Online citations, reference lists, and bibliographies.
← Back to Search

Neuromuscular Specializations Within Human Pharyngeal Constrictor Muscles

L. Mu, I. Sanders
Published 2007 · Medicine, Biology

Cite This
Download PDF
Analyze on Scholarcy
Objectives: At present it is believed that the pharyngeal constrictor (PC) muscles are innervated by the vagus (X) nerve and are homogeneous in muscle fiber content. This study tested the hypothesis that adult human PCs are divided into 2 distinct and specialized layers: A slow inner layer (SIL), innervated by the glossopharyngeal (IX) nerve, and a fast outer layer (FOL), innervated by nerve X. Methods: Eight normal adult human pharynges (16 sides) obtained from autopsies were studied to determine 1) their gross motor innervation by use of Sihler's stain; 2) their terminal axonal branching by use of acetylcholinesterase (AChE) and silver stain; and 3) their myosin heavy chain (MHC) expression in PC muscle fibers by use of immunocytochemical and immunoblotting techniques. In addition, the specialized nature of the 2 PC layers was also studied in developmental (newborn, neonate, and senescent humans), pathological (adult humans with idiopathic Parkinson's disease [IPD]), and comparative (nonhuman primate [adult macaque monkey]) specimens. Results: When nerves IX and X were traced from their cranial roots to their intramuscular termination in Sihler's-stained specimens, it was seen that nerve IX supplied the SIL, whereas branches of nerve X innervated the FOL in the adult human PCs. Use of AChE and silver stain confirmed that nerve IX branches supplying the SIL contained motor axons and innervated motor end plates. In addition to distinct motor innervation, the SIL contained muscle fibers expressing slow-tonic and α-cardiac MHC isoforms, whereas the FOL contained muscle fibers expressing developmental MHC isoforms. In contrast, the FOL became obscured in the elderly and in the adult humans with IPD because of an increased proportion of slow muscle fibers. Notably, distinct muscle fiber layers were not found in the human newborn and nonhuman primate (monkey), but were identified in the 2-year-old human. Conclusions: Human PCs appear to be organized into functional fiber layers, as indicated by distinct motor innervation and specialized muscle fibers. The SIL appears to be a specialized layer unique to normal humans. The presence of the highly specialized slow-tonic and α-cardiac MHC isoforms, together with their absence in human newborns and nonhuman primates, suggests that the specialization of the SIL may be related to speech and respiration. This specialization may reflect the sustained contraction needed in humans to maintain stiffness of the pharyngeal walls during respiration and to shape the walls for speech articulation. In contrast, the FOL is adapted for rapid movement as seen during swallowing. Senescent humans and patients with IPD are known to be susceptible to dysphagia, and this susceptibility may be related to the observed shift in muscle fiber content.
This paper references
M. Karnovsky (1964)
On the function of muscle and reflex partitioning
U. Windhorst (1989)
Neural organization of deglutition
RW Doty (1968)
Respiratory-related pharyngeal constrictor muscle activity in normal human adults.
S. Kuna (1997)
The innervation of the human larynx.
I. Sanders (1993)
Properties of the lingual and LVP branches of the glossopharyngeal nerve
K. Furusawa (1992)
Pathogenesis of upper airway occlusion during sleep.
J. Remmers (1978)
Aspiration pneumonia: a review.
Chokshi Sk (1986)
Etiologic factors in hypocalcemia secondary to operations for carcinoma of the pharynx and larynx.
S. Isaacson (1978)
Architectural, histochemical, and contractile characteristics of a unique biarticular muscle: the cat semitendinosus.
S. Bodine (1982)
A histochemical analysis of identified compartments of cat lateral gastrocnemius muscle
A. English (1982)
The sites of origin and termination of afferent and efferent components in the lingual and pharyngeal branches of the glossopharyngeal nerve in the Japanese monkey (Macaca fuscata)
T. Satoda (1996)
The innervation of the levator veil palatini muscle by the glossopharyngeal nerve
K. Furusawa (1991)
The innervation of the human upper esophageal sphincter
L. Mu (2004)
The innervation of the human posterior cricoarytenoid muscle: Evidence for at least two neuromuscular compartments
I. Sanders (1994)
Effects of aging on sensitivity of the pharyngeal and supraglottic areas.
