Para- and Retropharyngeal Spaces
The fascial spaces are theoretical spaces that are created between the layers of the deep cervical fascia and are filled with loose areolar connective tissue. The hyoid bone is the main anatomical structure that limits the spread of infection between the spaces and for that reason they are categorised according to their position in relation to the hyoid bone. The three main groups of fascial spaces are known as the:
- fascial spaces that span the entire length of the neck
This article will highlight the main anatomical information that is known about the parapharyngeal space and the retropharyngeal space. It will also give an extremely brief example of the pathology associated with the fascial spaces.
The Parapharyngeal Space
This fascial space is also known as the lateral pharyngeal space. It is classed as one of the suprahyoid fascial spaces because it is situated on the lateral aspect of the pharynx and is continuous with the retropharyngeal space posteriorly and the submandibular space anteriorly. It runs from the base of the skull caudally towards the hyoid bone and is limited anterosuperiorly by the pterygomandibular raphe. Medially it is bordered by the middle layer of deep cervical fascia known as the buccopharyngeal fascia which covers the superior pharyngeal constrictor muscle. The lateral border is comprised of the superficial layer of the deep cervical fascia which covers the medial pterygoid muscle and the deep portion of the parotid gland.
The Retropharyngeal Space
The retropharyngeal space is a fascial space that transverses the length of the neck in its entirety. It sits posterior to the buccopharyngeal layer of middle cervical fascia which covers the esophagus and the pharynx and is anterior to the alar fascia. It is continuous with the parapharyngeal space anteriorly and the sublingual space. The retropharyngeal space runs between the base of the skull to the level of the seconds thoracic vertebra where the fascial layers fuse. The inferior portion of the space which sits behind the esophagus is also known as the retrovisceral space.
Due to its position, the parapharyngeal space is likely to contract and transmit infections that stem from the teeth, the maxilla and the mandible and the pharynx, including the nasopharynx, the tonsils and the adenoids. The retropharyngeal space is more susceptible to infections that originate in Waldeyer’s tonsillar ring that spread to the retropharyngeal lymph nodes. Also, cellulitis on a dental abscess may infect this space which is worrisome because it may pass into the danger space, which is the space that connects the fascial spaces of the head and neck to the superior mediastinum and can carry an infection into the thorax.