Q5 - Contents of the Thoracic Cavity incl. Pleura & Organs
Terms
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- Origin
- This is the name for the attachment of a skeletal muscle that USUALLY remains motionless during the contraction of the muscle. It is also USUALLY proximal
- Sympathetic Trunk
- This nerve runs along each side of the vertebral column. It receives neurons from anterior rami of the spinal nerves via the sympathetic trunk ganglia. It serves many organs from the head to the pelvis. Because it receives nerves from the intervertebral foramina it is difficult to lift away from the body wall. In the neck it runs with the vagus nerve (X).
- Vagus Nerve
- This is the name for cranial nerve number X
- Pleural Fluid
- This is the name of a watery fluid produced in the thoracic cavity. The fluid comes from the blood. It has three major functions: lubrication, reducing heat buildup, and to create surface tension which causes the lungs to remain against the thoracic wall.
- Thoracic Duct
- This organ is part of the lymphatic system. It drains all lymphatic fluids from inferior to the diaphragm and everything superior to the diaphragm on the left side. It transports these fluids to the left brachiocephalic vein or sometimes the left subclavian or left internal jugular veins.
- Hiatal Hernia
- This is the name for a condition where the esophagus tears free from the two crura (left and right). It usually occurs because the stomach has been pushed superiorly and forces a separation of the crura and esophagus. It is problematic because it usually results in reflux of stomach contents back into the esophagus
- Sternal Angle
- This is at the level between the bodies of thoracic vertebrae 4 and 5. It is an important landmark as it is where the costal cartilage of rib 2, the first rib that can be palpated, joins the sternum. It is also where the manubrium and body of the sternum articulate. The first letter is not "A".
- Lymphatic system
- This system transports fluids that leak out of the capillaries in the tissues. It is also an important part of the imune system as it is where many white blood cells reside until they are needed.
- Dome of the Neck
- This is the superior boundary of the thoracic cavity
- Phrenic Nerve
- This is the spinal nerve that innervates the diaphragm. It originates from C1, C2, and C3 spinal nerves
- Pleural Recess
- This is the space inferior to the lung where there is a pleural cavity. It may fill with fluid and can be drained by entering it superior to rib 9, midaxillary on either side. One should not go inferior to the rib because of the neurovascular bundle that is situated in the subcostal groove.
- Cura (Crus)
- These two structures are associated with the diaphragm. The right one secures the diaphragm to the bodies of lumbar vertebrae 1, 2, and 3. The left one secures the diaphragm to the bodies of lumbar vertebrae 1 and 2.
- Bronchioles
- This is the name of the very small (smaller than 1 mm in diameter) respiratory tubes that lack the cartilaginous rings found in the larger bronchial tubes. They lack cilia and mucus secreting cells so particles that reach the these structures are no longer trapped and swept from the system. They terminate in the alveolar ducts, which in turn lead to the alveoli.
- Esophagus
- This structure is the tube that connects the pharynx with the stomach
- 4 Lobes
- This is the number of parts of the right lung in the cat.
- Lumbar Vertebrae 1 and 2
- This is the orign of the left crus.
- Posterior Vagus Nerve
- This is the name of the nerve found on the posterior side of the esophagus as it passes through the diaphragm
- Connective Tissue
- This is the type of tissue (one of the five major types) that makes up the majority of the trachea and bronchi
- Trachea
- This structure is a tube connecting the larynx with the primary bronchi. It is reinforced with 16 to 20 "C" shaped cartilaginous rings to prevent it from collapsing when the pressure inside drops. The diameter of the rings is approximately 1.5 inches. It is lined with ciliated epithelial cells that sweep mucous upward toward the pharynx. Its is found at the level of cervical vertebra 6 body. Inferiorly it extends to the level of the sternal level when the subject is supine and to thoracic vertebra 7 when standing.
- Obilique Fissure
- Each lung has one of these. It separates the superior lobe of the lung from the inferior lobe of the lung
- Cartilaginous Rings
- These structures have their origin in the gill arches of the developing embryo. In fact they have the same origin as the cartilage of the larynx, the hyoid bone, and the mandible. They support the trachea and help prevent collapse. The are "C" shaped.
- Visceral Pleura
- This is the generic name for the organ that covers one of the thoracic organs. It is primarily epithelial tissue. Its specific name will be derived from the organ it covers. It secretes serous fluid that lubricates, helps dissipate heat, and provides surface tension to help us breathe
- Carina
- This is the name for the ridge on internal surface of the most inferior tracheal ring. It marks the point where the trachea bifurcates into the two primary bronchi. The mucosa is very sensitive here and mechanical stimulation of the mucosa often initiates cough reflex. If a patient is intubated the nurse must be sure the tube does NOT go below this structure
- 3 lobes
- This is the number of major parts of the lung on the right side in humans and the number of parts on the left side in cats.
