🥇 7mo Par Craneal - NERVIO FACIAL 1/2 - (Origen, Trayecto y Relaciones)

Summary

Este vídeo educativo, presentado por Juan José Sánchez, explora el nervio craneal VII, el nervio facial. Se explica su origen real y aparente, destacando su naturaleza mixta con componentes motor y sensorio. Se describen sus núcleos: motor, sensorial para el gusto y parasimpáticos. Se detalla su recorrido intracraneo, incluyendo su complejo trayecto dentro del hueso temporal y su salida por el foramen mastoideo, culminando en la glándula parotida. La explicación detallada del nervio facial es crucial para comprender sus patologías comunes.

Takeaways

• 🧠 El vídeo trata sobre el nervio facial, también conocido como el séptimo nervio craneal, y se divide en dos partes: origen y ramificaciones.
• 📍 Se explica que el nervio facial tiene origen en varios núcleos, incluyendo motor, sensorial y parasimpáticos, y se relaciona con la parte más dorsal y inferior del pons.
• 🔗 El nervio facial es mixto, con componentes motores y sensoriales, y es uno de los cuatro nervios craneales con estructuras del sistema nervioso parasimpático.
• 🤓 El núcleo motor del nervio facial se encuentra en la parte más dorsal e inferior del pons y está organizado de manera craneocaudal, controlando los músculos de la cara.
• 🏞️ El nervio facial recorre un trayecto intrincado, incluyendo un giro característico conocido como la rodilla facial, antes de unirse con la rama intermedia.
• 🌐 El ganglio geniculado es un punto crucial donde se synapsan las fibras sensoriales gustativas, y es parte del nervio facial.
• 🧱 El nervio facial atraviesa el hueso temporal en un conducto conocido como el acueducto de Fallopio y se divide en tres segmentos: labiríntico, timpánico y vertical.
• 👂 Durante su recorrido, el nervio facial está en relación con estructuras auditivas como el tímpano y la ventana oval, y con el ganglio pterigopalatino y el ganglio submandibular.
• 💉 El nervio se encuentra en una posición superficial en ciertos puntos, lo que lo hace susceptible de lesiones y enfermedades, como el parálisis facial.
• 🌉 El último segmento del nervio facial dentro del hueso es vertical y termina en el forámino mastoides, antes de salir del cráneo.
• 📍 El nervio facial finalmente se divide en ramas dentro del glándula parotida, donde se encuentran sus últimas ramas antes de innervar los músculos faciales.

Q & A

¿Qué nervio craneal se discute en el video de anatomía?

Se discute el nervio craneal séptimo, también conocido como el nervio facial.

¿Cuál es la función principal del nervio facial?

El nervio facial es un nervio mixto que tiene una gran componente motor, para mover los músculos de la expresión facial, y también tiene una componente sensorial, incluyendo la percepción del gusto.

¿Cuál es la localización del núcleo motor del nervio facial?

El núcleo motor del nervio facial está situado en la parte más dorsal y inferior del pons, específicamente en la porción puente del mismo.

¿Cómo se organiza el núcleo motor del nervio facial con respecto a los músculos de la cara?

El núcleo motor del nervio facial está organizado de forma tal que la parte superior del núcleo controla los músculos de la mitad superior de la cara, mientras que la parte inferior del núcleo controla los músculos en la parte media y inferior de la cara.

¿Cuál es la relación anatómica entre el nervio facial y el nervio abducens?

El núcleo motor del nervio facial está situado anterior y medialmente al núcleo del nervio abducens, y ambos están relacionados en la parte posterior del cerebelo.

¿Cuál es el origen del componente sensorial del nervio facial?

El componente sensorial del nervio facial proviene de la porción superior del tracto solitario, que recibe las fibras del ganglio geniculado.

¿Qué es el ganglio geniculado y qué importancia tiene para el nervio facial?

El ganglio geniculado es donde se forma la sinapsis para las fibras gustativas que viajan a través del nervio facial, y es el primer neurona del camino gustativo.

¿Cuál es la ruta del nervio facial desde su origen hasta el punto donde sale del cráneo?

El nervio facial sale del cráneo a través del sulcus medullopontino, entre la medulla oblongata y el pons, y luego toma un camino intraosseo a través del hueso temporal hasta salir por el foramen mastoideo.

¿Cómo se divide la ruta intraossea del nervio facial?

La ruta intraossea del nervio facial se divide en tres segmentos principales: segmento labyrintino, segmento timpánico y segmento vertical.

