Which term refers to weakness of muscles specifically related to a neuromuscular disorder?

The term that specifically refers to weakness of muscles related to a neuromuscular disorder is "myasthenia." This word is derived from Greek roots "myo," meaning muscle, and "asthenia," meaning weakness. Myasthenia gravis, for example, is a well-known neuromuscular condition that causes varying degrees of weakness in the skeletal muscles, which can lead to impairments in voluntary movements.

Other terms in the choices don't pertain to muscle weakness in the context of neuromuscular disorders. Hysteratresia refers to a congenital condition involving the absence or closure of the uterus, thus it does not relate to muscle weakness. Atresia refers to the absence of a normal opening or the failure of a structure to be tubular in form, commonly used in discussions of anatomical conditions rather than neuromuscular issues. Aden/o refers to gland or glandular tissue and is not associated with muscle weakness. Thus, myasthenia is the correct answer as it directly addresses the condition of muscle weakness due to a neuromuscular disorder.