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James Baldwin Wickham
04-21-1996, 03:04 PM
original message,

Message 3/3 James Baldwin Wickham Apr 2, 96 10:40:06 am
+1000
shoulder musculature

Approved-By: James Baldwin Wickham
Reply-To: James Baldwin Wickham

I am a graduate student from Australia who, as a first experiment, needs
to document the biomechanics of certain shoulder muscles in order to
later use this information to help interpret EMG data from shoulder joint
movements (isometric and isotonic flexion/extension and
abduction/adduction) in subsequent experiments to follow.

The 3 muscles I am interested in are the pectoralis major, latissimus
dorsi and the deltoid. The data I would like from predetermined
(cadaveric) segments of these muscles are; the lines of action of each
intramuscular segment and the angle of the line of action from the
intended plane of movement, the moment arms and the axis of rotation
(ICR) of the glenohumeral joint for the ranges of movement utilised
(isotonic). Optimally, during the EMG experiments where miniature
surface electrodes are placed on the subject's segments I would like to
know the above information for each segment at any stage in the movement.
Also useful would be an indication of the force each segment was
producing.
: Some of the questions I have been pondering over are;

1. Is there one easy way that all this information can be gathered
preferably in vivo. Have looked at MRI (Rugg et al, 1990) but am not sure
whether the shoulder is an applicable joint and whether the images for
the segments would be clear enough. Have also looked at articles by Van
Der Helm and colleagues 1991, 1992 and 1994 but have been advised that
spatially digitizing 3D in vivo is difficult.

2. Would cameras and markers on segment origin and insertion followed by
digitizing give adequate 3D representation along with the Reuleaux method
(1875) for the axis of rotation work?

3. Is the straight line approach in comparison to the centroid line
approach (Jenson and Davy, 1975) adequate for these muscles and hence the
moment arm determination for each segment of each muscle?

Comments on any of the issues mentioned would be greatly appreciated and
a list of responses will be posted in the usual manner.

James Wickham
Department of Biomedical Science
: University of Wollongong
Northfields Avenue, Wollongong 2522
NSW, Australia

E-Mail Adress
jbw01@uow.edu.au

summary of responses,

Christian Hoegfors et al. introduced a model of the shoulder from which
you can determine the line of action and subsequent data for the muscles.
They also adressed the feasibility of representing the muscles as
straight lines in their discussion.

C Hoegfors et al. Biomechanical model of the human shoulder - I.
Elements. J Biomechanics v20 n2 157-166, 1987


You might also want to have a look at the follow up studies (I found
these two in our engineering database):

Karlsson et al. Internal shoulder forces due to an external load. J
Biomechanics v22 n10 1033, 1989

Hoegfors et al. Structure and internal consistency of a shoulder model.
: J Biomechanics v28 n7 767-777, 1995

Hope this helps!

Don't try to use the Reuleaux method in 3D - it doesn't work!
This method assumes PLANAR rigid body motion, hence, in the view
plane, the shape and size of the moving body is constant. In 3D, this
is unlikely to be the case, as rotations out of the view plane will
cause an apparent change of shape of the body in the view plane, due
to perspective. If you want to use a rotation axis technique, the
helical axis is basically a 3D extension of the instant centre. The
instant centre of rotation is a point on an axis normal to the view
plane (causing the restriction of all rotations to occur in this
: plane). The helical axis is a general axis in 3D space, and can hence
handle rotations in any plane.

Hope this helps!

ps, some helical axis refs:

1. Woltring, H.J., Huiskes, R., and De Lange, A. Finite Centroid and
Helical Axis Estimation from Noisy Landmark Measurements in the study
of Human Joint Kinematics. J.Biomechanics 18(5):pp379-389, 1985. 2.
Woltring, H.J., Long, K., Osterbauer, P.J., and Fuhr, A.W.
Instantaneous Helical Axis Estimation from 3-D Video Data in Neck
Kinematics for Whiplash Diagnostics. J.Biomechanics 27(12):1415-1432,
1994. 3. De Lange, A., Huiskes, R., and Kauer, J.M.G. Effects of Data
Smoothing on the Reconstruction of Helical Axis Parameters in Human
Joint Kinematics. J.Biomech.Engr. 112:pp107-113, 1990. 4. De Lange,
A., Huiskes, R., and Kauer, J.M.G. Measurement Errors in
Roentgen-Stereophotogrammetric Joint-Motion Analysis. J.Biomechanics
23(3):pp259-269, 1990.


Check the papers by John Wood (then at the U. Utah, now at U. New Mexico)
in the

J. Biomechanics in the early 90s. He checked lines of action of all the
muscles
in the arm and shoulder (I think).

Many thanks to those who replied.

James Wickham
Department of Biomedical Science
University of Wollongong
Northfields Avenue, Wollongong
2522. NSW. Australia.

E-Mail Address
jbw01@uow.edu.au