Brain stem Flashcards
The brainstem has three broad functions:
(1) It serves as a ____ for the ____ connecting the spinal cord to the different parts of the higher centers of the forebrain;
(2) it contains important ____ associated
with the control of ____ and the ____ with the control of ____; and
(3) it contains the important ____
(1)conduit for the ascending tracts and descending tracts
(2) important reflex centers associated
with the control of respiration and the cardiovascular system with the control of consciousness; and
(3) important nuclei of CNs III through XII.
The medulla oblongata connects the pons superiorly with the spinal cord inferiorly. The junction of the _____ is at the origin of the
anterior and posterior roots of the ____, which corresponds approximately to the level of
the foramen magnum.
medulla and spinal cord - first cervical spinal nerve
The medulla oblongata is conical in shape, its broad extremity being directed superiorly. The central canal of the spinal cord continues upward Into the lower half of the medulla; In the upper half of the medulla, It expands as the cavity of the _____.
central canal - fourth ventricle
On the anterior surface of the medulla is the _____, which is continuous inferiorly with the
anteriormedlan flume of the spinal cord.
anterior median fissure
Swellings on each side of the median fissure are called ___.
the pyramids
The pyramids are composed of bundles of nerve fibers, called _____, which originate In large nerve cells In the precentral gyrus of the cerebral cortex.
corticospinal fibers
______ taper Inferiorly, and here the majority of the descending fibers cross over to the cross over to the opposite side, forming the pyramids
The pyramids
The _____ emerge from the anterior median fissure above the decussation and pass laterally over the surface of the medulla oblongata to enter the cerebellum.
anterior external arcuate fibers -
Posterolateral to the pyramids are the ___, which are oval elevations produced by the underlying _____.
olives - Inferior olivary nuclei
The posterior surface of the superior half of the
medulla oblongata forms the lower part of the floor of the _____.
*On each side of the median sulcus. an elongated swelling, the ______ , is produced by the underlying gracile nucleus
*Lateral to this is a similar swelling, the _____, produced by the underlying cuneate nucleus.
fourth ventricle
*gracile tubercle - cuneate tubercle
The medulla oblongata consists of white matter and gray matter, but a study of transverse sections of this region shows that they have been extensively rearranged.
*This rearrangement can be explained embryologically by the expansion of the ___ to form the _____, which becomes the fourth ventricle.
*The extensive lateral spread of the fourth ventricle results in an alteration in the position of the derivatives of the _____ and ____ of the embryo.
neural tube - hindbrain vesicle
*alar and basal plates
In the spinal cord, the derivatives of the alar and basal plates are situated posterior and anterior to the ______, respectively.
sulcus limitans
The internal structure of the medulla oblongata Is
considered at four levels:
1) Level of decussation of ____
2) Level of decussation of ____
3)
4)
(1) level of decussation of pyramids
(2) level of decussation of lemnisci
(3) level of the olives
(4) level just inferior to the pons
The _____ and _____continue to ascend superiorly posterior to the central gray matter.
*The _____ and the ____ appear as posterior extensions of the central gray matter.
*fasciculus gracilis and the fasciculus cuneatus
*nucleus gracilis and the nucleus cuneatus
The _____ In the posterior gray column of the spinal cord becomes continuous with the inferior end of the ______. The fibers of the tract of the nucleus are situated between the nucleus and the surface of the medulla oblongata.
*The lateral and anterior white columns of the spinal cord are easily identified In these sections, and their fiber arrangement is unchanged.
Substantia gelatinosa - nucleus of the spinal tract of the trigeminal nerve
The lemnisci have been formed from the _____, which have emerged from the anterior aspects of the ____ and ____.
Internal arcuate fibers - nucleus gracilis and nucleus cuneatus
The internal arcuate fibers first travel ___ and ___ around the central gray matter. They then curve medially toward the midline, where they decussate with the corresponding fibers of the opposite side.
anteriorly and laterally
The nucleus of the ____ lies lateral to the internal arcuate fibers. Lies lateral to the nucleus.
spinal tract of the trigeminal nerve
The ____ and ____ and the _____ occupy an area lateral to the decussatlon of the lemnisci.
The lateral and anterior spinothalamic tracts and
the spinotectal tracts
A transverse section through the olives passes across the _____. The amount of gray matter has Increased at this level owing to the presence of the ______; the nuclei of the vestibulocochlear glossopharyngeal, vagus accessory, and hypoglossal nerves; and the arcuate
Inferior part of the fourth ventricle - olivary nuclear complex
The largest nucleus of this complex is the _____.
The gray matter is shaped like a crumpled bag with its mouth directed medially; it is responsible for the elevation on the surface of the medulla
called the ____.
inferior olivary nucleus - olive
The cells of the inferior olivary nucleus send fibers medially across the midline to enter the cerebellum through the ____.
*Afferent fibers reach the inferior olivary nuclei from the spinal cord (the spino-olivary tracts) and from the cerebellum and cerebral cortex.
*The function of the olivary nuclei is associated with _____
Inferior cerebellar peduncle - voluntary muscle movement
They are very close to one another and collectively are known as the _____.
spinal lemniscus
The vestibular nuclear complex is made up of the following nuclei:
(1) medial vestibular nucleus
(2) inferior vestibular nucleus
(3) lateral vestibular nucleus
(4) superior vestibular nucleus
The _____ consists of large motor neurons and is situated deep within the reticular formation. The emerging nerve fibers join the ____, ____, and cranial parts of _____ and are distributed to voluntary skeletal muscle.
nucleus ambiguus - glossopharyngeal, vagus, and cranial part of the accessory nerve
The _____ lies beneath the floor of the fourth ventricle at this level.
*Passing from medial to lateral, the following important structures may be recognized:
(1) the ____
(2) the ____
(3) the ____
(4) the ____
Central gray matter
(1) the hypoglossal nucleus
(2) the dorsal nucleus of the vagus
(3) the nucleus of the tractus solitarius
(4) the medial and Inferior vestibular nuclei
The ____are thought to be inferiorly displaced pontine and are situated on the anterior surface of the pyramids.
arcuate nuclei - pontine nuclei
(Central gray matter) The _____ forms a flattened tract on each side of the midline posterior to the pyramid. These fibers emerge from the decussation of the lemnisci and convey _____ to the thalamus.
medial lemniscus - sensory information
The _____ forms a small tract of nerve fibers situated on each side of the midline posterior to the medial lemniscus. It consists of ascending and descending fibers.
medial longitudinal fasciculus
The _____ is situated in the posterolateral corner of the section on the lateral side of the fourth ventricle
Inferior cerebellar peduncle -
