Hello again readers!
In this post I will talk about the things in my anatomy class during my time in Cyprus. The reason my blog was not updated for such a long time was because of the amount of studying and preparation I did for my anatomy final and because of an excursion to Polis where I spent most of my time exploring.
The class is held in the University of Nicosia Medical School, a really new program that is in affiliation with a medical school in London. The class itself is quite neat. My professors for the class are very nice and very smart. The one who runs lecture has an MD PhD and she uses terms that I often have to look up! The other instructor runs the clinical skills portion of the class, where we learn how to do examinations of various body systems on models and sometimes each other.
Our midterm was Wednesday, 6/19/13. It covered all of the classes up until the exam. As such, there was a ton of material to review. I believe in an earlier blog post I talked about what I learned about the respiratory system, so I will skip that here. The next section to know for the test involved the heart and associated diseases. We learned about the heart pretty in depth, which I was happy about because the structure and flow of the blood through the heart had always been confusing for me. FINALLY, I have begun to understand the heart. Obviously, there is a TON I don't know about it, but I feel I have the basics down. So, deoxygenated blood enters the right atrium of the heart via the inferior and superior vena cava. From the right atrium, the heart then enters the right ventricle after the opening of the tricuspid valve. Next, the deoxygenated blood exits the heart into the pulmonary trunk through the pulmonary valve and travels to the pulmonary artery. The pulmonary artery branches off into smaller and smaller vessels and finally becomes the capillaries of the alveoli in the lungs. The alveoli are responsible for gas exchange in the lungs. This is the sight where blood becomes oxygenated. The oxygenated blood travels through the pulmonary vein to the left atrium. From the left atrium, the blood enters the left ventricle through the bicuspid/mitral valve. Finally, the blood moves into the aorta through the aortic valve and oxygenated blood is supplied to the rest of the body!
Here is my crude drawing I made while studying:
I hope that some of you can see the anatomical words for the different parts of the heart as well as the arrows I put in to show the direction of blood flow in the heart.
In addition to learning about blood flow in the heart, we learned about heart sounds and the valves associated. S1 is the first heart sound and corresponds to closure of the tricuspid valve and the mitral valve. S2 is associated with closure of the pulmonary and aortic valves. S3 can sometimes be heard in normally healthy people. S4 is the pathological sound. In learning about the valves and the sounds we produced, we also learned about heart murmurs. We listened to heart murmurs in the simulation dummies and they were pretty obvious. Basically, a murmur is produced by backflow and turbulent flow of blood in the heart. I have actually heard a murmur in a real-life patient while I was shadowing my good friend and medical mentor Dr. Jim Boal. However, learning about this in class helped expand my knowledge.
There are other things that can go wrong in the heart. For example, cardiac tamponade occurs when blood enters the space between the pericardial leaflets (the membranes cover and enclose the heart), causing cessation of heart expansion and pumping. This can happen as a result of myocardial infarction (heart attack) and weakness of blood vessels or pericardial effusion (fluid in the pericardium).
After learning about the heart, we learned about the abdomen. We learned a lot about the anatomy of the stomach and intestines specifically. In the stomach, the part that connects to the esophagus is called the cardia. The fundus is the top left portion of the stomach. Inside the body of the stomach are folds called rugae that allow expansion of the stomach in meal time. The stomach opens into the duodenum of the small intestine via the pyloric sphincter. The pancreas and gallbladder drain into the duodenum to provide digestive secretions through one duct. From the duodenum, the small intestine progresses into the jejenum and then finally the ileum, which is the part before the large intestine. The ileum opens into the large intestine via the ileocecal valve (named due to passage of food from ileum of small intestine to cecum of large intestine). In digestion, contents move up the ascending colon, across the transverse colon, down the descending colon, through the sigmoid colon, and finally the rectum. The large intestine serves to absorb water while the small intestine absorbs nutrients.
