16th February 2024

A 24-year-old female has been admitted with chest pain.

A 24-year-old female has been admitted with chest pain. The pain is localised around her sternum without radiation. The pain is sharp, which was not worse on deep inspiration. Her pain is not relieved on leaning forward. She has been coughing for the past seven days and has an associated sore throat. Tests including troponins, D-Dimer, CXR and ECG were unremarkable. Palpation of her sternum recreates the pain. 

Which of the following structures is likely responsible for the pain?