Anatomy of the Sternoclavicular Joint (SC Joint)

Overview

• Presenter: Kevin Tohcough
• Channel: Catalyst University
• Topic: Anatomy and function of the sternoclavicular joint (SC Joint)

Definition and Location

• SC Joint: Articulation between the manubrium of the sternum and the sternal end of the clavicle
• Preview of clavicle: Two ends - sternal (medial/proximal) and acromial (lateral/distal)
• The acromioclavicular joint will be covered in the next video

Anatomical Landmarks of the Sternum

• Manubrium (superior part of the sternum)
• Sternal Body (inferior to manubrium)
• Sternal Angle (aka Angle of Louis, manubriosternal joint): Connects the manubrium to the body of the sternum
• Jugular Notch: Concavity at the top center of the manubrium
• Clavicular Notch: Right and left concavities where the clavicle articulates
• Attachment Sites: First rib (completely with manubrium), second rib (half with inferior manubrium, half with superior sternal body)

Detailed SC Joint Anatomy

• Articular Disc: Fibrocartilage within joint capsule, makes anatomical saddle joint function as a ball-and-socket joint
  • Creates two joint (synovial) cavities: one near sternal end of clavicle, one near clavicular notch of manubrium
• Joint Capsule: Includes the anterior and posterior sternoclavicular ligaments
• Costoclavicular Ligament: Connects costal cartilage of the first rib to the clavicle
• Interclavicular Ligament: Connects the superior aspects of both clavicles over the jugular notch

Blood Supply and Innervation

• Blood Supply: Internal thoracic artery, suprascapular artery
• Nerve Supply: Branches of the suprascapular nerve and nerve to subclavius

Functional Mechanics

• Static vs. Dynamic Points:
  • Manubrium is fixed, SC joint acts as a functional axis for movement
• Movements in Three Planes: Enabled by articular disc
  • Elevation/Depression: Scapular movement up/down moves acromial end of clavicle correspondingly
  • Protraction/Retraction: Moving scapula forward/backward mirrors movement at SC joint
  • Rotation: Posterior and anterior rotation of clavicle about an axis

Connections and Movements

• Scapula and SC Joint: Scapular movements (e.g., elevation, protraction) are mirrored by movements of the SC joint because of the fixed manubrium
• Exercise Examples:
  • Shoulder abduction (deltoid exercise): Elevates and rotates scapula, which moves SC joint
  • Bench press or dumbbell flyes: Protract scapula during upward phase, causing SC joint movement

Summary

• Every scapular movement produces corresponding SC joint movement
• Next video will cover the acromioclavicular joint

Closing

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