29 Esophagus Flashcards
Layers of the esophagus
Mucosa (squamous epithelium)
Submucosa
Muscularis propria (longitudinal muscle layer)
NO serosa
Musculature of the esophagus
Upper 1/3 - striated muscle
Lower 1/3 - smooth muscle
Middle 1/3 - mixed
Blood supply of the esophagus
Branches off the aorta
Blood supply of the cervical esophagus
Inferior thyroid artery
Blood supply of the abdominal esophagus
Left gastric and inferior phrenic arteries
Venous drainage of the esophagus
Hemi-azygous and azygous veins
Lymphatic drainage of the esophagus
Upper 2/3 drains cephalad
Lower 1/3 drains caudad
Path of the right vagus nerve
Travels on posterior portion of the stomach as it exits the chest - becomes the celiac plexus
Criminal nerve of Grassi
Branch of right vagus nerve
Causes persistent high acid levels if left undivided after vagotomy
Path of left vagus nerve
Travels on anterior portion of the stomach, goes to liver and biliary tree
Course of the thoracic duct
Travels from right to left at T5-4, ascends to mediastinum
Inserts into left subclavian vein
Upper esophageal sphincter
15cm from incisors
Cricopharyngeus muscle - circular muscles, prevents air swallowing
Innervated by the recurrent laryngeal nerve
Normal UES pressure at rest?
60mmHg
Normal UES pressure with food bolus?
15mmHg
What is the most common site of esophageal perforation?
Cause?
Cricopharynegeal muscle
Occurs with EGD
Cause of aspiration after brainstem stroke?
Failure of cricopharyngeus to relax
Lower esophageal sphincter
40cm from incisors
Relaxation mediated by inhibitory neurons
Normally contracted at resting state (prevents reflux)
Anatomic zone of high pressure (not technically a sphincter)
Normal LES pressure at rest?
15mmHg
Normal LES pressure with food bolus?
0mmHg
Anatomic areas of eosphageal narrowing?
Circopharyngeus muscle
Compression by the left mainstem bronchus and aortic arch
Diaphragm
What initiates swallowing?
CNS
Swallowing stages?
Primary peristalsis - occurs with food bolus and swallow initiation
Secondary peristalsis - occurs with incomplete emptying and esophageal distention; propagating waves
Tertiary peristalsis - non-propagating, non-peristalsing (dysfunctional)
State of UES/LES between meals?
Contracted
Swallowing mechanism
Soft palate occludes nasopharynx
Larynx rises and airway opening is blocked by epiglottis
Cricopharyngeus relaxes
Pharyngeal contraction moves food into esophagus
LES relaxes soon after initiation of swallow (vagus mediated)