Imaging of the bone marrow in the shoulder girdle, particularly the proximal humerus, is less studied compared to the pelvis. This chapter provides a comprehensive review of the normal MRI anatomy of the proximal humerus and explores ischemic and neoplastic marrow lesions. Understanding the normal distribution of red and yellow marrow, which changes predictably with age and sex, is essential for interpreting MRI. By adulthood, red marrow primarily localizes in the metaphyseal and diaphyseal regions, while yellow marrow dominates in the epiphysis and greater tuberosity. Osteonecrosis of the humeral head (ONHH), both traumatic and nontraumatic, is detailed, with insights into its etiology, vascular supply, imaging features, and natural history. Traumatic ONHH often follows proximal humeral fractures, while nontraumatic osteonecrosis (ON) is multifactorial, involving corticosteroids, sickle cell disease, or alcohol abuse. MRI is pivotal in early detection and staging. MRI patterns resemble femoral head osteonecrosis, and MRI may guide clinical assessment and prognosis. Beyond osteonecrosis, this chapter also addresses other patterns of bone marrow alterations, including bone marrow edema, focal or diffuse marrow replacement, and infiltration associated with various pathologies such as fractures, tumors, and infections. Imaging of the bone marrow of the shoulder girdle has been less extensively developed than imaging of the pelvis. This chapter focuses on the normal magnetic resonance anatomy of the proximal humerus and on the patterns of ischemic and neoplastic marrow lesions that involve the shoulder.