Internal Structure of the Brain

Question 1

What is the 4th ventricle?

Answer 1

This is the part of ventricle system located dorsal to the brain stem from mid-medulla through pons.

Question 2

Abducens nuclei

Answer 2

A nucleus in the doral, medial part of the caudal pons near the MLF. Motor neurons give rise to the abducens nerve (CNVI; innervate the lateral rectus muscle for lateral eye movement).

Question 3

Basal pons

Answer 3

see “pontine nuclei” Pontine nuclei /basal pons – This is the bulbous nucleus that forms the ventral aspect of pons. The termination of corticopontine fibers and origin for pontocerebellar projections through middle cerebellar peduncle.

Question 4

Pulvinar

Answer 4

This is the large posterior portion of the thalamus that forms a bulbous projection.

Pulvinar/ LP complex (association nuclei) project to the temporoparietal association cortex

Question 5

Pyramid

Answer 5

Medullary pyramid – This is the fiber bundle in the ventral part of the medulla containing corticospinal tracts, which are involved in skilled movements of contralteral limbs.

Question 6

Brachium conjunctivum

Answer 6

see “superior cerebellar peduncle” Superior cerebellar peduncle/brachium conjunctivum – This is the connection from cerebellum to midbrain. Most of cerebellar outputs traverse this pathway.

Question 7

Brachium pontis

Answer 7

ee “Middle cerebellar peduncle” Middle cerebellar peduncle/brachium pontis – This is the connection from the basal pons to cerebellum. It is a relay for connections from the cerebral cortex to cerebellum (cortico-pontine, ponto-cerebellar).

Question 8

Central canal

Answer 8

This is the canal at the center of the spinal cord and caudal medulla, filled with cerebrospinal fluid, connecting with the 4th ventricle at the obex of the medulla.

Question 9

Cerebellum

Answer 9

This is the region comprised of cortex and deep nuclei doral to the brain stem. It is involved in coordination of voluntary movements and the learning of motor skills.

Question 10

Cerebral aqueduct (Sylvius)

Answer 10

This is the cerebrospinal fluid path through midbrain from the third to fourth ventricle.

Question 11

Cerebral peduncle/crus cerebri

Answer 11

Located in the ventral midbrain. Comprised of cerebral cortical efferent projections to the brain stem (corticobulbar) and spinal cord (corticospinal).

Question 12

Cochlear nuclei

Answer 12

Situated on the inferior cerebllar peduncle at the ponto-mesencephalic junction. It is the site of termination of auditory nerve fibers in CNVIII and is the first relay nucleus in the auditory patheway.

Question 13

Deep cerebellar nuclei

Answer 13

Dentate, Interposed, Fastigeal The output nuclei from the cerebellum (listed from lateral to medial).

Question 14

Dorsal columns

Answer 14

This is the collective term for the fasciculus gracilis and cuneatus.

Question 15

Dorsal motor nucleus of the vagus

Answer 15

This is the collection of motor neurons for parasympathetic preganglionic neurons running in CNX. The rostral part is often called the inferior salivatory nucleus and contribues parasympathetic fibers to CN IX

Question 16

External/lateral cuneate nucleus

Answer 16

This nucleus is immeiately lateral to the nucleus cuneatus and relays proprioceptive information from the upper limbs to the cerebellum. At the level of the mid-medulla

Question 17

Facial nerve

Answer 17

CNVII has a long course through the caudal pons. It has an internal genu (a bend) around the abducens nucleus in the floor of the fourth ventricle. This leads to a bump in the floor of the 4th ventricle, the facial colliculus.

Question 18

Facial nucleus

Answer 18

This nucleus is located in the caudal pons and is the origin for motor nerve fibers to muscles of facial expression.

Question 19

Fasciculus gracilis and cuneatus

Answer 19

These are tracts conveying well-localized touch, pressure, vibration and joint position sense from legs (gracilis) and arms (cuneatus). Located in the dorsal funiculus of spinal cord. Collectively called the dorsal columns.

Question 20

Hypoglossal nucleus

Answer 20

This is the nucleus in the dorsal, medial medulla containing motor neurons for tongue muscles.

Question 21

Inferior cerebellar peduncle/restiform body

Answer 21

This is the connection from medulla to cerebellum. Conveys nerve fibers from spinal cord and brain stem to the cerebellum.

Question 22

Inferior olivary nucleus

Answer 22

This is the large nucleus in the ventral lateral medulla that is the origin of cerebellar climbing fibers and that is critical for normal cerebellar function.

