Neuroanatomy, timaNEUROANATOMY QUESTIONS

Ventricular system and cerebrospinal fluid

1. In passing from the spinal cord to the brain stem, the central canal moves progressively more dorsal until it opens into the fourth ventricle.

2. The fourth ventricle is circular shaped.3. On each side of the 4th ventricle, a lateral excess extends towards the medial

margin of the brain stem and is in continuity with the foramen of Luschka.4. Roof of the 4th ventricle is partly formed by the superior cerebellar peduncles

on either side.5. The median aperture of the 4th ventricle provides communication with the

cisterna magna.6. The 4th ventricle extends rostrally as far as the pontomesencephalic junction

where it becomes continuous with the cerebral aquaduct.7. The cerebral aquaduct passes through the whole length of the pons.8. The 3rd ventricle is a narrow slit like cavity whose lower walls are formed by

the hypothalamus and thalamus on either side.9. The interventricular foramen provides communication with the extensive

lateral ventricle located within the midbrain.10. The lateral ventricle is approximately C-shaped.11. Lateral ventricle consists of only the ant (frontal) horn, body and the post

(occipital) horn.12. The head of caudate nucleus makes up the lateral wall of the lateral ventricle.13. The septum pellucidum forms the medial wall of the lat ventricle.14. The small posterior horn of the lat ventricle lies in the occipital lobe15. The ventricular system contains cerebrospinal fluid (CSF)16. CSF is produced by the choroids plexus which is located in the lateral, third

and fourth ventricles.17. Choroid plexus is formed by invagination of the vascular arachnoid mater into

the ventricular lumen, where it becomes highly convoluted, producing a sponge like appearance.

18. The choroids plexus enters the 3rd and 4th ventricles through their walls and the lat fissure through the choroids fissure.

19. CSF is produced only by active secretory process.20. CSF is a colourless fluid containing little protein and few cells.21. Most of the CSF is produced by choroids plexus of the 4th ventricle.22. CSF leaves the ventricular system through the 3 apertures of the lat ventricle

entering the subarachnoid space.23. Most of the CSF flow through the lat apertures to enter the subarachnoid

space.24. CSF serves partially to cushion the brain from sudden movements of the head.25. CSF is reabsorbed into the venous system by passing into the dural venous

sinuses.26. Arachnoid granulations is normally found in children and adults alike.27. The hydrostatic pressure in the subarachnoid space is higher than in the sinus

lumen.

Answer:1. T2. F – rhomboid, diamond shaped

3. F – lat margin4. T5. T6. T7. F – whole length of midbrain8. F – lat wall9. F – within cerebral hemisphere10. T11. F – also has inferior(temporal) horn12. T13. T14. F - lies in the temporal lobe15. T16. T17. F – pia mater18. F – through the root of 3rd and 4th ventricles19. F – partially by active secretory process and partially by passive diffusion20. T21. F – most produced in lat ventricles22. F – 3 apertures of the 4th ventricle23. F – most passes into the median aperture to enter cisterna magna24. T25. T26. F – with age, arachnoid villi become hypertrophic to form arachnoid

granulations27. T

NEUROGLIA

1. Neuroglia are directly involved in information processing as well as being important for normal functioning of the nervous system.

2. Astrocytes and oligodendroglia both possess few processes.

3. It has been suggested that they may constitute the ‘blood-brain barrier’.4. The main role of oligodendroglia is production of the myelin sheath that

surrounds many axons in the PNS.5. Myeliation increases rate of conduction of axons.6. Each glial cell produces the myelin sheath over only a short region of axon,

thus a long axon is enveloped by the membranes of many glial cells.7. Microglia are small cells with numerous processes.8. Microglia increase in number at sites of damage in the CNS and have a

phagocytic role, similar to macrophages elsewhere.

Answer:1. F – indirectly involved2. F – astrocytes have numerous processes3. T4. F – CNS5. T6. T7. F – few processes8. T

CORPUS STRIATUM

1. The major components of the basal ganglia include the caudate nucleus, putamen and globus pallidus.

2. The caudate nucleus, putamen and globus pallidus are anatomically and functionally closely related to each other.

3. The putamen and globus pallidus are sometimes called the lentiform nucleus because they carry out the same function.

4. The striatum consists of the caudate nucleus and globus pallidus.5. The putamen lies lateral to the internal capsule and globus pallidus.6. Lateral to the putamen, lies white matter, sandwiched within which lies a thin

sheet of grey matter known as the claustrum.7. The head of the caudate nucleus forms a prominent bulge in the lat wall of the

post horn of the lat ventricle.8. The tail of the caudate nucleus descends into the temporal lobe where it lies

in the roof of the 4th ventricle.9. Afferents to the striatum come from 3 principals sources including the

cerebral cortex, thalamus and the substantia niagra.10. The function of the basal ganglia is to facilitate behaviour and movements

that are required and to inhibit any unwanted movements.11. The striatum has 2 routes by which it is able to control the activity of basal

ganglia output; the direct and indirect pathway.12. The ‘direct pathway’ through which striatopallidal and striatonigral neurons

directly induce inhibition of medial pallidal or pars reticulate neurons.13. The ‘direct pathway’ involves the subthalamic nucleus.14. In the ‘indirect pathway’, the thalamic and cortical cells are activated thus

inhibiting unwanted movements.15. Basal ganglia dysfunction leads to paralysis, sensory loss and ataxia.16. Unilateral basal ganglia lesions produce effects on the contralateral side as in

the case with cerebellar disorders.17. Basal ganglia dysfunction leads to increased tone.