¿En qué punto del tracto facial del nervio se forma el codo del nervio facial?

El codo del nervio facial se forma al final del segundo segmento del tracto, donde el nervio cambia de dirección de hacia atrás y hacia el lado a vertical.

¿Cuál es la importancia del nervio facial en la salud y las patologías del sistema craneal?

El nervio facial es muy importante en la salud ya que muchas patologías craneales, como la parálisis facial, están relacionadas con su compleja ruta y puede sufrir daños debido a la inflamación, fracturas óseas o crecimientos.

Outlines

00:00

🧠 Introducción al nervio craneal VII (Neuroanatomía del nervio facial)

El vídeo comienza con un saludo a los estudiantes de anatomía y una introducción al tema del día: el nervio craneal VII, también conocido como nervio facial. Se menciona que este vídeo es la primera de dos entregas sobre este nervio, enfocándose en sus orígenes y componentes. Se destaca la importancia de entender la anatomía del nervio facial, que incluye tanto componentes motores como sensores, y su relación con el sistema parasimpático. El presentador, Juan José Sánchez, utiliza un diagrama para explicar la relación del nervio facial con los demás nervios craneales y señala que el nervio facial está compuesto por dos partes: una porción motora y una porción sensitiva. Se describe la localización de los núcleos del nervio facial en la médula espinal y el cerebelo, destacando la organización de los núcleos motores y sensores.

05:08

🛤️ Viaje del nervio facial desde su origen real

En esta sección, se detalla el recorrido del nervio facial desde su origen real, que es donde se ubican los núcleos neuronales. Se explica que el nervio facial es un nervio mixto, con una gran componente motor y una gran componente sensorial. Se describen los tres grupos nucleares del nervio facial: motor, sensorial y parasimpático. Se enfatiza la importancia del núcleo motor del nervio facial, que se encuentra en la parte más dorsal y inferior del puente del cerebelo. Además, se describe cómo el nervio facial se curva alrededor del núcleo del VI par, formando el colículo facial en el suelo del cuarto ventrículo. Se menciona la fusión de los dos plexos del nervio facial: el motor rojo y el sensible azul.

10:08

🌐 Núcleo sensorial y parasimpático del nervio facial

Aquí se discute el núcleo sensorial del nervio facial, que se encuentra en la tercera parte superior del tracto solitario y es responsable de la sensibilidad del gusto. Se explica cómo los纤维 del ganglio geniculado entran en la médula a través del nervio facial y terminan su síntesis en el nivel de esa porción superior del tracto solitario. Además, se menciona la relación del núcleo motor del nervio facial con el córtex motor, a través de las fibras corticonucleares. Se describen los núcleos parasimpáticos, como el núcleo lacrimal y el núcleo salivario superior, y su papel en el control de las glándulas salivales y la glándula lacrimal a través de fibras preganglionares.

15:14

🚦 Origen aparente y trayectoria del nervio facial

En este apartado, se describe el origen aparente del nervio facial, que es el punto donde el nervio se puede observar por primera vez saliendo del cerebro. Se menciona que el nervio facial se origina en el sulcus medullopontino, entre la medulla oblongata y el puente. Se detalla la ruta del nervio facial, que se divide en dos grandes momentos: la trayectoria intraosósea y la extraosósea. Se explica que el nervio facial entra en la porción pétrea del hueso temporal y realiza una tubería, lo que puede resultar en múltiples puntos de compresión y lesiones, explicando la alta incidencia de patologías en el nervio facial.

20:15

🏞️ Trayectoria intraosósea del nervio facial

Se describe la trayectoria intraosósea del nervio facial, que comienza en la fosa craneal posterior y continúa hacia adelante, arriba y un poco hacia el lado. Se menciona que el nervio facial siempre está por encima del nervio cochleo-vestibular y se acerca al canal auditivo interno. Se detalla cómo el nervio facial se une al nervio intermedio en el 'rodilla' del conducto facial, formando el ganglio geniculado. Se describen los tres segmentos principales del conducto facial: laberíntico, timpánico y vertical. Se enfatiza la importancia de la 'rodilla' y la 'codo' del nervio facial en la comprensión de su ruta.

25:15

🏥 Trayectoria extraosósea del nervio facial y consideraciones clínicas

Por último, se describe la trayectoria extraosósea del nervio facial, que se divide en dos segmentos: supraglandular y intraparotidiano. Se menciona que el nervio facial perfora la glándula parotida y se relaciona con ciertos músculos del cuello. Se destaca la importancia de la ruta final del nervio facial dentro de la glándula parotida, donde se divide en sus ramas terminales. Se enfatiza la necesidad de cuidado durante las operaciones parotidectomías para evitar daños en el nervio facial, que podrían provocar síntomas en los músculos faciales.

