Complex sentence: The dorsal antibrachial cutaneous nerve (external cutaneous branch of musculospiral, posterior antebrachial cutaneous nerve, posterior cutaneous nerve of forearm) perforates the lateral head of the Triceps brachii at its attachment to the humerus.
Split into simpler sentences: The dorsal antibrachial cutaneous nerve (external cutaneous branch of musculospiral, posterior antebrachial cutaneous nerve, posterior cutaneous nerve of forearm) is a cutaneous nerve of the forearm. It perforates the lateral head of the Triceps brachii at its attachment to the humerus.