- Thymus Gland
- This is the an organ that is part of the lymphatic system. It is situated cranial and ventral to the heart in the cat. It also functions as an endocrine gland. It reaches maximum development at puberty and then becomes replaced by connective tissue. Functionally it is also important because it preconditions T-lymphocytes
- Left Vagus Nerve
- This is a nerve that serves the heart and runs parallel to the trachea and phrenic nerve on the left side
- Lungs
- This is the name of the thoracic organs responsible for absorption as well as excretion of respiratory gases.
- Diaphragmatic Pleura
- This is the name for organ that covers the superior surface of the diaphragm. It is primarily epithelial tissue and secretes a serous fluid that lubricates, reduces heat build-up, and creates surface tension that helps us breathe
- Miniaturization
- This is the result of having many small structures rather than a small number of large structures. The advantage of this is that it increases the surface area to volume ratio. This ratio is of great importance when there is absorption, secretion, or excretion occuring at the surface of structures.
- Lymph
- This is fluid that forms outside of the capillary beds in the tissues of the body. The fluid was originally part of the plasma. It is transported back to vessels in the superior portion of the thoracic cavity.
- Right Lymphatic Duct
- This is part of the lymphatic system. It is relatively short and drains the lymph superior to the diaphragm and on the right side into the right brachiocephalic or the great veins at the root of the neck.
- Primary Bronchi
- The trachea bifurcates at its inferior end to give rise to these
- Middle Mediastinum
- This is the subdivision of the mediastinum where we normally find the heart.
- Arcuate Ligament
- This structure forms the attachment of the diaphragm to the posterior abdominal wall and it has a curved shape.
- Pulmonary Pleura
- This is the name for organ that covers the lung. It is primarily epithelial tissue and secretes a serous fluid that lubricates, reduces heat build-up, and creates surface tension that helps us breathe.
- Wider Diameter
- In addition to being more vertical and shorter, this is what the right primary bronchus is relative to the left primary bronchus
- Pleural Ligament
- This is what we call pleura extending between organs, or between an organ and the thoracic wall. They are often two layers thick and we find structures such as veins, arteries, nerves and lymphatic ducts suspended between the layers.
- Superior Mediastinum
- This is the cavity between the pulmonary cavities and superior to the transverse plane connecting the sternal angle with the intervertebral disc between the bodies of thoracic vertebra 4 and 5.
- Inferior MediaStinum
- This is the cavity between the pulmonary cavities and inferior to the transverse plane connecting the sternal angle with the intervertebral disc between the bodies of thoracic vertebra 4 and 5.
- Ribs, Midaxillary Line
- This is the level to which both lungs decend at the midaxillary line
- Pericardium
- This is a special type of pleura that includes a serous membrane and fibrous tissue. The fibrous tissue helps with strength. It surrounds the heart
- More Vertical
- In addition to being wider and shorter, this is what the right primary bronchus is relative to the left primary bronchus
- Lobules
- The lobes are subdivided into these structures. They are functionally separate, but not physically separate. They vary in size from the size of a pencil eraser to the size of a penny.
- Right Vagus Nerve
- This nerve approaches the SA node of the right atrium of the heart. It runs parallel to the right phrenic nerve
- Central Tendon
- This is the name for the structure that serves as the insertion for the diaphragm
- Transverse Fissure
- Only the right lung has this feature that separates the superior lobe from the middle lobe of the lung
- Anterior Vagus Nerve
- This is the name of the nerve found on the anterior side of the esophagus as it passes through the diaphragm.
- Diaphragm
- This organ is primarily skeletal muscle. Functionally it is very important because it is responsible for most breathing at rest. It is dome shaped. In humans it's origin is along its outer margin to the deep surface of the bony thorax, costal cartilage of the ribs 7 to 12, sternum, and lumbar vertebrae 1 through 3. The insertion is at the central tendon. The phrenic nerve serves this organ
- Somatic Nervous System
- This system primarily serves the skeletal muscles (except the pharyngeal arch muscles) external to the body cavity, the bones, and the skin rather than smooth muscles, cardiac muscle, and viscera. We are aware of much of its activity, and often exert conscious control while it is active. It is a functional subdivision of the peripheral nervous system.
- Posterior Mediastinum
- This is the cavity between the pulmonary cavities, anterior to the vertebral column, posterior to the middle mediastinum, and inferior to the transverse plane connecting the sternal angle with the intervertebral disc between the bodies of thoracic vertebra 4 and 5.
