BIO 176: Human Anatomy Lab Bone Practical: Lecture Bone-Axial Skeleton Speaker: Heidi Peterson What you will see in the following presentation are all of the bones and features and markings you will need to know for your upcoming practical. We are going to start with the skull. On the skull you will see an anterior view, which is like looking at somebody face to face. On the anterior view the use of your regional terms is going to be necessary. You learned them for a reason and they are going to help you with bones. The first bone you are going to see is your forehead, but it is actually called the frontal bone. The next bone you see is the nasal bone. It also forms the bridge of your nose. You might know it as the cheek bone, but anatomically correct it is called the zygomatic. If you feel in between your two nostrils it might seem strange, but you are going to find a bony protuberance that is called the vomer. The vomer is the bone that gives shape to your lip. That little frenulum comes from the vomer. Also in the skull you will find two big jaw bones. The top jaw bone is the Maxillae. And the bottom jaw bone is the Mandible. There will be features on each of these bones but we will talk about those in just a bit. Starting with the markings or features you will see a circle around something above the orbit of your eye. Anything that is above something anatomically is called superior or supra. So what you are looking at is a hole or foramen so put it all together and it is the superior orbital foramen. What you see next is the glabella. The glabella is right between your eyes. It is often used for identification purposes to age a skull. The more closed it is the older a person is. Right below the glabella and right below the orbit, and again using our regional terms is another hole. Holes are foramens, so it is the infraorbital foramen. If you put it all together, the last little thing we are going to see at the bottom there on the mandible you will find another hole, the mental foramen. Your chin is your mental area, so again you can see how your regional terms will help you. An overview of this again, look for the frontal bone or your forehead. The nasal bone or the bridge of your nose, your cheek bone or your zygomatic, the vomer just like you are picking your nose, the maxillae; the top jaw, the mandible; the bottom jaw, the mental foramen, the infraorbital foramen, the superior orbital foramen, and the glabella. If we look at the next view of the skull, the lateral view, we are going to see a lot of the same bones. So I would be ready to be able to label all of the bones that you see on every view of the skull. The first bone you are going to see on the lateral view of the skull is the parietal bone. The parietal bone makes up the Sagittal suture when it comes together at the top of your skull. The next bone on the side is the temporal bone. Right where your temple is and having lots of processes and foramens on this bone. From the side you can also see a good view of the cheek bone, zygomatic. If you look at that closely the zygomatic is like the apple of your cheek, and we are going to learn about the zygomatic process which is the arch of your cheek. Looking at the features we are going to run first suture. Sutures are where two bones come together. It is a fibrous connective joint and it is called a suture, cuz it looks like where the bone has been sewn. The first suture we see is between the temporal and parietal bones and has the name squamosal or squamous suture. Back to the temporal bone and the features or markings you would find on it includes the zygomatic process, the arch of your cheek. The hole that you see is the Page 1 of 4 BIO 176: Human Anatomy Lab Bone Practical: Lecture same hole you can stick your finger or q-tip in. It is the most interior part, and it is called the external acoustic meatus. One of the reasons you don’t want to put a q-tip too far into your ear is because you will hit brain, brain is right on the other side of that. In the lateral view, you will also see on the temporal bone, the mastoid process. If you take your thumbs and go right behind the lobe of your ear you will see/feel a big bump, that big bump is the mastoid process. If you push your thumb in a little farther, it might start to hurt, that’s because the next process you felt is the styloid process. We will run into a lot of styloid processes as styloid just means sharp pointy piece of bone, at least in layman’s terms. So the last feature you are going to see on the skull is part of the mandible called the ramus. So again we have bones and markings on that lateral view, ramus, zygomatic process, squamosal suture, styloid process, mastoid process, external acoustic meatus. And bones that include, the zygomatic, parietal, and temporal. We are now going to take the skull and turn it over. When we turn it over it is an inferior view. The inferior view of the skull includes the mandible being removed so you just see the underpart of the maxillae. You know it is the maxillae because you can see teeth. The big hole that you see is also a landmark to show that you are inferior on the skull. So what we can see is the maxillae where all the teeth are and right behind is circled is the palatine bone. I always remember it because it looks like the McDonald’s arches. The little point is where the uvula hangs off of that, that is the soft tissue uvula so that is also a landmark and you know where it is in your body. In the skull from the bottom we can also see a really good view of the occipital bone. This is the bone that rests on your atlas and axis and helps you to nod your head yes and no. The little foramen that you see right behind the two front teeth is called the incisive foramen. It is called the incisive foramen because it sits right behind the incisors. So on this skull, we have the incisive foramen, the palatine bone, the occipital bone, and the big hole you see is the foramen magnum. And foramen magnum is actually Greek for big hole. One of the last views of the skull we will look at is the superior view. The superior is really easy to see some of the bones of the top of the skull. What you see first is the frontal bone. And if you look at the picture you can see where the nose would be because you can see the ridge of the nasal bone, so the anterior part of the skull is at the top of the picture. The posterior part is in the back of the picture. We can also see a really good view of the parietal bone. And two really nice sutures, again where two bones come together. We have the coronal suture where the frontal and parietal bones come together, and lastly the sagittal suture where the parietals come together. The next view of the skull we are going to look at is the posterior view. On the posterior view we see the back part of the parietal bone. If you haven’t noticed by now, the parietal bone is one of the largest bones in the skull being able to be seen on a superior, lateral, and posterior view. This posterior view also gives us, another nice view of the occipital bone. You see the kind of triangular shape? That occipital bone leads us to the sagittal suture where the two parietals meet and the sagittal suture leads us right into the last suture you need to know which is the lamdoidal suture. I always remember it because it looks like a triangle and just like “Revenge of the Nerds,” Netflix or google it if you haven’t seen it, look up Lambda, Lambda, Lambda, that was the name of the fraternity. Page 2 of 4 BIO 176: Human Anatomy Lab Bone Practical: Lecture The last view of the skull we have an internal view. The internal view means that we have removed the top of the skull which is called the calvaria. When the calvaria is removed we see the cranial floor or base. And internally we are going to find some very unique looking bones. The first bone or the most anterior bone you will see actually makes up the top portion of your nasal cavity. It is called the ethmoid bone. Right behind it is a bone called the sphenoid bone. There are two features you will find internally one is the crista galli, it looks a little bit like a shark’s fin and sticks up right off the ethmoid. The other feature you will find is the sella turcica. The sella turcica is actually where your pituitary gland sits, and since the pituitary gland is such an important part of your glandular system it is very well protected.