J. Aviv (1997)
Contributions of the glossopharyngeal nerve and the pharyngeal branch of the vagus nerve to the swallowing process in dogs.
A. J. Venker-van Haagen (1986)
Electromyographic activity from human laryngeal, pharyngeal, and submental muscles during swallowing.
A. Perlman (1999)
Slow tonic muscle fibers in the thyroarytenoid muscles of human vocal folds; a possible specialization for speech
Y. Han (1999)
Swallowing and speech production in Parkinson's disease
J. Robbins (1986)
Adult human mylohyoid muscle fibers express slow-tonic, alpha-cardiac, and developmental myosin heavy-chain isoforms.
L. Mu (2004)
Intrinsic Properties of the Adult Human Mylohyoid Muscle: Neural Organization, Fiber-Type Distribution, and Myosin Heavy Chain Expression
M. Ren (2005)
Muscle fiber types and function
J. F. Hoh (1992)
Gray's Anatomy: The Anatomical Basis of Clinical Practice
Susan Standring PhD DSc (2005)
Neurophysiologic observations of normal deglutition: I. ITS RELATIONSHIP TO THE RESPIRATORY CYCLE.
M. Kawasaki (1964)
One-dimensional polyacrylamide gel electrophoresis
B. Hames (1990)
Muscle Fiber-Type Distribution Pattern in the Human Cricopharyngeus Muscle
L. Mu (2002)
Pharyngeal Dysfunctions and Their Interrelationship in Patients with Dysphagia
O. Ekberg (1985)
Neurophysiologic observations of normal deglutition: Ii. Its relationship to allied phenomena.
M. Kawasaki (1964)
Anatomy and innervation patterns of cat lateral gastrocnemius and plantaris muscles.
A. English (1982)
Functionally complex muscles of the cat hindlimb
C. Chanaud (2004)
Myosin heavy chain–based fiber types in the adult human cricopharyngeus muscle
L. Mu (2007)
Neuromuscular compartments and fiber‐type regionalization in the human inferior pharyngeal constrictor muscle
L. Mu (2001)
Aspiration pneumonia: a review.
S. K. Chokshi (1986)
Pathogenesis of upper airway occlusion during sleep
Remmers Je (1978)
Regional differences in fibre type composition in the human temporalis muscle
J. A. Korfage (1999)
Unloaded shortening velocities of rabbit masseter muscle fibres expressing skeletal or alpha‐cardiac myosin heavy chains.
J. Sciote (1996)
Neuromuscular specializations of the pharyngeal dilator muscles: I. Compartments of the canine geniohyoid muscle
L. Mu (1998)
The Three Bellies of the Canine Cricothyroid Muscle
L. Zaretsky (1992)
EMG activity within the pharynx during speech production.
F. Minifie (1974)
Radiological assessment of dysphagia in Parkinson's disease.
J. Stroudley (1991)
Adult Human Upper Esophageal Sphincter Contains Specialized Muscle Fibers Expressing Unusual Myosin Heavy Chain Isoforms
L. Mu (2007)
Neurologic disorders and aspiration.
M. Brin (1988)
Identification of motor and sensory funiculi in cut nerves and their selective reunion.
H. Gruber (1976)
Muscle fiber types and function.
Hoh Jf (1992)
Pharyngeal narrowing/occlusion during central sleep apnea.
M. S. Badr (1995)
Fibro‐optic study of pharyngeal airway during sleep in patients with hypersomnia obstructive sleep‐apnea syndrome.
B. Borowiecki (1978)
An anatomical and functional analysis of cat biceps femoris and semitendinosus muscles
A. English (1987)
Chemiluminescent detection system for protein blotting
I Durrant (1994)
Sensory nerve supply of the human oro‐ and laryngopharynx: A preliminary study
L. Mu (2000)
Neuromuscular organization of the canine tongue
L. Mu (1999)
Acetylcholinesterase staining of fiber components in feline and human recurrent laryngeal nerve. Topography of laryngeal motor fiber regions.
