Shoulder Anatomy: Complete Guide
Understanding the bones, joints, muscles, and structures of the shoulder complex. By Dr. Deepthi Nandan Reddy, Shoulder Specialist, Hyderabad.
Understanding the Shoulder
The shoulder is the most mobile joint in the human body, allowing an incredible range of movement in multiple directions. This mobility comes from a complex arrangement of bones, joints, muscles, ligaments, and tendons working together.
The shoulder complex consists of 3 bones (scapula, clavicle, humerus), 4 joints(glenohumeral, acromioclavicular, sternoclavicular, and scapulothoracic), and over 20 muscles that provide movement and stability.
Understanding shoulder anatomy helps you better understand your injury, communicate with your doctor, and participate in your rehabilitation. Click on any structure below to learn about related injuries and conditions.
Bones of the Shoulder
A flat, triangular bone that forms the back of the shoulder. It provides attachment for 17 muscles and is crucial for shoulder movement.
Key Parts:
- • Glenoid (socket)
- • Acromion
- • Coracoid process
- • Scapular spine
Related Injuries:
An S-shaped bone connecting the shoulder to the sternum (breastbone). It's the most commonly fractured bone in the body.
Key Parts:
- • Medial end (sternum)
- • Lateral end (acromion)
- • S-shaped curve
Related Injuries:
The long bone of the upper arm. The rounded head articulates with the glenoid to form the main shoulder joint.
Key Parts:
- • Humeral head (ball)
- • Greater tuberosity
- • Lesser tuberosity
- • Bicipital groove
Related Injuries:
Joints of the Shoulder
The main shoulder joint where the humeral head (ball) meets the glenoid (socket). Provides the greatest range of motion of any joint in the body.
Key Structures:
Labrum, Capsule, Glenohumeral ligaments, Rotator cuff
Related Conditions:
Where the clavicle meets the acromion of the scapula. Commonly injured in falls onto the shoulder tip.
Key Structures:
AC ligament, Coracoclavicular ligaments, Articular disc
Related Conditions:
Where the clavicle meets the sternum. The only true bony connection between the arm and the trunk.
Key Structures:
Costoclavicular ligament, Interclavicular ligament, Articular disc
Related Conditions:
The gliding interface between the scapula and the ribcage. Essential for normal shoulder movement.
Key Structures:
Serratus anterior, Rhomboids, Trapezius, Levator scapulae
Related Conditions:
The Rotator Cuff
The rotator cuff is a group of four muscles and their tendons that surround and stabilize the shoulder joint. They work together to keep the humeral head centered in the glenoid socket during movement. Remember the acronym SITS: Supraspinatus, Infraspinatus, Teres minor, Subscapularis.
Initiates arm abduction (raising arm away from body). Most commonly injured rotator cuff muscle.
Learn about Rotator Cuff TearsExternal rotation (rotating arm outward). Second most commonly torn.
Learn about Rotator Cuff TearsExternal rotation and stabilization. Works with infraspinatus.
Learn about Rotator Cuff TearsInternal rotation (rotating arm inward). Largest rotator cuff muscle.
Learn about Rotator Cuff TearsDid You Know?
The rotator cuff muscles generate 50% of shoulder strength for elevation and 90% for external rotation. When these muscles are torn, the shoulder loses both strength and stability, leading to pain and difficulty with overhead activities.
Read more about Rotator Cuff Tear Treatment in HyderabadOther Important Structures
A ring of fibrocartilage that surrounds the glenoid socket, deepening it by 50% and providing stability. The labrum also serves as the attachment site for the biceps tendon (superiorly) and glenohumeral ligaments.
The long head of the biceps tendon attaches to the top of the glenoid (superior labrum) and travels through the shoulder joint before passing through the bicipital groove of the humerus. It's a common source of shoulder pain and is often injured along with the rotator cuff.
A fluid-filled sac between the rotator cuff and the acromion that reduces friction during movement. When inflamed (subacromial bursitis), it contributes to impingement syndrome and shoulder pain.
Quick Reference: Common Search Terms
Bone Names:
- • Scapula = Shoulder blade
- • Clavicle = Collarbone
- • Humerus = Upper arm bone
Joint Names:
- • GH Joint = Main shoulder joint
- • AC Joint = Top of shoulder
- • SC Joint = Collarbone to chest
Structure Names:
- • Acromion = Bony roof of shoulder
- • Glenoid = Socket of shoulder
- • Labrum = Cartilage rim