18. Normally, dopamine exert an excitatory influence upon striatal neurons of the ‘direct’ projection and an inhibitory effect upon neurons of the ‘indirect’ pathway.

19. Parkinson’s disease is characterized by tremor, rigidity, akinesia and a flexed posture.

20. Huntington’s disease is a degenerative disease inherited in an autosomal recessive manner.

Answer:1. T2. T3. F – coz they lie close to each other forming a single structure4. F – striatum = caudate + putamen5. T6. T7. F – ant horn of the lat ventricle8. F – roof of the inf horn9. T10. T11. T12. T13. F14. F – thalamic and cortical cells are inhibited15. F – basal ganglia dysfunction causes none of these16. F – cerebellar lesions effect ipsilat side of the body17. T18. T19. T20. F

CRANIAL NERVES AND CRANIAL NERVE NUCLEI

1. The first two cranial nerves attach directly to the forebrain, while the rest attach to the brain stem.

2. The trigeminal sensory nucleus extends the whole length of the midbrain extending into the thoracic spinal cord.

3. Visceral afferents, including taste fibres, terminate in the nucleus solitarius of the medulla.

4. The oculomotor nerve carries the majority of somatic motor neurons that innervate intraocular muscles and are responsible for moving the eye.

5. Postganglionic parasympathetic neurons arise from the nearby Edinger-Westphal nucleus.

6. Postganglionic neurons run in the short ciliary nerves to innervate the sphincter (constrictor) pupillae muscle of the iris and the ciliary muscle contained within the ciliary body.

7. Even if only one retina is illuminated, iris of both eyes constrict.8. Neurones of the pretectal area project bilaterally to the Edinger-Westphal

nuclei.9. The trochlear nerve contains only somatic motor neurons.10. The trochlear nerve supplies just one muscle, the superior oblique, which

moves the eyeball downwards and laterally.11. Cell bodies of origin are located in the abducens nucleus which lies beneath

the floor of the 4th ventricle in the pons.12. The trigeminal nerve innervates the muscles of mastication.13. The cell bodies of afferents in the trigeminal nerve are located within the

trigeminal sensory nucleus while their central processes terminate in the trigeminal ganglion.

14. Proprioceptive afferents from muscles of mastication and temporomandibular jointhave their cell bodies in the mesencephalic nucleus of the trigeminal.

15. The facial nerve contains both sensory and motor components.16. The facial nerve consists of 2 roots, the more lat containing sensory and

motor fibres, while the medial root has parasympathetic fibres.17. The sensory fibres of facial nerve supply taste sensation from ant 1/3 of

tongue, floor of the mouth and palate.18. Unilateral upper motor neuron lesion give rise to paralysis of the facial

muscles of one side of the face.19. Preganglioninc parasympathetic fibres of the facial nerve originate in the

nucleus solitarius of the pons.20. Postganglionic fibres originate from the submandibular and pterygopalatine

ganglia.21. Vestibulocochlear nerve is a sensory nerve conveying impulses from the inner

ear.22. The vestibular nerve make dendritic contact with hair cells and their cell

bodies are located in the vestibular ganglion in the internal auditory meatus.23. From the superior olivary nuclei, ascending fibres of cochlear nerve comprise

the lateral lemniscus and end in the superior colliculus.24. The inf colliculus will send axons to the medial geniculate nucleus of the

thalamus.25. The primary auditory cortex is situated in the superior parietal gyrus.26. Afferent fibres of glossopharyngeal nerve convey info from chemoreceptors in

the carotid body.27. Visceral and taste fibres of the glossopharyngeal nerve terminate in the

nucleus solitarius of the medulla.28. The motor component of the glossopharyngeal nerve which arises from the

nucleus ambiguous innervates only one muscle, the stylopharyngeus.29. Preganglionic parasympathetic fibres of glossopharyngeal nerve originate in

the sup salivary nucleus innervating the parotid gland.30. Afferent fibres of the vagus convey information from baroreceptors in the

aortic arch.31. The vagus nerve receive info from receptors widely located in the cervical and

thoracic area.32. Motor fibres of the vagus arise from the nucleus ambiguous innervating

muscles of the soft palate, pharynx, larynx and upper part of the esophagus.

33. The nucleus ambiguous is important in coordinating speech and swallowing.34. The accessory nerve is purely sensory in function.35. Spinal root of the accessory nerve arises from motor neurons located in

vebtral horn of grey matter at levels C1-C6.36. The spinal root of accessory nerve joins the vagus nerve at level of the jugular

foramen.37. Hypoglossal nerve is purely motor in function.38. Hypoglossal nerve serves to move and change the shape of the tongue.

Answer:1. T2. F – cervical spinal cord3. T4. F – extraocular muscles5. F – preganglionic6. T7. F – pupils constrict8. T9. T10. F – eyeball moves downward and laterally11. T12. T13. F – cell bodies located in trigeminal ganglion and terminate in trigeminal

sensory nucleus14. T15. T16. F – lat sensory + parasympathetic17. F – 2/3 ant18. F – paralysis of lower facial muscles19. F – originate in sup salivatory nucleus20. T21. T22. T23. F – end in inf colliculus24. T25. F- sup temporal gyrus26. T27. T28. T29. F – originate from inf salivary nucleus30. T31. F – thoracic and abdominal viscera32. T33. T34. F – purely motor35. F – C1-C536. F – cranial root37. T38. T