Full transcript
0:00Hello everyone , girls and boys , how are
0:02you ? I hope you are doing very well . My
0:06name is María Paula , I belong to the
0:08Museum of Morphological Sciences of the
0:10Normal Anatomy Department of the
0:12Faculty of Medical Sciences of the UNR ,
0:14and we are going to start talking about
0:16the digestive tract . In this case , we
0:19are going to talk about the oral cavity
0:21. Yes ? Let's start by defining the
0:25mouth as an irregular cavity that
0:27constitutes the first segment of the
0:30digestive tract . What do we mean by
0:33this ? The mouth is where the digestion
0:37and absorption process begins ,
0:39especially when talking about the
0:42digestion of food . In addition , it has
0:46important functions such as the sense
0:49of taste . It is the place where we
0:52perceive gustatory sensations and
0:56phonation and articulation of sounds
0:59are also important . Okay , well , we are
1:04going to divide the mouth or oral
1:07cavity into two very important parts .
1:11On the one hand , we have the vestibule .
1:12Yes , the vestibule , which is this
1:15region that was painted in orange , okay
1:19? Which has this horseshoe shape ,
1:21semicircular shape . And on the other
1:25hand , the oral cavity itself , which is
1:27what is shown in the image in red . Both
1:31portions of the oral cavity are
1:33separated by the gingival arches . Yes ?
1:37It is also important to note that
1:40despite this boundary , both the
1:43vestibule and the oral cavity are going
1:47to communicate with each other through
1:50the interdental spaces and mainly
1:53behind the last molar where both
1:56cavities open . Let's now look in a
2:00little more detail at these two
2:03portions , the boundaries of each of
2:14these portions . On the one hand , we
2:17have the vestibule , right ? which is
2:19going to have an anterolateral boundary
2:22formed by the labial and jugal mucosa
2:25and a posterolateral boundary formed by
2:28the gingival arches . Here we have two
2:31images , two different images , an
2:34anterior view and a frontal view of the
2:37vestibule and a lateral view of a
2:39sagittal section of the head . Yes , I am
2:43looking from the medial side . Now , look
2:46, then , we say that the vestibule is
2:49limited by the labial and jugal mucosa ,
2:52right ? To the front and to the sides ,
2:56right ? And behind by the gingival
2:59arches . So , if I go to this image , I
3:03will see the vestibule painted here .
3:05This is the vestibule . We can call the
3:08vestibule a virtual cavity . Right ? What
3:11does that mean ? That at rest this
3:13cavity is closed . Yes , it is almost
3:16obliterated and in order to see it
3:18properly we are going to have to do
3:21this , right ? Open the lips and the
3:24jugal mucosa well . Well , on the other
3:28hand we are going to see the limits of
3:31the oral cavity itself . Here we have an
3:34image , uh , also a sagittal section that
3:37includes the head and neck and I am
3:40seeing it from the side . Yes , I am
3:42seeing the medial face . Now , the
3:45anterolateral limit of the vocal cavity
3:47itself , which is what separates it from
3:50the vestibule , is going to be the
3:52inginal arches that communicate it with
3:54it forwards . The posterior limit is the
3:57fausceal arch , right ? Which is an
3:59orifice that is limited by several
4:01structures that we will see better and
4:03that communicates backwards with the
4:05oropharynx . The upper limit or roof is
4:10formed by the hard palate or bony
4:13palate , which is this structure that we
4:16see here , which communicates upwards
4:19with the nasal cavities , and the lower
4:22limit or floor is formed by a muscle
4:25group that we will see better . Okay ,
4:29looking at each of the limits , we are
4:30going to see on the one hand the
4:31anterior limit and the posterior limit .
4:34We say then that the anterior limit is
4:36the gingivae-dental arches , right ?
4:38Which are going to be marked by an
4:41upper innoventrial arch and a lower
4:44gingivae-dental arch . If we look at it
4:46from the side , like the previous image ,
4:49here we had the vestibule , here we see
4:51the arcade and this limit backwards .
4:53All this , all the rest of the mouth
4:55corresponds to the oral cavity itself .
