Flashcards in USMLE Road Map - Thorax Deck (98):
The manubrium contains ...?
1. The jugular notch.
2. Articulates with the medial end of each clavicle at the sternoclavicular joints.
3. Articulates with the costal cartilages of the first two ribs.
The body of the sternum articulates with the ...?
Manubrium at the sternal angle.
The costal cartilage of the 2nd rib articulates at the ...?
The xiphoid process articulates with the body and provides an ...?
Attachment site for the diaphragm and the abdominal musculature.
The sternal angle is located at the ...?
Junction of the manubrium with the body of the sternum.
The sternal angle is an important anatomic landmark:
1. Located at the level of the horizontal plane intersecting the sternal angle and the disk between the T4 and the T5 vertebrae.
2. The trachea bifurcates into the right and left primary bronchi.
3. The arch of the aorta rises from the ascending aorta.
4. The azygos vein drains into the SVC.
12 pairs of ribs articulate posteriorly with the thoracic vertebrae. The HEAD of most ribs articulates ...?
With the bodies of the adjacent thoracic vertebrae and the intervertebral disk at the costovertebral joints.
12 pairs of ribs articulate posteriorly with the thoracic vertebrae. The TUBERCLE of most ribs articulates with ...?
A transverse process at a costotransverse joint.
Fractures of a rib occur ...?
Just anterior to the angle of the rib, the weakest point of the rib, and may cause a pneumothorax.
Main muscles of respiration:
2. External/internal intercostals.
3. Transversus thoracis muscle.
Sensory innervation of the diaphragm:
Phrenic nerves and sensory fibers in intercostal nerves that innervate the periphery of the diaphragm.
An irritative lesion of the phrenic nerve causes ...?
Involuntary contractions of the diaphragm and may result in HICCUPS.
A destructive lesion of a phrenic nerve may result in ...?
Paralysis and PARADOXICAL movement of 1/2 of the diaphragm.
--> The paralyzed dome of the diaphragm fails to descend upon inspiration, and is forced superiorly by an increase in intra-abdominal pressure.
The external intercostal muscles:
1. Elevate the false ribs, which increases the transverse diameter of the thorax.
2. They also elevate the true ribs, which increases the anteroposterior diameter of the thorax.
The internal intercostal and transversus thoracic muscles aid in ...?
EXPIRATION - Passive elastic recoil is the main mechanism of expiration.
The SCM, scalene (anterior, middle, and posterior), and pectoralis major/minor also ...?
Attach to ribs and act as accessory muscles of inspiration.
Muscles of the anterior abdominal wall - The rectus abdominis, the external oblique, and the internal oblique - are used in ...?
Forced expiration and in the Valsalva maneuver (forced expiration against a closed airway).
Innervation of thoracic wall - Intercostal nerves:
The ventral rami of the T1 through T11 spinal nerves + The subcostal nerve - The ventral ramus of T12 - Innervate the intercostal muscles and the skin of the thoracic wall.
Blood supply to the thoracic wall:
Branches of 3 arteries --> A pair of internal thoracic arteries and the descending aorta - Supply the thoracic wall.
The anterior intercostal arteries supply the anterior thoracic wall:
Arise from the internal thoracic artery or a branch of it, the MUSCULOPHRENIC artery.
The internal thoracic arteries are branches of ...?
Tributaries of the internal thoracic veins and the azygos system drain the ...?
Anterior intercostal veins drain ...?
The anterior chest wall and empty into the internal thoracic veins, which drain into the brachiocephalic veins.
Posterior intercostal veins drain the ...?
Posterior and lateral thoracic walls and empty into hemiazygos veins on the left and the azygos vein on the right.
The hemiazygos vein ...?
Crosses the midline to drain into the azygos vein.
The intercostal nerves and the intercostal blood vessels course ...?
Through the superior part of each intercostal space protected by the costal margin of an underlying rib.
--> In these neurovascular bundles, the vein lies superior, the artery is in the middle, and the nerve lies inferiorly (a "VAN" arrangement).
Breasts are ...?
Modified sweat glands situated in the superficial fascia of the thoracic wall that enlarge in females during menstrual cycle and during pregnancy and produce milk after the birth of an infant.
Breasts consists of ...?
15-20 lobes that open by way of individual lactiferous ducts on to the nipple.
Suspensory (Cooper's) ligaments:
Separate the lobes and attach to the skin.
The breasts are supplied by ...?
1. Internal thoracic artery.
2. Lateral thoracic artery.
3. Anterior/posterior intercostal arteries.
Lymphatic drainage of the breast:
1. Most --> Axillary nodes.
2. Parts of the medial quadrants drain to parasternal lymph nodes.
Breast adenocarcinomas mainly metastasize to ...?
