Infraspinatus

Last updated on Monday, June 1 2009 by blondarb

Muscle Name: Infraspinatus

AKA:

Abbreviation:

Spinal Nerve Roots:

    C5
C6

Brachial Plexus Trunks: upper

Brachial Plexus Cords: NA

Named Nerves: suprascapular nerve

Proximal Attachment:   infraspinous fossa of the scapula

Distal Attachment:   middle facet of greater tubercle of the humerus

Action: External rotation and adduction of the arm.

Needle Insertion: With the arm internally rotated and relaxed the needle is inserted approximately 2-3cm distal to the midpoint of the spine of the scapula.

Activation for EMG: Externally rotate te arm.

Pitfalls:

Notes: Compression of the nerve at the spinoglenoid notch may lead to an isolated infraspinatous lesion.

Related videos:

Infraspinatus EMG Technique
A demonstration of needle placement and activation technique in an EMG study of the Infraspinatus muscle.

Infraspinatus activation Technique
A demonstration of the activation technique in an EMG study of the Infraspinatus muscle.

Related images:

Muscles connecting the upper extremity to the vertebral column.
This image shows the superficial and deep muscles of the back.

Supraspinatous nerve
This image shows the course of the supraspinatous nerve. Initially it passes through the suprascapular notch and subsequently through the spinoglenoid notch.