Posterior triangle of the neck which divides the space into two triangles: A) Nerves and plexuses: B) Vessels: C) Lymph nodes: D) Muscles: The accessory nerve (CN XI) is particularly vulnerable to damage during lymph node biopsy. Damage results in an inability to shrug the shoulders or raise the arm above the head, particularly due to compromised trapezius muscle innervation. The Internal jugular vein's superficial location within the posterior triangle also makes it vulnerable to injury. Posterior triangle of the neck The posterior triangle (or lateral cervical region) is a region of the neck. It has the following boundaries: Apex: Union of the sternocleidomastoid and
Triangles of the neck the neck, from the sternum and clavicle below, to the mastoid process and occipital bone above. The triangular space in front of this muscle is called the anterior triangle of the neck; and that behind it, the posterior triangle of the neck. The anterior triangle is further divided into muscular, carotid, submandibular and submental and the posterior into occipital and subclavian triangles. The use of the divisions described as the triangles of the neck permit the effective communication of the location of palpable masses located in the neck between healthcare professionals. The common anterior midline of the swellings are: Triangles