Language of Medicine

In order to appreciate various injuries that occur to the body, it is helpful to also learn the language of medicine. Terms referencing the human body are frequently described in what is known as the anatomic position. This means when the body is standing tall with the face forward, the arms at the sides and with the palms of the hands facing forward. With that position in mind, superior, or also is known as cranial or cephalic, means toward the head. Inferior or caudal means towards the feet. Anterior means towards the front. Posterior or dorsal means towards the back. Medial means towards the midline. Lateral means towards the side. External means towards the surface. Internal means away from the surface. Proximal means towards the main mass of the body. Distal means away from the main mass of the body. Central means towards the center of the body. Peripheral means away from the center of the body. This language is utilized to determine where a certain part of the body is in relation to other parts of the body.

Sometimes, medical professionals also describe planes of the body in relation to anatomic position. Three of those planes are sagittal, coronal, and transverse. Sagittal and coronal planes are both vertical planes along the long axis of the body while the transverse plane is at right angles to the longitudinal axis of the body.

The skeletal system has more than two hundred bones. It also is comprised of many cartilaginous parts which are described as hyaline, elastic and fibrous. Bones provide support for the body and protect its organs. Their cavities inside the bones contain marrow and is where blood formation and storage of minerals occurs, especially calcium and phosphorous. Muscles attach to bones and assist in providing movement of body parts. Most bones can be described as either long, short, flat or irregular.

The contact or union between two or more bones or cartilages is referred to as articulations. This term also describes the degree of motion occurring at joints. The joints are sometimes described by the type of tissue between the boney surfaces. Bones joined by a small amount of fibrous tissue are called fibrous joints. Joints united by cartilage are often referred to as primary or secondary cartilaginous joints. These often are viewed as suggestive of growth. Synovial joints are often encapsulated by an outer sleeve of connective tissue and are freely movable. The term range of motion in joints is suggests the degree of laxity of the joint capsule and the amount of give present in the ligaments that unites adjacent bones. Range of motion indicates the freedom of motion of a joint.

Normally, three types of muscle tissue are present in the body. Blood vessels and organs usually have smooth muscle. The walls of the heart contain what is called cardiac muscles. The muscles of the body are usually referred to as skeletal muscle. The control that we exercise over our body is conducted by approximately six hundred and fifty skeletal or voluntary muscles. Collagen fibers are present at the end of a muscle and they help form tendons which unite the muscle to a bone, for example, that allows movement.

Terms used to describe the specific movement of a muscle away from the anatomic position indicates the direction the muscle moves a part of the body. The terms used for these movements include flexion, extension, abduction, adduction, medial or lateral rotation, circumduction, suppination, pronation, inversion, and eversion. Flexion means bringing a muscle towards the body. Extension means taking the extremity away from the body. External rotation means turning the hand so that the thumb and palm are away from the body. Internal rotation means turning the hand and thumb and palm of the hand towards the body. Abduction means closing fingers together. Adduction means opening fingers. Circumduction means rolling the hand over completely. Suppination means turning the hand away from the body as it extends downward. Pronation means turning the hand towards the body. Inversion means turning the foot onto its outside surface. Eversion means turning the foot on its inside surface or big toe.

The movement of blood to and from capillary beds for the exchange of respiratory gasses, nutrients and metabolites is what is normally referred to as the cardiovascular system. The heart, arteries, capillaries, veins and lymphadics comprise the circulatory system. Frequently, the heart is discussed as if there are two hearts. Venous blood is received in the right chamber of the heart. It is low in oxygen content. It is pumped towards the lungs to be oxygenated. The oxygenated blood is received from the lungs into the left chamber of the heart which in turn pumps it to the rest of the body by way of the aorta. Blood is carried away from the ventricles of the heart by arteries to the beds of the capillary vessels. When there is a weakened section of the wall of an artery or vein that bulges outward this is called an aneurysm. Sometimes this phenomena causes a permanent dilation of the blood vessel. Eventually, if the aneurism continues to dilate the vessel wall becomes so thin it bursts and can cause massive hemorrhage with shock, pain, stroke or death. Varicose veins of the lower extremities is caused by increase venous pressure with dilation of the veins, due mostly to valvular incompetence and gravity from the upright position. This is another common disorder of the vascular system.

