Medulla Anatomy Flashcards
Why is meant by the closed medulla?
The medulla below the opening of the 4th ventricle.
What structure becomes the 4th ventricle?
The spinal canal.
Which direction does the spinal canal migrate to become the 4th ventricle?
Dorsally.
Which portion of the medulla is referred to as the “true” medulla?
The open medulla
What does the (non-horn) gray matter of the spinal cord become in the medulla?
The reticular formation
Is the motor decussation found in the upper or lower closed medulla?
Lower
Is the sensory decussation found in the upper or lower closed medulla?
Upper
What cranial nerve motor nucleus is found in the lower closed medulla?
Cranial nerve XI.
What fibers make up the pyramids found in the medulla?
Corticospinal fibers
What portion of the corticospinal fibers cross in the medulla?
85 %
Where are the 15% of corticospinal fibers that do not cross found?
In anterior funiculus
Where do the cranial nerve XI fibers exit the medulla?
Through the ventral horn
Do the CN XI fibers ascend or descend after leaving the medulla?
Ascend
What spinal region contributes fibers to CN XI?
The upper C-region
What sulcus disappears in the lower closed medulla?
The ventral median sulcus
What muscles are supplied by CN XI?
SCM
Upper trapezius
What cranial nerve sensory nucleus is found in the lower closed medulla?
Spinal nucleus of CN V.
What sensory information is sent to the spinal nucleus of CN V?
Pain and temperature of the face.
What nuclei are found in the upper closed medulla?
- Nucleus gracilis
- Nucleus cuneatus
What do the crossing fibers of the NG and NC form?
The medial lemniscus
What are the crossing fibers of the NG and NC called individually?
Internal arcuate fibers
Do the fibers of the lower extremity (sensory or motor) cross rostrally or caudally in the medulla?
LE cross more caudually
Do the fibers of the upper extremity (sensory or motor) cross rostrally or caudally in the medulla?
UE cross more rostrally.
What is the somato-topical arrangement of the medial lemniscus?
From anterior –> posterior
Sacral –> Cervical
What 4 nuclei are begin at/ are unique to the open medulla?
- CN XII nuclei
- CN X motor nucleus
- Solitary Nucleus/ Nucleus of Tractus Solitarii
- Nucleus Ambiguus
What nucleus continues from the closed medulla into the open medulla?
- Spinal Nucleus of CN V
What tract begins at the level of open medulla?
- Inferior cerebella peduncle
What is the path of CN XII’s fibers from its nucleus in the open medulla to the tongue?
- Travels ventrally and exits medulal between pyramids and olive
- Ascends upwards
- Enters tongue
To which side will a tongue deviate when protracted in a unilateral CN XII lesion?
To the lesioned side
How do the fibers of the dorsal motor nucleus of the vagus nerve exit the open medulla?
Laterally, with a ventral orientation
What autonomic nervous system makes up the dorsal motor nucleus of CN X?
Parasympathetic NS
What structures are innervated by the motor elements of CN X?
- Neck and below, except for lower GI
What 3 cranial nerves make up the cell column of the nucleus ambiguus?
9
10
11
How are the cranial nerves oriented in the nucleus ambiguus from superior to inferior? (dorsal to ventral???)
9
10
11
What structures are innervated by the efferent fibers of the nucleus ambiguus?
- Pharynx
- Larynx
What symptoms result from a lesion to the nucleus ambiguus?
- Dysarthria
- Dysphagia
What 3 cranial nerves make up the cell column of the solitary nucleus?
7
9
10
What information is processed by the lower half of the solitary nucleus?
- General visceral afferent information from the neck and body wall
What information is processed by the upper half of the solitary nucleus?
VII: Anterior 2/3rds of tongue (SVA/ Taste)
IX: Posterior 1/3rds of tongue (SVA/ Taste)
X: Afferent information of oropharynx
What 3 nuclei at the level of the open medulla are involved with fibers of CN X?
- Solitary nucleus
- Nucleus Ambiguus
- Dorsal motor nucleus of CN X
What 3 nuclei are found in the transitional area between the medulla and pons?
- Vestibular nuclei
- Cochlear nuclei
- Accessory Cuneate Nucleus
What CN projects to the cochlear and vestibular nuclei? From what orientation does it enter the brain stem?
- CN VIII
- Enters laterally
What is the function of the vestibular nuclei?
Communicate with the vestibular apparatus in the inner ear
What component of CN VIII projects to the vestibular and cochlear nuclei?
Special somatic afferent
What tract originates at the accessory cuneate nucleus?
Cuneocerebellar tract
What structure communicates the medulla to the cerebellum in the transitional area between the pons and medulla?
The inferior cerebellar peduncle
What effect will a lesion to the ICP at the transitional area have on an individual?
Pt will lose proprioception of the body and face
