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Dear All
Recently I had a discussion with a group of medical students about the
function of ligaments. Coming from a mechanical engineering backgound I
expected the answer to the question,"What is the primary function of a
ligament?", to be ,"to hold two bones together". The answer I got from a
student who's background was in biology was that the primary function of a
ligament was proprioception. A discussion followed as to what we each meant
by function and what the definition of primary was!
We were talking about the anterior cruciate ligament in particular and I
started thinking afterwards about how this ligament could give
proprioceptive signals. I believe the ACL is reasonably isometric during
the full range of knee flexion. If this is the case it can't give
information as to the position of the Tibia relative to the Femur. Other
ligaments don't actually stretch much during normal activities either, or
the muscles would be working against their resistance all the time.
In conversation with anatomists and physiologists I have been told that the
small muscles around joints tend to have more stretch receptors than the
large motor muscles and the suggestion is that these small muscles are in
fact the joint position transducers. At the extremes of joint motion
signals from the ligaments might augment the muscle signals to provide a
safety mechanism to prevent injury.
What is the current thinking of those involved in this area?
As I've only just been connected to the world I'm sorry if this subject has
been done to death already but I'd appreciate your thoughts.
I'll compile and post the replies as is usual.
Regards
Mark Pearcy
************************************************** **************************
***********
Mark Pearcy
Associate Professor of Biomedical Engineering
Email egmjp@cc.flinders.edu.au
School of Engineering
Flinders University of South Australia
GPO Box 2100
Adelaide
South Australia 5001
Australia
Phone: (+61) 8 201 3612
Fax: (+61) 8 201 3618
Recently I had a discussion with a group of medical students about the
function of ligaments. Coming from a mechanical engineering backgound I
expected the answer to the question,"What is the primary function of a
ligament?", to be ,"to hold two bones together". The answer I got from a
student who's background was in biology was that the primary function of a
ligament was proprioception. A discussion followed as to what we each meant
by function and what the definition of primary was!
We were talking about the anterior cruciate ligament in particular and I
started thinking afterwards about how this ligament could give
proprioceptive signals. I believe the ACL is reasonably isometric during
the full range of knee flexion. If this is the case it can't give
information as to the position of the Tibia relative to the Femur. Other
ligaments don't actually stretch much during normal activities either, or
the muscles would be working against their resistance all the time.
In conversation with anatomists and physiologists I have been told that the
small muscles around joints tend to have more stretch receptors than the
large motor muscles and the suggestion is that these small muscles are in
fact the joint position transducers. At the extremes of joint motion
signals from the ligaments might augment the muscle signals to provide a
safety mechanism to prevent injury.
What is the current thinking of those involved in this area?
As I've only just been connected to the world I'm sorry if this subject has
been done to death already but I'd appreciate your thoughts.
I'll compile and post the replies as is usual.
Regards
Mark Pearcy
************************************************** **************************
***********
Mark Pearcy
Associate Professor of Biomedical Engineering
Email egmjp@cc.flinders.edu.au
School of Engineering
Flinders University of South Australia
GPO Box 2100
Adelaide
South Australia 5001
Australia
Phone: (+61) 8 201 3612
Fax: (+61) 8 201 3618