Test Your Knowledge of Upper Limb and Thoracic Wall Anatomy

Anatomy of Upper Limb and Thoracic Wall

• Pectoralis major is a thick and fan-shaped muscle that starts at the sternal end of the clavicle and anterior surface of the sternum, inserts into the intertubercle sulcus of the humerus, and is involved in flexion, adduction, and internal rotation.
• Pectoralis minor is a thin and triangular muscle that starts at ribs 3-5, inserts into the coracoid process of the scapula, and moves the scapula around the chest wall.
• Subclavius is a small muscle between the first rib and clavicle, and its role is unclear but it may stabilize the sterno-clavicular joint.
• Serratus anterior starts from ribs 1-9, its fibers run posteriorly around the thoracic wall, inserts on the medial border of the costal surface of the scapula, and is involved in scapular movement on the thoracic wall.
• Trapezius is a large triangular muscle that originates from the occipital bone, vertebral process in neck and thorax, and inserts into structures in the shoulder, such as clavicle, acromion, and spine of scapula; it moves the neck and stabilizes the scapula and forms a diamond shape.
• Latissimus dorsi is a large muscle that overlies the lumbar and lower thoracic region, starts from vertebrae from the lumbar and thoracic region and ileac crest, inserts into the intertubercular groove of the humerus, and is involved in spine movement and adduction, extension, and internal humerus rotation.
• Rhomboid major and minor originate from different vertebrae and insert onto the medial scapula, maintain the position of the scapula, and aid movement.
• Levator scapulae is the antagonist of latissimus dorsi, originates from different vertebrae, inserts into the medial scapula, maintains the position of the scapula, and aids movement.
• Deltoid is a curved, triangular muscle that starts from the lateral third of the clavicle, acromion, and scapula spine, inserts midway down the humerus shaft into the deltoid tubercle, and is involved in abduction, flexion, extension, and rotation.
• Rotator cuff muscles (supraspinatus, infraspinatus, subscapularis, and teres minor) are involved in the movement of the upper limb and are often injured where the muscle inserts into the tubercle.
• Frozen shoulder is a condition where the capsules and ligaments of the glenohumeral joint become inflamed, common in females 40-60 with underlying conditions, and causes pain, stiffness, and functional loss with active and passive movement affected.
• The irregular pyramidal shape between the upper thor