Keywords

💡Nervio craneal

Los nervios craneales son los que surgen directamente del cerebro o medula espinal y se dirigen hacia diferentes partes del cuerpo. En el vídeo, el nervio craneal número siete, el nervio facial, es el foco principal, y se discute su origen, trayectoria y ramificaciones.

💡Núcleos

Los núcleos son grupos de neuronas en el cerebro que tienen una función específica. En el vídeo, se mencionan los núcleos del nervio facial, incluyendo el núcleo motor, el núcleo sensorial y los núcleos parasimpáticos, que son esenciales para el entendimiento de sus funciones.

💡Nervio facial

El nervio facial es un nervio craneal mixto que controla la expresión facial, la secreción lacrimal y salivar, y la sensibilidad del gusto en la parte anterior de la lengua. El vídeo ofrece una descripción detallada de su origen y trayectoria.

💡Ganglio geniculado

El ganglio geniculado es un ganglio del nervio facial donde se originan las fibras sensoriales gustativas. En el vídeo, se destaca su importancia como punto de conexión entre las fibras sensoriales y el núcleo sensorial del nervio facial.

💡Raíz motora

La raíz motora del nervio facial es la parte que se origina del núcleo motor y se encarga de la innvación de los músculos faciales. Se menciona en el vídeo como una de las dos raíces que componen el nervio facial.

💡Raíz sensitiva

La raíz sensitiva es la parte del nervio facial que se origina del núcleo sensorial y se encarga de la sensibilidad facial y del gusto. En el vídeo, se describe su unión con la raíz motora en el ganglio geniculado.

💡Vía intraossea

La vía intraossea del nervio facial se refiere a la ruta que sigue dentro del hueso temporal, incluyendo el conducto facial o aqueducto de Fallopio. Es una parte complicada de su trayectoria, como se describe en el vídeo.

💡Colículo facial

El colículo facial es una elevación en el suelo de la cuarta ventrícula que se forma debido a la curvatura del nervio facial. Se menciona en el vídeo como un punto de referencia anatómico importante.

💡Rama del nervio facial

Las ramas del nervio facial son las divisiones finales que se dirigen a diferentes destinos, como los músculos faciales y las glándulas. Aunque en el primer vídeo se centra en su origen y trayectoria, las ramas se explorarán en detalle en una segunda entrega.

💡Glandula parotida

La glandula parotida es una de las glándulas salivales mayores y el nervio facial la cruza en su camino extracraneal. En el vídeo, se menciona cómo el nervio facial perfora la glandula parotida antes de dividirse en sus ramas terminales.

Highlights

Introducción a un nuevo vídeo sobre el nervio craneal VII, el nervio facial.

Explicación de los dos orígenes del nervio facial: nuclear y aparente.

El nervio facial es mixto y tiene componentes motor y sensorial.

Mención de que el nervio facial es uno de los cuatro nervios craneales con estructuras del sistema nervioso parasimpático.

Ubicación del núcleo motor del nervio facial en la parte más dorsal y inferior del pons.

Relación espacial del núcleo motor del nervio facial con el núcleo del nervio abducens.

Organización craneocaudal de las neuronas del núcleo motor del nervio facial.

Curva característica del nervio facial que rodea el núcleo del nervio abducens.

Formación del colículo facial debido a la curva del nervio facial.

Descripción de las dos ramas del nervio facial: la rama roja motora y la rama azul sensible.

Ubicación del núcleo sensorial del nervio facial en la porción superior del tracto solitario.

Importancia del núcleo sensorial del nervio facial en la percepción del gusto.

Conexión del núcleo motor del nervio facial con el córtex motor a través de fibras corticonucleares.

Descripción de los núcleos parasimpáticos del nervio facial: núcleo lacrimal y núcleo salivario superior.

Ubicación del origen aparente del nervio facial en el sulcus medullopontino.

Descripción de la ruta intraossea del nervio facial y su relación con la arteria cerebelosa anterior inferior.

Importancia de la vía intraossea del nervio facial en la理解 de las patologías faciales.

Descripción de los tres segmentos mayores del conducto facial: segmento labyrintino, segmento timpánico y segmento vertical.

