[DiMarie]

Re-post on scalense and entrapment....

I have Dr.Sanders book here, I pulled up the chapter about the scalene triangle. Here is the information from the book, maybe this is why the neck is as you feel....

There is a diaghram, I can fax it to you...
Under a diagram it states: The scalene triangle contains the subclacian artery and the nerves of the brachial plexus. The subclavian vein lies anterior to the triangle
The diagram is from the jaw to the collar bone with the other structures in order from what appears to be towards the back as Middle sclene, then the nerves of the brachial plexus, next the anterior scalene.

Laying under them traveling under the collar bone above the first rib is the subclavian artery on the left and front is the subclavian vein.
...............................................
Then the section discribes the positions in medical terms.

Scalene traingle
This area is bounded by the anterior scalene muscle anteriorly, the middle scalene muscle posteriorly, and the first rib to its base. Any one of these three structures can cause compression of the neurovascular bundle and the clinical picture of TOS.

Anterior scalene
The anterior scalene muscle has a constant site of origin from the third through the sixth vertebrea, but its point of insertion, generally on the scalene tubercle of its instertion on the first rib, can vary.
The insertion of the tubercle is between the subclavian artery and vein, with the expansion of the plural dome. Variants include insertion behind the artery and brachial plexus, or an extended area of insertion behind the artery, between the artery and brachial plexus, or extended area of insertion that includes the entire base of the scalene triangle.

The latter variant may result in the anterior and middle scalene muscles forming a vise around the neurovascular bundle. The insertion of the anterior scalene muscle merges with the middle scalene muscle in 20% of individules. In half of all individules, the insertions are overlapping the first rib, while the other half of all individules they are joined in a common insrtion.


Deep into the anterior scalene muscle lie the subclavian artery and nerve trunks of the brachial plexus. Usually the nerves pass through a slit formed by the anterior and middle scalene muscles. IN some cases, howevere, the fifth and sixth cervical roots actually pass between bundles of the anterior scalene muscle rather than the hiatus between the anterior and middle scalene muscles. In one study this variant was seen in 45% of cadavers and 21% of TOS patients.

Middle scalene muscle
The middle scalene muscle originates from the transverse process of the second through the seventh vertebrae and inserts on the superior aspect of the first rib at "CHassaignac's Retroarterial tubercle." This insertion is broader and more posterior thatn that of the anterior scalense muscle. The middle scalene mucle may also have an expansion that inserts on the fibrous septum of the pleural dome.

Lateral fibrers of the middle scalene decend past the first rib to insert on the second rib. Insertion of the middle scalene muscle in a more forward or anterior position can cause copression of the middle trunks of the brachial plexus by contact with the sharp, anterior edge of the muscle. In a cadaver study published in 1948, the most frequently encountered anatomy was that of the lower trunk of the brachial plexus resting on the anterolaterial margin of the middle scalene muscle.

Fibromuscular bands along this border of the muscle may be one of the pathology mechanisms for TOS in the absence of a cervical rib. Among 33 patients treated for TOS by Thomas et al., middle scalene muscle abnormalities were observed in 58%.

good info.. Thanks Di !!
G ~

[DiMarie]

Hi Grom,
The part that hits me is the displacement in 45 % cadavers and in 21 % TOS patients, where the vascular comes through the wrong scalense and it is vised in between..
makes sense to why some of us are vascular or start as neuro and develope vascular problems.
Di

Anterior scalene
The anterior scalene muscle has a constant site of origin from the third through the sixth vertebrea, but its point of insertion, generally on the scalene tubercle of its instertion on the first rib, can vary.
The insertion of the tubercle is between the subclavian artery and vein, with the expansion of the plural dome. Variants include insertion behind the artery and brachial plexus, or an extended area of insertion behind the artery, between the artery and brachial plexus, or extended area of insertion that includes the entire base of the scalene triangle.

The latter variant may result in the anterior and middle scalene muscles forming a vise around the neurovascular bundle. The insertion of the anterior scalene muscle merges with the middle scalene muscle in 20% of individules. In half of all individules, the insertions are overlapping the first rib, while the other half of all individules they are joined in a common insrtion.

Deep into the anterior scalene muscle lie the subclavian artery and nerve trunks of the brachial plexus. Usually the nerves pass through a slit formed by the anterior and middle scalene muscles. IN some cases, however, the fifth and sixth cervical roots actually pass between bundles of the anterior scalene muscle rather than the hiatus between the anterior and middle scalene muscles. In one study this variant was seen in 45% of cadavers and 21% of TOS patients.

[DiMarie]

Bump up for new and renew
Di