4:59The posterior limit is going to be the
5:01fausceal arch . As we said , it is an
5:03orifice delimited by several structures
5:06that connect it to the oropharynx . This
5:10is delimited upwards by the free edge
5:13of the soft palate , laterally by the
5:17pillars of the soft palate and the
5:20tonsil . Yes . And inferiorly by the base
5:24of the tongue . Yes . It is an orifice
5:27that is completely open towards the
5:30back . Okay , talking a little about what
5:35the upper limit of the oral cavity or
5:38roof is , we are going to find the
5:40palatine cavity . Let's clarify first
5:43that the palate has two different
5:46portions , a bony portion and the soft
5:49palate , which forms the roof of the
5:51oral cavity , is going to be the bony
5:54portion , the bony palate . Here we see
5:57it in an image , the same image that we
5:59had in this sagittal section . We see
6:01the bony palate on one side and the
6:04soft palate on the other . Note that the
6:07bony palate is very horizontal . Yes .
6:11And it literally forms a partition
6:14between the oral cavity and the nasal
6:17cavity . And the soft palate is the one
6:21that hangs behind it . It is a more
6:26fibromuscular structure . Let's see how
6:31the palate is formed . We will see that
6:34it is formed on each side by two bones .
6:37On the one hand , the palatine bone ,
6:39which is the one we have painted in
6:41blue . Note that this is also a sagittal
6:44section of the skull . We are seeing the
6:48lateral surface of the nasal cavities
6:50and the oral cavity . This palatine bone
6:54gives me this apophysis called the
6:57horizontal physis , articulated forward
7:01with the maxillary bone , which is the
7:04one painted in pink , which gives me
7:08this apophysis , which is the palatine
7:11process of the maxillary bone . Well ,
7:15let's see now . Note , if I see an image
7:18of a skull from below and I focus on
7:20this part , I see the hard palate from
7:23its lower surface . We will see that on
7:27this surface we will find what is known
7:30as a cruciform suture . This cruciform
7:33suture is formed by an intermaxillary
7:36suture , which is the one that
7:39articulates both palatine processes of
7:41the upper jaw on each side ; an
7:44interpalatine suture , which is the one
7:47that articulates both horizontal
7:49processes of the palatine bone on each
7:52side ; and the horizontal suture , which
7:55is the maxillopalatine suture , which is
7:58the one that articulates both maxillae
8:01with both palatines . Yes ? Note that at
8:05the anterior end of this suture we will
8:08find this canal , which is the anterior
8:11palatine canal , through which the
8:14nasopalatine nerve passes . The
8:18nasopalatine nerve is an important
8:20branch of the trigeminal nerve , right ?
8:23of the maxillary branch of the
8:26trigeminal nerve that runs through the
8:29nasal cavities and enters this canal to
8:33exit to the roof of the oral cavity ,
8:36innervating the anterior portion of the
8:40palatine vault and the anterior
8:42alveolar arcades , right ? the upper and
8:46anterior part of this roof . Behind and
8:51on both sides , we have these other two
8:54small holes which are the posterior
8:57palatine canals through which the
8:59descending palatine artery passes . Yes ,
9:03one on each side . The descending
9:06palatine artery is a branch of the
9:09internal maxilla , so it is a
9:11bifurcation of the carotid artery ,
9:15which passes through these canals ,
9:18right ? And it is responsible for
9:20innervating the soft palate . Note that
9:22the artery comes from here , crosses the
9:26canals , irrigates , sorry , the soft
9:29palate , runs along the entire roof ,
9:32right ? Of the palate and crosses the
9:35canal to anastomose at this level with
9:39arteries that come from the nasal
9:42cavity . Okay , now let's see what the
9:47floor of the mouth is . Note that here
9:50we see , in an image of a mouth , how we
9:53can observe it when we raise the tongue
9:56and underneath this buccal mucosa , we
9:58are going to find the muscle group that
10:01forms it . Look , here we have a top view
10:04and a bottom view of these muscles , and
10:07we're going to have an important
10:09reference here , which is the iodine
10:12bone . The iodine bone is an
10:15odd-numbered bone and a half . It's the
10:18only bone in the entire human body that
10:20doesn't articulate with any other , but
10:23it's a very important bone , especially
10:25for the insertion of muscles that form
10:28important structures in the entire
10:30skull , the mandible , and the pharynx .
