The dermatome covering the neck and the posterior aspect of the cheek corresponds to the C3 spinal nerve. This is because C3 supplies the skin over the neck region, while the posterior cheek area lies within its sensory distribution. Understanding these dermatome patterns is crucial in surgeries involving the neck and face to avoid nerve injury and ensure effective regional anesthesia. This knowledge is particularly important during cervical lymph node biopsies or parotid gland surgeries to preserve sensory function. Incorrect identification may lead to inadequate anesthesia or postoperative sensory deficits.

Reference: Gray's Anatomy, Susan Standring, 42nd Edition.