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Neuro Block 6 Lect 3
Brainstem and External Features
| Question | Answer |
|---|---|
| What does the brainstem consist of? Covered posteriorly by? Covered inferiorly by? Covered superiorly by? | Medulla oblongata, pons, midbrain Posteriorly - cerebellum Inferiorly - with spinal cord at Foramen Mag Superiorly - diencephalon |
| What are 5 external features of the Medulla that we talked about in class? | Anterior Median Fissure Pyramids Olive Preolivary sulcus Postolivary (retro-olivary) sulcus |
| What are the nerves that attach along the medullopontine sulcus: (medial to lateral)? | abducens nerve 2 roots of facial nerve (motor root; intermediate nerve) vestibulocochlear nerve |
| What are 2 longitudinal columns on either side of anterior median fissure? | Pyramids of the Medulla |
| T/F - Pyramids contain descending fibers? | True |
| Pyramids contain what kind of fibers of what tract? | Descending fibers of corticospinal tracts |
| What is the pyramidal/motor decussation? | Where about 90% of corticospinal fibers cross to the contralateral side. |
| After crossing at pyramidal/motor decussation, where do the fibers run? | fibers descend in lateral funiculus of spinal cord as lateral corticospinal tract |
| What is the anterior corticospinal tract? | fibers that do not cross at pyramidal/motor decussation, descend in the anterior funiculus of spinal cord. |
| What nerve rootlets attach on the preolivary sulcus? | hypoglossal nerve |
| Where can you find attachment of rootlets of glossopharyngeal and vagus nerves? | postolivary (retro-olivary) sulcus |
| The pons is continuous on each side with what fiber bundle that terminates in the cerebellum? | Middle cerebellar peduncle |
| What are the pontocerebellar fibers and where are they located? | Pons anterior surface marked by transverse bands formed by fiber bundles that originate in pons and enter cerebellum via middle cerebellar peduncle. |
| What is the boundary between the pons and middle cerebellar peduncle? | attachment of trigeminal nerve |
| What is the shallow groove along anterior midline of pons related to basilar artery? | basilar sulcus |
| The midbrain has 2 columns of descending fibers that emerge from cerebral hemisphere, run inferiorly and medially, and disappear into the pons. What are these called? | Cerebral Crura (crus) |
| What nerve attaches to the medial border of cerebral crus? | Oculomotor nerve |
| What is the space between the cerebral crura called? | interpeduncular fossa |
| What is the posterior perforated substance and where is it located? | Many small perforations from numerous vessels that penetrated the floor of the interpeduncular fossa |
| T/F - "Open" medulla refers to the lower part of medulla that has a small cavity or upward continuation of the central canal of spinal cord. | False |
| T/F - The upper part of the medulla forms part of floor of 4th ventricle referred to as open medulla. | True |
| What plate gives rise to sensory nuclei? | Alar plate |
| The basal plate gives rise to what? | Motor nuclei |
| A lesion on the right side below the pyramidal/motor decussation involves which fibers/tracts and results in what condition? | Involves the anterior corticospinal tract results in paralysis/paresis on the right |
| What needs to be removed to see the posterior surface of the brainstem completely | 3 pairs of cerebellar peduncles Superior, Middle, Inferior |
| What are the gracile and cuneate tubercles and what kind of fibers? | gracile and cuneate fasciculi terminate superiorly in slight enlargements formed by the corresponding nuclei underneath. Where ASCENDING fibers of gracile and fasciculi terminate. |
| What forms a prominent elevation in posterolateral medulla, superior to gracile and cuneate tubercles? | Restiform body |
| T/F - The restiform body consists of fibers that originate in spinal cord and medulla and terminate in cerebellum. | True |
| What kind of fibers are associated with restiform body? | cerebellar AFFERENT fibers |
| What forms the inferior cerebellar peduncle? | restiform body + juxtarestiform body(small bundle of fibers in lower pons) |
| What is the floor of the 4th ventricle called? | rhomboid fossa |
| What divides the right and left halves in the rhomboid fossa? | median sulcus of rhomboid fossa |
| What is the sulcus limitans? | longitudinal sulcus on each half of rhomboid fossa(right/left) |
| What is the area between the median sulcus and sulcus limitans? | medial eminence of 4th ventricle |
| What is the difference between the location of the cranial nerve motor nuclei and sensory nuclei? | motor nuclei located between median sulcus and sulcus limitans sensory nuclei located lateral to sulcus limitans |
| What are the small triangular areas in the lower part of medial eminence and what lies deep to them? | hypoglossal and vagal trigones deep to them lie hypoglossal nucleus and dorsal motor nucleus of vagus |
| What marks the location of the abducens nucleus and internal genu of facial nerve in lower pons? | facial colliculus (rounded elevation of medial eminence) |
| What is the vestibular area and where is it located? | marks location of vestibular nuclei located lateral to sulcus limitans in upper medulla and lower pons |
| What constitutes the boundary between medulla and pons on dorsal surface of brainstem and crosses the widest part of rhomboid fossa? | striae medullares of 4th ventricle |
| What is the inferior (caudal) tip of the 4th ventricle called? | obex |
| The posterior surface of midbrain is marked by how many elevations and what are they? | 4 2 inferior colliculi - part of auditory sys 2 superior colliculi - part of visual sys |