L. Malmgren (1981)
Myosin isoforms in mammalian skeletal muscle.
S. Schiaffino (1994)
Compartmentalization of muscles and their motor nuclei: the partitioning hypothesis.
A. English (1993)

This paper is referenced by
Diagnostik und Therapie neurogener Dysphagien
M. Prosiegel (2015)
Newly Revealed Cricothyropharyngeus Muscle in the Human Laryngopharynx
L. Mu (2008)
Pharyngeal width and aspiration after stroke
Il Hwan Jung (2019)
Radiation-Related Dysphagia: From Pathophysiology to Clinical Aspects
S. Ursino (2019)
Craniofacial Muscles
L. McLoon (2013)
Functional Anatomy Underlying Pharyngeal Swallowing Mechanics and Swallowing Performance Goals
William G. PearsonJr. (2019)
Anatomie des oberen Ösophagussphinkters
Michael Jungheim (2014)
Classification of pharyngeal muscles based on innervations from glossopharyngeal and vagus nerves in human
Y. Sakamoto (2009)
Altered Pharyngeal Muscles in Parkinson Disease
L. Mu (2012)
Human tongue neuroanatomy: Nerve supply and motor endplates
L. Mu (2010)
Neurology of Swallowing and Dysphagia
Mario Prosiegel (2011)
Differential isoform expression of SERCA and myosin heavy chain in hypopharyngeal muscles
Mohammed ELRABIE AHMED (2019)
The Pharyngoesophageal Segment in Dysphagia and Tracheosophageal Speech
Beatriz Arenaz Búa (2017)
Alpha-synuclein pathology and axonal degeneration of the peripheral motor nerves innervating pharyngeal muscles in Parkinson disease.
L. Mu (2013)
Innervation of the human cricopharyngeal muscle by the recurrent laryngeal nerve and external branch of the superior laryngeal nerve
M. Uludag (2016)
Assessment and behavioural modulation of the upper oesophageal sphincter in healthy swallowing.
Katharina Sophie Winiker (2019)
Parkinson disease affects peripheral sensory nerves in the pharynx.
L. Mu (2013)
Changes in Pharyngeal Width Over Time as an Indicator of Dysphagia in Stroke Patients
Seungki Baek (2020)
Soft Palate and Its Motor Innervation: A Brief Review
Liancai Mu (2019)
Voice outcome following electrical stimulation-supported voice therapy in cases of unilateral vocal fold paralysis
Yehia A.A Ras (2016)
Nerve fiber analysis of the lingual branch of the glossopharyngeal nerve in human adult subjects
H. Saigusa (2020)
Sihler's whole mount nerve staining technique: a review
L. Mu (2010)
Diagnostik und Therapie neurogener Dysphagien
med. Mario Prosiegel (2014)
The Sensory Innervation of the Human Pharynx: Searching for Mechanoreceptors
F. Carlos (2013)
The functional role of the pharyngeal plexus in vocal cord innervation in humans
M. Uludag (2016)
Implications of Peripheral Muscular and Anatomical Development for the Acquisition of Lingual Control for Speech Production: A Review
M. Denny (2012)
Development, Anatomy, and Physiology of the Pharynx
P. Belafsky (2013)
The pharyngeal plexus: an anatomical review for better understanding postoperative dysphagia
S. Gutiérrez (2020)
Effects of neuromuscular electrical stimulation intensity and bolus size on hyoid movement
Christine M. Carmichael (2008)
Transnasal odontoid resection: is there an anatomic explanation for differing swallowing outcomes?
Kathryn M Van Abel (2014)
Anatomy of the Airway
B. Finucane (2010)
Anatomy of the Airway: An Overview
Ronald C. Auvenshine (2010)
See more
Semantic Scholar Logo Some data provided by SemanticScholar