• Posted on February 13, 2013 10:47 pm
    By Chris
    Pulvinus Dentalis - The dental pad in the cow and ruminants

    Today’s Diary Entry sponsored by Spikes World Ltd

    Well now that I know the bones, muscles and ligaments it is time to learn about everything else that actually makes the body work. The start of this is with Splanchnology which is the study of viscera or soft internal organs of the body. Today started at 7am with the anatomy lecture which was looking at the structures of the mouth, tongue and teeth which was pretty interesting (and a relatively easy topic to learn before we start the stomach next week).

    Now the mouth is where digestion starts, with the teeth being responsible for the mastication or mechanical breakdown of food and a wide range of glands secreting digestive enzymes and saliva to help the process. Now within the mouth there are two cavities, the space inside the teeth, and the space between the teeth to the lips and cheeks. Within the space inside the teeth (Cavum oris proprium) there is the tongue which has a range of different types of glands at various positions and in varying numbers depending on the species. In fact the actual shape of the tongue even varies within species with the tongue of a horse containing cartilage, the tongue of the dog having a groove in the middle, and the tongue of the cow being split into two parts divided by.a groove across the middle.

    There is also the mouth to pay attention to with the hard palate forming the roof of it lined with ridges across it and off course the teeth Now some of you may already know that ruminants (cows) actually do not have upper front teeth. Instead the have a hard pad made from tough tissue called the pulvinus dentalis. Wanna see it? Thought you would so here goes maybe my one and only dissection picture ever!

    Pulvinus Dentalis - The dental pad in the cow and ruminantsAs you can see it looks almost like the same material as horns at the front where the incisors normally are, you also have papilla along the sides which help with movement of food. At the front if you can look closely you can see that there is something that looks like an upside down “v” – this is the papilla incisiva which are the openings for the ductus incisivi which secrete digestive juices.

    There are several classes of teeth when it comes to animals, with some animals having combinations of more than one type.

    • Brachyodont – Where the tooth has stopped growing after reaching a certain point and its surface wears down with use. This type of tooth is divided into the crown, body and root and is the type of teeth that humans have.
    • Hypsodont – Where the tooth never stops growing (as long as the animal is alive) which means that it does not have a crown, instead it is just divided into the root and body. The most common examples are the teeth in rodents, rabbits, and more exotically the tusks of the boar or elephant!
    • Semihypsodont – Where the tooth continues to grow until it starts to wear out, the most common example are the incisors of the horse. This has the benefit of the tooth growing so that the surfaces of the teeth perfectly meet allowing the cutting of fine grass.

    The patterns of the occlusial surface (the part that meets with the opposite upper or lower tooth allowing chewing) actually also vary among different species, with some being multitubercular where it has bumps or bunodont where it is flat. These are also divided into selenodont where it has moon like patterns, or lophodont where it has folds and ridges.

    Posted in categories: Vet School Diary
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