As we did for the heart, we learned about a ton of abdominal abnormalities. For instance, we learned about diverticulosis of the colon. Diverticula are outpocketings of mucosa in the colon due to weakness of muscle layers in the wall of the colon. Diverticula have a possibility of rupture, which could lead to bleeding and infection. We also learned about pancreatic cancer that occurs in the head of the pancreas, near the pancreatic duct. If the cancer is found here, often the opening to the duodenum is sealed off, leading to a backup of bile from the gall bladder, which can lead to the yellow coloring of the body known as jaundice. With regards to the liver, we learned about the portal system and hypertension in the portal vein. I was somewhat familiar with this as well, due to shadowing Dr. Boal. Basically, we learned that portal hypertension is high blood pressure in the portal system as a result of liver diseases such as cirrhosis. Cirrhosis is a replacement of normal liver tissue with scar tissue as a result of damage such as alcoholism. There are other problems that result from cirrhosis and portal hypertension, such as esophageal varices. I had never heard of these until taking this anatomy course. Esophageal varices are a consequence of liver cirrhosis and portal hypertension and results in bleeding.
During the abdominal section we also learned about the different types of abdominal hernias. There is the umbilical hernia, which is just a protrusion in the umbilical region caused by excess intra-abdominal from obesity, weight-lifting, etc. Then there is the inguinal hernia, of which there are direct and indirect inguinal hernias.
We learned about the male and female reproductive systems in the next few lectures. The most interesting things we learned about were cancers that can occur in these systems. In men, the prostatic urethra can become closed off as a result of either benign enlargements or malignant prostate cancer. Patients with enlarged prostate will complain about frequent urination and incomplete emptying of the bladder. Cancer can also occur with cryptorchidism, a condition where the testes do not descend completely. The undescended testes are more likely to become malignant than normal testes. In females, we learned about cervical cancer. In a pap smear, a brush is used to swipe the surface of the cervical os (the opening) and the cells are assessed under a microscope for changes. While talking about the female reproductive system, we also learned about abnormal pregnancies. Ectopic pregnancies occur whenever the fertilized egg implants anywhere except the uterine wall, where it is supposed to be. Before taking this class, I only knew that ectopic pregnancies could occur in the fallopian tubes and the ovaries. However, they can also occur in the mesentary membranes of the intestine and other sites are also possible. These pregnancies are life-threatening and not viable in most cases, sadly. Other disorders we studied included endometriosis and polycystic ovarian syndrome. Endometriosis occurs when cells from the lining of the uterus grow outside of the uterine cavity. This condition causes extreme pain for most women who have it. Endometriosis can occur anywhere in the body, we even learned of a case that had occurred in the lungs! Polycystic ovarian syndrome is an endocrine disorder that results in irregular menstruation and is caused by the presence of cysts on the ovaries. We also talked about hysterectomies, or removal of the uterus and possible errors. Our instructor stressed the anatomical position of the uterine artery, which needs to be cut during a hysterectomy, in relation to the ureter. The uterine artery runs above the ureter. Unfortunately, it is a common mistake in a hysterectomy to accidentally cut the ureter instead of the artery, leading to obvious problems for the patient.
The next lecture covered the kidneys and ureters. We talked about the filtration mechanisms of the kidney and its corresponding anatomy. We talked about the infamous kidney stones, or calculi that can form all along the urinary tract and cause excruciating pain for people with the stones. The clinical skills portion of this lecture consisted of learning to do a urinalysis. The main point being that high glucose levels in the urine indicate diabetes.
The above information covers all of the topics we learned for our midterm exam. Well, its really a summary, we learned a ton of in depth information, these are just the main take away points. The next exam was our final, which we had on July 2, 2013.
The first topic covered on the final exam was the Central Nervous System! This was incredibly interesting to study and I loved every minute of learning about it. The brain and spinal cord comprise the central nervous system, and the rest of the nervous system falls under the category of the peripheral nervous system. The brain and spinal cord have 3 important membranes known as the meninges. The dura mater is the outer layer, and is in close contact with the second layer known as the arachnoid mater. The subarachnoid space contains the cerebrospinal fluid and rests between the arachnoid mater and the pia mater, which covers every surface of the brain and spinal column. The meninges can become infected, known as meningitis, which is a very serious condition. Bacteria, viruses, and fungi can cause meningitis. We learned about diagnosis of meningitis, which requires a spinal tap. To do this, the vertebrae must be punctured between L3 and L4, as the spinal cord terminates around L2. If a spinal tap were done any higher, the spinal cord would be damaged, rendering the patient with paralysis. However, an epidural, which is a common procedure done to relieve pain during birth, can be performed anywhere along the vertebral column. This is because the epidural space (hence the name epidural) is between the dura mater and the bony wall of the vertebral canal, meaning the spinal cord is less likely to be damaged.