Relación del nervio facial con la cavidad timpánica y la cavidad del estapedio en el segundo segmento del conducto facial.

Formación del codo del conducto facial y su relación con el músculo estapedio.

Descripción del tercer segmento vertical del conducto facial y su relación con la arteria estilomastoidea.

Ubicación del nervio facial en la glándula parotida y su importancia en la cirugía parotidectomía.

Conclusión del primer vídeo sobre el nervio facial y anticipación del siguiente vídeo sobre sus ramas.

Transcripts

Hello, hello my dear anatomy students, how are you? Welcome to a new

anatomical video on this channel easy anatomy by Juan José Sánchez. Today I bring you the delivery,

the first delivery of two in total of the seventh cranial nerve, we will then talk about the very famous

facial nerve, in this first delivery we will talk about what its real origins are, which we are going to see

are several nuclei, we are going to see which one is their journey and their relationships; In the second

installment, which I invite you to see once and for all, we will address the branches and only the distribution of

this facial nerve. So well, the diagram that I am used to showing you in

these cranial nerve videos is the diagram of all the cranial nerves, this would be the seventh

cranial nerve, the facial nerve that will be made up of two phyletics, okay? See that I put

the arrow between the two so that you understand that the two make up the facial nerve itself, so

well, let's start first by talking about the real origin, reminding you that the real origin is

where the beginnings, the nuclei, the neuronal bodies are. Let's say it is the center

that commands the nerve, either a motor nucleus that gives the order to the nerve what to

do or a sensitive nucleus where the nerve fibers are reaching to give it some

information about some sensitivity that it collected. peripherally, in the case of the facial nerve

it is a mixed nerve, that is, it has a large motor component but it also has a large

sensory component and apart from that it is one of the four cranial nerves that has

structures of the parasympathetic nervous system as its nuclei, reminding them that there are four nerves in the

parasympathetic nervous system; It is the third cranial nerve, the seventh, the ninth and the tenth,

it does not mean that in some other nerves such as the trigeminal nerve there is no

autonomous information, let's say, they just do not have an autonomous nucleus, those that have autonomous nuclei

are these. only the third, the seventh, the ninth and the tenth, then we are going to see what

the real origin of the facial nerve is, we are going to see that it has three nuclear groups, first the motor nucleus,

then the sensitive sensory nucleus because we are going to see that it has quite importance in taste

and parasympathetic nuclei that correspond to the autonomic nervous system. We start with the

motor nucleus of the facial, which you will almost always read in books as the nucleus of the facial, okay? This

is the one that is the most well-known, most named nucleus of the facial, when you see that they say

facial nucleus they are probably referring to this motor nucleus that you see that the Netter

puts it on the right side of a posterior view of the brain stem , then this motor nucleus of the

facial is specifically located in the most dorsal and inferior part of the pons, okay? in the

bridge part, then it will be found medial, okay? something ventral to the nucleus of the sixth cranial nerve which

is the nucleus of the abducens nerve, what happens is that since here we are seeing it from posterior we cannot

see how the east one is more anterior, remember that this is a posterior view,

that is, this is further away, further forward and this nucleus that

leads it is a little further back, now in a lateral view you will see it better,

but well, once and for all I tell you that this nucleus of the facial is related to the nucleus of

the abducens because that of the facial is anterior to that of the abducens, with respect to the sensory nuclei

we are going to see what it is located, he spoke of the motor nucleus of the facial, it is located within medial,

that is, anterior and medial to the main nucleus of the trigeminal and to the spinal trigeminal tract,

if we see it from the side we are going to see it now you are going to notice this relationship as this nucleus is seen to be

a little more anterior and a little more medial with respect to these sensory nuclei of the trigeminal,

we are going to also notice that the neurons of the motor nucleus of the facial are organized

cranial caudally. What do I mean by this? that the most rostral, most superior position of the

motor nucleus is the one responsible for moving the muscles of the upper half of the face, while the

lower half of the motor nucleus of the facial is the one responsible for moving the muscles in the

middle bottom of the face, everything very organized, if we see it from the sides, look there, there you can see

the motor nucleus of the facial, this would be that of the abducens, so notice how the facial

