Neuroanatomy Theorectical CNS

What is the anatomical/histological substrate of the enlargements of the spinal cord?

The cervical (C5-Th1) and lumbosacral (L2-S2) intumescences; the anterior horn holds many more motoneurons (several lamina IX groups) to supply the limbs.

At which vertebral level is the medullary cone located in adults?

At the L1-L2 disc level.

What sort of nerve fibers travel in the anterior root?

Efferent fibers: alpha and gamma motoneuron axons (somatomotor) and preganglionic autonomic axons (sympathetic Th1-L3, parasympathetic S2-S4).

What sort of nerve fibers travel in the posterior root?

Afferent (sensory) fibers: central processes of the pseudounipolar neurons of the dorsal root ganglion.

Which cisterns are used for CSF withdrawal?

The lumbar cistern (lumbar puncture, only cauda equina there, no cord); the cisterna magna (cerebellomedullary cistern) is the other one. †

What are the names of (both potential and real) spaces between the layers of the spinal meninges?

Epidural space (real; fat and venous plexus, between periosteal and meningeal dura layers); subdural space (potential); subarachnoid space (real; contains CSF).

Which pathways travel in the anterior funiculus?

Anterior corticospinal tract; anterior spinothalamic tract; tectospinal tract; medial (pontine) reticulospinal tract; medial longitudinal fasciculus (medial vestibulospinal).

Which pathways travel in the lateral funiculus?

Lateral corticospinal tract; rubrospinal tract; lateral (medullary) reticulospinal tract; olivospinal tract; lateral spinothalamic tract; anterior and posterior spinocerebellar tracts.

Which pathways travel in the posterior funiculus?

Gracile fasciculus (Goll; lower limb; medial) and cuneate fasciculus (Burdach; upper limb; lateral) = epicritic dorsal column system.

What are Rexed laminae (spinal laminae of Rexed)?

Cytoarchitectonic layers of the spinal gray matter, numbered from the dorsal horn to the ventral horn, each with typical cell types and functions.

How many Rexed laminae are found in the gray matter of spinal cord?

Ten (I-X). †

Where does the 1st cervical nerve exit from the vertebral column?

Between the occipital bone and the atlas (above C1).

Where does the 8th cervical nerve exit from the vertebral column?

Between the C7 and Th1 vertebrae.

What make up the cauda equina?

The lumbar, sacral and coccygeal roots running down in the dural sac below the conus (L2 to S2); the filum terminale accompanies them.

Which cranial nerves exit from the retro-olivary groove?

IX (glossopharyngeal), X (vagus) and XI (accessory).

Which cranial nerve exits from the pre-olivary groove?

XII (hypoglossal).

Which cranial nerves exit from the pontocerebellar angle?

VII (facial) and VIII (vestibulocochlear).

Where does the oculomotor nerve exit from the brainstem?

From the interpeduncular fossa (sulcus nervi oculomotorii) of the midbrain.

Where does the trochlear nerve exit from the brainstem?

From the dorsal midbrain just caudal to the inferior colliculus; the fibers decussate before exit, then wind around the midbrain to the ventral side.

Where does the trigeminal nerve exit from the brainstem?

From the lateral surface of the pons.

Where does the abducent nerve exit from the brainstem?

From the bulbopontine sulcus (medial part).

Where does the hypoglossal nerve exit from the brainstem?

From the preolivary sulcus of the medulla oblongata.

What is the name of the floor of 4th ventricle?

The rhomboid fossa (dorsal surface of the pons and medulla).

What are the names of the outlets of 4th ventricle?

The median aperture (Magendie) and the two lateral apertures (Luschka), opening into the subarachnoid space / cisterna magna.

What is the name of the channel which connects the 3rd and 4th ventricles?

The cerebral (mesencephalic) aqueduct of Sylvius.

Name the vital centers of reticular formation.

The vasomotor (cardiovascular) center and the respiratory centers (nucleus tractus solitarii and ventrolateral medullary reticular formation, with pontine pneumotaxic control).

What is the function of the ventral posteromedial nucleus?

Somatosensory relay nucleus for the head: receives the trigeminal lemniscus and solitariothalamic tract (taste); projects to the postcentral gyrus (taste to the insular cortex).

What is the function of the ventral posterolateral nucleus?

Somatosensory relay nucleus for the body: receives the medial lemniscus and spinothalamic tract; projects to the postcentral gyrus.

What is the function of the ventral anterior and ventral lateral nuclei?

Motor relay nuclei in the basal ganglia and cerebellar loops: VA (from globus pallidus, substantia nigra) projects mainly to premotor areas; VL (from globus pallidus, cerebellar nuclei) projects mainly to the primary motor cortex.

What is the function of the anterior thalamic nuclei?

Limbic relay nuclei with access to the cingulate cortex; part of the Papez circuit (emotion, memory); lesions cause emotional instability.

Which thalamic nucleus belongs to the limbic system?

The anterior nucleus (the lateral dorsal nucleus is also listed as a limbic relay).

Name at least three functions of the hypothalamus.

Food intake and energy balance; thermoregulation; sleep-wake and circadian rhythms; endocrine integration; volume and osmoregulation; cardiovascular and respiratory control; reproductive functions; stress and fight-or-flight responses.

What does the arcuate (infundibular) nucleus produce?

Orexigenic NPY-positive and anorexigenic POMC-positive neurons (first-order neurons of appetite regulation); as a parvocellular nucleus it also makes releasing and inhibiting hormones.

What do the paraventricular and supra-optic nuclei produce?

Magnocellular neurons making oxytocin (mainly paraventricular) and ADH/vasopressin (mainly supraoptic), released from the neurohypophysis.

