60. Oesophagus - nerve supply Flashcards
(21 cards)
What are the two main types of nervous supply to the oesophagus?
The oesophagus receives both somatic (voluntary) and autonomic (involuntary) nerve supply.
Which nerve provides voluntary (somatic) motor control to the upper oesophagus?
The vagus nerve (cranial nerve X) provides motor fibers via branches from the recurrent laryngeal nerve to control the skeletal muscle in the upper third.
Which nerve controls involuntary movement in the lower oesophagus?
The vagus nerve (parasympathetic fibers) controls the smooth muscle in the lower two-thirds of the oesophagus.
Which nervous system controls oesophageal peristalsis?
Peristalsis is controlled by the enteric nervous system (local nerve plexuses) and modulated by the vagus nerve.
What is the myenteric (Auerbach’s) plexus?
A nerve network located between the circular and longitudinal muscle layers of the oesophagus, coordinating muscle contractions for peristalsis.
What is the submucosal (Meissner’s) plexus?
A nerve plexus in the submucosa that controls secretions and blood flow within the oesophagus wall.
How does sympathetic nervous supply affect the oesophagus?
Sympathetic nerves reduce peristalsis and decrease gland secretion; they originate from the thoracic sympathetic trunk (T1–T4).
How does parasympathetic nervous supply affect the oesophagus?
Parasympathetic nerves (via vagus) increase peristalsis and gland secretion.
Which nerve provides sensory fibers (pain, stretch) to the oesophagus?
Both vagal afferents and sympathetic sensory fibers carry sensations (like stretch or pain) to the central nervous system.
Why does pain from the oesophagus sometimes feel like chest pain?
Because visceral pain fibers from the oesophagus enter the spinal cord at the same levels as cardiac nerves (T1–T4), leading to referred pain.
What is the role of the recurrent laryngeal nerve in oesophageal innervation?
It provides motor innervation to the upper oesophagus and sensory fibers to the cervical oesophagus.
Does the phrenic nerve supply the oesophagus?
No, the phrenic nerve supplies the diaphragm but does not directly innervate the oesophagus.
Where are the enteric nerve plexuses located in the oesophagus?
Myenteric (Auerbach’s) plexus: between muscle layers
Submucosal (Meissner’s) plexus: in submucosa
What happens to nervous control at the gastroesophageal junction?
Parasympathetic fibers continue to the stomach; neural control shifts focus from peristalsis to gastric motility and sphincter regulation.
What happens to oesophageal nervous control during swallowing?
Swallowing starts voluntarily (somatic control) but quickly shifts to involuntary (reflex control) through the swallowing center in the brainstem and vagus nerve.
Where is the swallowing center located in the brain?
In the medulla oblongata and lower pons (nucleus ambiguus and dorsal motor nucleus of vagus).
How does the nervous system coordinate closure of the airway during swallowing?
By motor signals from the brainstem to the larynx and pharynx muscles, closing the vocal cords and moving the epiglottis.
How does sympathetic stimulation affect the lower oesophageal sphincter (LES)?
It increases tone (contraction) of the LES, reducing likelihood of reflux.
How does parasympathetic stimulation affect the lower oesophageal sphincter (LES)?
It causes relaxation of the LES to allow food to enter the stomach.
What is the role of inhibitory neurons in the oesophagus?
They release nitric oxide and vasoactive intestinal peptide (VIP) to relax smooth muscle during peristalsis and sphincter relaxation.
What neurotransmitters are used by excitatory neurons in the oesophagus?
Mainly acetylcholine, causing muscle contraction during peristalsis.
