Tight upper trapezius?

Hi guys im having some problems with my left shoulder and was wondering what you make of it.

This is hard for me to explain so bare with me lol...

When overheading pressing with my right shoulder everything is fine, i feel i can keep my scapula depressed and pretty firmly fixed while my humourus rotates 90 degrees straight upwards. My upper trap feels like its minimally involved and my deltoid feels like it gets strongy activated...my deltoid feels independant to my upper trapezius fibres another words, standard pressing motion i guess.

http://i50.tinypic.com/xlyush.jpg

However with the left shoulder when i repeat the same movement and press upwards it feels like theres hardly any seperation between my deltoid and my upper trapezius and when looking in the mirror instead of seeing the nice single crease seperation between the trapezius and the deltoid like in the above picture theres a second crease alone the trapezius muscle which makes it look and feel bunched up and theres slightly limited ROM.
Activation wise it feels like my trapezius gets heavily activated whereas my deltoid doesn't.

Im wondering now whether its possible a short or overactive trapezius muscle would pull the shoulder in towards the body when being raised overhead and limiting deltoid activation?

Heres some pics to get a better look at what im talking about..



http://img707.imageshack.us/img707/1492/1012430.jpg

http://img13.imageshack.us/img13/1460/1012424.jpg



At a glance it doesn't seem like theres hardly anything wrong but if you look at the left side around the trapezius area the gap between my shoulder and my neck is smaller than on the right hand side, its almost as if the shoulder is bunched up closer to the spine on the left hand side than on the right and as a result looks like im shrugging a bit on that side.
Whenever i try lift overhead with the left side it feels like its trapezius dominant and that my deltoid isn't contracting optimally or at least not as strongly as my right side.

Now the weird thing is when my arms are overhead like this and i protract my scapula a little on the left side then it seems to look more even only it feels tighter to get my humerus vertically pointing straight up.
Would it be possible that i have a flexibility & muscle balance issues on the left side, maybe a bit of a weak serratus anterior, weak external rotators or tight trapezius ect that would cause this?

Any help or feedback is much appreciated, thanks.

i would suggest having a look at your cervicothoracic junction C4 to T4 but mainly c7/T1 is porboably really stiff and hypo to start off with. perform a few self mobilisations with movemement with your fingers anchored about he spinous processess while you lift up the oppisite arm into flexion or abduction or with cervical rotation to release these joints. pulloverswould be a great exercise to looses the area also. another favourite is to wrap your hands around your neck attempt to straighten, either standing, on a gymnastic ball or against a wall, this is a tuff exericse so exercise caution while performing it. after releasing the stiff cervicothoracic joints have a look at whats happening at the shoulder joint and scapula with a few simple exercises. look at the joint glide while performing a bicep curl; is the glenohumeral joint moving excessively and in what direction, what is happening at the shoulder blade; when you peform a front raise does the shoulder blade lift or does the shoulder blade lock up with very little movement. check out upper crossed syndrome for more details. the final point i would like to make is; think of the shoulder as bones suspended in a myofascial web forget about the classis anatomy description of muscle attachments ,now remember this: muscles tdo not attach to bone it only ataches to periosteum. periosteum is encapsulated about the bone as a part of the myofascial web and continues on with muscles about the the opposite side forming a myofascial plane. see the work from Thomas myers for further detail, the bones are suspended and maintained in that position through tension of the myofascial cables about the shoulder girdle now identify the imbalance and release.