Lymph channels and lymph nodes make up what is called the lymphatic portion of the vascular system. This system does not have pumping apparatus and does not form a complete circuit. Lymph nodes are usually found along the course of the lymph vessels and act as small filtering stations for the lymph. Surgeons need to understand the location of the lymph nodes and the direction of the lymph flow because of its relationship to the diagnosis of cancer metastasis. It is commonly thought that cancer cells spread through the lymphadic system. When the cancer cells accumulate they can produce tumor cells at that location. As a result, physicians can often approximate where secondary tumor sites may be located because of our knowledge of lymph flow.

The nervous system and the endocrine system provide for the body’s ability to coordinate its functions. Various stimuli provide for voluntary and reflex actions between various parts of the body. Environmental changes affect how the nervous system responds. The fundamental aspect of the nervous system is the neuron or what is sometimes referred to as the nerve cell. The neurons can transmit nerve impulses from various organs or structures of the body to the brain and spinal cord or they can transmit impulses away from the brain or spinal cord towards the parts of the body. A receptor ending located at the end of each nerve cell respond to sensations such as pain, temperature and pressure. In injury situations involving intractable pain, a neurosurgeon may cut or ablate the sensory nerve roots to eliminate the pain from reaching those nerve endings and hence being transmitted to the brain or spinal cord. Immediate relief can be achieved sometimes below the level of the section ablated. Cutting the nerve endings is called a rhizotomy. When there is sectioning of the pain pathways in the spinal cord, this is called a cordotomy.

The peripheral nervous system includes the distributing nerves of the body and small clusters of nerve cell bodies located in ganglia. Referred pain, that pain on a body surface often far removed from the organ involved, is a function of the peripheral nervous system being activated by pain. Some of the examples of referred pain are: cardiac arrest with pain in the chest wall and also radiating down the inside of the left upper extremity, or gallbladder disease with pain in the right upper abdominal area. Shingles (herpes zoster) is a type of a viral infection of a sensory root ganglion.

The body also has what is known as an autonomic nervous system which is part of the peripheral nervous system. This system gives motor innervation to smooth muscles, cardiac muscles and glands. The autonomic nervous system has two essential parts, the sympathetic and parasympathetic system. The sympathetic portion of the autonomic nervous system can be found in the thoracic and upper two lumbar segments of the spinal cord. The parasympathetic portion of the autonomic nervous system can be found in the brain stem or in the lateral horn of the second, third and fourth sacral segments of the spinal cord.

The elastic covering of the body is known as the skin. This protects against injury and disease, loss of body fluids and temperature changes. The skin has nerve endings that provide information to the brain about the surrounding environment. It also consists of four appendages including the hair, nails, oil glands and sweat glands.

The muscles of the back are layered. The upper limbs are attached to the vertebral column by muscles. For example, a very large muscle called the trapezius muscle is located over the upper portion of the back. The latissimus dorsi muscle is located laterally to the chest. The lavator scapulae and the rhomboidei minor and major are found posteriorly near the medial edge of the scapula. These muscles assist in elevation of the scapula. The serratus anterior muscle is also located near the medial border of the scapula. It provides adherence for the scapula onto the ribcage. There are three muscles that cover the scapula: the superspinatus, infraspinatus and subcapularus. Several tendons that cross the scapula provide the main stability of the shoulder joint. The tendons that cross the scapula form what is called the rotator cuff which acts as a strength for the joint itself. The inferior aspect of this joint is also where dislocations and subluxations can occur.

