Subscapularis muscle
Musculus subscapularis
Subscapularis is the large rotator cuff muscle on the front of the shoulder blade that turns the arm inward.
At a glance
- English
- Subscapularis muscle
- Latin (TA2)
- Musculus subscapularis
- System
- Muscle
- Region
- Upper limb
- Side
- Paired, left and right
About the subscapularis muscle
Subscapularis is a broad, triangular muscle filling the subscapular fossa, the hollow front surface of the scapula that faces the ribs. It is the largest and strongest of the four rotator cuff muscles and the only one on the front of the joint. Together with teres major and latissimus dorsi it forms most of the posterior wall of the axilla.
It arises from the medial two thirds of the fossa and from tendinous septa fixed to bony ridges across the fossa, which give it a multipennate, powerful build. Its fibres converge laterally into a broad tendon that passes in front of the shoulder joint, blending with the capsule. It attaches to the humeral lesser tubercle and to the capsule in front, and some lower fibres reach the bone just below the tubercle. A bursa between the tendon and the neck of the scapula usually opens into the joint cavity.
Subscapularis is the main medial rotator of the arm, and it also helps draw the arm towards the body. As part of the cuff it holds the humeral head in the glenoid cavity and is the chief block to the head slipping forward, especially when the arm is lowered. It is served by two short subscapular nerves, upper and lower, which leave the posterior cord of the plexus. Blood reaches it from the subscapular artery and from the suprascapular artery.
Tears of its tendon, often in older people or after a dislocation, cause weakness of inward rotation and can let the long biceps tendon slip out of its groove. Clinicians test it with the lift-off test, in which the patient pushes the back of the hand away from the lower back, and the belly-press test.
Attachments, action and supply
- Origin
- Medial two thirds of the subscapular fossa and its tendinous septa.
- Insertion
- Humeral lesser tubercle, and the anterior capsule of the shoulder.
- Action
- Medially rotates and adducts the arm; holds the humeral head in the glenoid cavity and resists forward displacement.
- Nerve supply
- Upper and lower subscapular nerves (C5, C6, C7).
- Blood supply
- Subscapular and suprascapular arteries.
Anthromica
See the subscapularis muscle where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