| The inferior colliculus is connected to what by brachium of inferior colliculus? | medial geniculate body (part of thalamus) |
| The superior colliculus is connected to what by brachium of superior colliculus? | lateral geniculate body (part of thalamus) |
| What is located between superior colliculi? | pineal body/gland (part of epithalamus, component of diencephalon) |
| What is the only cranial nerve attached to posterior surface of brainstem? Where does it attach? | Trochlear nerve attaches to brainstem immediately below inferior colliculus |
| What kind of fibers are the General Visceral Efferent (GVE) Cranial Nerves? Which CNs are involved? | preganglionic parasympathetic CN 3,7,9,10 |
| What type of nerve are the Special Visceral Efferent (SVE)? What do they innervate? Which CNs are involved? | Branchial Motor innervate skeletal muscle fibers derived from pharyngeal (branchial) arches CN 5,7,9,10 |
| What does the General Somatic Efferent innervate? What CNs are involved? | innervate skeletal muscle fibers derived from somites and somitomeres CN 3,4,6,12 |
| What do General Visceral Afferent (GVA) fibers innervate? What CNs are involved? | carry SENSORY information from receptors in internal organs CN 9,10 |
| What do Special Visceral Afferent (SVA) fibers innervate? What CNs are involved? | carry olfactory and gustatory information CN 1,7,9,10 |
| What do General Somatic Afferent (GSA) fibers innervate? What CNs are involved? | carry SENSORY information from receptors in skin, muscles, tendons, ligaments CN 5,7,9,10 |
| What do Special Somatic Afferent (SSA) fibers innervate? What CNs are involved? | carry visual, auditory, and balance information CN 2,8 |
| Where are the General Somatic Efferent (GSE) motor nuclei located? | close to midline and adjacent to lumen of ventricular system |
| Where is the oculomotor nucleus located? | in midbrain at the level of the superior colliculus |
| What nucleus is located in the lower pons (deep to facial colliculus of rhomboid fossa)? | abducens nucleus |
| What nuclues is located in the medulla? | hypoglossal nucleus |
| Where is the trochlear nucleus located? | in midbrain at the level of the inferior colliculus |
| What motor nuclei give rise to preganglionic parasympathetic fibers? | General Visceral Efferent (GVE, Parasympathetic) |
| Edinger-Westphal nucleus is associated with what CN? Where is it located? | CN 3 in midbrain at the level of superior colliculus, immediately posterior to oculomotor nucleus |
| Which motor GVE nucleus is associated CN 7 and located in lower pons? | Superior Salivatory Nucleus |
| Which motor GVE nucleus is located in medulla and associated with CN 10? | Dorsal motor nucleus of Vagus |
| The Inferior Salivatory Nucleus is associated with which CN? and located where? | CN 9 located in UPPER medulla |
| Of the Special Visceral Efferent nuclei, which is located in midpons, innervates muscles derived from 1st pharyngeal arch (muscles of mastication)? | trigeminal motor nucleus |
| Where is the SVE facial nucleus located and what muscles does it innervate? | located in lower pons innverates muscles derived from 2nd Pharyngeal arch (muscles of facial expression) |
| Where is the SVE nucleus Ambiguus located and what muscles does it innervate? | located in medulla contributes SVE fibers to CN 9,10 innervates muscles derived 3rd,4th,6th Pharyngeal arches (muscles of pharynx,larynx,soft palate) |
| What sensory nuclei (GSA) receives general sensory information like pain, temp, touch, propioception from the Trigeminal nerve? It also receives some GSA fiber from what other CN? | Trigeminal Sensory Nucleus CN 7,9,10 |
| The Trigeminal Sensory Nucleus extends the whole length of the brainstem and divides into 3 parts which are? | spinal nucleus of trigeminal nerve principal sensory (pontine) nucleus of trigeminal nerve mesencephalic nucleus of trigeminal nerve |
| Explain the 3 parts of the Trigeminal Sensory Nucleus. | Spinal nucleus - extends from lower pons to medulla-spinal cord junction: rec pain/temp information Principal sensory (pontine) - located in midpons; rec touch information Mesencephalic nucleus - extends from midpons to upper midbrain; rec propioceptive |
| What sensory information received and location of the ventral and dorsal cochlear nuclei? (SSA) | rec auditory information from organ of Corti (internal ear) via cochlear part of CN 8 located posterolaterally at pontomedullary junction (on surface of restiform body) |
| How many vestibular nuclei (SSA) are there and what are they? Where are they located and what information do they receive? | 4: superior,inferior,medial,lateral located posterolateral part of upper medulla and lower pons just underneath vestibular area of rhomboid fossa Receive information from maculae and ampullary crests (internal ear) via vestibular part of CN 8 |
| Where is the solitary nucleus (sensory) located and what CN fibers does it receive? | located in medulla upper part: rec SVA fibers (taste) from CN7,9,10 - gustatory nucleus lower part: rec GVA fibers from CN 9,10 - cardiorespiratory nucleus |
| Of the different nuclei, which are General Somatic Efferent (GSE)? THESE ARE MOTOR NUCLEI | oculomotor nucleus, trochlear nucleus, abducens nucleus, hypoglossal nucleus |
| Of the different nuclei, which are General Visceral Efferent (GVE)? THESE ARE MOTOR NUCLEI | Edinger-Westphal nucleus, superior salivatory nucleus,inferior salivatory nucleus, dorsal motor nucleus of vagus |
| Of the different nuclei, which are considered to be Special Visceral Efferent (SVE Branchial Motor)? THESE ARE MOTOR NUCLEI | trigeminal motor, facial nucleus, nucleus ambiguus |
Created by:
MichaelR
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