hello anatomy friends this is dr alsup and in this video we will be discussing
one of the structural classifications of joints which are the fibrous joints
so we will talk through what makes a fibrous joint so what is the connective tissue that's present
and what are the different types of fibrous joints so we'll give a few examples of each
if that's possible so fibrous joints are within that structural classification of a joint where
bones are connected by a solid sheet of connective tissue so what i mean
by that is say this is a bone and this is a bone there will be a completely solid sheet
or as close to solid as possible of connective tissue that is actually what is connecting
the bones it does not have that space in between like you'll have in a synovial joint
so in the case of fibrous joints which is what we're talking about here
the connective tissue that we're talking about is dense irregular connective tissue and how much of
that dense irregular connective tissue is between the bone differs between the different types of
fibrous joints sometimes it can be really short sometimes you can have longer sheets of connective
tissue so let's talk through these three types of fibrous joints that we have named here
the first type and my personal favorite is
the suture and suture means seam which you can see here a suture does kind of look like a seam
between the two bones and you only have sutures between the bones of the skull and so you'll have
sutures nowhere else in the body so only related to between bones of the skull and the amount
of fibrous tissue is pretty short between the two bones and this fibrous tissue is
specifically called a sutural ligament so this would be an example of an intrinsic ligament
the fact that the ligaments are relatively short is indicative of the fact that there
is very little movement allowed at these joints in fact in juveniles these joints are
very slightly movable so not much movement and it will become these
joints will become increasingly immovable with age all right in fact these would be
would be labeled as synarthrosis and these can actually in individuals of advanced stage
and sometimes younger the fibrous connective tissue will can be entirely replaced with bone
becoming what we call a bony joint or synostosis so instead of having a sutural ligament this would
all be completely replaced by bone and at that point that would that would be called a synostosis
so not every single joint in an adult will do this or not every single suture in an adult
will do this with advanced age but many do okay so those are sutures the second type of fibrous joint
is a gomphosis which is a super awesome name and this is a unique one because it isn't between
a bone and bone it is actually between a tooth and bone so i have peg and socket
here because it's like a peg so that peg would be the tooth sitting in a socket and
the socket would be that bony socket so here is the bone and that tooth sits right in there
sometimes you will see gomphoses categorized in the next category we're going to talk about or
the syndasmosis um but we're going to keep it separate for our purposes because i think it's
unique enough to have its own category the amount of connective tissue is a little bit longer than
what you see in some sutures and instead of the sutural ligament these intrinsic ligaments
that connect the the bone to the tooth are referred to as the periodontal ligament or the pdl
lastly and the most movable but still would be in the amphiarthrotic category
so certainly not freely movable these are not synovial joints you will have the category
of ascendesmosis or sendismosis if you're talking plural so this little bit of movement
is allowable because of the longer or more fibrous connective tissue between the bones
and the most notable type of synthesmosis is an interosseous membrane which sometimes the
interosseous membrane is put into its own category of fibrous joints but we are going to include
them within the syndesmosis these will connect the diaphyses of the forearm bones when we're
talking about interosseous membrane so between the radius and the ulna which we can see in this
image here so this whole this sheet right here is going to be that interosseous membrane joint
so this whole complex and you'll also have an interosseous membrane for
between the diaphyses of the leg bones the fibula and tibia you will have other syndesmosis in the
body like on the distal ends of the tibia and the fibula around the epiphyseal portions there
and so these are the three categories of fibrous joints so let's do a quick recall question
question is the interosseous membrane between the tibia and the fibula is an example of which
type of fibrous joint is it a gomphosis a suture or syndesmosis pause the video if you need to
but when you are ready let's discuss how c or syndesmosis is the correct answer recall that
syndesmoses have comparatively longer sheets of fibrous connective tissue between the bones and
that is definitely the case for the interosseous membrane also just as a reminder sometimes you see
the interosseous membrane as its own category of fibrous joints but i think it fits quite
well with the syndesmosis so that's how we're categorizing it for our purposes in this course
the suture isn't correct um because these are only found in the skull or between the bones of
the skull as argonfocuses these are only between teeth and bone so also associated with the skull
all right please make sure to review this these materials and reach out with
any questions you may have thank you for your time and attention