Identification of unopposed intact muscle pair actions affecting swallowing: Potential for rehabilitation

Abstract

Abstract, Muscular actions that cause specific intrinsic distortions of the erec~ pharynx have not been described in detail. This anatomical study utilized three fresh cadaver specimens to determine specific deformations of the larynx and pharynx caused by simultaneous traction oriented along the long a~is Ofspecific paired muscles. Two specimens were axially transected at the midchest to allow the cephalic portion to stand erect. The first spccimen was dissected, distracted, and photographed. Individual muscles of the final specimen were minireally dissected to disturb soft tissue relationships as little as possible. Radiographs in the lateral posleroa~terior projections of the barium-coated pharynx of the final specimen were then obtained during maximum distraction of each muscle pair.Tracings of the pharyngeal outlines were made from these radiographs.Key words: Pharynx, amttomy -Pharynx, physiology ~ Swallowing, rehabilitation.The pharyngeal space is a tube lined by mucosa, Surrounded hy muscle, and supported from the skull base by the mandible, ligaments, multiple Pairedsome "enmUscles" , the. hyoid, and the larynx [I 6]. the "h~ eric ~aesertptions of muscle actions upon .,. ~ arynx exist, with limited descriptions of the ~tcect of COntractions upon the laryngopharynx [2, This study was designed to examine the deformity caused by manual traction upon paired musclcs of thc pharyngeal tube in the erect fresh cadaver, to obtain a better understanding of the effect of individual muscular actions during the normal swallow to complement existing electromyographic data [11]. It is hoped this study will assist in the diagnosis and therapy of specific dysfunctions in the pharynx. Materials and MethodsThree fresh, previously frozen cadaver specimens were variously dissected after thawing. The first was dissected to familiarize us with the normal relalionships and responsiveness of fresh tissue to deforroation in the supine position. The second specimen was dissected following axia{ torso transection at the upper chest level. The specimen was photographed in the erect position while muscle action of matched muscle pairs was simulated using surgical forceps to provide maximal traction oriented along the muscle tiber axis (Fig. II. The third specimen was also axially transsected at the upper chest to allow it to stand upright. Lateral erect radiographs were obtained with the head supported in mild hyperextenskm. The dermis and platysma were then removed and additional lateral radiographs were obtained with the specimen in the tni/dy extended erect position. The remaining intrathoracic structures (trachea, lung, great vessels) were removed to reduce gravitational resistance to pull and, hence, more realistically simulate the {iving condition by which the inflated lungs and diaphram support the trachea. I.aterul radiographs were then obtained while maximal traction using surgical clamps ~vas applied to each muscle pair toward the muscle origin along the fiber orientation (Fig. 2). The mouth and pharynx were then coated wit...

Biofeedback in the treatment of a selected dysphagic patient

“…Curtis et al presented a detailed account of specific muscle pairs responsible for pharyngeal muscular movement, which provides a detailed resource for the clinician to refer to in planning clinical treatment [2]. Palmer presents an excellent review of electromyography of the muscles involved in swallowing as well as a comprehensible explanation of electromyography and muscle potentials in general [3].…”

“…Foam-pad-style disposable surface sensors (Biomedical Instruments, Inc., Warren, MI) were selected. Since surface electrodes are generally used to record information from a larger area, they were placed vertically under the patient's chin to record not the electrical output from specific muscles but a combined output from what are referred to as the collected suprabyoid muscles responsible for laryngeal elevation during the swallow [2]. This muscle group would specifically include the anterior belly of digastric muscle, the stylohyoid muscle, and the mylohyoid muscle.…”

Swallowing therapy in patients with neurological disorders causing cricopharyngeal dysfunction

“…the pulsion forces exerted by the bolus, which depend on tongue retraction (responsible for oropharyngeal pressures) and laryngeal elevation (responsible for hypopharyngeal pressures). [3,4,8] 2. the traction on the CP segment which is exerted by the superioranterior movement of the larynx [8][9][10][11][12].…”