Gastrointestinal tract and salivary glands
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha in Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
The pharynx is a 12.5 cm long tube of skeletal muscle that extends from the base of skull (CV1) to the lower border of the cricoid cartilage (CV6) where it is continuous with the oesophagus. It lies anteriorly to the cervical vertebral bodies and associated fascia, posteriorly to the nasal cavities, oral cavity and larynx, and medially to muscles of the neck, thyroid gland and carotid sheath. It has three coats: inner mucous coat, central fibrous coat and an outer coat of constrictor muscles, which when contracting serves to push the bolus of food through to the oesophagus. The pharynx can be divided into three parts: nasopharynx; oropharynx; laryngopharynx (hypopharynx). The nasopharynx communicates with the nasal passages via the two posterior nares, while the oropharynx communicates anteriorly with the oral cavity. The laryngopharynx communicates anteriorly with the triangular entrance to the larynx, which is closed off during deglutition by the epiglottis cartilage. Anatomical structures that may also be visualised within the pharynx include the paired piriform sinuses and valleculae, and the indentation of the cricopharyngeus muscle, forming the upper oesophageal sphincter (UOS).
History Stations
Joseph Manjaly, Peter Kullar, Alison Carter, Richard Fox in ENT OSCEs: A Guide to Passing the DO-HNS and MRCS (ENT) OSCE, 2019
The palatine tonsils form part of Waldeyer’s ring of lymphoid tissue in the pharynx along with the adenoid pad, lingual tonsils and mucosa-associated lymphoid tissue (MALT). They sit within the tonsillar fossa, bordered anteriorly by the palatoglossal arch (anterior pillar) and posteriorly by the palatopharyngeal arch (posterior pillar). Acute tonsillitis involves inflammation of the palatine tonsillar tissue and is extremely common in the United Kingdom, especially in the paediatric population; and contributes to missed days of school and work every year. There are other causes of ‘sore throats’ that are worth bearing in mind including viral upper respiratory tract infections, pharyngitis, and in the adult population, Candida, gastro-oesophageal reflux and malignancy. The history is vital for both diagnosis and importantly establishing frequency of episodes and the impact on the child in context, e.g. looming GCSEs. In the exam setting it is important to remember the potential ‘hidden agenda’ that could be held by the parents, in this case arranging a tonsillectomy for their child. Acute tonsillitis can be viral or bacterial in origin, with group A beta-haemolytic streptococcus being the most common organism. Glandular fever, secondary to Epstein–Barr virus, can present similarly to acute bacterial tonsillitis, with a typically longer history of symptoms. There are other viral causes including adenovirus and respiratory syncytial virus which may be complicated by superadded bacterial infection.
The digestive system
Laurie K. McCorry, Martin M. Zdanowicz, Cynthia Y. Gonnella in Essentials of Human Physiology and Pathophysiology for Pharmacy and Allied Health, 2019
The pharynx is the cavity at the rear of the throat and links the mouth with the esophagus. It serves as a common passageway for both the respiratory and the digestive systems. The swallowing reflex takes place largely in the pharynx. This is an example of an all-or-none reflex in which, once the process has begun, it cannot be stopped. Swallowing may be initiated voluntarily when the tongue pushes a bolus of food toward the back of the mouth and into the pharynx. The stimulation of pressure receptors in the pharynx results in the transmission of nerve impulses to the swallowing center in the medulla of the brainstem. This elicits a coordinated, involuntary reflex that involves the contraction of muscles in the appropriate sequence. A wave of contraction sweeps down the constrictor muscles of the pharynx. The epiglottis moves downward over the larynx to seal off the trachea and the upper esophageal sphincter (UES) relaxes, allowing the bolus of food to enter the esophagus. Once the food bolus enters the esophagus, the UES closes to prevent the swallowing of air. This phase of the swallowing reflex is referred to as the pharyngeal stage and lasts approximately 1 s.
Targets for obstructive sleep apnea pharmacotherapy: principles, approaches, and emerging strategies
Published in Expert Opinion on Therapeutic Targets, 2023
The mechanical properties of the upper airspace have been well characterized [23–25] and only the key points relevant to this review focussing on therapeutic targets are identified here. Ultimately, the pharynx is the collapsible region of the upper airway situated between two non-collapsible regions above and below. Contraction of the diaphragm and other primary respiratory muscles creates the driving sub-atmospheric airway pressures necessary for airflow into the lungs (Figure 1). The resulting pressure gradient along the conducting airways from nose to lung includes sub-atmospheric airway pressures in the pharynx that constitute an airway narrowing force (PAirway, Figure 1). The positive pressure applied on the collapsible airway by the surrounding tissue also constitutes a closing force (PTissue, Figure 1). PTissue results from the tissue and bony structures that surround the airspace, with the tissues constrained within those bony structures and compartment (i.e. the mandible and spinal vertebrae).
Liposomal drug delivery to the lungs: a post covid-19 scenario
Published in Journal of Liposome Research, 2023
S. Swathi Krishna, M. S. Sudheesh, Vidya Viswanad
Other than biopharmaceutical hurdles, mechanical, chemical, immunological, and behavioral barriers are the barriers to successful pulmonary drug delivery, also known as a lung defense mechanism. The combined effect of this barrier makes the bioavailability lower for inhaled drugs (, Newman 2017). The human respiratory system can be divided into upper and lower airways act as a mechanical barrier for pulmonary drug delivery. The upper part, also known as the extrathoracic airway, consists of the nose and oro-pharynx. This region prevents the entry of particles into the lungs. The lungs consist of bronchioles, also known as large airways, which restrict the delivery of drugs to the peripheral lung region. The mechanical barrier is more formidable during certain diseases that causes airway narrowing, hypersecretion of mucus, and plugging of mucus. Other than this, lung mucociliary clearance of a drug is another mechanism of drug removal. They remove the deposited drugs from the airways to the oropharyngeal region. As a result, the deposited drug gets cleared from the target site, and the effect diminishes (Ganesan et al. 2013).
Relationship between epilarynx tube shape and the radiated sound pressure level during phonation is gender specific
Published in Logopedics Phoniatrics Vocology, 2023
Alexander Mainka, Ivan Platzek, Anna Klimova, Willy Mattheus, Mario Fleischer, Dirk Mürbe
Another aspect of the perceived loudness of singing is the influence of formants. Bartholomew observed that opera singers produced vowel spectra containing a marked envelope peak near 2.8 kHz, which he ascribed to the larynx tube [7]. Mostly, it is referred to as the singers’ formant cluster. Male singers use articulatory strategies to boost the energy in that frequency region. In this regard, the lowering of larynx and the widening of pharynx are considered crucial mechanisms. In contrast, female singers are adjusting the first two formants when increasing loudness [8]. Based on modelling approaches the VT can contribute an acoustic gain of 10–15 dB [2]. Increase of vocal intensity is typically associated with an increase of formant levels. For adult speakers this holds true only up to 6–8 dB below the personal maximum SPL [9]. According to Cleveland and Sundberg [10] and Sjolander et al. [11], the increase of the level of the third formant (LR3) is roughly 1.4–1.6 times greater than the increase of the level of the first formant (LR1). Within these articles, the peaks of the envelope of sound spectra are defined as formants. For definition and nomenclature of formants see [12] and citations.