The next thing we covered in the central nervous system was the regions of the brain. The frontal lobe contains the primary motor cortex, used for planned movements. The frontal lobe also contains the prefrontal cortex, which is primarily responsible for the high degree of intelligence humans maintain. Broca's area is found in the frontal lobe region, and is a key language area. The parietal lobe lies directly behind the frontal lobe, at the top of the brain. It processes information about touch and pain as well as spatial information. The temporal lobe lies below the parietal lobe, and contains the auditory cortex as well as Wernicke's area, which is responsible for written and spoken language processing and understanding. The temporal lobe also is responsible for long-term memory and visual memory. Finally, there is the occipital lobe, which is the visual processing center of the brain. The occipital lobe is at the very back of the head. Strokes can cause different types of brain injuries. The dysfunction of a patient who has undergone stroke gives clues as to where the stroke has occurred. Broca's and Wernicke's area can be affected, for instance, which gives rise to language problems in the patient known as "aphasia." As an aside, there are different types of strokes. An ischemic stroke occurs when an embolus or clot blocks a blood vessel in the brain, causing tissue of the brain to die. A hemorrhagic stroke occurs when a blood vessel bursts and bleeding in the brain occurs.
In learning about the Central Nervous System, we also covered the some of the main spinal tracts and nerves. The spinothalamic tract transmits information to the thalamus of the brain about pain and temperature. The posterior column-medial lemniscus pathway is responsible for transmitting touch and vibration from the body to the cerebral cortex. Both the spinothalamic tracts and the posterior column-medial lemniscus pathway are known as ascending tracts because information travels upwards from the body to the brain. The corticospinal tract projects motor nerves from the sensorimotor areas of the cortex through the brainstem to motor neurons of several cranial nerve nuclei and to the ventral (bottom) root of the spinal cord. This is a descending tract. Both the posterior column-medial lemniscus pathway and the corticospinal tract cross-over to the other side of the body from the origin in the brain at the level of the brainstem, while the spinothalamic tract crosses over at the level of the spinal cord. In either case, the opposite hemisphere of the brain controls the opposite side of the body. This is why the information in the nerves crosses to the other side of the body at some point.
After studying the nervous system, we covered the muscles of the back, upper and lower limbs. We were taught the main extensors and flexors of the arms and legs. The triceps brachii are on the posterior arm and are responsible for extenstion (straightening) of the elbow joint. The biceps brachii is found on the anterior (front) of the arm and is responsible for flexion of the elbow joint as well as supination (rotation) of the forearm. We also learned the muscles associated with the ulna and radius, the two bones of the forearm. The anterior arm contains the flexors and the posterior arm contains the extensors. The muscles that flex the fingers in the hand are also found in the forearm. The contraction and relaxation of these muscles is transmitted along tendons, through the carpal tunnel of the wrist to the fingers. You may recognize the term carpal tunnel from the medical condition known as carpal tunnel syndrome. This occurs when the median nerve of the arm and hand is compressed as a result of overuse of the fingers and associated tendons. There are nine tendons that pass through the carpal tunnel along with the median nerve. The lower limbs also contain flexors and extensors. The Rectus femoris is the extensor of the knee. The biceps femoris long head forms part of the hamstrings group of muscles on the posterior portion of the leg. The sartorius forms part of the border of what is known as the femoral triangle. The femoral triangle contains the femoral nerve, artery, and vein, as well as lymph nodes. The sartorius aids in flexion and adduction/abduction and lateral rotation of the hip along with flexion of the knee. The gastrocnemius muscles are in the posterior leg and are commonly known as the calf muscles. They are responsible for flexion of the knee and foot. Underneath the gastrocnemius is the soleus muscle. As I stated before, we also learned about the various muscles of the back. The trapezius muscle is a big muscle covering the shoulder blades and back that moves the scapula. The scalenes are the muscles responsible for moving the neck from side to side. These are some of the crucial muscles in the back, legs, and arms that we learned about, and these are just a sampling of the muscles that we learned. Learning about the mechanics of body movement and how each muscle acts in conjunction to produce complex movements was extremely interesting!
