Inferior pharyngeal constrictor muscle
Encyclopedia
The Inferior pharyngeal constrictor, the thickest of the three constrictors, arises from the sides of the cricoid
and thyroid cartilage
. Similarly to the superior
and middle
pharyngeal constrictor muscles, it is innervated by the vagus nerve (cranial nerve X), specifically, by branches from the pharyngeal plexus and by neuronal branches from the recurrent laryngeal nerve.
From these origins the fibers spread backward and medialward to be inserted with the muscle of the opposite side into the fibrous pharyngeal raphe
in the posterior median line of the pharynx
.
The inferior fibers are horizontal and continuous with the circular fibers of the esophagus
; the rest ascend, increasing in obliquity, and overlap the Constrictor medius.
of food is received in the pharynx, the elevator muscles relax, the pharynx descends, and the constrictores contract upon the bolus, and convey it downward into the esophagus.
and/or impaired relaxation of this muscle are currently considered the main factors in development of a Zenker's diverticulum
.
Motor incoordination of the cricopharyngeus can cause difficulty swallowing
.
Cricoid
The cricoid cartilage, or simply cricoid , is the only complete ring of cartilage around the trachea.-Location:...
and thyroid cartilage
Thyroid cartilage
The thyroid cartilage is the largest of the nine cartilages that make up the laryngeal skeleton, the cartilage structure in and around the trachea that contains the larynx....
. Similarly to the superior
Superior pharyngeal constrictor muscle
The superior pharyngeal constrictor muscle is a quadrilateral muscle, thinner and paler than the inferior pharyngeal constrictor muscle and middle pharyngeal constrictor muscle.-Origin and insertion:The four parts of this muscle arise from:...
and middle
Middle pharyngeal constrictor muscle
The middle pharyngeal constrictor is a fanshaped muscle, smaller than the Inferior pharyngeal constrictor muscle.-Origin and insertion:It arises from the whole length of the upper border of the greater cornu of the hyoid bone, from the lesser cornu, and from the stylohyoid ligament.The fibers...
pharyngeal constrictor muscles, it is innervated by the vagus nerve (cranial nerve X), specifically, by branches from the pharyngeal plexus and by neuronal branches from the recurrent laryngeal nerve.
Origin and insertion
The muscle is composed of two parts. The first (and more superior) arising from the thyroid cartilage (thyropharyngeal part) and the second arising from the cricoid cartilage (cricopharyngeal part).- On the thyroid cartilage it arises from the oblique line on the side of the lamina, from the surface behind this nearly as far as the posterior border and from the inferior cornu.
- From the cricoid cartilage it arises in the interval between the Cricothyreoideus in front, and the articular facet for the inferior cornuInferior horn of thyroid cartilageThe inferior horn of thyroid cartilage is short and thick; it is directed downward, with a slight inclination forward and medialward, and presents, on the medial side of its tip, a small oval articular facet for articulation with the side of the cricoid cartilage....
of the thyroid cartilage behind.
From these origins the fibers spread backward and medialward to be inserted with the muscle of the opposite side into the fibrous pharyngeal raphe
Pharyngeal raphe
The Pharyngeal raphe is a raphe that serves as the origin and insertion for several of the pharyngeal constrictors .-External links:*...
in the posterior median line of the pharynx
Pharynx
The human pharynx is the part of the throat situated immediately posterior to the mouth and nasal cavity, and anterior to the esophagus and larynx. The human pharynx is conventionally divided into three sections: the nasopharynx , the oropharynx , and the laryngopharynx...
.
The inferior fibers are horizontal and continuous with the circular fibers of the esophagus
Esophagus
The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...
; the rest ascend, increasing in obliquity, and overlap the Constrictor medius.
Action
As soon as the bolusBolus (digestion)
In digestion, a bolus is a mass of food that has been chewed at the point of swallowing. Once a bolus reaches the stomach, digestion begins....
of food is received in the pharynx, the elevator muscles relax, the pharynx descends, and the constrictores contract upon the bolus, and convey it downward into the esophagus.
Role in human disease
Uncoordinated contraction, and/or Cricopharyngeal SpasmCricopharyngeal Spasm
Cricopharyngeal spasms occur in the cricopharyngeus muscle of the pharynx. These spasms are frequently misunderstood by the patient to be cancer due to the 'lump in the throat' feeling that is symptomatic of this syndrome. In practice, real lumps in the throat, such as a cancer, are generally not...
and/or impaired relaxation of this muscle are currently considered the main factors in development of a Zenker's diverticulum
Zenker's diverticulum
In anatomy, Zenker's diverticulum, also pharyngoesophageal diverticulum, also pharyngeal pouch, is a diverticulum of the mucosa of the pharynx, just above the cricopharyngeal muscle...
.
Motor incoordination of the cricopharyngeus can cause difficulty swallowing
Swallowing
Swallowing, known scientifically as deglutition, is the process in the human or animal body that makes something pass from the mouth, to the pharynx, and into the esophagus, while shutting the epiglottis. If this fails and the object goes through the trachea, then choking or pulmonary aspiration...
.