I told you this previous with respect to that of the abducens, in this image we can see it and we also see

there more lateralized to the main nucleus of the trigeminal and the spinal trigeminal tract ,

that is why I told you that the motor nucleus of the facial is medial with respect to these

sensory nuclei of the trigeminal nerve. We are going to see that it immediately makes a shortening, a very particular curvature

because the motor nucleus of the facial instead of the fiber coming out forward, it comes out

backwards, that first branch that comes out backwards is called the posteromedial branch or they also

call it medial root branch, this branch, see that it goes backwards a little to the side

to surround the abducens nucleus, when it surrounds the abducens nucleus it makes an elevation in the

floor of the fourth ventricle, which is what we know as the facial colliculus, which is why We know that

the facial colliculus is formed by the curvature that this facial nerve makes here and by this it also

helps to protrude the nucleus of the abducens itself a little, okay? but see that it is closely related

to the floor of the fourth ventricle and after it makes the kinking that surrounds them, it heads

forward, that is why this branch, when it heads forward, is called the

lateral or anterolateral root branch, so This would be the medial or posteromedial and this would be the

anterolateral or lateral because it already goes towards anterior, so finally you see that they emerge,

and then he explained to you what the apparent origin is, but see how the facial nerve

is made up of two rootlets. : the red motor and the sensitive one that will be explained

in what follows, which is the blue one. We are going to talk now about the sensitive sensory nuclei, but

first do not go away from the video [Music] subscribe to the channel below where you see that

it says subscribe, click on it and you are subscribed to the more than 280 videos, do not forget to tell me from

What university are you watching me from, what country are you writing to me from and if there is a video that you can't

get, well, write to me in the comments that you always took them into account to know what

you need most. With respect to the sensitive sensory nucleus, we are going to see that it is

given by the solitary tract, it is said to be the most superior part or the most superior third of the

solitary tract. When we advance in the cranial nerves, we will see that the solitary tract

is a nucleus. which is the middle part, let's say the middle third, sensitive for the glossopharyngeus,

the lower third is sensitive for the vagus and this upper third is sensitive, so see for the

same facial nerve, then this upper part of the solitary tract is what we call the

sensory nucleus sensory of the facial nerve, just remember that this is a

nucleus that does not emit fibers, it is receiving the fibers that come from the geniculate ganglion,

so the geniculate ganglion, for example, brings gustatory type fibers that will bring the

chorda tympani nerve and well they enter the brainstem there through the facial nerve and

well there they see how the synapse ends up making the synapse at the level of that upper part of the solitary tract,

another thing that I forgot to tell you about with the motor nucleus of the facial, remember that the muscles it

innervates The facial muscles are the muscles of mimicry, muscles of facial expression

and we find this at will, so that there is communication at the level of the

motor cortex through cortico-nuclear fibers with this motor nucleus of the facial, because the

motor nucleus of the facial well tells the muscles of the face what to do but what commands it

is my will and my will is in the motor cortex that is located at the level of the brain,

so there are nuclear cortico fibers that are what we say govern this facial motor

nucleus ; So through the intermediate nerve we are going to see now that the facial

was made up of two nerves, remember I told you, one main and an intermediate nerve,

that intermediate nerve that was the little one is precisely the one that brings the sensory fibers

that end up arriving to this upper part of the solitary tract, here we can see it,

see how the sensitive part enters, penetrates like an intermediate nerve and inside

look for the solitary tract, do not confuse it with the spinal trigeminal tract, which is this one,

the solitary tract specifically is this nucleus of the solitary tract, it is somewhat posterior

and lateral with respect to the motor nucleus, see that the motor nucleus is more anterior and medial

However , this upper part of the solitary tract is a little more posterior and more lateral with

respect to this motor nucleus, of course with respect to the parasympathetic nuclei,

very important are the large parasympathetic nuclei, we are talking about the

superior salivary nucleus and we are talking about the lacrimal nucleus. ; This is going to contain the parasympathetic center, that is, from there

pre-ganglion fibers are born that you see are going to join the motor root to be able to reach

the structures where they want to reach, with respect to the superior salivary nucleus it is very, very ,

very close to the lower pole of the motor nucleus, see that it is located quite close, what it

will carry are pre-ganglion fibers that will search for the ganglia: the pterygopalatine ganglion

and the submandibular ganglion; ganglia that we already explained separately in the videos, here I am not going

to go into those ganglia too much but when you read those ganglia you will see then what these

preganglionic parasympathetic fibers are doing that this superior salivary nucleus is giving them, finally

from these ganglia, ok? From the submandibular, above all, the fibers come out that will innervate the

submandibular gland and the sublingual gland. Regarding the lacrimal nucleus, you will not see it

in the image because it is said that the lacrimal nucleus is corresponded to the lowest part of the

