What is external rotation of humerus?

External or lateral rotation of the arm represents the movement of the humerus when an arm flexed to 90° at the elbow is externally rotated around the longitudinal plane of the humerus such that the hand moves away from the midline of the body. It is the opposite of arm internal rotation.

What muscles perform shoulder external rotation?

The infraspinatus muscle abducts and externally rotates the shoulder; it works best as a rotator with a patient’s prone position, and it is considered a pennate muscle. The teres minor muscle externally rotates the shoulder; It is considered a fusiform muscle.

Which muscle contributes to external rotation of the glenohumeral joint?

The infraspinatus and teres minor aid in external rotation of the shoulder. The subscapularis muscle aids in internal rotation of the shoulder. The supraspinatus and infraspinatus muscles are innervated by the suprascapular nerve.

What muscles help with external rotation of the humerus bone?

The prime muscle groups that externally rotate the glenohumeral joint are the posterior deltoid, infraspinatus, and teres minor.

What causes limited shoulder external rotation?

A post-operative shoulder with isolated limitation of external rotation with the arm at the side is likely to have some combination of the following problems: scarring at the humeroscapular motion interface between the coracoid muscles and the subscapularis excessive tightness of the subscapularis and anterior capsule …

What is shoulder external rotation?

Lateral rotation With your arms at your sides, palms facing your body, bend your elbows 90 degrees. Keeping your elbows against your body swing your forearms away from your body. This is lateral rotation — also referred to as external rotation — and the normal range of motion for a healthy shoulder is 90 degrees.

What muscles laterally rotate the humerus?

Infraspinatus: Originating at the infraspinous fossa of the scapula, this muscle inserts into the greater tubercle on the humerus. It laterally rotates the humerus.

What is normal shoulder external rotation?

Normal range of active movement of the shoulder has been specified by the American Academy of Orthopedic Surgeons (AAOS) to be 180° for flexion and abduction and 90° for external rotation [6].

What prevents external rotation of the shoulder?

Ligaments. Superior Glenohumeral Ligament: Limits external rotation and inferior translation of the humeral head. Arises from the glenoid and inserts on the anatomical neck of the humerus.

How is the glenohumeral joint related to the humeral head?

Both bands stabilize the humeral head when the arm is abducted above 90°. The anterior band limits external rotation of the arm, while the posterior band limits internal rotation. The glenohumeral joint is innervated by the subscapular nerve (C5-C6), a branch of the posterior cord of brachial plexus.

What causes the head of the humerus to be in the opposite direction?

Anterior-inferior tightness limits external rotation of the elevated arm. Capsular tightness not only limits motion but causes obligate translation. When rotational torque is applied to the humerus in a direction that tightens one aspect of the capsule the head of the humerus may be forced in the opposite direction.

Where does the rotator cuff border the humeral head?

The humeral attachments of the capsule and rotator cuff border the articular surface of the humeral head. The labrum borders the articular surface of the glenoid. When these two groups of structures come into contact motion is limited unless the cuff insertions slide past the labrum and into the joint.

What are the muscles that move the humerus?

– Subscapularis, supraspinatus, infraspinatus, & teres minor muscles – attach to the front, top, & rear of humeral head – point of insertion enables humeral rotation – vital in maintaining humeral head in correct approximation within glenoid fossa while more powerful muscles move humerus through its wide range of motion