10:33Right ? Okay , let's see then that this
10:36floor of the mouth is formed by the
10:39genioid muscle in the upper part , which
10:41is the one that was drawn here . There's
10:44one on each side . As its name suggests ,
10:47the genioid muscle goes from the
10:49genioid processes of the horizontal
10:53ramus of the mandible . Yes . It goes
10:57backward to insert into the anterior
10:59surface of the body of this iodine bone
11:02. Yes . On the other hand , we have the
11:06myloid muscle , which we see here both
11:09on the upper and lower surfaces , let's
11:12say , below the genioid muscle , which is
11:16a flattened muscle , right ? In a
11:18triangular shape , it is inserted in the
11:22anterior part , in the myloid line of
11:24the horizontal ramus of the mandible
11:27and its fibers are directed backward to
11:30insert into the ossioid bone . And if we
11:35look from the lower surface , we will
11:38find this muscle , which is the
11:40digastric muscle . Its name comes from
11:44the word " gastric " which has two
11:46muscular bodies , right ? Separated by a
11:50median raphe . The digastric muscle
11:54forms part of its anterior portion ,
11:56mostly of the floor of the mouth , but
11:58mostly as a reinforcement . Right ? In
12:02this case , the raphe is also inserted
12:04into the ossioid bone and in the
12:06anterior portion it is also inserted
12:09into what is the lower surface or the
12:11lower border of the mandible . Right ?
12:15The conclusion I want to reach from all
12:17this is that the main muscle of the
12:19floor of the mouth is the myloid . This
12:22is the most important muscle , the one
12:23that plays an important role in mouth
12:28movement . I also want to highlight some
12:33important relationships that the floor
12:36of the mouth has , mainly with the
12:38submandibular gland , which is the one
12:40we see here . We see how the myloid
12:44forms a partition for this gland
12:47through which a small portion of the
12:50upper surface of this gland is
12:53suspended . Yes , let's remember that the
12:56maxillary gland releases its secretions
12:58through this duct , which is Warton's
13:01duct . Yes , it also has a relationship
13:03with the upper surface of the floor of
13:05the mouth . And on the other hand , on
13:08the upper surface of the floor we also
13:10find this other small gland , which is
13:12the sublingual gland , the other
13:14salivary gland that releases its
13:16secretions at this level of the floor
13:18of the mouth . So , look , on the upper
13:21surface through these small salivary
13:25ducts . Okay , let's now take a look at
13:30the contents of the oral cavity . We're
13:33talking about the different structures
13:36inside the oral cavity . We have the
13:38tongue , the soft palate , which is the
13:41other part of the palate that we need
13:43to look at . We have the gingival arches
13:47to characterize them a little better ,
13:50and we have the tonsils . In this video ,
13:53we're going to talk about the last two ,
13:55and we're going to look at the first
13:57two in separate videos . Okay ? Okay ,
14:01let's talk a little about the gingival
14:03arches . There are two gingival arches .
14:07We have an upper arch , which is formed
14:10by the lower edge of the maxillary bone
14:13. The upper one , obviously , and the
14:17lower gingival arch , which is formed by
14:20the upper edge of the horizontal ramus
14:24of the mandible . Yes , we're going to
14:27see that in these bones , what we have
14:30are several alveolar canals , or pardon
14:33me , alveolar grooves , into which the
14:36teeth are inserted . Yes , each one of
14:39the teeth . Let's see that these
14:42allelular grooves differ in that the
14:46incisors and canines , which have a
14:50single root , and the premolars and
14:53molars , which have several roots , will
14:56have several holes for their insertion .