S-shaped bones called the clavical acts as a strut between the shoulder and the sternum. This bone permits to swing outward from the body. The clavical breaks easily during a fall where the arm is extended as a brace against the fall. The pectoralis major, pectoralis minor and subclavius muscles are the main muscles of the pectoral region.

The female breast is found in the fascia of the pectoral region. It is considered a modified sweat gland and covers the pectoralis major muscle. The female breast is normally located between the second and sixth rib. The patient frequently is the first person to notice any signs of cancer of the breast. Personal exam can sometimes reveal a mass present in the breast. It is important to recognize when a mass exists because any mass could be malignant. Depression or dimpling of the skin occurs when the cancer cells located in the gland enlarge and attach to ligaments thereby causing shortening of the ligaments. As a result of this process, the nipple can retract or invert. In more severe cases, if the cancer is deeper and invades the pectoralis major muscle, upper movement of the whole breast can occur as a result of contraction of this major muscle. Statistics reveal that the most common metastatic neoplasm in women is cancer of the breast. The cancer can also spread to other surrounding tissues. Studies reflect that cancer cells frequently travel through the lymphatics and blood vessels to other parts of the body. A radical mastectomy is often the operation chosen to remove the cancer. This involves taking out a wide margin of tissue and the corresponding lymph nodes. In addition it includes the removal of the breast and the pectoralis major and minor muscles.

The arm is comprised of the biceps muscle, brachia muscle and the triceps muscle. Part of the brachial plexus and cervical plexus innervate the arm The arm is supplied by the ulnar, median, and radial nerves, all of which assist in the cutaneous innervation of hand. The area of the skin supplied by a spinal nerve is called a dermatome. Treating physicians often refer to dermatome patterns to verify the existence of objective manifestation of injury. For example, a part of the forearm and hand is supplied by the eighth cervical spinal nerve. A treating physician attempts to determine whether there is a correlation between a subjective complaint and the corresponding dermatome pattern by testing sensory loss or areas provided by spinal nerves. This assists in obtaining a working diagnosis of specific neurological involvement. Erb-Duchenne paralysis, or what is called upper arm birth palsy (paralysis of the abductors and lateral rotators of the shoulders and the flexors of the elbow), is one of the most common types of injury during childbirth. It can be caused by widening of the angle between the head and the shoulder by force by pulling on the head at birth or using forceps to rotate the fetus in utero. Similarly, it can also be caused by direct force to the shoulder by falling on it for example. This injury can be catastrophic and involves the C5 and C6 vertebrae area of the cervical spine. Damage to the lower cervical spine in the C8-T1 area can cause lower arm injuries (Klumpke’s paralysis). Often, this happens when the arm is stretched upward very forcefully, often resulting in a claw-hand appearance. Fractures of bones near related nerves and blood vessels such as the humerus are often serious as well. Tennis elbow, or what is also called lateral epicondylitys, indicates an inflammation of the lateral epicondyle of the humerus or tissues surrounding it. Physicians usually prescribe rest to cure the problem. Serious injuries to the media nerve, ulnar nerve or radial nerve can also occur in a traumatic incident. For example, a nerve injury to the median nerve can cause loss of sensation for most of the palm and middle fingers and the ring finger. Moreover, an injury to the ulnar nerve can cause motor and sensory loss to the hand. Loss of extension with wrist drop can occur with a radial nerve injury. This could result in the injured person not being able to extend the wrist against gravity.

The hand has basically three muscle groups- thenar, hypothenar and interossein lumbricales. Synovial sheathes surround the tendons at the wrist and in the hand. An injury that occurs frequently is what is called tendo synovitis which is an infection of the synovial tendon sheath. Wounds from a sharp object which carries germs into the sheath can cause this infection. A symptom the injured person feels is tenderness over the sheath and significant pain at the tip of the finger.

