Identify the landmark or structure
Pyramid
Identify the landmark or structure
Decussation of Pyramids*
*At the caudal medulla, where the corticospinal tracts decussate!
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Dorsal root of spinal nerve
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Gracile fasciculus
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Spinal accessory nucleus (CN XI)
Identify the landmark or structure
Medial motor nuclei
How far down does the trigeminal tract go?
What is it analogous with?
the trigeminal tract goes all the way into the spinal cord
it becomes analogous with Lissauers tract
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Solitary nucleus (CN VII, IX, X)
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Spinal trigeminal nucleus (CN V, VII. IX, X)
Identify the landmark or structure
Solitary nucleus (CN VII, IX, X)
Identify the landmark or structure
Spinal trigeminal nucleus (CN V, VII. IX, X)
What does the red line represent?
What nuclei are found lateral to the line? medial?
The red line is the sulcus limitans
Lateral to the sulcus limitans are the sensory nuclei
Medial to the sulcus limitans are the motor nuclei
Identify the landmarks or structures of the Pons marked by the red and yellow stars
The red star is the basal portion of the pons
The yellow star is the Tegmental portion (ventral to the 4th ventricle)
Identify the landmark or structure
Facial colliculus
What are the Major Longitudinal Regions of the Pons (“Bridge”)
Basal Pons (Basis Pontis)
and
Pontine Tegmentum
What are the major components of the Basal Pons (Basis Pontis)
- Corticospinal and corticobulbar tracts (descending)
- Pontine nuclei (cerebellar circuitry)
What are the major components of the Pontine Tegmentum
- Is separated from cerebellum via 4th Ventricle
- Cranial nerve nuclei
- Reticular formation
- Medial lemniscus (ascending pathway heading to VPL of thalamus)
- MLF (mostly ascending here; keeps dorsomedial position)
Whats unique about the Pons?
- Reticular formation in medulla and caudal pons involved in _____ and _____ functions.
- Large, lateral connections with cerebellum via superior and middle _____ _____
- Shares vestibular nuclei of CN VIII with medulla (at _____ junction)
- Nuclei of CN ___, ___, and ___
Whats unique about the Pons?
- Reticular formation in medulla and caudal pons involved in motor** and **autonomic functions (also sleep, wakefullness, conciousness).
- Large, lateral connections with cerebellum via superior and middle cerebellar peduncles (hence, “bridge”)
- Shares vestibular nuclei of CN VIII with medulla (at pontomedullary junction)
- Nuclei of CN VII, VI, V
Identify the landmark or structure
Corticospinal and corticobulbar tracts
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Medial longitudinal fasciculus (MLF)
NOTE: medial longitudinal fasiculus, connects vestibular and cochlear nuclei to nearby nuclei controlling extraocular muscles (III, IV, VI)
Identify the landmark or structure
Facial colliculus
Identify the landmark or structure
Nucleus of abducent nerve
Identify the landmark or structure
Motor nucleus of facial nerve
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Facial nerve
Identify the landmark or structure
Abducent nerve
Identify the landmark or structure
Transverse pontine fibers
Study the cross section of the rostral to mid ponsnd be able to recognize the major landmarks and structures
Study the cross section of the rostral to mid pons and be able to recognize the major landmarks and structures
Study the cross section of the Pontomesencephalic Junction and be able to recognize the major landmarks and structures
Study the cross section of the Pontomesencephalic Junction and be able to recognize the major landmarks and structures
Identify the landmark or structure
Cerebral aqueduct
Identify the landmark or structure
Pontine nuclei
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Pontocerebellar fibers
Identify the landmark or structure marked by the red star
Tectum
Identify the landmark or structure
Tegmentum
Identify the landmark or structure
Oculomotor nerve
Identify the landmark or structure
Cerebral aqueduct
Which section of the brain stem is between the red dotted lines?
Midbrain
Identify the landmark or structure
Superior colliculus*
*note there are 2 Superior colliculi and 2 Inferior colliculi; together the 4 colliculi are collectively called corpora quadrigemina (four bodies)
Identify the landmark or structure
Inferior colliculus*
*note there are 2 Superior colliculi and 2 Inferior colliculi; together the 4 colliculi are collectively called corpora quadrigemina (four bodies)
Identify the landmark or structure
Trochlear nerve (CN IV)
Note: The trochelar nerve is the only CN that exits the brain stem dorsally!
Identify the landmark or structure
Crus cerebri
Identify the landmarks or structures marked by the red and yellow stars
The yellow star is Tectum
The red star is Tegmentum
The Trigeminal Ganglia consist of primary _____ neurons, with one exception:
_____ is both motor and sensory
The Trigeminal Ganglia* consist of primary sensory neurons, with one exception:
V3 mandibular is both motor and sensory
Review the functions of V1, V2, amd V3!!!
What else does CN V provide sensation for?
Review the functions of V1, V2, amd V3!!!
CN V also provides sensation for supratentorial dura!
What else does CN IX provide sensation for?
CN IX also provides sensation for the middle ear, posterior 1/3 tongue, and pharynx.
What else does CN X provide sensation for?
CN X also provides sensation for infratentorial dura and probably pharynx, too
What are the 3 Trigeminal Nuclei in the brainstem?
Trigeminal Nuclei:
- Mesencephalic
- Chief or (Principal)
- Spinal
Trigeminal Nuclei:
- the spinal trigeminal nucleus runs in the same column as the _____ _____ of the spinal cord.
- Trigeminal sensory “column” is analogous to _____ and _____ “systems” of the spinal cord.
Trigeminal Nuclei:
- the spinal trigeminal nucleus runs in the same column** as the **dorsal horn of the spinal cord.
- Trigeminal sensory “column” is analogous to DC-ML and anterolateral “systems” of the spinal cord.
General somatic sensory mainly from _____ and a little from ___, ___, and ___
General somatic sensory mainly from CN V and a little from VII, IX, and X (at ear).
Where does brainstem fit into 3-neuronal sensory pathway???
Where does brainstem fit into 3-neuronal sensory pathway???
Know and understand this chart
Know and understand this chart
Mesencephalic Trigeminal Nucleus:
- Here’s the exception: _____ _____ nucleus is located in the CNS/brainstem.
- Receive _____ input from muscles of mastication, tongue, extraocular muscles
- Clinical Relevance: Involved in _____ _____ reflex
Mesencephalic Trigeminal Nucleus:
- Here’s the exception: Primary sensory nucleus is located in the CNS/brainstem.
- Receive proprioceptive input from muscles of mastication, tongue, extraocular muscles
- Clinical Relevance: Involved in _jaw jerk reflex*_
- In this reflex, there are fibers that run from the mesencephalic nucleus DOWN to the pons to the MOTOR NUCLEUS of V (that ultimately innervate muscles of mastication via the mandibular division of V3)
- Other roles of this nucleus are “under investigation”
Note DECUSSATION in Secondary Neurons!!!
Note DECUSSATION in Secondary Neurons!!!