15:01Let's talk a little bit now about the
15:03structure of the tooth . Let's see that
15:06morphologically , the tooth is formed by
15:09three portions . The upper part , the
15:12crown , which is the visible part , is
15:14what we see when we open our mouth . The
15:18neck , which is the narrowed part of the
15:21tooth , which joins it to the last
15:24portion , the lower portion , which is
15:27the root , which is the one in charge of
15:30articulating with the dental arches of
15:33the upper jaw and mandibular bones
15:36respectively . The structure of the
15:40tooth is formed by a tissue known as
15:44dentin . And its upper part is covered
15:48by a tissue known as enamel , right ? And
15:52its lower part , in the root part , is
15:56covered by cementum . Yes , in any case ,
15:59you will see these structures a little
16:01better in histology . Yes . What I want
16:04to highlight is that , in the central
16:07portion , inside each tooth , we will
16:09have this tissue that is known as the
16:12pulp of the tooth ; a soft , reddish
16:15tissue that contains the tooth's own
16:17vessels and nerves , as we see in this
16:20image , and that opens , uh , through what
16:23is called the allolar duct , to the
16:26allolar , and through which these
16:29vessels and nerves travel and reach the
16:32tooth . Okay , now we are going to see a
16:36little better , uh , the different types
16:39of teeth that we have . Look , here we
16:42have a small box in which we will see
16:45that we have medial , lateral , canine ,
16:48premolar , and inolar incisors . The
16:52medial incisors have the function of
16:55cutting . Yes , we will have four in
16:57adults and four in children . Let's
17:00remember , well , first of all , that
17:03children have temporary teeth , which
17:06begin to fall out around the age of 6 ,
17:10after which the permanent teeth begin
17:13to emerge . Right ? That's why there's a
17:16difference . Then we have the lateral
17:19incisors , which have a cutting function
17:22. Yes , just like the medial incisors .
17:25There are four in adults and four in
17:27children . Two lower and two upper . Then
17:31we have the canines , which have a
17:34function of tearing food . There are
17:37also four in adults , out of four in
17:39children , two lower and two upper . Then
17:43we have the premolars , which have a
17:46crushing function , of which there are
17:50eight in adults and none in children .
17:53There are no premolars . Temporary teeth
17:56do not have premolars . And here we see ,
18:00as we mentioned before , how premolars
18:03can have more than one root and
18:05therefore more than one orifice when
18:08breaking into the dental arches . And
18:12finally , we have the molars , which also
18:15have a function of crushing food . In
18:18adults , we can have up to 12 molars ,
18:21while children only have eight , four
18:25lower and four upper , whereas adults ,
18:29as we said , can have six lower and six
18:32upper . Why do we say they can have ?
18:38Because as we know , the third molar ,
18:40also known as wisdom teeth , may not
18:43emerge , and that is not an indicator of
18:45pathology . It depends on each person .
18:50Okay , so adults have a total of 32
18:55permanent teeth , while children have a
19:00total of 20 primary teeth . Okay ,
19:11finally , let's talk about the tonsils .
19:14Yes , let's remember that the tonsils ,
19:18as we saw in growth and development ,
19:21are lymphoid structures that are part
19:24of the immune system that defend us
19:28against any pathogen that enters our
19:31body . In this case , mainly through the
19:34mouth and also partly through the
19:36respiratory tract . Yes , we can see that
19:39the tonsils are two small structures
19:42located on each side of the dorsum .
19:45Here we see them , and I see them from
19:48the front with my mouth open , and here
19:50I see them from the side , right ? From a
19:53sagittal section of the head . And we
19:59will see that they are limited by two
20:01important structures towards the front .
20:04The anterior pillar of the soft palate ,
20:06this anterior pillar formed by the
20:09palatoglossus muscle , which is a muscle
20:13that , let's say , connects the soft
20:16palate with the tongue . Yes , it depends
20:19on both structures . And behind , the
20:22posterior pillar , which is formed by
20:25the palatopharyngeus muscle , right ?