Compression of the median nerve by the transverse carpal ligament can cause carpal tunnel syndrome which is very painful. A burning sensation or numbness is felt in fingers as well as weakness or atrophy of the thenar muscles. Inflammation from chronic irritation of the transverse carpal ligament, often from repetitive motion, can cause this problem. Trauma can also cause carpal tunnel syndrome. A surgeon will attempt to divide the transverse carpal ligament can in order to decompress the carpal tunnel and median nerve. If successful, function to the area can occur. Unfortunately, the longer carpal tunnel injury goes untreated, the more difficult it is to obtain full recovery.

The ball and socket shoulder joint consists of the head of the humerus, articulating with a much smaller flat glenoid fascia of the scapuli. It has the greatest freedom of movement of any joint in the body. It is an inherently unstable joint. Dislocation of the shoulder joint is not uncommon. The stability of the joint depends on the strength of the tendons of the scapula muscles.

The elbow is a double-hinged joint. The most common injury to the elbow is inflammation or what is commonly called epicondylitys.

When one falls on an outstretched arm, the radius bears most of the force of the fall, transmitted through the hand. Frequently, one obtains a Colles’ fracture of the lower end of the radius. The hand in this type of an injury is displaced backward and upward.

The thoracic cage is formed by the sternum, the ribs and the thoracic vertebrae. It gives protection for the lungs and heart and attaches to muscles of the thorax, upper extremity and diaphragm. There are generally twelve pair of ribs in the body. What is known as intercostal muscles, intercostal arteries and nerves serve the thoracic area of the body. The thorax contains two pleural sacs and a midline pericardial cavity. The pleural cavity and lung extend into the neck. Therefore, a puncture wound from a knife, needle or bullet superior to the clavicle can penetrate the pleura and the lung and produce air in the pleural cavity which is known as pneumothorax. The lungs are organs of respiration. Inspiration is an active process whereas expiration usually is passive. The trachea functions as the air conduction system for the body. A tracheotomy is a life-saving procedure that is used to provide inspiration and expiration which bypasses an obstruction. This is usually performed by making a midline skin incision above the jugular knotch and deepened so that a metal or plastic tracheal tube can be inserted into the trachea and breathing is re-established.

The pericardial cavity surrounds the heart and proximal portions of the great cardiac vessels. Inflammation of the pericardium can be life-threatening as it results in compression of the heart and circulatory failure. Insufficient blood supply to the heart muscle (myocardial ischemia) can cause a heart attack. This is usually preceded by severe chest pain (angina pectoris) over the area of the heart. A common cause for the reduced blood supply is reduction of the diameter of the lumen of one or more of the coronary arteries caused by accumulation of athlerosclerotic plaques within the inner wall of the artery. Another cause can be a blood clot in the coronary artery. If blood flow is of significant time, local tissue in and around the heart may result, causing permanent loss of muscle fiber. If the damage covers a substantial portion of the heart wall, the heart is unable to maintain function and cardiac arrest or heart attack results. The aorta has a higher incidence of aneurysms than any other artery.

The abdomen consists of the lumbar plexus, diaphragm, abdominal cavity, gastrointestinal tract, small intestine, large intestine, liver, pancreas, spleen, kidney, ureter, and suprarenal gland. The lumbar plexus is formed by the first four lumbar spinal nerves and the twelfth thoracic nerve. The femoral nerve is the larger branch of the lumbar plexus. The diaphragm is a movable, musculotendinous partition between the thoracic and abdominal cavities. It forms the concave roof of the abdominal cavity and the convex floor of the thoracic cavity. A hiatal hernia (esophageal hernia) is the most common site of a diaphragm hernia. It is usually associated with heartburn and often accompanied by regurgitation of gastric contents into the mouth.

The abdominal cavity is the largest cavity in the body. The peritoneum is a membrane that lines the walls of the abdominal cavity. Peritonitis is an inflammation of the peritoneum.

