Mediastinum Lecture 5 Please check our Editing File. ھذا العمل لا یغني عن المصدر الا ساسي للمذاكرة
Objectives At the end of the lecture, students should be able to: Define the Mediastinum. Differentiate between the divisions of the mediastinum. List the boundaries and contents of each division. Describe the relations between the important structures in each division. Text in BLUE was found only in the boys slides Text in PINK was found only in the girls slides Text in RED is considered important Text in GREY is considered extra notes
The Mediastinum Definition It is a thick movable partition between the two pleural sacs & lungs. It contains all the structures which lie in the intermediate compartment of the thoracic cavity. Any structure in the thoracic cavity except the lungs and their pleura
BOUNDARIES OF MEDIASTINUM Superior: Thoracic outlet: manubrium(anterior) 1 st Rib (laterally) 1 st Thoracic vertebra T1(posterior) Anterior: Sternum Posterior: Thoracic vertebrae Inferior: Diaphragm Lateral: Lungs & pleura
DIVISIONS OF THE MEDIASTINUM The mediastinum is subdivided by a Horizontal plane (extending from the Sternal angle* to the lower border of T4) into: Superior mediastinum (S): above the plane Inferior mediastinum: below the plane. Inferior mediastinum is subdivided into: Middle mediastinum (M): contains heart Anterior mediastinum (A): in front of heart S Posterior mediastinum (P): behind heart A M P *Sternal angle is at the junction of the manubrium and the body of the sternum
BOUNDARIES OF SUPERIOR MEDIASTINUM Superior: Thoracic outlet Anterior: Manubrium of sternum Inferior: Horizontal plane Posterior: Upper 4 thoracic vertebrae Lateral: lungs & pleurae
RBV CONTENTS OF SUPERIOR MEDIASTINUM LBC BRACHIO LCC TD SVC T PHERINC LSUB VAGUS T ES (A) Superficial: Thymus Gland. Three Veins: Left brachiocephalic vein Right brachiocephalic vein Superior vena cava Left brachiocephalic vein and Right brachiocephalic vein join together to give superior vena cava. (B) Intermediate: Arch of aorta & its 3 branches: Brachiocephalic artery. Left common carotid artery. Left Subclavian artery Nerves: Left & Right Phrenic Left & Right Vagus (c) Deep: Trachea Esophagus Thoracic Duct
CONTENTS OF SUPERIOR MEDIASTINUM (A) Superficial: (B) Intermediate: (C) Deep:
CONTENTS OF SUPERIOR MEDIASTINUM 4 ARTERIES: arch of aorta, brachiocephalic, left common carotid, left subclavian 4 NERVES: right & left vagus, right & left phrenic 3 VEINS: right & left brachiocephalic, Superior Vena Cava 2 TUBES: trachea & esophagus 1 GLAND: thymus 1 DUCT: thoracic duct
CONTENTS OF SUPERIOR MEDIASTINUM **Extra picture for illustration
Level Of: Level of T4 1- Sternal angle 2- Second costal cartilage Why is it important? 1-Bifurcation of pulmonary trunk. 2-Beginning & termination of arch of aorta. 3-Bifurcation of Trachea.
Boundaries of Posterior Mediastinum Behind the heart Superior: Horizontal Plane. *Superior mediastinum. Inferior: Diaphragm Anterior: Heart Posterior: Thoracic vertebrae From T5 to T12 Lateral: Lungs & Pleurae
Contents of Posterior Mediastinum Esophagus* Vagus nerve*: around esophagus Thoracic duct*: posterior to esophagus Azygos vein: posterior & to the right of esophagus Descending aorta: posterior & to the left of esophagus Right & Left sympathetic trunks Lymph nodes *pass through both the superior & posterior mediastina
MIDDLE MEDIASTINUM (الا كبر) contains the heart. Site: Between anterior & posterior mediastinum Contents : 1- Heart & Pericardium (all the big vessels entering and leaving the heart) Pulmonary Trunk 2- Ascending Aorta (from left ventricle) 3- Pulmonary trunk (at the level of T4) 4- Superior*& inferior vena cava 5-Right & Left pulmonary veins 6-Right & Left phrenic nerve Ascending Aorta Superior vena cava Right Pulmonary Veins Right Phrenic nerve Inferior vena cava Diaphragm Heart Left phrenic nerve Left Pulmonary veins 7- lymph nodes(it will be in all the mediastinum)*the superior vena cava appears in BOTH the superior (upper part of SVC) and middle (lower part SVC) mediastinum
Boundaries : ANTERIOR MEDIASTINUM Superior: Horizontal plane Inferior: Diaphragm Anterior: Body & xiphoid process of sternum* Posterior: Heart Lateral: Lungs & Pleurae Content: 1- Thymus gland** 2-Lymph Nodes *Do not say the manubrium **Appears in both the superior and the anterior mediastinum ** the thymus is most anterior of superior and most superior of anterior
It is the 10th cranial nerve. Vagus nerve The right vagus descends to the right side of trachea, forms the posterior esophageal plexus & continues in abdomen as posterior gastric nerve. The left vagus descends between left common carotid & left subclavian arteries, forms the anterior esophageal plexus & continues in abdomen as anterior gastric nerve.