Which hormone does the pineal gland produce?

Melatonin (regulates circadian rhythm).

What is the interpretation of the association fibers?

They connect different cortical areas within the same hemisphere. †

What is the interpretation of the commissural fibers?

They connect corresponding areas of the two hemispheres across the midline. †

Which pathways travel in the anterior limb of internal capsule?

Frontopontine fibers and the anterior thalamic radiation (thalamofrontal fibers).

Which pathways travel in the genu of internal capsule?

Corticonuclear (corticobulbar) fibers.

In which part of the internal capsule does the optic radiation run?

The retrolenticular part (posterior). †

In which part of the internal capsule does the acoustic radiation run?

The sublenticular part. †

In which part of the internal capsule do the corticospinal fibers run?

The posterior limb.

Which branch of the internal carotid artery supplies the internal capsule?

The anterior choroidal artery supplies the posterior limb; lenticulostriate branches of the MCA and ACA (Heubner's artery) supply the rest.

In which gyrus is the primary somatomotor area located?

The precentral gyrus.

In which gyrus is the primary somatosensory area located?

The postcentral gyrus.

In which gyrus is the primary auditory area located?

The transverse temporal gyrus of Heschl (superior temporal). †

In which gyrus is the primary visual area located?

Occipital lobe around the calcarine sulcus (cuneus and lingual gyri). †

In which gyrus is the Broca's motor speech area located?

The inferior frontal gyrus (dominant hemisphere).

In which gyrus is the Wernicke's sensory speech area located?

The superior temporal gyrus (dominant hemisphere).

In which gyrus is the Brodmann areas 3, 1, 2 located?

The postcentral gyrus.

In which gyrus is the Brodmann area 4 located?

The precentral gyrus.

In which gyrus is the Brodmann area 6 located?

Frontal lobe, just anterior to the precentral gyrus (premotor and supplementary motor areas). †

In which gyrus is the Brodmann area 8 located?

The caudal middle frontal gyrus (frontal eye field). †

What is the major function of the Brodmann area 17?

Primary visual cortex.

What is the major function of the Brodmann area 22?

Auditory association and speech comprehension (Wernicke).

What is the major function of the Brodmann area 41?

Primary auditory cortex.

What is the major function of the Brodmann areas 44, 45?

Broca's area: motor speech production.

What make up the striatum?

The caudate nucleus and the putamen (the nucleus accumbens is the ventral part).

Name the cerebellar nuclei.

Dentate, emboliform, globose and fastigial nuclei.

Name the lobes of the cerebellum.

Anterior lobe, posterior lobe and flocculonodular lobe.

Name some functions of the cerebellum.

Fine motor coordination; regulation of muscle tone; balance and posture; vestibulo-ocular reflexes; motor learning, timing and error correction.

Which artery gives rise to the vertebral artery?

The subclavian artery.

Which direct branch of the internal carotid artery supplies the largest part of the superolateral surface of cerebral cortex?

The middle cerebral artery (MCA).

Which direct branch of the internal carotid artery supplies the largest part of medial surface of cerebral cortex?

The anterior cerebral artery (ACA); the PCA supplies the occipital part.

Name three areas of the brain which are devoid of blood-brain barrier.

Area postrema; subfornical organ; OVLT; median eminence; neurohypophysis; pineal gland; subcommissural organ (all circumventricular organs).

What are the names of (both potential and real) spaces between the layers of the cranial meninges?

Epidural space (potential); subdural space (potential); subarachnoid space (real, contains CSF).

Which diencephalic structures are parts of the Papez circuit?

The mammillary bodies (hypothalamus) and the anterior thalamic nucleus (the rest of the circuit: hippocampus, fornix, cingulate gyrus).

What are the functions of the limbic system?

Emotion, memory, motivation, behavior and autonomic/visceral regulation.

What brain areas are connected by the fornix?

The hippocampus and the mammillary bodies (and septal area). †

What are choroid plexuses? What are their function?

Vascular folds of tela choroidea in the ventricles; they secrete CSF, form the blood-CSF barrier and resorb some substances (drugs, bilirubin).

What are the layers of the meninges?

Dura mater, arachnoid mater and pia mater.

Where does the absorption of CSF take place? Which anatomical structures are involved in this process?

Mostly through the arachnoid granulations into the dural venous sinuses; smaller amounts drain by lymph vessels around the spinal nerves.

What is the interpretation of the allocortex?

Phylogenetically old cortex with fewer than six layers (archicortex, paleocortex), e.g. hippocampus and olfactory cortex. †

What is the interpretation of the isocortex?

The six-layered neocortex. †

Which artery passes through the cavernosus sinus?

The internal carotid artery (cavernous part).

What brain areas does basilar artery supply?

Brainstem (pons, midbrain), cerebellum (AICA, SCA) and, through the PCA, the occipital lobe, inferior temporal lobe and thalamus.

Name three association fiber systems of the telencephalon.

Cingulum; superior longitudinal (arcuate) fasciculus; uncinate fasciculus (also the inferior longitudinal fasciculus and short U-fibers). †

Which mesencephalic area contains the highest density of dopaminergic neurons?

The substantia nigra (pars compacta).

What is the function of the area postrema?

Circumventricular organ at the caudal floor of the 4th ventricle with no blood-brain barrier; senses blood chemistry and acts as the chemoreceptor trigger zone for vomiting.

Which anatomical/physiological system includes the Papez circuit?

The limbic system.

Name three commissural fiber systems of the telencephalon.

Corpus callosum; anterior commissure; commissure of the fornix (hippocampal commissure). The posterior and habenular commissures are epithalamic.