GA-8-24-06
Terms
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- Mediastinum
- -portion of the thoracic cavity found between the two pleural cavities on either side
- Borders of Mediastinum
-
1. Anterior = sternum and costal cartilages
2. Posteriorly = thoracic vertebral bodies and intervertebral discs T1-T12
3. Left and Right = mediastinal pleura - Inferior mediastinum
- -divided into 3 parts, mainly by relationship of pericardium
- Anterior mediastinum
-
-bordered anteriorly by sternum and transversus thoracis muscles
-bordered posteriorly by anterior border of pericardial sac - Superior mediastinum
- -separated from posterior mediastinum by imaginary line drawn from sternal angle directly posteriorly to intervertebral disc between T4 and T5
- Thymus
-
-located in superior mediastinum
-gradually becomes involuted as we become older
-usually bilobed
-a primary lymphoid organ of the body
-receives blood from anterior mediastinal branches of internal thoracic artery as well as from anterior intercostals
-venous drainage through inferior thyroid vein which drains into internal thoracic vein - Thyoma
-
-cancer of thyroid
-can be deadly - Right brachiocephalic vein
- -formed by right subclavian v. and right internal jugular vein
- Left brachiocephalic vein
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-formed by junction of left subclavian vein and left internal jugular
-much longer than right brachiocephalic vein
-passes anterior to vessels coming off arch of aorta - Arch of the aorta
-
-crosses over left main bronchus as it ascends at the bifurcation of the trachea
-at this point it is anterior to the esophagus - 3 Branches of arch of aorta
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1. brachiocephalic trunk
2. left common carotid
3. left subclavian - Phrenic nerve
-
-descends down on lateral aspect of pericardial sac
-runs with pericardiacophrenic artery (branch of internal thoracic artery) - Left Vagus nerve
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-descends between trachea and esophagus
-gives off recurrent left laryngeal branch that hooks under ligamentum arteriosum - Ligamentum arteriosum
-
-remant of ductus arteriosus from embryological development
-connects pulmonary trunk to aorta - Recurrent laryngeal nerve
-
-closely associated w/ left main bronchus
-innervates larynx
-gives off motor branches that innervate esophagus for voluntary movements - Superior part of esophagus
- -voluntary skeletal muscle
- Middle 1/3 of esophagus
- -mixture of skeletal and smooth muscle
- Distal 1/3 of esophagus
- -made up of involuntary smooth muscle
- Are phrenic nerves posterior or anterior to the vagus nerves?
- -anterior
- Posterior mediastinum
-
-area below the superior mediastinum
-border w/ superior mediastinum is intervertebral disc between T4 and T5 - When the esophagus passes through the diaphragm is it anterior or posterior to the aorta?
- -anterior
- Hiatal hernia
-
-when stomach or other organs push back up through diaphragm
-common in obese people - Branches of descending thoracic aorta
-
-right bronchial artery
-2 small left bronchial arteries
-intercostal arteries (posterior)
-superior phrenic branch
-subcostal branch - Thoracic duct
-
-ascends from inferiorly
-drains into the junction of the internal jugular and subclavian vein
-usually lies on left side of esophagus deep to aortic arch - Cisterna chyli
-
-large structure below diaphragm that receives lymphatic drainage from abdominal viscera
-3 major channels pass into here
-gives rise to thoracic duct - Main thoracic duct
- -drains almost entire body except right upper half of torso
- Right lymphatic duct
-
-drains right arm, head, and neck
-terminates by draining into the junction on the right between the right subclavian and internal jugular veins - Esophageal plexus
-
-receives sympathetic innervation from sympathetic chain
-vagus nerve contributes
-inferior 1/3 has parasympathetic and sympathetic innervation
-inferior portion innervated by recurrent laryngeal nerve for voluntary movement
-inferior portion innervated by by sympathetic and parasympathetic for involuntary movement - Anterior vagal trunk
- -continuation of left vagus nerve
- Posterior vagal trunk
- -made up primarily of continuation of right vagus nerve
- Greater Splanchnic nerve
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-T5-T9
-preganglionic sympathetic nerve - What accompanies the aorta through the diaphragm?
-
-thoracic duct
-azygos vein - Lesser splanchnic nerve
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-T10-T11
-preganglionic sympathetic nerve - Least splanchnic nerve
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-T12
-preganglionic sympathetic nerve - Celiac ganglion
- -receives greater and lesser splanchnic nerves
- Aorticorenal ganglion
- -receives least splanchnic nerve
- Accessory hemiazygos vein
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-descends on left side of vertebral column from T5-T8
-crosses over T7-T8 vertebra posterior to thoracic aorta and thoracic duct to join azygos vein - Azygos vein
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-ascends in posterior mediastinum, passing close to right sides of bodies of the inferior eight thoracic vertebrae
-arches over superior aspect of root of right lung to join SVC