Cranial Nerves (Part 1)- أ.د. عمرو حسن الحسني أستاذ المخ و الأعصاب

Cranial nerves I (olfactory), II (optic), and VIII (vestibulocochlear) are considered purely afferent. Cranial nerves III (oculomotor), IV (trochlear), VI (abducens), XI (spinal accessory), and XII (hypoglossal) are purely efferent. The remaining cranial nerves, V (trigeminal), VII (facial), IX (glossopharyngeal), and X (vagus), are functionally mixed (sensory and motor).[1]
Cranial nerve I (olfactory nerve)
Special visceral afferent bipolar sensory neurons reside in the olfactory mucosa, an area of approximately 2 to 4 cm^2 over the superior nasal concha and nasal septum). Here they organize into nerve bundles termed the filia olfactoria, which, together, comprise the olfactory nerve. They enter the cranium through the cribriform plate of the ethmoid bone to synapse in the olfactory bulb, which forms the anterior-most aspect of the olfactory tract at the inferior aspect of the frontal lobe, and which extends posteriorly between the orbital gyrus and the gyrus rectus until bifurcating at the olfactory trigone as the medial and lateral olfactory stria which terminate in higher-order cortex.[2] Some olfactory projections travel medially to the septal area and the contralateral bulb via the anterior commissure, while other fibers travel laterally to the amygdala and piriform cortex, also known as the primary olfactory cortex, where conscious odorant sense is processed.[3]
Cranial nerve II (optic nerve)
Cranial nerve II, the optic nerve, conveys special somatic afferent (SSA) visual sensory information from the rods and cones retinal sensory receptors to the thalamus, especially the lateral geniculate nucleus (LGN) and the superior colliculus (SC). Ganglion cells, whose cell bodies are located deep in the retina, have central projections that form the optic nerve fibers, which traverse the optic canal to enter the cranium. From there, fibers representing the medial visual fields travel posteriorly without crossing at the optic chiasm, while fibers of the lateral visual fields do cross within the chiasm. Therefore, regions of the visual field are retinotopically organized within the optic nerve and at their synapses in the LGN. Collaterals are also given off centrally to innervate the SC, responsible for the pupillary light reflex, and connections within the pulvinar of the thalamus, providing unconscious optic input responsible for the phenomenon of blindsight.[4] In cortically blind individuals, these pulvinar collaterals from the optic nerve allow for unconscious eye movements in response to the detection of light as well as a weak directional sense of the location of the light within the visual field.[5][6][7]
Cranial nerves III, IV, and VI (oculomotor, trochlear, and abducens nerve)
Cranial nerves III, IV, and VI (oculomotor, trochlear, and abducens nerves, respectively) are general somatic efferent (GSE) nerves responsible for innervating the extraocular muscles within the orbit. These nerves travel ipsilaterally from the brainstem to the calvarium through the superior orbital fissure from synonymous brainstem nuclei. The oculomotor nerve (CN III) travels through the common tendinous ring, the common attachment in the posterior orbit for the four extraocular recti muscles, along with the abducens nerve (cranial nerve VI). The trochlear nerve (CN IV) travels into the orbit outside the common tendinous ring to innervate the superior oblique muscle of the eye. The abducens nerve innervates the lateral rectus muscles only; thereby, this nerve can be tested by evaluating the abduction of the eye gaze.
Cranial nerve III innervates most of the eye muscles by splitting into a superior and an inferior branch to innervate the remaining three recti muscles, the inferior oblique, and the skeletal muscle component of the levator palpebrae superioris. However, cranial nerve III also has a general visceral efferent (GVE) component originating in the Edinger-Westphal nucleus (also called accessory oculomotor nucleus or visceral oculomotor nucleus). These fibers travel with cranial nerve III to synapse in the ciliary ganglion within the orbit. The post-ganglionic sympathetic fibers of the ciliary ganglion pierce the sclera of the eye to innervate the pupillary sphincter and ciliary smooth muscles responsible for pupillary constriction and lens accommodation. Pupillary constriction can be tested using the pupillary light reflex through the efferents from the superior colliculus to the accessory oculomotor nucleus.[8]

[@Mohamed-xc3cf]

دكتور درجة فنان

[@amrhasanneuro]

متشكر جدا كلك ذوق🌹🌹

[@user-fl2mb4jb5f]

كل ثانيه وانت طيب يا مبدع❤❤❤❤❤❤❤

[@amrhasanneuro]

ربنا يخليك ويبارك فيك

[@amirsallam6360]

Ramadan Kareem ❤
Great content Doctor ❤

[@amrhasanneuro]

Thank you very much

[@user-fi7li2iw5v]

كل سنه وانت طيب يا دكتور رمضان كريم عليك ربنا يديك الصحه تقدم ان شاء الله يا دكتور

[@amrhasanneuro]

وحضرتك بخير وصحه وسعاده دايما

[@hossamsakr3995]

ربنا يجازيك كل خير يدكتور
كنا محتاجين استكمال محاضرات الماجستير
وياريت موضوع GBS و CIDP وال EPILEPSY

[@user-tb2kp4bc9x]

كان تكرار الحمام خت أدوية المثانه العصبية لمده 5شهور ماجيليش رغبة قوية في الحمام اروح من نفسي لقيت مياه كتير اعمل ايه

[@amrhasanneuro]

استشير استشاري مسالك بوليه

[@oyage.]

السلام عليكم يا دكتور أنا اقسم بالله تعبت نفسيا و جسديا من الدكاترة و المستشفيات كل شويه احاول اخش دكتور مخ و اعصاب بالتأمين ما اقدر أبدا و أنا حاليا في روسيا و عائق اللغة متعبني و حالتي المرضية أتوقع انها adhd تشتت مفرط و تأخر بالإدراك و سرحان و خمول و كسل و تسويف و حياتي دراسة و شغل و أشياء كثير ضغط ف ضغط و أنا مو لاحق اسوي حاجة كل شي فوق راسي و مقصر مع كل حاجة و وضعي مره صعب و كرهت موضوع الدكاترة يا دكتور أنا عاوز احسن من إدراكي و تركيزي و نشاطي و تواصلي مع الناس و التزامي بالرياضة و الروتين الاكل الصحي و الدش البارد لكن كله مخربط و معقد عاوز حل بدون ما اروح دكتور اقدر اخذ علاج كويس بدون وصفة طبية يا دكتور بالله عليك يمكن أجربة و يكون تمام أنا أكبر اخواني و لازم انجح في شغلي و دراستي لكن التفكير فل عندي بس بدون اي حركة

[@abuhamzayahya6901]

الدحيح مش بيفقس كتب ؛ بيفقس معلومات 😂😂