Question 23

Internal arcuate fibers

Answer 23

Caudal Medulla - Mid-Medulla 1 These are nerve fibers arising from neurons of the nucleus gracilis and cuneatus, passing ventrally and decussating. The are a distinctive feature of the caudal to mid medulla

Question 24

Lateral geniculate nucleus

Answer 24

Rostral Misencephalon This nucleus is located in the caudal part of thalamus (part of diencepahlon). It is the termination of the optic tract and is a critical relay in the visual pathway.

Question 25

Medial geniculate nucleus

Answer 25

Rostral Misencephalon This nucleus is located in the caudal part of thalamus (of the diencepahlon) and relays auditory information from the inferior colliculus to the auditory cortex.

Question 26

Medial longitudinal fasciculus (MLF)

Answer 26

Caudal Medulla- Mesencephalon This is a distinctive bundle of axons this includes several ascending and descending tracts. It is especially important in yoking together horizontal eye movements. Located near midline, just ventral to ventricle system.

Question 27

Nucleus gracilis and cuneatus

Answer 27

These are nuclei in the caudal medulla for termination of fasciculus gracilis and cuneatus, respectively. They are the relay for well-localized touch, pressure and vibrattory sense.

Question 28

Nucleus solitarius

Answer 28

This is the visceral sensory nucleus for CNX and CNIX. The rostral portion receives taste input (gustatory nucleus).

Question 29

Obex

Answer 29

The location where the central canal opens up to the fourth ventricle.

Question 30

Periaqueductal gray

Answer 30

This is a conspicuous nucleus surrounding the cerebral aqueduct that contains endogenous opiate neurons and activates descending pain suppression pathways

Question 31

Pineal gland

Answer 31

This is a gland located just dorsal to midbrain. It is involved in circadian secretion of melatonin.

Question 32

Pyramidal decussation

Answer 32

This is the crossing site of corticospinal tracts at caudal end of medullary pyramid. Marks the junction between spinal cord and brain stem.

Question 33

Raphe nuclei

Answer 33

Caudal pons Serotonin-containing neurons in midline of brain stem.

Question 34

Red nucleus

Answer 34

This is a large and distinctive motor nucleus in midbrain. It is the origin of the rubrospinal tract and projections to the inferior olivary nucleus

Question 35

Solitary tract

Answer 35

A distinctive tract in the dorsal medulla that distributes vagal and glossopharyngeal visceral sensory axons to the proper parts of the nucleus solitarius.

Question 36

Spinal nucleus of the trigeminal

Answer 36

A long nucleus of the latreral brain stem that is the termination of trigeminal pain and temperature sensory fibers in the spinal tract of the trigeminal.

Question 37

Spinal tract of the trigeminal

Answer 37

A collection of trigeminal pain and temperature sensory fibers running caudally through the lateral medulla. They are first order sensory fibers from the trigeminal nerve.

Question 38

Substantial nigra

Answer 38

A large nucleus of the midbrain located just dorsal to the crus cerebri. The pars compacta ia the major source of dopamine in basal ganglia. Degenerates in Parknson’s disease.

Question 39

Superior colliculus

Answer 39

A nucleus that receives input from many sensations (especially vision) and is involved in producing reflex head and eye movement to novel stimuli.

Question 40

Tectum

Answer 40

The portion of the midbrain dorsal to the cerebral aqueduct (comprised of the colliculi).

Question 41

Tegmentum

Answer 41

The term used for the “core” of the brain stem between the ventricle system dorsally and the motor structures in the ventral part of the brain stem (the pyramids and inferior olive in the medulla, the pontine nuclei in the pons and the crus cerebri and substantia nigra in the midbrain.

Question 42

Trapezoid body

Answer 42

Crossing fibers in the pons for auditory pathway.

Question 43

Trigeminal nerve

Answer 43

CNV passing through middle cerebellar peduncle in mid pons.

Question 44

Trigeminal nuclei

Answer 44

The motor neurons to jaw muscles. Termination of touch and pressure sensory fibers from the face (chief sensory nucleus).

Question 45

Ventral tegmental area

Answer 45

Mesencephalon A region of dopaminergic neurons in the midline of the ventral midbrain. The major dopamine source in the mesolimbic and mesocortical dopamine reward system. Major site of addiction research.

Question 46

Vestibular nuclei/complex

Answer 46

The termination of vestibular nerve fibers of CNVIII.

Question 47

Inferior colliculus

Answer 47

A relay for auditory pathway. It is located dorsal to cerebral aqueduct (in tectum).