ROTATOR CUFF MUSCLES - Musculotendinous cuff of the shoulder

on

ROTATOR CUFF MUSCLES - Musculotendinous cuff of the shoulder

Musculotendinous cuff of the shoulder is a fibrous sheath formed by the four flattened tendons which blend with the capsule of the shoulder joint and strengthen it. The muscles which form the cuff arise from the scapula and are inserted into the lesser and greater tubercles of the humerus. The tendons, while crossing the shoulder joint, become flattened and blend with each other on one hand, and with the  capsule of the joint on the other hand, before reaching their points of insertion. The cuff gives strength to the capsule of the shoulder joint all around except inferiorly. This explains why dislocations of the humerus occur most commonly in a downward direction.

The muscles involved are:

  • Subscapularis
  • Infraspinatus
  • Supraspinatus
  • Teres minor



Attachments of rotator cuff muscles:

SUPRASPINATUS:

ORIGIN: Medial two-thirds of the supraspinous fossa of the scapula.

INSERTION: Upper impression on the greater tubercle of the humerus.

NERVE SUPPLY: Suprascapular nerve (C5, C6)

ACTION: (1) Along with other short scapular muscles it steadies the head of the humerus during movements of the arm. lts action as abductor of shoulder joint from 0-15' is controversial. Both supraspinatus and deltoid are involved in initiation of abduction and continuation of abduction.

(2)Lateral rotator of arm


INFRASPINATUS:

ORIGIN: Medial two-thirds of the infraspinous fossa of the scapula.

INSERTION: Middle impression on the greater tubercle of the humerus

NERVE SUPPLY: Suprascapular nerve (C5, C6)

ACTION: Lateral(external) rotator of arm


TERES MINOR:

ORIGIN: Upper two-thirds of the dorsal surface of the lateral border of the scapula.

INSERTION: Lowest impression on the greater tubercle of the humerus.

NERVE SUPPLY: Axillary nerve (C5, C6)

ACTION: Lateral(external) rotator of arm


SUBSCPULARIS:

ORIGIN: Medial two-thirds of the subscapular fossa.

INSERTION: Lesser tubercle of the humerus

NERVE SUPPLY: Upper and lower subscapular nerves (C5, C6)

ACTION: Medial(internal) rotator and adductor of arm

In general, during arm movements, the rotator muscles contract and prevent the sliding of the head of the humerus, allowing full range of motion and providing stability. Additionally, rotator cuff muscles help in the mobility of the shoulder joint by facilitating abduction, medial rotation, and lateral rotation.




Thank you for reading and keep supporting us. 

Click on the following link/TOPIC to know important points about clavicle:

Comments

Post a Comment