The stomach is the first abdominal subdivision of the alimentary canal which is part of the gastrointestinal tract. A gastric ulcer usually involves bleeding, recurrent pain and gastric outlet obstruction. The small intestine is a tube that is located centrally in the abdominal cavity and is surrounded by the large intestine. The small intestine gradually gets smaller as it descends. A duodenal ulcer can occur in the small intestine. Often patients with serious complications are treated surgically. The large intestine extends from the ilium to the anus.

The liver is the largest gland in the body. The gall bladder is a small sac that serves as a reservoir for bile. Bile secreted by the liver cells is carried away from the liver. The pancreas is an elongated endocrine and exocrine gland that lies on the posterior abdominal wall. Insulin is essential in carbohydrate metabolism. Diabetes mellitus is a deficiency of insulin production from the cells of the pancreas. Loss of carbohydrate metabolism results in increased blood sugar levels, increased sugar in the urine and increased urine output, thirst, hunger and weakness. This is controlled by strict dieting, proper injection of insulin and/or anti-diabetic drugs.

The spleen is a flattened, highly vascular organ. The spleen is usually well protected from traumatic injuries. It is often damaged from blunt abdominal trauma, especially significant blows over the lower left chest or upper abdomen. If the spleen is injured it may rupture and cause hemorrhage and shock. This requires a prompt splenectomy to keep the patient from bleeding to death.

The kidney is a structure that lies on the posterior abdominal wall. It is made up of a left and right kidney. The kidney is surrounded by fat that helps stabilize the organ. If injured, urine may accumulate in the renal pelvis and result in distention of the pelvis, permanent damage to the kidney may result. A blow to the kidney from a blow to the lumbar region of the back or jarring of the body may cause mobility of the kidney leading to permanent damage. The supra renal (adrenal) gland is an endocrine organ next to the kidney.

The ureter carries urine from the renal pelvis to the urinary bladder. The pelvic ureters are the most vulnerable organs in surgery performed on other pelvic areas such as the uterus. The ureter may accidentally be cut with the ovarian vessels. It may be crushed by a clamp or a tie.

The inferior extremity consists of the hip, thigh, knee, leg, ankle and foot. Injury can occur to the bones, muscles, ligaments, tendons and nerves in these respective anatomical parts. Phantom pain, for example, is often felt by patient who have a limb amputated. They still experience pain in the extremity as if it were still there. Apparently stimuli from those nerves are interpreted by the brain as coming from the non-existent limb. The gluteal region is a common site for needle injections. However, care must be given to not injure the sciatic nerve. The injection should be made in the upper, outer quadrant of the buttocks which is not nearly as close to the sciatic nerve and large blood vessels.

A femoral hernia may result from weakness of the lower abdominal wall. This may allow entrance of tissue into the thigh. A herniated disc is a protusion of the nucleus pulposus and pressure on a spinal nerve. This frequently causes pain in the lower back which is usually a result of spasm of the muscles of the back. The level of the disc involved is frequently determined by the sensation deficit of the involved dermatome to the lower extremity and/or by loss of specific muscle reflexes.

Foot drop can be caused by lack of nerve supply to the extensor muscles in the leg. The patient will be unable to extend his foot against resistance. This is frequently due to herniated discs or trauma to the common peroneal nerve which is the most frequently damaged nerve in the lower extremity.

Dislocation of the hip is fairly rare. The hip has stability at the ball and socket joint. It is strong and tough. The ligaments surrounding it are usually strong as well as the musculature. Dislocation of the hip, however, must be reduced surgically and a cast or traction is used to prevent reccurring dislocation.

The integrity of the knee joint depends on the strength of the femoral tibial ligaments and the muscles surrounding the joint, especially the quadriceps femoris. This muscle is capable of functionally assisting the joint even if ligaments are damaged. One of the most common athletic injuries is the rupture of the medial collateral ligament which is frequently accompanied by tearing of the medical meniscus. As the medical meniscus is torn, it may become stuck between the surface of the femur and tibia causing a locking of the joint. Trauma to the lateral side of the knee may damage the anterior and posterior cruciate ligaments.