nucleus itself. superior salivary nucleus, that is, it is like a subdivision of the superior salivary nucleus and it

is located a little more medial to the motor nucleus, which is the one you see here. So finally

these fibers that come from the lacrimal nucleus go to look for the pterygopalatine ganglion. They are also

pre-ganglion parasympathetic fibers, they look for the pterygopalatine ganglion and through the

pterygopalatine ganglion they reach the lacrimal gland to stimulate the secretion of the gland,

this with respect to to the real origin; So, starting from the path of the facial nerve,

remember that it is a mixed nerve, as I told you at the beginning, it has a large

motor component and it has a large sensory component. What are the two roots that we are going to see

that make up the facial nerve? a slightly thick medial root that makes up the facial nerve

itself, which we call the facial nerve, and a slightly more lateral, smaller root

that we call the intermediate nerve. Both roots together make up the facial nerve;

What will be its apparent origin? Remember that the apparent origin is the place where

I apparently see that the nerve is originating, in the brain is where I begin to see it because those

fibers of the nucleus are inside the bridge, I cannot see them, so the apparent origin of the

facial nerve of both roots is at the level of the medullopontine sulcus, which is the sulcus that is between

the medulla oblongata or medulla oblongata and the pons, so see that its apparent origin

will be between the olive below and the inferior cerebellar peduncle above. Ok?, they are

the two structures that are very close to each other, medially is the abducens nerve which is the

sixth cranial nerve, the origin of the apparent abducens nerve, that is, this facial is

located lateral to the abducens and let's go Let's see that a little more anterolateral you will find the

vestibulo-cochlear nerve, which is the cranial nerve that follows in number, which is the eighth, see

that they are in order, fifth, sixth, seventh, which is facial, and the eighth, which is the cochlear vestibule,

seen from the side here we see the cochlear vestibule which is a little more posterior and lateral

and a little more anterior and medial we see here the facial nerve itself as such, here well we see

the inferior cerebellar peduncle, more or less down here and we see That's why they tell you that

it is between the inferior cerebellar peduncle and the olive, which we can see a little better here.

Very well, we are going to divide your journey into two big moments, let's say; an intrapetrous moment

that is the longest, this is a nerve that has a quite particular route, okay? about

all due to its intrapetrous path and an extrapetrous path, which is when it practically leaves

the skull and becomes exocranial. We are going to see this facial nerve, which is very studied because

it is a nerve that is very prone to pathology, it is very common in patients with paralysis. facial and

in parts the large number of pathologies that concern the facial nerve is precisely because of the

intricate route it has, you will see that the majority of the paracranial nerves

after they emerge almost immediately look for a hole to pass through, this

seventh cranial nerve It gets into the petrous portion of the temporal bone and makes a conduit,

a tunnel, then many places where it can be compressed, where it can be injured and that is why

the abundant pathologies that we see in the facial nerve. We are going to continue then and we are going to begin

with the intrapetrosal path, which is the path that occurs practically inside the skull,

so the intrapetrosal path begins first when it comes out, when it emerges and remember when

it emerges it is immediately in the posterior cranial fossa, okay? It is in the posterior cranial fossa,

it emerges there at the level of the subarachnoid space in the pontocerebellar cistern, when it comes out it is already

in the pontocerebellar cistern. What is he going to do? He's going to head forward, up and

somewhat to the side, okay? forward, upward and somewhat lateral, it will always be

above the vestibulo-cochlear nerve, and in the cochlear vestibule this would be the facial

and this would be the abducens, see that the facial is always above the vestibulo-cochlear nerve,

these two nerves have a close relationship because the two will finally look for the

internal auditory canal, the cochlear vestibule because well it comes from the ear and the facial because

it needs to go through the canal to be able to reach the exocranial part, we are going to see that also in

its Originating at the level of the posterior cranial fossa, the facial is crossed by the anterior

inferior cerebellar artery, which is this artery that you see here, it is called the anterior inferior cerebellar artery. What is it

going to be? finally it gets inside the internal auditory canal, let's see what happens

now inside the internal auditory canal, to locate it this is a posterior view,

all this is the posterior cranial fossa and more or less here the bridge rests, so see that

it immediately gets At this level of the bridge you are heading outwards looking for the entrance

to the internal auditory canal, which is in the petrous portion of the temporal bone, then once

you reach the vicinity of the opening of the internal auditory canal, both roots enter

what? I mean both roots? The main branch of the facial nerve enters and below you see that

the intermediate root enters, but they do not enter alone because through this internal auditory canal, as