1. Axillary nodes.
2. Parasternal nodes.
3. Opposite breast.
4. Nodes of the anterior abdominal wall.
In a radical mastectomy:
The breast is removed along with the pectoralis major/minor muscles + axillary nodes + vessels + tributaries of the axillary vein.
Which nerves may be damaged during mastectomy?
1. Long thoracic nerve.
2. Thoracodorsal nerve.
Lesion of the long thoracic nerve:
Weakness in protraction and upward rotation of the scapula and a "winged scapula" at rest.
Lesion of the thoracodorsal nerve:
May result in weakness in extension, adduction, and medial rotation of the arm at the glenohumeral joint.
Cervical parietal pleura (the cupola) extends into the ...?
Root of the neck superior to the medial 1/3 of the clavicle and the 1st rib.
Parietal or visceral pleura is sensitive to pain?
Visceral pleura innervation?
Sensory nerves that course with autonomic nerves - Insensitive to pain.
The needle may be introduced into the pleural cavity in the midaxillary line in the 9th intercostal space after passing through:
2. Superficial fascia.
3. The 3 layers of intercostal muscles.
4. Parietal pleura.
--> To avoid intercostal nerves, the needle is inserted into the inferior part of the interspace.
To anesthetize the intercostal nerve for relief of pain associated with a rib fracture, the needle is inserted into ...?
The superior part of the interspace.
Each lung has a ... at the site where the lung becomes covered by visceral pleura.
Structures in the root enter or exit the lung through the hilus. Each root contains:
1. A main bronchus.
2. A pulm. artery and two pulmonary veins.
3. Bronchial arteries that supply lung tissue.
4. Autonomic nerves + sensory nerves.
5. Lymphatic vessels.
In the hilus of the right lung, the upper lobar bronchus is ...?
SUPERIOR to the pulm. artery and the pulm. veins.
In the hilus of the left lung, the ...?
Pulmonary artery is superior to the main bronchus and the pulmonary veins.
Each lobar bronchus divides into ... segmental bronchi.
MC site of a spontaneous pneumothorax is ...?
The visceral pleura of the SUPERIOR lobe of a lung.
Lymphatic drainage of each lung:
1. Mainly to bronchopulmonary nodes at the hilus.
2. Tracheobronchial nodes.
3. Tracheal nodes adjacent to the trachea.
4. Bronchomediastinal trunk.
Lymph from the right lung enters ...?
A right bronchomediastinal trunk, which empties into the right lymphatic duct.
--> Right lymphatic duct drains into the junction of the right internal jugular vein and the right subclavian vein.
Most of the lymph from the left lung enters a left ...?
Bronchomediastinal trunk, which empties into the thoracic duct --> Lymph from the inferior lobe of the left lung drains into the right lung pathway.
--> The thoracic duct drains into the junction of the left internal jugular vein and the left subclavian vein.
Enlarged supraclavicular node on the right/left:
Right --> Malignancy in the thorax.
Left --> Malignancy in the thorax/abdomen/pelvis.
Thoracic outlet syndrome:
Results from compression of the:
1. Sympathetic trunk at the level of the stellate ganglion.
2. The inferior trunk of the branchial plexus in the root of the neck.
3. The subclavian vessels.
4. Recurrent laryngeal nerve.
Lung autonomic innervation:
PNS/SNS fibers innervate glands and smooth muscle in the trachea, bronchi, and the lungs.
--> Both fibers reach respiratory structures by way of pulm. plexuses --> Extension of the cardiac plexus.
Each pulm. plexus contains:
1. Preganglionic PNS fibers from the vagus.
2. Postganglionic PNS fibers from terminal ganglia in the plexus.
3. Postganglionic SNS axons from cervical and upper thoracic (cardiopulmonary) splanchnic nerves.
These cardiopulmonary splanchnic nerves have their cell bodies ...?
In the superior, middle, and inferior, cervical paravertebral ganglia and in the T1 through T5 paravertebral ganglia.
Preganglionic SNS axons that synapse in these paravertebral ganglia arise from ...?
The T1 through T5 spinal cord segments.
Sensory fibers from baroreceptors in the trachea, bronchi, and lungs:
1. These fibers course with and enter the CNS in the vagus nerves.
2. The lungs and visceral pleura are insensitive to pain.
The SNS innervation of the lung facilitates ...?
Relaxation of smooth muscle in the bronchial tubes --> Dilation of the tubes and allowing a greater volume of respiration.
The PNS innervation of the lung facilitates ...?
Contraction of smooth muscle, which constricts the bronchial tubes.
The mediastinum is the region ...?
Between the PLEURAL CAVITIES.
Thymoma - Signs and symptoms:
1. Obstructed left branchiocephalic vein.
2. Chest pain.
Anastomoses of the SVC to the IVC may occur:
1. Between lateral thoracic veins and superficial epigastric veins.
2. Between superior epigastric veins and inferior epigastric veins.
COTA - Anastomoses in the intercostal spaces:
Between the anterior intercostal arteries (from the internal thoracic artery) and posterior intercostal arteries (from the descending aorta) provide collateral circulation that bypasses the coarctation.