20:28Which is part of both the soft palate
20:31and the muscles of the pharynx . In this
20:35way , we will be able to limit the
20:37tonsil to what we know as a tonsillar
20:40fossa , which has a triangular shape . It
20:43is a space , a region of the oral cavity
20:46, which has the soft palate as its
20:49upper vertex , with the pillars on both
20:51sides . And as the base of this triangle
20:54we have the tongue . Something I want
21:00you to keep in mind about the tonsil
21:02and the fosamidalin is the different
21:05relationships they will have , because
21:07we are going to see some important
21:10spaces , okay ? I want you to listen and
21:14see them . Note that we are going to
21:17have this image which is an axial
21:20section at the level of the second
21:23cervical vertebra in which we are going
21:26to have as a reference the pharyngeal
21:29wall , it is this one that we see here ,
21:33the tonsil which is this structure here
21:35. Note that this is going to be the
21:38oral cavity laterally and towards the
21:40back we are going to find the parotid
21:43gland . Yes . And between the
21:47latero-posterior wall of the pharynx
21:50and the parotid we are going to have
21:53this structure which is the styloid
21:56process . Do you remember the styloid
21:58process of the temporal bone ? Okay ,
22:01here we have the rows of muscles that
22:04insert into it , and these structures
22:07are going to delimit different spaces
22:10for me , along with these partitions
22:12that are the fascia of the neck . Yes ,
22:15that's okay . I want you to see that
22:19there is a peritonsillar space , right ?
22:22Which is the space that is inside the
22:25tonsillar fossa , which is not occupied
22:27by the tonsillar . That's right .
22:29Everything that surrounds the tonsillar
22:32, right ? Behind this pharyngeal wall ,
22:35and in front of the cervical vertebrae
22:39and the paravertebral muscles , we have
22:43this space that is the retropharyngeal
22:46space , and this styloid pituitary gland
22:50is going to delimit laterally what is
22:54the peramyganin space , a prestylar
22:57space and a space . Retrostylar , why am
23:00I mentioning these spaces ? Simply so
23:03that you keep in mind how important the
23:05relationships between the different
23:07structures may be . Note that the tonsil
23:10, as we said , is a defense organ that
23:12can become inflamed in the face of any
23:14injury or pathogen . So , if it becomes
23:17inflamed and generates a fairly serious
23:20inflammatory process in this region , in
23:23the peramygdal space , this , due to its
23:25contiguity , can affect the spaces
23:28around it . Retropharyngeal space ,
23:31affecting the cervical and
23:33paravertebral regions ; prestylar space ,
23:37affecting the parotid gland ; or it can
23:40also affect the retrostylar space ,
23:43which we see is occupied by very
23:47important structures such as the
23:50carotid artery , the jugular vein , and
23:53the chronal nerves 9 , 10 , 11 , and 12 ,
23:56and this , as you will see later , can
23:59give me very variable clinical symptoms
24:04. Yes , that is why it is sometimes
24:06important to take into account the
24:08relationships in anatomy , although
24:11sometimes it is a bit difficult . Well ,
24:14finally , I wanted to show you some real
24:17tonsils . Yes , these are normal tonsils .
24:21Look , here we have the soft palate with
24:23the ula , we have the anterior pillar ,
24:26here we have the midriff in basal
24:28conditions and from behind , look , here
24:30you can see the posterior pillar . You
24:33can only see this because of how the
24:35image was taken . Yes , let's see that
24:37these tonsils , as we said , can suffer
24:41from various injuries . Look at the size
24:44that the tonsils can get to . It is also
24:48a problem that these tonsils are this
24:50size . Look how the space through which
24:53air passes narrows . Yes ? And that
24:58happens recurrently throughout the year
25:01, yes ? What is known as recurrent
25:04tonsilitis . This usually happens in
25:07children . Note that this is an adult ,
25:11and we can see the soft palate with the
25:14uvula , the anterior pillar , the
25:16supermarket , and look here behind how
25:19the posterior pillar is born and the
25:22tonsil is not there . What does this
25:25mean ? That this person had a
25:27mydalectomy when he was a child . Why ?
25:30Because when this tonsillitis recurs ,
25:33there is a risk of air entering , right ?
25:36Through the airways . Well , guys , that
25:41was all . I hope this was helpful . Here
25:44is the contact information , our
25:46different networks , and the means by
25:48which you can contact us with any
25:51questions or queries . This is the
25:54biography that we use and until next
25:57time . Thank you very much .