GROSS ANATOMY

Detailed explanation-1: -The medial pectoral nerve (also known as the medial anterior thoracic nerve) is (typically) a branch of the medial cord of the brachial plexus and is derived from spinal nerve roots C8-T1. It provides motor innervation to the pectoralis minor muscle, and the lower half (sternal part) of the pectoralis major muscle.

Detailed explanation-2: -Due to the insertion of the pectoralis minor muscle to the coracoid apophysis, this muscle helps produce a medial rotation of the scapula against resistance, with the scapula and the upper limb fixed. Therefore, an injury to the medial pectoral nerve can lead to an inability to elevate the shoulder.

Detailed explanation-3: -Clinical findings of medial pectoral nerve injury in-clude asymmetry of the anterior chest wall associated with muscle atrophy (inferior sternal portion of the pec-toralis major), weakness, limited range of motion, as well as regional pain.

Detailed explanation-4: -The medial pectoral nerve arises from the medial cord of the brachial plexus with fibers arising from the eighth cervical and first thoracic nerve roots.

Detailed explanation-5: -Innervation of the Pectoralis Major Both the lateral and medial pectoral nerves, nerves that are branches of the brachial plexus, provide motor innervation to the PM muscle. The lateral pectoral nerve arises from the lateral cord of the brachial plexus and is composed of branches of C5, C6, and C7.