While we learned about the arms and legs, we also learned about nerves and arteries in these areas. We studied the art of venipuncture, used for phlebotomy. The most common vein used for phlebotomy is the median cubital vein of the elbow found in the region known as the cubital fossa. The next time you go to the doctor and need to get blood drawn, you will now know what vein and what region of the body you are being poked! Yay! Another area we learned about is the axilla, or the armpit. The axilla contains the axillary artery and vein as well as the cords of the brachial plexus. Any of these structures can be severely damaged in a shoulder dislocation. In studying the legs and hip, we learned about hip arthritis. This is a condition that develops with age and interferes with walking in those affected. The ball joint of the hip loses its cartilage, leading to the arthritis. Patients will have a gait that shows difficulty with adduction and the appearance of dragging their legs as they walk. Another condition we learned about is known as Deep Vein Thrombosis. This can occur anywhere in the body, but most often it occurs in the leg, hence why we studied it in this part of the class. Basically what happens is a blood clot forms in the deep veins of the leg as a result of prolonged periods of sitting, such as during travel (it is very important to get up and stretch periodically). If a clot forms, it can be dislodged upon disturbance and can lead to stroke! This is a condition that has several risk factors associated with it so it is relatively unlikely in healthy people, but it is still possible. An important nerve that we learned about in the leg is called the sciatic nerve. This nerve derives from the saccral spinal nerves and is implicated in the common condition known as sciatica. This is a type of nerve pain associated with compression or irritation of the sciatic nerve. It produces pain along the entire length of the leg and is extremely uncomfortable for patients.
After this in depth examination of the nerves, muscles, veins, and arteries of the arms, legs, hips, and back, we moved on to the endocrine system, involved in hormonal responses. The main thing we learned about in this section was the thyroid. The thyroid produces the hormones T3 and T4, which are responsible for numerous bodily signals. T3 and T4 negatively regulate the pituitary gland, which produces thyroid stimulating hormone (TSH) to stimulate production of T3 and T4. The regulation of these hormones is a delicate balance that if thrown off can lead to inconvenient conditions. Hypothyroidism is underactive thyroid. It occurs when the thyroid gland does not produce a sufficient amount of T3 and T4, leading to an abnormal amount of TSH in the blood. This is diagnosed by measuring TSH levels in a patient's blood sample. Hyperthyroidism is the opposite, meaning there is too much T3 and T4 and not enough TSH. Both of these conditions cause changes in mood, weight, sleep patterns, etc. and can be very debilitating if left untreated.
The next section of the class covered the cranial nerves. There are 12 pairs of cranial nerves. The olfactory nerve is the first one and is responsible for smell. Nerves 2, 3, 4 and 6 are involved in vision and control of eye movement/pupil responses to light. The 5th nerve is known as the trigeminal nerve. As its name suggests, it has 3 divisions. The trigeminal nerve transmits information about pain, temperature and touch from the face to the pons of the brain. These nerves are destroyed in serious dental infections and are anesthetized by dentists during root canals and other dental procedures to prevent excruciating pain in the patient. The Facial nerves are categorized as the 7th pair of cranial nerves, and these control facial expression and facial movement. The 8th nerve is the vestibulocochlear nerve and it is involved in hearing and balance. The 9th nerve is the glossopharyngeal nerve and this nerve is responsible for sensation in the tongue and pharynx. The Vagus nerve is nerve 10, and probably the most important cranial nerve. It is the only cranial nerve to extend beyond the head and neck region and innervates the skeletal muscles of the pharynx and larynx as well as the heart, lungs, and abdominal viscera. The 11th pair of nerves are the accessory nerves, which innervate the trapezius and sternocleidomastoid muscles of the head and neck. Finally, nerve 12 is the hypoglossal nerve and is responsible for tongue movements.
