clinically oriented anatomy of Esophagous.pptx

the anatomy of esophagus

1. A natomy of the esophagus C.O.A 208 Session; 8th session/ 2 nd sems ; pages; 267/ 326-327/339-358/731 References; C.O.A By Richard Snell & Frank Netters atlas

2. Outline Overview Anatomical location and anatomical relations Anatomical course Structure; parts, curvatures, sphincters and layers Constrictions Neurovascular bundle; arterial supply, venous and lymphatic drainage Nerve supply Clinical conditions/ relevance!

3. Anatomical Course The   oesophagus  begins in the neck, at the level of C6. Here, it is continuous superiorly with the laryngeal part of the  pharynx  (the laryngopharynx). It descends downward into the  superior mediastinum  of the thorax, positioned between the  trachea  and the vertebral bodies of T1 to T4.  Then it enters the abdomen via the  oesophageal hiatus (an opening in the right crus of the diaphragm) at T10. The abdominal portion of the oesophagus is approximately 1.25cm long – it terminates by joining the cardiac orifice of the stomach at level of T11.

4. Anatomical Structure The esophagus shares a similar structure with many of the organs in the alimentary tract: Adventitia  – outer layer of connective tissue. Note: The very distal and intraperitoneal portion of the oesophagus has an outer covering of  serosa,  instead of adventitia. Muscle layer  – external layer of longitudinal muscle and inner layer of circular muscle. The external layer is composed of different muscle types in each third: Superior third – voluntary striated muscle Middle third – voluntary striated and smooth muscle Inferior third – smooth muscle Submucosa Mucosa  – non- keratinised stratified squamous epithelium (contiguous with columnar epithelium of the stomach).

5. Parts The esophagus is subdivided into three anatomical segments: cervical, thoracic, and abdominal. Cervical part (4cm):   descends behind the trachea and in front of the bodies of the  cervical vertebrae. Thoracic part (20 cm) : passes down through the superior and posterior mediastinum in from of thoracic vertebrae.  It lies behind the trachea in superior mediastinum and from the  bifurcation of trachea onwards, it passes behind the right  pulmonary artery. left principal bronchus and left atrium ( in the posterior mediastinum).   Abdominal part (1-2cm):  enters the abdomen by passing  through the opening in the diaphragm (at the level of T10 vertebral level. After a short course in the abdomen ( 2cm) opens in the cardiac end of stomach.

6. Curvatures Two gentle curvetures Esophagus sits to the right of the aorta in its upper extent and anterior to it in the lower extent, with the left atrium in close relationship in the anterior aspect . The esophagus also has  antero -posterior curvatures that correspond to the curvatures of the cervical and thoracic part of the vertebral column.  Lateral curvature;

7. Esophageal Sphincters There are two sphincters present in the oesophagus , known as the upper and lower oesophageal sphincters. They act to prevent the entry of air and the reflux of gastric contents respectively. Upper Oesophageal Sphincter The upper sphincter is an anatomical, striated muscle sphincter at the junction between the pharynx and oesophagus . It is produced by the  cricopharyngeus  muscle. Normally, it is constricted to prevent the entrance of air into the oesophagus . Lower Oesophageal Sphincter The lower oesophageal sphincter is located at the  gastro- oesophageal junction  (between the  stomach  and oesophagus ). The  gastro- oesophageal junction is situated to the left of the  T11 vertebra , and is marked by the change from oesophageal to gastric mucosa. The sphincter is classified as a  physiological  (or functional) sphincter, as it does not have any specific sphincteric muscle. Instead, the sphincter is maintained by four factors:

8. Esophageal constrictions These constrictions are: At the start of the esophagus, where the laryngopharynx joins the esophagus, behind the cricoid cartilage. Where it is crossed on the front by the aortic arch in the superior mediastinum. Where the esophagus is compressed by the left main bronchus in the posterior mediastinum.

9. Anatomical Relations

10. Neurovascular bundle Arterial  that supply esophagus: Cervical part of esophagus:   esophageal branches of  inferior thyroid artery. Thoracic part of esophagus  : esophageal branches of descending thoracic aorta and bronchial arteries. Abdominal part of esophagus  : oesophageal branches of left gastric  and left inferior phrenic arteries.

11. Venous drainage of esophagus Cervical part:   into inferior thyroid veins Thoracic part  : into azygous and hemiazygous veins Abdominal part  : into hemiazygous vein (tributary of inferior vena cava) & into left gastic vein ( tributary of portal vein)  *Abdominal part of esophagus is one of the sites portocaval anastomosis.

12. Lymphatic drainage of esophagus Cervical part : into deep cervical nodes Thoracic part : into posterior mediastinal nodes draining into supraclavicular nodes Abdominal part : into left gastric nodes * Hard fixed supraclavicular nodes may be palpated in patients with advanced esophageal cancer .

13. Clinical relevance! Gastro-esophageal reflux disease (GERD) is a common condition in which the stomach contents move up into the esophagus. Reflux becomes a disease when it causes frequent or severe symptoms or injury. Reflux may damage the esophagus, pharynx or respiratory tract.

14. Tracheo -esophageal fistula A  tracheo -esophageal fistula  is a congenital, or acquired, condition in which there's an abnormal connection between your esophagus and trachea (windpipe).

15. Esophageal cancer is more common among men than among women. The lifetime risk of esophageal cancer in the United States is about 1 in 127 in men and about 1 in 434 in women.  Squamous cell esophageal cancer is linked to smoking and drinking too much alcohol. Adenocarcinoma is the more common type of esophageal cancer. Having Barrett esophagus increases the risk for this type of cancer.

16. End