The first arrow is in the patient on the left side, entering anteriorly between the 7th and 8th ribs in a 15-degree angle with the arrowhead protruding posteriorly. The serosa cavities that have been penetrated are the parietal serosa and the visceral serosa. The parietal serosa is the outermost layer. The visceral serosa is the innermost layer. Between these two layers are serosal cavities that contain serous fluid. Serosal fluid is blood filtrate, plus secretions by two layers of membrane. This allows for the movement of organs with reduced friction. In this case, the serous membranes affected are the plural, which surrounds the lungs and the peritoneal, which surround some abdominal organs. The pleural membrane is thin, slippery, and moist. It also lines the inside of the rib cage and the diaphragm. It is vital in lubricating the surface so that the lungs can move easily within the thoracic cavity. The peritoneum is the membrane, which forms the lining of the abdominal cavity. It covers most organs, is composed of a layer of mesothelium, and a thin layer of connective tissue. Like a sheet or band of fibrous tissue which lies outside the parietal layer of a serosa and lines the wall of a body cavity. The parietal fascia of the thorax is the endothoracic fascia and the abdomen is the endoabdominal fascia. The endothoracic fascia is tightly connected to the costal pleura, and posteriorly blends with the prevertebral fascia. In the position of the arrow, it passed through the serous membrane, which allows the frictionless movement between the heart and the lungs, which allows the movement of the smooth muscle without damaging the organs. This membrane regulates the movement of fluids and other substances throughout the membrane. Having it punctured by an arrow in this position, it affected the abdomen endoabdominal fascia, passing through the endothoracic fascia which is attached to the costal pleura, and would have passed by or close to the liver moving into the parietal layer of the serosa which lines the wall of the body cavity. The mediastinum lies between the right and left pleura and the position of the arrow would threaten the left pleural space causing potential lung collapse, possible tension pneumothorax or massive haemothorax.
The Autonomic Nervous System works in conjunction with the Sympathetic (SNS) and Parasympathetic Nervous System (PSNS). They help control the heart rate or pulse, respiratory rate, blood pressure and ultimately body mechanism to heat and cool itself – temperature. When there are blunt & penetrating injuries as in the arrow penetration you will see various changes in the Vital Signs; heart rate will definitely increase (higher than usual) to offset the trauma and loss of blood while the cardiac output or blood pressure will drop due to internal bleeding or “shock” symptoms. Due to the Arrow location entering upward into the pleural spaces you would find a dysfunctional respiratory pattern, going from fast to slow, difficulty breathing or shortness of breath “SOB”, which could be a result of the arrow penetrating the pleural space and collapsing the lung causing “air hunger” in the lungs. Reduced tissue perfusion would be the long-term effects of a high heart rate and low blood pressure; blood not going to the extremities but splinting only to the internal major organs; heart, spleen, liver, head. The patient will also probably experience “hypoxia”, inadequate oxygen levels due to blood in the lungs. The result of damaged capillaries; blood and other fluids accumulating in the lungs would cause this. Normal vital signs in adults should be Heart Rate: 60-100 beats a minute, Respiratory Rate: 12-20 breaths per minute, Blood Pressure: 100-139 mmHg/ 60-90 mmHg, Oxygen saturation: 96-100%.
The first arrow penetrated through the endoabdominal fascia, moving upward at a 15-degree angle to the endothoracic fascia continuing into the parietal fascia of the thorax potentially damaging the liver, spleen, left pleural space between the 7th & 8th ribs at this 15-degree angle, with the head protruding posteriorly. The organs that would be of great concern from the arrow penetration the patient would be the diaphragm, lungs, stomach, and spleen, and if lucky the arrow would barely miss the apex of the heart. Membranes that would be affected would be the serosa cavities passing through the serous membranes, which would affect the frictionless movement between the heart and lungs. The mediastinum lies between the right and left pleura; it extends anteriorly from the sternum (under surfaced by the endothoracic fascia) to the vertebral column posteriorly (prevertebral fascia), it contains all the thoracic viscera except for the lungs.
The cardiovascular system is affected by the Autonomic Nervous System and this is blunt penetrating trauma which ultimately affects the heart rate by speeding it up, blood pressure would drop, due to internal bleeding from the damage of the arrow passing through vessels and pleural spaces, respirations due to the penetration into the pleural space as well as the temperature as the loss of blood cools the body and puts the body into “shock” from blood loss. The ANS activation can induce significant changes in atrial electrophysiology and induce atrial tachyarrhythmias, including atrial tachycardia and atrial fibrillation. The heart is rich and innervated by the autonomic nerves.
