USMLE Step 1 Review 03 03 Anatomy Three Sections of the Esophagus

USMLE Step 1 Review 03 03 Anatomy Three Sections of the Esophagus

 

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Let’s continue our USMLE Review with Anatomy from the Gold Standard USMLE Step 1 Audio Review program.

Play USMLE Audio MP3 03 03 Anatomy Three Sections of the Esophagus Below

 

Begin 03 03 Anatomy Three Sections of the Esophagus Transcription

There are three sections to the esophagus, what are they called?

  • The cervical portion, the thoracic portion and the abdominal portion.

The cervical portion runs from just below the inferior pharyngeal constrictor down to where?

  • The upper thoracic opening.

What gland covers the cervical portion of the esophagus in front and extends to the sides?

  • The thyroid gland.

And what artery supplies both the cervical portion of the esophagus and the thyroid gland at that level?

  • The inferior thyroid artery.

What branch of the vagus travels up along the cervical portion of the esophagus sending branches into the cervical portion and diving into the inferior part of the larynx?

  • The recurrent laryngeal nerve. One on each side.

The thoracic portion of the esophagus begins and ends where?

  • It begins at the upper thoracic opening and it ends at the diaphragm.

What is the narrowing called almost half way down the thoracic esophagus?

  • The aortic narrowing.

This is also called?

  • The middle constriction of the esophagus.

What two structures are squeezing the esophagus at this level to create the middle constriction?

  • The arch of the aorta and the tracheal bifurcation, including the left principal bronchus.

What nerve has come down the left side of the left common carotid artery, come underneath the arch of the aorta and then back up along the left side of the esophagus?

  • The left recurrent nerve of the vagus.

What artery does the right recurrent laryngeal nerve branch of the vagus come down the right side of the right common carotid artery, pass underneath this artery and then come back up to the inferior portion of the larynx?

  • The right subclavian artery.

Ok, we’ve talked about upper and middle constriction sphincters of the esophagus, where is the lower esophageal sphincter where the esophagus passes through the diaphragm? And what is the name for the very short portion of the esophagus below the diaphragm and above the cardia of the stomach?

  • The abdominal portion, very short, only one to three centimeters long.

When the esophagus passes through the diaphragm, it is accompanied by what?

  • Two nerves, the vagus trunks.

On what sides of the esophagus to these vagal trunks pass as it goes through the diaphragm?

  • These nerves pass along the esophagus on the ventral and dorsal sides through the diaphragm.

Now these vagal trunks here form a plexus, what is the name of the plexus?

  • The esophageal plexus.

And the esophageal plexus is a continuation of what plexus of the vagus?

  • The pharyngeal plexus.

During inspiration, does the esophagus move away or toward the lower thoracic spine?

  • It moves away.

How far?

  • Up to seven centimeters away.

What is the name for the hole in the diaphragm, where the esophagus goes through?

  • The esophageal hiatus of the diaphragm.

What type of structure or tissue anchors it there?

  • A circular elastic membrane.

And what is the name of this membrane?

  • The phrenoesophageal ligament.

And how many parts does it have?

  • Two, an ascending phrenoesophageal ligament above the diaphragm and a descending phrenoesophageal ligament below the diaphragm.

The phrenoesophageal ligaments are attached to the diaphragm by what two types of fascia?

  • The supradiaphragmatic fascia and the infradiaphragmatic fascia.

What is between the descending limb of the phrenoesophageal ligament and the esophagus just below the diaphragm?

  • The subhiatal fat ring.

What visible feature marks the juncture of the esophageal mucosa and the gastric mucosa at the region just below the diaphragm?

  • The zigzag line.

What physiological factor works to keep the lower sphincter part of the esophagus also called the cardiac sphincter closed?

  • Intra-abdominal pressure.

What is the most important function of this physiological sphincter?

  • To prevent gastric acid from getting up into the esophagus.

If it does so, what is this condition called in its mild form?

  • Reflux esophagitis.

Now we said the cervical part of the esophagus was supplied by branches from the inferior thyroid artery what artery supplies the thoracic part of the esophagus?

  • Two or more esophageal arteries.

And where do they come from?

  • They come directly off the descending aorta.

What artery supplies the abdominal portion of the esophagus?

  • The left gastric artery.

What is the disease called when the autonomic innervation of the smooth muscles of the esophagus degenerate or are destroyed for some reason?

  • Achalasia of the esophagus.

What happens to the esophagus when there is achalasia?

  • It becomes grossly distended, filled with food.

What causes the esophagus to become so distended with food?

  • The lower esophageal sphincter does not open up.

What two paths carry esophageal pain back to the CNS?

  • Both branches of the vagus and branches to the sympathetic chain ganglia in the thorax.

Accordingly, where is esophageal pain felt and where may it radiate?

  • It is felt substernally and it may radiate to the back.

We talked about there being three sphincters of the esophagus, the superior, middle and inferior. But there are actually four places of narrowing of the esophagus where foreign bodies can lodge, where corrosives cause the most injury and where passing down instruments tends to traumatize the tissue and also where carcinoma most frequently happens.

What’s the first?

  • The upper constriction sphincter of the esophagus at the sixth cervical vertebrae and the cricoids cartilage.

What is the second narrowing?

  • This is the first part of the middle constriction of the esophagus where the arch of the aorta presses against the esophagus.

Where is the third narrowing?

  • This is a little further down in the middle constriction of the esophagus where the left bronchus presses against the esophagus.

And finally, where’s the fourth narrowing?

  • This is the lower sphincter part of the esophagus or the cardiac valve where it goes through the diaphragm.

In pediatric patients there is still another area of constriction, where is this?

  • Where the esophagus passes into the thorax.

****END OF TRANSCRIPTION****

 

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