|MadSci Network: Anatomy|
Dear Shaley, I hope my answer makes it before the weekend is over...:-) There is no bone inside the human tongue (and I do not know of any animal that has one, since with the tongue, flexibility is the key). However, there is a „tongue bone“ in many mammals, among them, humans. This bone is not inside the tongue but below it. You can feel it with your own hands (carefully! Do not use force, especially if you try to feel it at someone else’s neck!! These structure hurt a lot when you treat them roughly, and they can break relatively easily!): Touch your Adam’s apple with thumb and forefinger; let the two fingers slip sideways on either side of the Adam’s apple, until you feel the border between the hard tissue of the Adam’s apple and the adjacent musculature. Then, slip upwards trying to keep this „border“ at your fingertips. You may have to exert some (careful!) pressure here in order not to lose yourself in the soft tissue of the neck. Having gone upward half an inch or so, you will feel that the hard structure broadens a bit. You can move it sideways with your two fingers. That is the bone we are talking about. The tongue bone (os hyoideum, hyoid bone in the anatomical naming system) is a very special bone because it does not make any contact with the other bones: It is freely suspended between the muscles of the oral floor (reaching towards it from above), the muscles of the front part of the neck (reaching at the bone from below), ligaments linking it to one of the big cartilages of the larynx,. and a ligament linking it to the base of the skull. Since the bone is completely separated from the rest of the skeleton, it is not depicted in most representations of the human skull. I have three pictures for you: One showing the bone in the context of the neck muscles, one that shows its relationship to the rest of the skull, and one showing it in isolation with its main body and the two „horns“. The function of the hyoid bone is, broadly speaking, to act as a lever for the muscles responsible for swallowing. The bone is sometimes broken in people who have been strangled in a murder or murder attempt, which makes the bone interesting to a forensic expert. As for your second question: You can say that, in a way, there are more bones in a baby than in an adult, although I think to say this is a bit misleading: On the one hand, there are no bones in a baby that disappear later in life. On the other hand many bones are not mature when we are born. So in a baby, some bones that form a single bone later in life exist a s separate bones at birth. They are only joined by cartilage which is replaced by bone later in life. So in this sense, yes, you can count them as two bones. There are some examples of bones in the skull that merge only after a few years – this is not noticed much. But there is on field in which this process is very important indeed: Very often you will have one of the long bones of the body end a few inches off the joint. The joint is made completely of cartilage. Inside the cartilage there will be a small pellet of bone, the „bone core“ or ossification center. This is a very important fact, because most of our bones can only grow in length along such a cartilage-bone juncture. The growth of the long bone and the ossification center and, finally, the closure of the juncture between them (called epiphyseal growth), proceeds with great regularity – so much so that by counting and measuring ossification centers in X-rays, you can tell how old a child is, for how long he or she will continue to grow and how tall they will be when growth is finished! If, however, a juncture is closed prematurely (after an fracture with inadequate treatment for example), the bone stops growing at this site – and imagine what kind of impairment it is if one of your legs is 10 cm shorter than the other one! So I hope this helps a bit – and always keep asking questions! Yours truly Jens Peter Bork P. S. As for references:  Here is an article about the hyoid bone – note that in the last paragraph, the course of ossification of this bone is described in detail: http://www.bartleby.com/107/45.html  A quite technical explanation of epiphyseal growth you find here: http://www.orthoteers.co.uk/Nrujp~ij33lm/Orthbonephysis.htm
Try the links in the MadSci Library for more information on Anatomy.