Main Model
D ESOPHAGUS
Esophagus
The esophagus is a muscular tube that connects the pharynx to
the stomach. It begins in the neck where it is continuous with the
laryngopharynx at the pharyngo-esophageal junction. The esophagus consists of striated (voluntary)
muscle in its upper third, smooth (involuntary) muscle in its lower
third, and a mixture of striated and smooth muscle in between.
Its first part, the cervical esophagus, is part of the voluntary upper third. It begins immediately posterior to, and at
the level of, the inferior border of the cricoid cartilage in the
median plane. This is the level of the C6 vertebra.
Externally, the pharyngo-esophageal junction appears as
a constriction produced by the cricopharyngeal part of
the inferior pharyngeal constrictor muscle (the superior
esophageal sphincter) and is the narrowest part of the esophagus. The cervical esophagus inclines slightly to the left as it
descends and enters the superior mediastinum via the superior
thoracic aperture, where it becomes the thoracic esophagus.
When the esophagus is empty, it is a slit-like lumen. When
a food bolus descends in it, the lumen expands, eliciting reflex
peristalsis in the inferior two thirds of the esophagus. The cervical esophagus lies between the trachea and the cervical vertebral column. It is attached to the trachea by loose connective tissue. The recurrent laryngeal nerves lie in or near the tracheo-esophageal grooves
between the trachea and esophagus. On the right
of the esophagus is the right lobe of the thyroid gland and the
right carotid sheath and its contents.
The esophagus is in contact with the cervical pleura at the
root of the neck. On the left is the left lobe of the thyroid
gland and the left carotid sheath. The thoracic duct adheres
to the left side of the esophagus and lies between the pleura
and the esophagus.
Vessels of Cervical Esophagus
The arteries to the
cervical esophagus are branches of the inferior thyroid arteries. Each artery gives off ascending and descending branches
that anastomose with each other and across the midline.
Veins from the cervical esophagus are tributaries of the inferior thyroid veins. Lymphatic vessels of the cervical part of
the esophagus drain into the paratracheal lymph nodes and
inferior deep cervical lymph nodes.
Nerves of Cervical Esophagus
The nerve supply to the
esophagus is somatic motor and sensory to the upper half and parasympathetic (vagal), sympathetic, and visceral sensory to
the lower half. The cervical esophagus receives somatic fibers
via branches from the recurrent laryngeal nerves and vasomotor fibers from the cervical sympathetic trunks through the
plexus around the inferior thyroid artery.