I told you, the vestibulo-cochlear nerve also comes, which is the eighth cranial nerve and is accompanied by the artery.

labyrinthine, so that the four structures, I am talking about the two roots of the facial nerve, plus the

cochlear vestibule, plus the labyrinthine artery seek that internal auditory canal, at this

level each of the nerves separately is surrounded by a sheath of pious mother, it's like I

grabbed and surrounded each one, like they wrapped it and then the three together wrap it

again but the arachnoid, then in the pious mother it wraps each one separately

and then the arachnoid packs them together. all three together so that they can penetrate the

internal auditory canal practically as a unit, here we can see it, we see the facial, we see the

intermediate and here we see the cochlear vestibule, then he is going to penetrate the

internal auditory canal from medial to lateral , see almost that in a straight line this is all inside the

petrous portion of the temporal bone because remember that that is where the inner ear is located,

what is going to happen? In a short distance this is medial, this is lateral, see here

you can even see the stapes, it means that we are in the vicinity of the middle ear,

all of this is the inner ear and here well, here would be the entrance to the internal auditory canal, so

see how the cochlear vestibule has gotten involved and see how the facial nerve always accompanied it;

When it reaches the bottom of that entrance, the internal auditory canal separates,

okay? They separate, remember that they are all united by the arachnoid, here it is separated, the facial

only remains along with the intermediate nerve only as well and the cochlear vestibule remains only because here the

cochlear vestibule is when it is starting, ok? Now what is going to happen? He

goes to the bottom of the internal auditory canal to penetrate this canal, which is the canal that

makes it so intricate to study, which is the famous duct or canal of the facial nerve,

they also call it the fallopian aqueduct, it is the same, it is the same, So in this

facial canal there is only the facial nerve left along with the intermediate nerve, okay? both penetrate,

so this duct with the facial we are going to describe three large segments to be a little easier to study

: a first segment that we call labyrinthine that is horizontal that

comes from medial to lateral, see, from medial to lateral Where does it begin? this?

This first segment begins when the facial nerve together with the intermediate, remember

that it is always with the intermediate, it is not seen in the image but it is always accompanying me, then

it begins when the facial nerve with the intermediate enter through that facial canal until It makes this

sudden curvature that it makes from anterior to posterior, this sudden curvature that the

facial nerve makes is known as the facial knee, that's what it's called the knee, not the elbow, no,

the facial knee, I'm going to explain to you that the Elbow is something else but students really

confuse the elbow with the knee, okay? The first is the knee, where the first segment

of this facial canal ends ; So what are the relationships of that first segment of this

facial canal? Well, the facial nerve heads laterally in front, see that the

cochlea is located anterior to the cochlea and posteriorly is the vestibule, which are the two large

structures of the inner ear, so it goes between the cochlea and the vestibule continues heading

outwards. and at this level it is quite superficial so much so that the capital, the capital of

petrous bone of the temporal bone that is above is very minimal, that is why you are going to read that the Latarjet

tells you that it becomes thinner because in reality it becomes very very minimal, or Be it that it is very easy to excavate and

practically reach this facial nerve canal; then at the lateral end, as

I just told you, the knee of the facial canal is formed, this knee is important because in this

knee an event occurs that is the intermediate root joins the facial nerve and becomes one

, so see the entire route What did the intermediate root do to join the facial, finally

it is at the level of the knee, okay? There it works in both roots and the fusion of both roots, that is,

the main one of the facial nerve with that of the intermediate nerve, creates a ganglion that is the

geniculate ganglion, which is the ganglion, well imagine, it is the first neuron of the pathway gustatory, look

where the first neuron of the gustatory pathway is in the genicular ganglion, remember that it is

very important because the sensory part has to do with the genicular ganglion, okay? Then what is going to

happen? comes the second segment of that Fallopian aqueduct, the second segment goes from the

knee, which was where the first one was determined, to the elbow of the facial duct, so here it makes

the knee, it becomes posterior and in one area it makes another curvature to now go down

vertically, but we are going to first describe this second segment between the knee and the elbow,

well we are going to see that this segment goes backwards, somewhat to the lateral and we are going to

see that it is related medially, well, not medially Excuse me, it is related

laterally to the tympanic cavity in the middle ear because there I see the stapes that the stapes is

part of the middle ear, that is, the canal is in the medial wall of the tympanic cavity, it is

well placed in the image, It is in the medial wall of the tympanic cavity, see that it is

very superficial there, in fact right now I showed you an image from inside the tympanic surface so

