anatomy sheet 7 Flashcards
Internal Structures of Medulla
- Level of** pyramidal decussation** (closed part)
1) Motor pathways هيك من العقل للجسم وزي ما حكينا بتمر من قدام
* Pyramids (descending tract, projection fibers,
corticospinal tract)
– Decussation of pyramids
2) Somatosensory pathways (ascending)من الجسم للعقل وزي ما حكينا بتمر من ورا
من نفس المكونات )
* Nucleus gracilis (medial)& cuneatus (lateral)
* Fasciculus gracilis & cuneatus
(*as we go above the nuclei be more dominant)
3) Cranial nerve nuclei اعصاب نن العقل للوجه
* Spinal tract & nucleus of trigeminal nerve→🔺5 Glu
most important sensory nuclei in brain
stem( as a continuation of substantial
gelatinosa{same location})
* Start from upper cervical region up to mid of
pons)
Internal Structures of Medulla
- Level of internal arcuate fibers
(closed part)
نفس الي فوق بس زاد تشابك من ورا
arcuate: compose the gracile and cuneate
1) Somatosensory pathways
* Fasciculus gracilis & cuneatus (axons of 1st order neuron)
* Nucleus gracilis & cuneatus (cell body of the 2nd order neuron)
** Internal arcuate fibers (ascending tract)
– Decussation ( medial lemnisci)*
2) Motor pathways
* Pyramids
3) Cranial nerve nuclei
* Spinal tract & nucleus of trigeminal nerve
Level of olivary nucleus (open part)
(* lowest part of rhomboid fossa)
https://biologydictionary.net/wp-content/uploads/2020/07/Nerves-in-Brain-Stem-optimized.jpg
1) Cranial nerve nuclei زي لما شفناها بالصورة كانو طالعين نن قدام
* Hypoglossal nucleus 12
* Dorsal vagal nucleus 10
* Vestibular nuclei (most lateral part of rhomboid fossa) 8
Nucleus of tractus solitarius
* Spinal tract & nucleus of trigeminal nerve
2) Motor pathways لانه جاي من قدام رح يوخد اسمه وكمان اسم بمر من قدام
* Pyramid
* Olivary nucleus (→ open part)
* Inferior cerebellar peduncle
3) Somatosensory pathways
* Medial lemniscus (*2nd order neuron go to
thalamus which have 3rd order neuron,
and start to separate )
Internal Structures of the Pons
* Caudal part
1) Cranial nerve nuclei (motor)
* Nucleus of abducent nerve 6
* Motor nucleus of facial nerve 7
(facial colliculus الوجه معبا كرات→ axon of facial nerve in rhomboid fossa)
* trigeminal 5
2) Motor pathway (* corticospinal tract)
(* the bulge part of pons contain more than one part)
* Middle cerebral peduncle
3) Somatosensory pathways
* Medial lemniscus (* go more laterally)
*target of sensory fiber → Thalamus
لانه تكملة الاغصلب هي 6،7
Internal Structures of the Pons
* Cranial part
1) Cranial nerve nuclei
* Motor nucleus of trigeminal nerve
* Main sensory nucleus of trigeminal
(continue of spinal trigeminal nuclei)
2) Motor pathways
* Middle & superior cerebellar peduncles
* Pontine nuclei بوتين زي البونس من فوق
* Corticospinal fibers
3) Somatosensory pathways
* Medial lemniscus (more lateral)
بشكل صريح رح بكون العصب 5 هون
Internal Structures of the Midbrain
* Level of inferior colliculi
1) Cranial nerve nuclei
* Nucleus of trochlear ترو 4nerve (general somatic efferent)
* Mesencephalic nucleus of trigeminal nerve رح مص ام العصب من فوق كمان
2) Motor pathways
* Inferior colliculi
* Decussation of superior cerebellar peduncles بعملوا شبكه مع اخته الي فوق النايمة
* Substantia nigra (motor nucleus) كورة النيجره من تحت
* Crus cerebri (peduncle)
* (interpeduncular fossa) البيدنكل بتوخد راحتها تحت وبتحفر عادي
3) Somatosensory pathways
* Medial lemniscus (* more lateral)
(*central aqueduct between tectum and tegmentum) في مربع كمان بالكورة من تحت
*cerebellum act on same area of body
Internal Structures of the Midbrain
* Level of the superior colliculi
1) Cranial nerve nuclei
* Nucleus of oculomotor nerve 3
2) Motor pathways
* Superior colliculi
* Red nucleus الدماغواحمرمن فوق
* Substantia nigra نيجرة الكورة
* Crus cerebri
3) Somatosensory pathways
* Medial lemniscus (* more lateral)
(*note the mammillary bodies →hypothalamus ) الكورة من فوق ام بتكون
1-2 →
3-4 →
5-6-7 →
8-9-10-11-12 →
cerebrum
midbrain
pons
medulla
Blood Supply to Brainstem
- Blood supply to BS is from posterior circulation
1> Vertebral a.
– Anterior spinal a.
– PICA
2> Basillar a.
– AICA
– Paramedian branches
– Circumferential branches- Short & long
– SCA
– PCA
- Short & long
The upper part is more forward than lower part
Blood Supply Medulla
- Anterior spinal a. → *most medial part (pyramid + medial lemniscus + hypoglossal nucleus + …)
- Vertebral a. →* lateral
- PICA → * posterolateral
Medial medullary syndrome
* Anterior spinal a.
Lateral medullary (Wallen
Blood Supply: Pons
$$Caudal pons
– Basilar a. * midline
* Paramedian
* Circumferential
– AICA *posterolateral
$$ Rostral pons
– Basilar a.
* Paramedian
* Circumferential
– SCA *upper posterior part
Blood Supply: Midbrain
- Paramedian branches (Basilar a.) *midline
- PCA *some posterior part,
– Quadrigeminal - SCA *posterior
Reticular Formation
Scattered nuclei in medulla, pons & midbrain
1) Lateral one third have small cells (parvocellular)
– Receive sensory inputs and cortical inputs
2) Medial two thirds have large cells
(magnocellular) (*largest neurons in CNS)
– Output to spinal cord, brainstem nuclei, thalamus, hypothalamus & cerebral cortex
Reticular Formation Functions
- The reticular formation modulates (excite or inhibit) the activities of:
1) Sensory systems – e.g. pain
2) Motor systems – e.g. muscle tone, segmental reflexes, eye movements
3) Autonomic systems – e.g. respiration, blood pressure, cardiac function
4) Consciousness – e.g. vital centers in the brainstem, awareness, attention & arousal
Organization of Reticular Formation
three longitudinal columns
– Midline raphe group
– Parasagittal medial zone (* largest cells)
– Parasagittal lateral zone (* small cells)
*receive information from all over the body