Phrenic nerve Root value C3 - C4 - C5 Course in the thorax: It supplies: The right phrenic descends on the right side of SVC and heart. The left phrenic descends on the left side of heart. Both nerves terminate in the diaphragm. 1. Motor and sensory fibers to diaphragm. 2. Sensory fibers to pleura and pericardium.
Lymphatic vessels in the thorax
Thoracic duct BEGINNING: It is the continuation of cisterna chyli (At the level of L1). COURSE: It passes through aortic opening of diaphragm. It ascends in posterior mediastinum (posterior to esophagus). It ascends in superior mediastinum (to the left of esophagus). TRIBUTARIES: It receives: Lymphatics from all body EXCEPT: right side of thorax. right upper limb. right side of head & neck. End: It ends in the left brachiocephalic vein.
Aorta Ascending aorta: Beginning: at aortic orifice of left ventricle. Course: in middle mediastinum End: continues as arch of aorta (at level of T4) Arch or aorta: Course: in superior mediastinum End: continues as descending thoracic aorta (at level of T4) Descending aorta: Course: in posterior mediastinum End: continues as abdominal aorta through diaphragm Descending Aorta
Questions 1-How many boundaries surround the mediastinum A-2 b-3 c-4 d-5 2-How many main divisions for the mediastinum: A-2 b-3 c-4 d-5 3-The horizontal plane is extending from: A-sternal angle to the upper border of T4 B-sternal angle to the lower border of T4. C-manubrium to the lower border of T4 D-manubrium to the upper border of T4 4-Which of the following is the most superior vein of the mediastinum? A-inferior vena cava C-ascending aorta B-azygos vein D-brachiocephalic veins 5-How many nerves are in the superior mediastinum? A-2 B-3 C-4 D-5 6- Which structure appears in both the superior and posterior mediastinum A-azygos vein B-thymus gland C- thoracic duct D- descending aorta 7- Which of the following is in the posterior border of the anterior mediastinum: A- lung pleura B-heart C- vertebral column D-trachea 8- Which of the following is at the level of T4: A- Bifurcation of the larynx B-Bifurcation of aorta C- Bifurcation of pulmonary trunk D-1st costal cartilage 9- The vagus nerve is the: A- 9th cranial nerve B- 10th cranial nerve C- 11th cranial nerve D- 8th cranial nerve 10- The phrenic nerve gives only sensory fibers to: A-diaphragm B-lungs and trachea C-pleura and pericardium D-esophagus Answers: 1-D 2-A 3-B 4-D 5-C 6-C 7-B 8-C 9-B 10-C
Team Members Lamia Abdullah Alkuwaiz (Team Leader) Rawan Mohammad Alharbi Abeer Alabduljabbar Afnan Abdulaziz Almustafa Ahad Ahmed Algrain Albandari Alshaye AlFhadah abdullah alsaleem Ghaida Alsanad Lojain Azizalrahman Maha Barakah Majd Khalid AlBarrak Nouf Alotaibi Rinad Musaed Alghoraiby Wejdan Fahad Albadrani Faisal Fahad Alsaif (Team Leader) Abdulaziz Al dukhayel Abdulelah Aldossari Abdulrahman Alduhayyim Hamdan Aldossari Mohammed Alomar Saud Alghufaily Hassan Aloraini Abdullah Alomar Fahad Alfaiz Saad Aloqile Abdulmajeed Alwardi Rayyan Almousa Sultan Alfuhaid Ali Alammari Fahad alshughaithry Fayez Ghiyath Aldarsouni Mohammed Alquwayfili Saleh Almoaiqel Abdullah Almeaither Abduljabbar Al-yamane Sultan Al-nasser Majed Aljohani Zeyad Al-khenaizan Mohammed Nouri Abdulaziz Al-drgam Fahad Aldhowaihy Omar alyabis Akram Alfandi Abdulhaziz Alabdulkareem