that you can see how clearly that facial nerve conduit looks; let's see what medially it's going to

be applied to the vestibule, then lateral is the middle ear or tympanic cavity and medial

is the vestibule. Very well, this is a view from the side to the world that in fact

here I see the knee, here begins the second portion of this duct the second segment which

is the tympanic, see how it goes backwards and to the side as I have been telling you. and

then here you stand, what happens is that the image is lost but more or less here it bends again

and becomes an elbow, this knee then here becomes an elbow and here it becomes vertical to

finally emerge towards its extra cranial portion, But what I was telling you is that if I see the

tympanic cavity, which is exactly what I am seeing, and the medial wall of the tympanic cavity

stops internally, you will see that the facial nerve conduit is very noticeable. In fact, you will see that this second

segment is above this duct, which is the duct through which the tensor

tympani muscle passes, okay? This one that you see here and we are going to see what is above the oval window,

remember that the oval window is closed by the stapedium, that is, by the stapes; then see

how the canal is just above the oval window and what you see here

is the external semicircular canal or lateral semicircular canal, then notice that the

facial canal itself is anterior and is inferior to this lateral semicircular canal,

so Finally, the elbow is formed; the elbow is the one that ends in the second segment of the

facial canal to begin the third, then that elbow contours to the canal where this muscle is located,

which is the stapedius muscle, okay? The elbow contours to the canal where the

stapedius muscle is. Finally then it becomes vertical and begins, see here the knee was made,

second segment, third segment which is the vertical one from the elbow, then this third

segment which is the last of the facial canal is located between the elbow and the emergence through the

spinomastoid foramen, which is the hole where the facial finally comes out of the skull, so

this segment is vertical, see that it is a segment that pierces the thickness of the mastoid process,

it is located in front of all these cells that you see here, which are the mastoid cells

and always at this level the facial nerve is accompanied by the mastoid style artery so much that

when they emerge, both the mastoid style artery and the facial nerve emerge, the hole through

which it comes out is the mastoid style foramen, which is a hole that is at the base of the skull, see

here is the emergency that this hole is located lateral to the styloid process, okay?

lateral to the styloid process, it is the way to locate it inside the skull, so you see that

the intra petrosal portion is quite intricate, that is why I told you to imagine how it pierces

so much bone and has so much conduit inside the bone and makes curves, it is so easy that he has some

pathology in any part of his segments because it became inflamed, because the bone was fractured,

because the bone grew, that is, the facial nerve has many weak points, finally the

extra petrosal path to finish if it is shorter, we divide it in two large segments, a

large supra glandular segment in relation to the parotid gland, which we call its satellite gland because

it pierces the parotid gland and a segment already inside the parotid gland called the

intra parotid segment, starting with the supra glandular segment we will see that the nerve is first arranged

behind the parotid cell, then pierces the parotid cell because in the end what

it wants is to seek to pierce the parotid gland, at this moment it is related

to certain muscles of the neck, let's see which medial It has the styloid process left and it has

the hyoid style muscle, which is the same one that is cut here, it has the medial and lateral left,

the posterior belly of the digastric remains, of course here they drew the posterior belly of the

gastric far away but well, in theory they say that The posterior belly of the digastric, which is

this one, is lateral to the facial nerve. What will finally be seen is that the segment,

actually its preliminary is quite short, what it finally does is pierce the parotid gland.

where its final segment begins, which is the intraparotid, here it goes obliquely

downwards, forwards and to the side, it pierces the thickness of the parotid gland but we say

that it is so deep, it is said that it is a fairly superficial path in the parotid gland. gland,

in fact in operations where it is necessary to remove the parotid gland,

careful care must be taken not to damage the facial nerve because it makes a network, see that it makes a network

inside the parotid gland and that is why any parotid pathology already Whether infectious

or neoplastic, it causes so many symptoms in the facial muscles because I see that the

final branches of the facial nerve that speak to the facial muscles also cross the parotid,

so the intra-parotid path is actually quite short, 1.5 centimeters,

where its terminal branches divide. How good we will see it in the next video of the facial nerve and

here we can see it just entering the parotid cell, see how it perforates the parotid and well

inside the parotids is that it gives all the branches that you are going to study in the next video. This

was then the entire first installment of the facial nerve, it is one of the most studied nerves of

the cranial nerves due to the number of pathologies it has, do not forget to subscribe to the channel, I hope

you liked it, like the video if you liked it and you can Find me on Instagram at @juan_sanchez1315