INFRASPINATUS
By : Karam Alanaz
infraspinatus, tells us that one of this muscle’s attachments is the infraspinous fossa of the scapula (below the spine) .
*The infraspinatus is one of the four rotator cuff muscles. The rotator cuff muscles are the supraspinatus, infraspinatus, teres minor, and subscapularis. Sometimes the rotator cuff muscles are called the SITS muscles.
*The infraspinatus is one of the four rotator cuff muscles. The rotator cuff muscles are the supraspinatus, infraspinatus, teres minor, and subscapularis. Sometimes the rotator cuff muscles are called the SITS muscles.
General
*it is thick triangle muscle ,has fibers architecture is pennate .. *Sometimes the infraspinatus blends with the teres minor.
*There is usually a thick layer of fascia overlying the infraspinatus muscle.
*it works on shoulder joint . * *ATTACHMENTS : Infraspinous Fossa of the Scapula and Greater * Tubercle of the Humerus .
*There is usually a thick layer of fascia overlying the infraspinatus muscle.
*it works on shoulder joint . * *ATTACHMENTS : Infraspinous Fossa of the Scapula and Greater * Tubercle of the Humerus .
Supply
INNERVATION : The Suprascapular Nerve (C5,C6) , from the upper trunk of brachial plexus .
ARTERIAL : The Suprascapular Artery (a branch of the Thyrocervical Artery) and the Circumflex Scapular Artery (a branch of the Subscapular Artery) .
ARTERIAL : The Suprascapular Artery (a branch of the Thyrocervical Artery) and the Circumflex Scapular Artery (a branch of the Subscapular Artery) .
Origin
Infraspinous Fossa of the Scapula (the medial 2⁄3) ,partly covered by .the deltoid and trapezius
inserion
Greater Tubercle of the Humerus(the middle facet).
Note 1 : The infraspinatus is one of three muscles that attach onto the greater tubercle of the humerus. The two other muscles that attach here are the supraspinatus and the teres minor.
Note 2 :The distal tendon of the infraspinatus adheres to the capsule of .the glenohumeral joint, which is deep to the infraspinatus
Note 1 : The infraspinatus is one of three muscles that attach onto the greater tubercle of the humerus. The two other muscles that attach here are the supraspinatus and the teres minor.
Note 2 :The distal tendon of the infraspinatus adheres to the capsule of .the glenohumeral joint, which is deep to the infraspinatus
Movement(Action)
( laterally rotates shoulder joint , helps to hold humeral head in glenoid cavity of scapula )
A-Standard Mover Action
1-when the infraspinatus contracts and the humeral attachment is pulled toward the scapular attachment, the posterior side of the humerus moves medially. This movement is called lateral rotation of the arm at the GH joint, because the anterior side of the humerus rotates laterally. Note the similarity of the direction of fibers of the .infraspinatus to the direction of fibers of the teres minor
2-When the arm is in a position of 90 degrees of abduction, the infraspinatus’s line of pull is horizontal and can pull the arm directly posteriorly. This motion is called horizontal extension (or horizontal abduction) of the arm at the GH joint..
B- Reverse Mover Action
Reverse Mover Action Notes
When the infraspinatus contracts and the humerus is fixed, the • scapula is pulled toward the humerus. This causes the medial border of the scapula to lift away from the rib cage wall. This motion is called .lateral tilt (or medial rotation) of the scapula.
Notes :
it helps to Stabilize the GH joint and Stabilize the scapula .
There is controversy regarding whether the infraspinatus can abduct or adduct the arm at the GH joint. Some sources state that the upper fibers can abduct the arm and the lower fibers can adduct the arm. Other sources state that whether one or the other occurs is due to the position of the GH joint at the time. In either case, because of the poor lever arm, the infraspinatus has little strength as an abductor or adductor of the arm at the GH joint.
A-Standard Mover Action
1-when the infraspinatus contracts and the humeral attachment is pulled toward the scapular attachment, the posterior side of the humerus moves medially. This movement is called lateral rotation of the arm at the GH joint, because the anterior side of the humerus rotates laterally. Note the similarity of the direction of fibers of the .infraspinatus to the direction of fibers of the teres minor
2-When the arm is in a position of 90 degrees of abduction, the infraspinatus’s line of pull is horizontal and can pull the arm directly posteriorly. This motion is called horizontal extension (or horizontal abduction) of the arm at the GH joint..
B- Reverse Mover Action
Reverse Mover Action Notes
When the infraspinatus contracts and the humerus is fixed, the • scapula is pulled toward the humerus. This causes the medial border of the scapula to lift away from the rib cage wall. This motion is called .lateral tilt (or medial rotation) of the scapula.
Notes :
it helps to Stabilize the GH joint and Stabilize the scapula .
There is controversy regarding whether the infraspinatus can abduct or adduct the arm at the GH joint. Some sources state that the upper fibers can abduct the arm and the lower fibers can adduct the arm. Other sources state that whether one or the other occurs is due to the position of the GH joint at the time. In either case, because of the poor lever arm, the infraspinatus has little strength as an abductor or adductor of the arm at the GH joint.
Relation
.1- The infraspinatus is inferior to the spine of the scapula .
.2-Inferior to the infraspinatus are the teres minor and teres major. 3-Much or most of the infraspinatus is superficial in the infraspinous .fossa.
Medially, a small portion of the infraspinatus lies deep to the trapezius. .4- Distally the infraspinatus is deep to the deltoid.
5- The infraspinatus is located within the deep back arm line ..myofascial meridian.
Note :
Sometimes there is a bursa located between the infraspinatus and the .glenohumeral joint capsule
.2-Inferior to the infraspinatus are the teres minor and teres major. 3-Much or most of the infraspinatus is superficial in the infraspinous .fossa.
Medially, a small portion of the infraspinatus lies deep to the trapezius. .4- Distally the infraspinatus is deep to the deltoid.
5- The infraspinatus is located within the deep back arm line ..myofascial meridian.
Note :
Sometimes there is a bursa located between the infraspinatus and the .glenohumeral joint capsule
clinical note
HOW DO YOU EXAMINE THE INFRASPINATUS MUSCLE (PALPATION )?
A-With the client prone with the arm on the table and the forearm . hanging off the table, place palpating hand on the infraspinous fossa. (Make sure you are inferior to the deltoid.).
B-Have the client laterally rotate the arm at the GH joint (this requires the client’s hand to swing anteriorly and up) through a small range of motion and feel for the contraction of the infraspinatus. Resistance can be given. (Note: It can be challenging to discern the infraspinatus from the teres minor.).
C-Palpate the infraspinatus in the infraspinous fossa and then follow it distally to the greater tubercle of the humerus.
A-With the client prone with the arm on the table and the forearm . hanging off the table, place palpating hand on the infraspinous fossa. (Make sure you are inferior to the deltoid.).
B-Have the client laterally rotate the arm at the GH joint (this requires the client’s hand to swing anteriorly and up) through a small range of motion and feel for the contraction of the infraspinatus. Resistance can be given. (Note: It can be challenging to discern the infraspinatus from the teres minor.).
C-Palpate the infraspinatus in the infraspinous fossa and then follow it distally to the greater tubercle of the humerus.
Note :
To test the function of the suprascapular nerve, which supplies the
supraspinatus and infraspinatus, both muscles must be tested as .described
To test the function of the suprascapular nerve, which supplies the
supraspinatus and infraspinatus, both muscles must be tested as .described