An uncommon but serious injury to the ankle joint is called Pott’s fracture. The lower part of both the tibia and fibular are broken in this trauma. A physician needs to be very careful that necrosis of the distal end of the fibula does not occur because of poor blood supply.

The neck is made up of a series of triangles such as the anterior triangle, the muscular triangle, the carotid triangle, the submandibular triangle and the submental triangle. An example of an injury to the head and/or neck is an injury to the external laryngeal nerve. This may occur during a thyroidectomy. If the nerve is involved in the ligature used for the superior thyroid artery, the nerve to a muscle is interrupted and the vocal cord cannot be lengthened. With this loss of tension on the vocal cord, the voice may become weak, hoarse and easily fatigued. Similarly, during a thyroidectomy, the inferior laryngeal nerve may be injured. This nerve must be identified and dissected away from the thyroid before removing the gland, otherwise permanent post-operative hoarseness may result. In addition, if only one nerve is involved, the speech is not totally affected and the vocal cord is still functional. However, bilateral cutting of the nerves results in loss of speech and impaired breathing. Horner’s syndrome is a condition that is caused by paralysis of the cervical sympathetic nerves. It may result from pressure of a malignant tumor in the neck or upper lung, surgery or penetrating injuries to the neck. A drooped shoulder may be caused from a wound in the posterior triangle because it can sever a spinal nerve. This in turn denervates the trapezius muscle. Cervical rib syndrome may result from compression of the brachial plexus and sumclavian artery. This condition may cause pain, numbness and weakness if not corrected and may result in muscular atrophy and reflex disorders.

A parathyroid tetany results from the inappropriate removal of all or most of the parathyroids during a total thyroidectomy. Accordingly, a surgeon must identify and leave the parathyroid glands which are usually four in number during the surgery. Removal of the parathyroids may cause muscular spasm, weakness, and nervousness as well as death unless adequate calcium or vitamin D or a parathyroid hormone is provided promptly.

The vertebral column forms the central portion of the axial skeleton of the body. In its normal form, it presents primary and secondary curvatures. An abnormal curvature of the spine is a condition in which a lateral bending of the vertebral column in the thoracic region is present. This is called scoliosis. It may be congenital or acquired from severe sciatica.

The component parts of the typical vertebra are the body and number of processes that surround the centrally located vertebral foramen. This gives strength to the vertebral column and is separated by vertebral bodies and the intervertebral discs. This transverse processes project from the junction of the pedicles and laminae. Intervertebral discs unite adjacent unfused vertebral bodies. These consist of an annulus fibrosus and a nucleus pulposus. This is a soft, gelatinous mass that separates the discs. A herniated intervertebral disc may come from a degenerative process or trauma. If a compression force is excessive, a rupture of the disc occurs. The nucleus pulposus herniates partially or completely through the annulus fibrosis to impinge on a spinal nerve that emerge from the vertebral column adjacent to the disc in this region. This frequently is accompanied by nerve compression, a painful neuralgia, (sciatica) down the back and the lateral side of the leg and into the sole of the foot. Often traction, bedrest and analgesia relieve the pain. If this treatment is ineffective then surgical decompression of the spinal nerves by laminectomy or removal of some of the nucleus pulposus may be necessary to relieve pain.

Another procedure performed for various purposes is called a lumbar puncture. Usually performed at the L4-L5 level, since the spinal cord does not extend inferior to the second lumbar vertebrae. The spinal cord is considerably shorter than the vertebral column. It is important for the surgeon to know the origin of the nerves from the spinal cord and their exit through intervertebral foramina of the vertebral canal. These do not necessarily correspond numerically. For example, in the lower cervical and upper thoracic region, the spinal cord segment is approximately two vertebra proximal to the vertebral level, therefore, the spinus process at C6 overlies spinal segment C8. In the lower thoracic and upper lumbar regions, T11 and T12 spinus process overlie the 5 lumbar spinal cord segments while L1 spinus process overlies the five sacral segments. A surgeon must know this in order to locate a tumor, loss of sensation and similar problems. Loss of sensation over the thumb, an area intervated by C6, would therefore suggest a lamienectomy be performed on vertebra C4.

