Mandible and Teeth

00:01 Now let's talk about the mandible and the teeth.

00:05 The anterior portion of the mandible is called the body.

00:10 Then the more vertically oriented portion is called the ramus.

00:14 And where the two meet is called the angle.

00:18 Superiorly, the ramus has a couple of processes.

00:22 We see posteriorly, there's a neck and a head, that together make up the condylar process, and more anteriorly, we have the coronoid process.

00:33 In between we have a notch called the mandibular notch.

00:37 On the body, we see there's a little hole or frame and called the mental foramen.

00:42 And mental in this sense actually refers to the chin.

00:47 And this is where we'll have the mental branch of cranial nerve V3 or the mandibular branch of the trigeminal nerve.

00:55 Again, if we zoom in, we see the base of the mandible here.

00:59 And we see the superior portion of it is what's called the alveolar part.

01:04 Alveolar in this context refers to the sockets of the tooth.

01:07 So alveolar tells you were talking about the teeth.

01:12 The bump most anteriorly is called the mental protuberance and again, in this case, mental means chin.

01:20 We also have another bump, a little more laterally called the mental tubercle which can serve as attachment points for muscles.

01:29 If we swing around to a posterior view, we can see some more bumps, here we see the pterygoid tuberosity.

01:37 And of course we have muscles of mastication or chewing that are called pterygoid muscles hence the name.

01:43 Again, we have a spine called the mental spine which is towards the chin, hence how it gets the name mental.

01:50 And we have an opening here called the mandibular foramen, which is the entrance to the mandibular canal.

01:56 And it's protected by a little piece of bone called the lingula.

02:01 We also have a little groove here called the mylohyoid line, On either side of the mylohyoid line, we have little depressions or fovea.

02:13 Superiorly, we had the sublingual fovea, and inferiorly, we have the submandibular fovea.

02:19 And these depressions are where we're going to find the sublingual and submandibular glands, respectively.

02:27 If we look at the mandible from above, from a superior point of view, we can see the teeth.

02:32 We see going from posterior to anterior, we have three molars, to premolars, one canine and two incisors on either side.

02:46 When it comes to the innervation of these lower teeth, at least, we're talking about the mandibular branch of the trigeminal nerve, or cranial nerve V3.

02:57 This is going to give a few branches.

03:00 One is going to be the lingual branch and as the name implies, it's going to supply the tongue.

03:05 Then the other branch is called the inferior alveolar branch.

03:10 And that's going to travel inside that mandibular foramen or mandibular canal to supply the lower teeth.

03:19 It's going to continue on through the mental foramen more anteriorly in the body of the mandible to become the mental branch.

03:29 Superiorly, we have the maxillary branch of trigeminal or cranial nerve V2.

03:36 Giving multiple superior alveolar branches: anterior, middle and posterior.

03:42 The mandible is essentially the only bone of the skull that actually moves since all of the other bones of the skull are held tightly together by sutures.

03:53 The mandible actually has a true synovial joint called the temporomandibular joint.

04:00 So here we see the coronoid process more anteriorly and more posterior really on the ramus of the mandible, we see the head.

04:08 On the temporal bone we have the styloid process and mastoid process.

04:13 As well as the external acoustic meatus.

04:17 We have the zygomatic arch in this area which again is composed of portions of both the zygomatic bone and the temporal bone.

04:28 And if we were to fade away the mandible to see it a little bit better, here we see the styloid process with a ligament that keeps the mandible in place called the stylomandibular ligament.

04:41 We also see a bit of the sphenoid bone here and another ligament, holding things in place called the sphenomandibular ligament.

04:52 If we zoom in a little bit more, we have yet another ligament with the temporal bone, this one called the temporal mandibular ligament.

05:01 Zooming in a little bit, we have another joint between the temporal bone and mandibular bone called the temporomandibular joint.

05:08 Just deep to that is the capsule for the temporal mandibular joint.

05:14 And again, this joint is an actual synovial joint just like you would have in the near the elbow, in the sense that it has a lot of movement here.

05:25 It's a joint capsule surrounding a joint space just like any other synovial joint.

05:31 But what makes this joint special is that it actually has an articular disc, which actually separates the synovial cavity into two separate cavities above and below.

05:42 And this helps achieve the multiple degrees of freedom we have at the temporomandibular joint during chewing.