The 2nd arrow is in the posterior cervical triangle of the neck which borders are formed by the trapezius muscle posteriorly, the sternocleidomastoid muscle anteriorly and the omohyoid muscle inferiorly. This is important since the spinal accessory nerve (Cranial Nerve XI), as well as the Subclavian artery, transverse cervical artery, suprascapular artery, and external jugular vein, is in this area. Other nerves are the spinal accessory nerve, cervical plexus, and brachial plexus. This penetration of both these arrows affects the systemic circuits through the Autonomic Nervous System, Sympathetic and Parasympathetic nervous systems, which affect the vital signs as well as the lowering of the hematocrit and hemoglobin values from loss of blood from both sites of these arrows. Abnormally high or low hemoglobin can lead to symptoms like dizziness, exhaustion, and shortness of breath. The external jugular vein is one of the major veins of the neck region, which could affect the jugular venous pressure. The 2nd arrow could penetrate a vein or artery of the neck as well. Normal hemoglobin levels in a male adult are from 13 to 16.5 and normal hematocrit levels in a male adult should be between 40 to 54%, anything outside of these values will indicate that there is something wrong with the patient and that additional testing or interventions should be done.
The 2nd arrow as in question 4 passes through many of the Nerves and Plexuses; spinal accessory nerve, cervical plexus, brachial plexus, and phrenic nerve. The muscles that can be affected are the posterior triangle, which is crossed about 2.5cm above the clavicle, by the inferior belly of the omohyoid muscle, which divides this into 2 triangles: occipital triangle or subclavian triangle. If you damage the Cranial nerve you may not have the ability to shrug your shoulders or raise your arm above your head (like with combing your hair). The deep layer of cervical fascia surrounds the deep muscles of the neck and the cervical vertebrae column. Damage to this area could cause paralysis of the face, neck through the brachial plexus and nerves. Communication between a neuron and muscle fiber occurs through the neurotransmitters. This will cause a loss of muscle function on the neck, shoulder, and arms.
The neuromuscular junction includes neurons from the spinal cord that excites skeletal muscle, and the many neurons stimulate coordinated muscle contraction. Electrical signals from the brain through the spinal cord travel through the axon of the motor neuron. The axon then branches through the muscle and connects to the individual muscle fibers at the neuromuscular junction. Then the sarcolemma of the muscle fiber that interacts with the neuron is called the motor end plate. In simpler terms, the axon of a motor neuron approaches a muscle that it innervates, it divides into multiple branches, each of which makes a synapse called a neuromuscular junction with an individual muscle fiber. Thus, follows that anyone muscle fiber is innervated by only one motor neuron. This causes the muscles to move, an interruption can alter body movement.
HYALINE CARTILAGE: Is a translucent cartilage; bluish-white in color, with firm consistency and a lot of collagen. This cartilage does not contain nerves or blood vessels. It is covered externally by a fibrous membrane; perichondrium. The main cell types in cartilage are chondrocytes, the ground substance is chondroitin sulfate, and the fibrous sheath called perichondrium. There are 3 types of cartilage: hyaline, fibrous, and elastic cartilage. The most common found location of hyaline cartilage is in the ribs, trachea, nose, and larynx. It can also be found in adults at the end of bones in free-moving joints as articular cartilage. This cartilage provides flexibility and support.
EPITHELIUM LINING OF THE TRACHEA: To the left of the hyaline cartilage in the wall of the hyaline cartilage is the mucosa, including epithelium, which has cilia and which includes mucus-secreting goblet cells, which are only one cell layer thick, but appears to be stratified. The epithelium is also found in the linings of the upper respiratory tract. Epithelial cells produce mucus, which helps to moisten and protect the airways. The cartilage ring is immediately covered, on both surfaces with bright pink perichondrium.
LAMINA PROPRIA: Is a thin layer of loose areolar connective tissue, which helps line various tubes in the body, like the respiratory tract. The epithelium and Lamina Propria is the combination that makes mucosa or mucous membrane. The Lamina Propria supports the epithelium, which contains an abundance of elastic fibers. It is rich in immune cells known as lymphocytes. This tissue is very important in helping with inflammation and wound healing.
Any injury to this area from a penetrating trauma to the neck or chest could cause obstruction of the airway resulting in life-threatening respiratory insufficiency, which can lead to death. The tracheal fragments would splinter and not be able to maintain airway continuity. Clinically the patient would have hoarseness, stridor, crepitus or respiratory distress. The position of arrow #2 could cause damage to any of these areas of the trachea. Stabilizing the airway would be the first thing you would do if you were caring for this patient, then you would check for excessive bleeding through visual bleeding or X-ray or through a complete blood count (CBC), which provides the Hemoglobin and Hematocrit levels. You would look at the chest with arrow #1 and check for pneumothorax that may require a chest tube and presence of a haemothorax; bleeding into the pleural spaces. You would also be very concerned that the arrow penetrated the cardiac sack or liver, and spleen. This person would be very critical and would require immediate treatment for survival to occur.