Anatomy and Physiology of the Esophagus Flashcards

1
Q

4 layers of esophagus

A
  • Mucosa
    • mucous membrane (non-keratinized squamous epithelium)
    • lamina propria
    • mucosa muscularis
  • Submucosa
    • contains vascular, lymphatic, nerve plexus
  • Muscularis propria
    • inner circular muscle layer
    • outher longitudianl muscle layer
  • Adventitia
    • loose connective tissue
    • some vascular, lymphatic, nerve networks
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2
Q

Esophagus does not have what histologic layer that is present throughout the rest of the GI tract

A

Serosa

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3
Q

Properties of muscularis proria throughout esophagus

A

Transition in muscle fiber type:

  • Striated muscle fibers (proximally)
  • Smooth muscle fibers (distally)
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4
Q

Longitudial muscle layer originates from what structure?

A

Posterior aspect of cricoid cartilage

  • Two muscle bundles wrapping laterally and meeting on dorsal aspect of esophagus roughly 3 cm below cricoid
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5
Q

V-shaped area of weakness on dorsal esophagus just distal to cricopharyngeus muscle (covered only by circular muscle layer of mulcularis propria)

A

Laimer’s triangle

  • Due to presence of two muscle bundles wrapping laterally and meeting on dorsal aspect of esophagus roughly 3 cm below cricoid
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6
Q

Area of esophageal weakness that is proximal to cricopharyngeus muscle

A

Killian’s triangle

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7
Q

Inner cicular muscle layer of the muscularis propria is in continuity with what structure?

A

Inferior constrictor muscles

  • Thicker than outer longitudial muscle layer of muscularis propria
  • Transverse orientation in proximal and distal esophagus
    • Remaining fibers have oblique orientation to aid in peristalsis
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8
Q

Blood supply to esophagus

A

Segmental Supply

  • Cervical esophagus: Inferior thyroid artery
  • Thoracic esophagus:
    • Bronchial arteries (1 right, 2 left)
    • Descending Aorta branches
  • Abdominal esophagus:
    • Left gastric
    • Inferior phrenic arteries
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9
Q

Venous drainage of esophagus

A

Segmental

  • Cervical esophagus: inferior thyroid veins
  • Thoracic esophagus:
    • Bronchial veins
    • Azygous vein
    • Hemiazygous vein
  • Abdominal esophagus:
    • Coronary vein of the portal system
  • Submucosal venous plexus of stomach and esophagus connected, permiting coronary-azygous vein portosystemic shunt seen in portal hypertension
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10
Q

Lymphatic drainage of esophagus

A

Not Segmental

  • Lymphatic networks (submucosa most extensive)
    • Drain into collecting trunks that pierce muscularis propria and drain to perisophageal regional lymph nodes and/or thoracic duct
  • Esophageal Lymphatic Drainage Patterns:
    • Proximal esphagus: drains to deep cervical LN
    • Middle 1/3 esophagus: superior and posterior mediastinal LN
    • Distal 1/3 esophagus: gastric and/or celiac LN
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11
Q

Majority of innervation of esophagus

A

Vagus nerve

  • Directly (including recurrent laryngeal nerves)
  • Indirectly (via its fibers)
  • Includes motor, sensory, parasympathetic and sympathetic pathways
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12
Q

Recurrent laryngeal nerve innervates what structures?

A
  • Cricopharyngeus muscle
  • Cervical esophagus
  • Injury may lead to aspiration and dysmotility
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13
Q

Innervation to mid and distal esophagus

A
  • Mid esophagus: direct branches of vagus nerve
  • Distal esophagus: anterior and posterior esophageal plexuses
    • Fibers of each plexus coverge to form left (anterior) and right (posterior) vagus nerves to stomach
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14
Q

Intrinsic innervation of esophagus

A

Myoenteric (Auerbach’s) plexus

  • Between outer (longitudinal) muscle fibers of muscularis propria and submucosal (Meissner’s plexus)
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15
Q

Endoscopic points of esophageal narrowing and average measurements

A
  • Upper esophageal sphincter (14-15cm)
  • Crossing of left main bronchus and Aortic Arch (24-26 cm)
  • Lower esophageal sphincter (36-40 cm)
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16
Q

3 phases of swallowing

A
  • Oral (voluntary)
  • Pharyngeal
  • Esophageal
17
Q

Purpose of esophageal phase of swallowing

A

Transport of volus through opened UES, down esphagus, and through opened LES

18
Q

Defintion of UES

A

High-pressure area ~ 2-3 cm in length that separates pharynx from esophagus

19
Q

Key muscle involved in UES function

A

Cricopharyngeaus

  • At rest, UES tonically contracted (prevents reflux into pharynx and lung aspiration)
20
Q

Definition of LES

A

Physiologic and anatomic area of esophagus that prevents esophageal reflux by remaining tonically contracted.

21
Q

Characteristics of LES

A
  • Relaxation occurs in response to peristalsis
  • Transient relxation (5-30 sec) can lead to normal, brief periods of physiologic reflux
22
Q

GI hormones that can cause relaxation of LES

A
  • Secretin
  • Cholecystokinin (CCK)
  • Glucogon
  • Gastric inhibitory peptide (GIP)
  • Vasoactive intestinal peptie (VIA)
  • Neurotensin
23
Q

Extrinsic factos that can cause increased LES pressure

A
  • Increased intra-abdominal pressure
  • Contraction of diaphragm at level of crus during Valsalva maneuver
24
Q

GI hormone that increases LES tone

A

Gastrin

25
Q

Categories of esophageal contraction

A
  • Primary waves:
    • normal peristaltic contractions triggered by voluntary swallowing
  • Secondary waves:
    • peristaltic waves occuring in response to esophageal distention or irritation
    • carry out “housekeeping” function
  • Tertiatry waves:
    • not coordinated; do not produce effective peristalsis
    • occur in normal patients
    • can occur spontaneously or in response to swallow
    • may be seen in dysmotility disorders
26
Q

Category of esophageal contraction:

Normal peristaltic contractions triggered by voluntary swallowing

A

Primary wave

27
Q

Category of esophageal contraction:

Peristaltic waves occuring in response to esophageal distention or irritation

A

Secondary wave

“Housekeeping” function

28
Q

Category of esphageal contraction:

Not coordinated contraction

May be seen in normal esophagus

May be present in dysmotility disorder

A

Tertiary wave