Nerves of the skin supplied by the spinal cord are known as dermatomes. We learned how to assess feeling in these nerves using cotton balls and prickly objects. The hand alone has 3 different dermatomes associated with it. The hand also has three different nerves. The median nerve, the radial nerve, and the ulnar nerve are all responsible for sensation in different parts of the hand. The radial nerve is only found palm side down and is responsible for the thumb and part of the index finger. The ulnar nerve is responsible for the same regions, but on the palmar side of the hand. The median nerve innervates the rest of the hand.
The final section of the class dealt with the eye and ear. The basic structure of the human eye involves the cornea and conjunctiva, which cover the eye surface. The lens is responsible for focusing light. The retina captures and collects light images. The optic nerve carries visual information to the occipital lobe for processing. There are also muscles that move the eye and intrinsic muscles of the eye that contract and dilate the pupils. Using an ophthalmoscope, the interior of the eye can be viewed. The optic disk is the "blind spot" of the eye where the optic nerve exits. We do not notice this blind spot because the blind spots of both eyes are in different locations, so they complement each other. The fovea of the eye is found in the retina and has the highest visual acuity. The retina contains tiny cells with photoreceptors called rods and cones: rods are responsible for low intensity light, and cones are responsible for color vision and high intensity images. There are 3 cones, red, green, and blue, some of which may be absent in color blind patients.
There are several eye injuries. Perhaps the most painful one we learned about is the orbital blow-out fracture. The eye sits in a pit of the skull called the orbit. Upon blunt trauma to the eye, the floor of the orbit can break, causing the soft tissues of the eye to herniate into the sinuses below. A patient with orbital blow-out fracture is unable to look up completely in the affected eye. It sounds extremely painful to me and I thought of myself as a doctor someday helping patients with this horrific injury. This was the injury that made me the most squeemish, not because its particularly gross, but because of the empathy I felt for patients who have had this. There are several other eye injuries that can happen. Blepharitis is inflammation of the follicles of the eye lashes. Myopia is nearsightedness and hyperopia is farsightedness, a condition common in the elderly. Presbyopia occurs with aging as well and is defined by the loss of the ability of the lens to change shape. Presbyopia leads to loss of the ability to read in older patients. Astigmatism occurs with a nonspherical cornea, and disturbs image quality. Diabetic retinopathy occurs when numerous, fragile blood vessels innervate the eye. Accumulation of sugars in the blood vessels leads to damage and loss of vision. Diabetic retinopathy is one of the main causes of blindness in diabetes patients. Glaucoma leads to visual field deficits and is often associated with elevated intraocular pressure. Finally, cataracts occur when the lens shows opacity.
Lastly we looked at the ear. This was also really cool to learn about. The outer ear is known as the pinna and it collects sound, which enters the external ear canal. The ear drum vibrates, which then causes the smallest bones of the body, the malleus and incus with the stapes connected to the cochlea, to vibrate as well and transmit the sound. The cochlea is filled with liquid and transmits the sound to the vestibulocochlear nerves. The middle ear contains the small bones and is bounded by the ear drum and cochlea. The cochlea and semicircular canals (responsible for balance) comprise the inner ear. The auditory tube leads down through the nasopharynx. As a result, middle ear infections are a complication of cold that often occurs because of the drainage of fluids between the two systems. We also learned about deafness. There are two types of deafness, each can be assessed using the Weber and Rinne tests. Air conduction and bone conduction hearing loss can occur. To correct deafness, cochlear implants can be used. The cochlear implant contains a speech processor and electrodes that replace the damaged circuitry of the natural ear to stimulate the vestibulocochlear nerve.
So I know that was a TON of information for one blog post. Welcome to the club of feeling firehosed! :D It was a lot of information to learn, and there was more that we talked about that I did not post here, but this is very reflective of the things we learned. I hope you all found it as interesting as I did! I learned a ton of useful clinical skills and medical terminology that I will use for the rest of my career and my life!
-Julia
