower pons and medulla S - vestibular nuclei 4 nuclei: superior, inferior, lateral and medial tegmentum of medullaM - ambiguus nucleus tegmentum of upper medulla P - inferior salivatory nucleustegmentum of medulla S - lower part of solitary nucleus (nonconscious somatic sensation) as described above S - sensory nuclei of trigeminal nerve (conscious somatic sensation) tegmentum of lower pons S - upper (gustatory) part of solitary nucleus tegmentum of pontomedullary junction S - cochlear nuclei 2 nuclei: dorsal and ventral

38. X, vagus nerve XII, hypoglossal nerve XI, accessory nerve, spinal part XI, accessory nerve, cranial part M - spinal accessory nucleus upper cervical spinal cord M - nucleus ambiguustegmentum of medulla P - dorsal nucleus of vagus tegmentum of medulla M - hypoglossal nucleustegmentum of medulla M - ambiguus nucleus tegmentum of medulla S - lower part of solitary nucleus (nonconscious somatic sensation) as described above S - sensory nuclei of trigeminal nerve (conscious somatic sensation) tegmentum of lower pons S - upper (gustatory) part of solitary nucleus