MadSci Network: Anatomy

Re: is there a bone in the human toung, eather at birth or adulthood?

Date: Sun Mar 6 15:26:59 2005
Posted By: Jens Peter Bork, M.D., Internal Medicine, Erlangen University Hospital
Area of science: Anatomy
ID: 1109398866.An

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:
[1]	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:
[2]	A quite technical explanation of epiphyseal growth you find here:

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