Excruciating pain over the face, especially areas near the mandibular and maxillary divisions of the fifth cranial nerve, is associated with trigeminal neuralgia. Injections are frequently used to treat this pain. Nerve block is a term signifying loss of sensation in a region. A good way of thinking about this is considering the injection a dentist might perform in order to work on a tooth. Such an injection blocks sensations carried centrally by this nerve. The same procedures are used for nerves extending to the cervical, thoracic and lumbar regions.

Partial or complete surgical removal of the parotid gland and the facial nerve may be damaged thereby causing facial paralysis (Bell’s paralysis). A physician must be careful to identify, dissect and preserve the facial nerve. This is done by seeing where the nerve exits from the stylomastoid foramen and then follow it through the parotid gland. Although sometimes removal of the facial nerve may be necessary, for example, in a malignant tumor. Usually an attempt is made to salvage the nerve if possible. The parotid gland is the largest of the three major salivary glands. Mumps is a common viral inflammatory lesion of the parotid gland and it may spread to the testes and cause sterility. Another injury to the head area is what is called a contrecout fracture. It is a term applied to the fracture of the skull at some distance from the point of contact from the blow. This is because part of the skull is hollow and elastic. The force of the blow may be transmitted to the opposite side. On the other hand, an extradural hemorrhage can result from a trauma to the side of the head over the inferior part of the parietal bone causing fracture of the bone. A subdural hemorrhage is a blood collection in the space between the dura and the arachnoid. It results from a rupture of the large veins that return blood from the surface of the brain. It often is caused by trauma on the front or back of the head, causing significant movement of the brain within the cranium. A subarachnoid hemorrhage often comes from leakage of blood vessels. Aneurysms of the cerebral arteries often occur in or near the circle of Willis. Rupture of such an aneurysm bleeds into the subarachnoid space and is a common cause of a cerebrovascular accident in a young person. Blood detected in cerebral spinal fluid aspirated during a lumbar spinal puncture may be due to hemorrhage of this nature.

There are many lesions of the cerebrum. Usually the symptoms involve vomiting, dizziness, headache, convulsions, partial or complete paralysis. Where the lesion is located usually causes specific symptoms to specific areas of the body. Lesions of the cerebellum may be from tumors, abscesses, cysts or inflammation. These usually involve instability of equilibrium and locomotion with dizziness. Hydrocephalus (water on the brain) is due to an abnormally large accumulation of cerebrospinal fluid within the ventricles of the brain. If this occurs in infants when the cranial bones are not yet united, the internal pressure greatly enlarges the skull as well as the ventricles of the brain. The cerebral cortex becomes thinned out and degenerates causing severe mental retardation. Hydrocephalus may be caused by obstruction of some part of the ventricular system, excessive production of fluid or interference with the absorption of the fluid. It is most commonly caused by scar tissue produced by inflammation, or a tumor.

A stroke or cerebrovascular accident (CVA) is the rupture or occulsion of certain cerebral arteries leading to the internal capsule of the brain. Frequently, a lesion of this nature produces hemiplegia on the opposite side of the body. If the hemorrhage is significant, the portion of the brain supplied by the ruptured artery will degenerate and the neurological deficits will be permanent. Early dissolution of a blood clot and release of the pressure on the cerebral cortex may allow partial or complete return of function. Another common injury to the face caused by trauma is detachment of the retina. The tear in the retina causes blindness in the corresponding field of vision. The retina may be reattached by surgical procedure.