A. An anticholinergic is a drug used in the treatment of diseases such as asthma, muscular spasms, insomnia and gastrointestinal cramps (Healthline, 2016). The drug is also used with anesthetics as it inhibits the action of parasympathetic nerve impulses by preventing acetylcholine reaching the receptor cells of nerve impulses. This may lead to memory loss, confusion, drowsiness and even sedation. These effects are more pronounced in old-aged people. Loss of muscular strength and fainting is a symptom which could be seen in the patient. Use of anticholinergic drugs is not recommended for patients with conditions like glaucoma, hyperthyroidism, heart failure, liver disease, constipation etc.
B. The four major plexus of the spinal nerves are:
a. Cervical Plexus – It is located underneath the sternocleidomastoid muscle (from C1-C4). Its branches extend into the neck and neck muscles. The Phrenic nerve is a branch of the Cervical Plexus.
b. Brachial Plexus – It extends from the neck into the armpit (from C5 – T1). The Brachial Plexus is highly branched and complicated. Musculotaneous nerves innervating biceps muscles are branches of the Brachial Plexus which leads into the biceps. The Median nerve is another branch which innervates forearm muscles (Antranik, 2011).
c. Lumbar Plexus- It lies between L1 and L4 within the iliopsoas muscle. Its branches reaches the thigh and also into the abdominal wall. The Femoral nerve is a branch of the Lumbar Plexus which innervates the quadriceps. Another branch is the Obturator nerve which innervates adductor muscles and the skin lying over it.
d. Sacral Plexus- It is situated caudal to the Lumbar Plexus (from L4- S4) and is commonly known as the Lumbosacral Plexus. It branches out into the pelvis, buttocks and lower limbs. The Sciatic nerve is the major nerve of the Sacral Plexus which is made up of two nerves wrapped together: the Tibial nerve and the Common Fibular nerve (Antranik, 2011).
C. Errors of Refraction are abnormal conditions of the eye caused the inability of the eye to focus light exactly on the retina (NIH, 2010). As a result, objects appear dim and blurred. There are several factors which may be the cause of such conditions such as inappropriate size of the eye ball, inadequate transparency of the cornea, inappropriate reading habits or just age. The four main kinds of errors of refraction are:
a. Myopia- Myopia or nearsightedness is a condition of the eye in which it is unable to focus light exactly on the retina. Instead, it focuses the light in front of the retina due to which far-off objects cannot be seen clearly.
b. Hyperopia- Hyperopia or farsightedness is a condition in which the eye focuses light beyond the retina due to which objects at close range cannot be seen clearly.
c. Astigmatism- In this condition, there is uneven focus of light by the retina. As a result of this, images appear blurred and stretched.
d. Presbyopia- This condition is a result of old age when the eye ceases to function normally. Here, the lens is unable to adjust light normally, thus impairing vision (NIH, 2010).
Inner Ear
The inner ear consists of three main parts: the cochlea, the auditory nerve and the vestibular.
a. Cochlea: It resembles a snail shell and is filled with a liquid called perilymph. The perilymph is separated by membranes which are lined by fine hair fibers (The Inner Ear, 2016). These hair fibers are set in motion when sound enters the inner ear.
b. The auditory nerve: It connects the cochlea to the brain. It is made up of bundles of nerve fibers which transmit nervous impulses to the brain on reception of impulses from the cochlea.
c. The vestibular: It is also known as the organ of equilibrium as it controls balance of the body and tracks down body movements. It is made up ring-shaped passages which are at perpendicular planes to each other. They send impulses to the brain where they are interpreted (The Inner Ear, 2016).
References
Antranik. (2011). Peripheral Nervous System: Spinal Nerves and Plexuses. Retrieved from
Antranik.Org:
http://www.antranik.org/peripheral-nervous-system-spinal-nerves-and-plexuses.htm
Health Line. (2016). What are Anticholinergics? Retrieved from Health Line.com
http://www.healthline.com/health/anticholinergics.htm
Hear It. (2016). The Inner Ear. Retrieved from Hear It.Org
http://www.hear-it-org/The-inner-ear.1.htm
National Eye Institute. (2016). Facts About Refractive Errors. Retrieved from NIH.Gov
http://www.nih.gov/health/errors/errors.htm
