Morphology of the Human Larynx during the First Five Years of Life Studied on Whole Organ Serial Sections

Abstract

The morphologic development of the human larynx during the first years of life is poorly understood to date. This study used plastinated whole organ serial sections to determine the growth and structure of the infant larynx. The larynges of 43 children 1 to 60 months old were plastinated. Whole organ serial sections were obtained by cutting the resulting specimen with a diamond band saw. The slices were then submitted to computer-assisted morphometric investigation. We found that the subglottic airway rapidly increases in size during the first 2 years of life. Further growth follows a linear mode. The relative proportion of the mucosal lining decreases likewise. In contrast to that in adults, and comparable to that in most mammals, the cartilaginous glottis accounts for 60% to 75% of the vocal folds' length at <2 years. No sexual dimorphism of the larynx exists during childhood. This study supplies detailed morphometric data on the growth and structure of the human larynx during the first years of life. It is the first to use plastinated whole organ serial sections for morphology of the pediatric larynx. Therefore, this study provides quantitative anatomic data of clinical interest that have not been available to date.

Applied Surgical Anatomy of the Larynx and Trachea

“…The data in the following section come from studies on whole organ serial sections of the paediatric larynx during the first 5 years of life [14,15], as well as CT-scan measurements of the paediatric trachea, during the first 6 years of life, in subjects who are asleep or resting quietly [27,28]. These data have been correlated with recommended uncuffed ETT sizes for intubation [59] and with rigid bronchoscopes routinely used for diagnostic and therapeutic endoscopies.…”

“…Eckel et al [14,15] published cross-sectional area measurements of the cartilaginous subglottis (cricoid ring) and subglottic airway (cricoid ring with mucosa) in 43 infant (n = 24) and child (n = 19) larynges. Crosssectional surfaces were converted into diameters for this work, in order to compare them with ETT sizes (Fig.…”

“…Oversized tubes primarily induce pressure necrosis on the medial aspect of the arytenoids. [14] Medical personnel involved in intubation and ETT • management in the PICU should know the tube outer diameter corresponding to the patient's age or be able to refer to a chart containing this information. Although considerable progress has been made and • incidences of postintubation laryngotracheal sten oses have dropped to less than 1-3%, this complication can be devastating for the individual patient and family.…”

Cranial base angulation and growth of the human fetal pharynx

“…Indeed, researchers have already observed broad similarities between the airway morphology seen in the human fetus and the primitive condition found in many extant adult nonhuman primates (Tucker and Tucker, 1975;Harding, 1984;Crelin, 1987;Magriples and Laitman, 1987;Wolfson and Laitman, 1990). For instance, in both the human fetus and the adult nonhuman primates, the midline cranial base is less flexed and the larynx sits much higher in the neck than in adult modern humans (Crelin, 1987;Laitman and Reidenberg, 1993;Eckel et al, 1999). Perhaps therefore the increased cranial base angle documented for mid-term fetal growth (Jeffery and Spoor, 2002) is associated with changes in the configuration of the pharynx, or more specifically, perhaps disproportionate enlargement of the oropharynx relative to the nasopharynx drives basicranial retroflexion in order to preserve the functional integrity of the nasopharyngeal space (Moss, 1968;Burdi, 1976;Jeffery and Spoor, 2002).…”

Anaesthetic Management of Unexpected Subglottic Stenosis in a Neonate with Tracheoesophageal Fistula

“…It extends from lower surface of the true vocal cords to the lower surface of cricoids cartilage. The subglottic airway is considered the narrowest part of airway as it is complete, non expandable and non pliable tube and does not have posterior membranous or muscular section like trachea and larynx [4]. At birth infant larynx is about 1/3rd of size of adult larynx however, it is proportionately larger than that of adult compared to remaining tracheobronchial tree.…”