- Heart
- This is one of the three components required to have a functional circulatory system. It provides pressure for bulk flow
- Right Crus
- This structure secures the diaphragm to the bodies of lumbar vertebrae 1, 2, and 3
- Parietal Pleura
- This is the name for the serous membrane that covers the thoracic wall. This organ is primarily epithelial tissue
- Insertion
- This is the name for the attachment of a skeletal muscle that USUALLY moves during the contraction of the muscle. It is also USUALLY distal
- Superior Vena Cave
- This vessel is found in the superior mediastinum. It transports all the blood from superior to the diaphragm back to the right atrium of the heart. It begins where the two brachiocephalic veins join in the superior thoracic region.
- Anterior Mediastinum
- This is a relatively small space occupied by only one organ, the thymus gland
- Cranial Nerve X
- This is the only cranial nerve to pass into the body cavities inferior to the neck. It is primarily parasympathetic in nature and is the major nerve affecting the heart and most of the gastrointestinal tract. It slows the heart down and speeds up the activity of the gastrointestinal tract. The first letter of this answer is not "V".
- Axis Rotated to Left
- This is what happens to the bottom of the axis of the heart in addition to being tilted anteriorly and tilted to the left. With these three things the heart is in it's anatomical position.
- Left Crus
- This structure secures the diaphragm to the bodies of lumbar vertebrae 1 and 2.
- Potential Space
- When two structures are touching each other, but are not physically attached we say there is one of these between them. For example, there is one of these between the dura mater and arachnoid mater. Normally they touch each other. It would be possible for the space between them to expand, as with a subdural hematoma
- Shorter
- In addition to being wider and more vertical, this is what the right primary bronchus is relative to the left primary bronchus is
- Cardiac Notch
- This feature is found in the superior lobe of the left lung. It begins at the fourth costal cartilage and passes laterally. It is caused by the heart displacing the lung to the left.
- Mediastinum
- This space is a subdivision of the thoracic cavity. It is of importance because this is where we find the heart and most other thoracic organs
- Azygos Vein
- This vessel is dorsal to the right lung in the cat - therefore, it should not be confused with the caudal vena cava that is found medial to the right lung. It drains the blood from the dorsal (posterior) thoracic wall into the cranial (superior) vena cava. It also can serve as an alternate path for the return of blood from caudal (inferior) to the diaphragm if the caudal (inferior) vena cava were to be blocked.
- Surface Tension
- This is a physical property of fluids. It is caused by the attraction of molecules at the surface of the fluid for each other, and effectively creates a "skin" at the surface. This allows things like water insects to walk on the surface of the water. It has functional importance in humans as it is responsible for the lungs staying against the thoracic wall when a person breathes.
- 2 Lobes
- This is the number of parts in a human left lung
- Alveolar Duct
- This structure is the duct between the bronchiole and the alveoli. As with the bronchiole, it lacks cartilaginous rings and cilia. The thin epithelial tube has abundant capillaries surrounding it as well as alveoli attached to the walls. At its terminus it leads to an alveolar sac. The alveolar sac is similar to a cluster of grapes, the grapes being the alveoli.
- Alveolus
- This is the singular spelling for the structures that are the functional units of the lungs. This is where the exchange of the respiratory gasses occurs. They are an example of miniaturization. That means that because of their small size the surface area to volume ration is very high, thereby increasing the efficiency of the exchange. Oxygen is absorbed from the air into the blood and carbon dioxide is released from the blood to the air. Their combined surface area is about 1500 square feet, or about the size of a tennis court
- Pleural Cavity
- This is the space between the layers of pleura. It has a little pleural fluid in it. It is often only a potential space
- Inferior Vena Cava
- This vessel is medial to the right lung - therefore, it should not be confused with the azygos vein that is found posterior to the right lung. It transports all the blood from inferior to the diaphragm back to the right atrium of the heart. It begins where the two common iliac veins join in the inferior abdominal region. In the thoracic cavity the phrenic nerve runs to the diaphragm along this structure.
- Aorta
- This structure is the great vessel that carries blood away from the left ventricle to all the systemic arteries of the circulatory system. The blood in this vessel is normally enriched with oxygen and deficient in carbon dioxide.
- Hyaline Cartilage
- This tissue is of great importance because it is found at articular surfaces of bones as well as forming the epiphyseal cartilage. It is the most common type of cartilage. It is tough and flexible, and at the articular surfaces very smooth. The smooth nature is important in reducing friction between the bones