--> Blood flows in the retrograde direction through the posterior intercostal arteries into the descending aorta.
The 2 indentations of the esophagus in the thorax:
On the left --> By the aortic arch.
Anteriorly --> By the left main bronchus.
--> Constricted esophagus.
The 2 other sites of constriction are at the ...?
Origin of the esophagus in the neck and at the esophageal hiatus of the diaphragm.
Carcinomas of the esophagus commonly develop ...?
At one of the 3 sites of constriction in the mediastinum.
A shallowed foreign body may become lodged at ...?
1/3 sites of constriction of the esophagus in the mediastinum.
The thoracic duct courses ...?
Posterior to the esophagus, then deviates to the left, and enters the root of the neck to drain lymph into the junction of the left subclavian and left internal jugular veins.
The left/right vagus nerves pass ...?
Through the superior mediastinum, enter the posterior mediastinum, and pass posterior to the root of the lung, where they form an esophageal plexus on the esophagus.
The fibrous pericardium consists of ...?
Connective tissue, which forms a non-distensible external layer of parietal pericardium - It is fused to the central tendon of the diaphragm.
The oblique and transverse pericardial sinuses are ...?
Recesses of the pericardial cavity situated between the vessels of the heart.
The transverse pericardial sinus is found ...?
Between the ascending aorta and the pulm. trunk and SVC.
The oblique sinus is found ...?
Inferior to the pulmonary veins and to the left of the inferior vena cava.
Sensory branches of the ... nerves innervate the parietal layers of the pericardium.
A site for pericardiocentesis is ...?
At the LEFT XIPHOCOSTAL angle.
Pericardiocentesis - The needle enters the pericardial cavity after passing ...?
Through the skin, fascia, the rectus sheath, the rectus abdominis, the fibrous layer, the serous layer of the parietal pericardium.
The epicardium is the ...?
Visceral layer of the serous pericardium.
The base of the heart forms the posterior surface and is formed mainly by ...?
The left atrium and the 4 pulm. veins entering the left atrium.
The RA consists of ...?
A smooth-walled part (the sinus venarum) + A rough-walled part (including the anterior wall and the auricle) that contains the pectinate muscles.
The crista terminalis separates the ...?
Sinus venarum from the part of the atrium containing pectinate muscles.
The RA contains the openings of ...?
1. Superior vena cava.
3. Ostium of coronary sinus.
4. Openings of anterior cardiac veins.
The RV consists of ...?
1. A rough-walled part with thick muscular walls that contain trabeculae carneae.
2. A smooth-walled part, the conus arteriosus or infundibulum.
The conus arteriosus leads to ...?
The pulm. trunk.
The RV contains the ...?
Septomarginal trabecula or moderator band, which extends from the base of the ANTERIOR papillary muscle to the interventricular septum.
--> The septomarginal trabecula contains the right bundle branch of the interventricular bundle of His, a part of the cardiac conduction system.
The LA consists of ...?
A smooth-walled part and a rough-walled part + the auricle, which contains pectinate muscles.
The LV consists of ...?
1. A muscular wall with trabeculae carneae that is twice as thick as the wall of the RV.
2. A smooth-walled part --> Aortic vestibule, which leads to the ascending aorta.
Sternum - Consists of:
2. The body.
3. Xiphoid process.
The coronary arteries are functional end arteries that establish collateral circulation with each other through anastomoses:
1. Between the anterior and posterior interventricular arteries in the posterior part of the interventricular sulcus in a right dominant heart.
2. Between the circumflex branch of the left coronary artery and the right coronary artery in the posterior part of the coronary sulcus.
Patients have substernal pain that may be referred over the ...?
T1-T5 dermatomes of the thoracic wall that correspond to the same segments of the spinal cord that provide the sympathetic innervation to the heart.
1. Great cardiac vein.
2. Middle cardiac vein.
3. Small cardiac vein.
4. Anterior cardiac veins.
The great cardiac vein courses ...?
With the anterior interventricular artery and drains into the coronary sinus.
The middle cardiac vein courses:
With the posterior interventricular artery and drains into the coronary sinus.
The small cardiac vein courses ...?
With the marginal branch of the right coronary artery and drains into the coronary sinus.
The anterior cardiac veins are ...?
EXCEPTIONS --> They drain the RV and empty directly into the RA.
The AV node is located in ...?
The interatrial septum near the right atrioventricular orifice.
The septomarginal trabecula or moderator band carries ...?
Purkinje fibers from the right bundle branch to the base of the anterior papillary muscle.
Both types of ANS fibers reach the heart by passing ...?
Through either the superficial cardiac plexus situated inferior to the arch of the aorta or the deep cardiac plexus situated anterior to the bifurcation of the trachea.