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Parapharyngeal space
Parapharyngeal space
Parapharyngeal space
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Parapharyngeal space
Lateral head anatomy detail
Muscles of the pharynx and cheek.
Details
Identifiers
Latinspatium lateropharyngeum,
spatium pharyngeum laterale,
spatium parapharyngeum
MeSHD000080886
TA98A05.3.01.117
TA22883
FMA84967
Anatomical terminology

The parapharyngeal space (also termed the lateral pharyngeal space), is a potential space in the head and the neck. It has clinical importance in otolaryngology due to parapharyngeal space tumours and parapharyngeal abscess developing in this area. It is also a key anatomic landmark for localizing disease processes in the surrounding spaces of the neck; the direction of its displacement indirectly reflects the site of origin for masses or infection in adjacent areas, and consequently their appropriate differential diagnosis.[1]

Anatomical boundaries

[edit]

The parapharyngeal space is shaped like an inverted pyramid. Lateral and inferior to the parapharyngeal space is the carotid sheath, containing the internal carotid artery and cranial nerves IX, X and XI. Behind both the parapharyngeal space and carotid space lies the retropharyngeal space, and deep to this a potential space known as the danger space. The danger space serves as an important pathway for complicated infections of the posterior pharynx to enter the chest and spinal column. Anterior to the parapharyngeal space is the masticator space which contains the lower dental row, muscles of mastication, the inferior alveolar nerve as well as branches of cranial nerve V. Lateral to the parapharyngeal space lies the parotid space, which contains the parotid gland, the external carotid artery and cranial nerve VII.[1] Although initial evaluation is typically by physical exam and endoscopy, follow up with CT and MRI usually is needed if surgical intervention is planned.[2]

Bony anatomy around the space includes the skull base superiorly, and the greater cornu (or greater horns) of the hyoid bone the apex, inferiorly. The superior aspect is the base of skull, namely the sphenoid and temporal bones. This area includes the jugular and hypoglossal canal and the foramen lacerum (through which the internal carotid artery passes superiorly across).

The medial aspect is made up of the pharynx. Anteriorly it is bordered by the pterygomandibular raphe. Posteriorly it is bordered by carotid sheath posteriolaterally and the retropharyngeal space posteriomedially. The lateral aspect is more involved, and is bordered by the ramus of the mandible, the deep lobe of the parotid gland, the medial pterygoid muscle, and below the level of the mandible, the lateral aspect is bordered by the fascia of the posterior belly of digastric muscle. These anatomical boundaries make it continuous with the retropharyngeal space. It also communicates with other cervical and cranial fascial spaces, as well as the mediastinum.

Divisions

[edit]

The parapharyngeal space is divided into 2 parts by the fascial condensation called the aponeurosis of Zuckerkandl and Testut (stylopharyngeal fascia - see diagram),[3] joining the styloid process to the tensor veli palatini. These two compartments are named the pre-styloid and post-styloid (retrostyloid)[4] compartments or spaces. However, some classification schemes call the pre-styloid compartment the parapharyngeal space and the post-styloid compartment the carotid space,[5] which can be a source of confusion.

Contents

[edit]

It includes the maxillary artery and ascending pharyngeal artery.[6]

  1. Glossopharyngeal nerve (IX)
  2. Vagus nerve (X) together with
  3. Internal carotid artery
  4. Internal jugular vein in the carotid sheath
  5. Accessory nerve (XI)
  6. Hypoglossal (XII)
  7. Sympathetic trunk and superior cervical ganglion of the trunk
  8. Ascending pharyngeal artery
  9. Deep cervical lymph nodes

Clinical significance

[edit]

First bite syndrome is a rare complication of a surgery involving the parapharyngeal space, especially removal of the deep lobe of the parotid gland. It is characterized by facial pain after the first bite of each meal, and is thought to be caused by autonomic dysfunction of salivary myoepithelial cells.

References

[edit]

Bibliography

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Parapharyngeal space

View on Grokipedia
from Grokipedia
The parapharyngeal space is a deep, in the suprahyoid , located lateral to the and shaped like an inverted pyramid that extends superiorly from the skull base to the greater cornu of the inferiorly. This space is bounded medially by the covering the superior constrictor muscle of the , laterally by the and the deep lobe of the , anteriorly by the , and posteriorly by the retropharyngeal space and prevertebral muscles. It is subdivided into a prestyloid compartment anteriorly, which primarily contains fat, the deep lobe of the , and lymph nodes, and a poststyloid compartment posteriorly, which houses critical neurovascular structures including the , , IX–XII, and the sympathetic chain. Anatomically, the parapharyngeal space serves as a central conduit in the , facilitating the passage of vessels and nerves while being filled with loose areolar that allows for potential expansion in pathological conditions. Its relations to adjacent spaces, such as the masticator space laterally and the retropharyngeal space posteriorly, are key for understanding lesion displacement patterns on , where masses typically bow the medially and the posteriorly. The space's fascial boundaries, derived from the deep cervical fascia, limit direct communication with some neighboring compartments but permit spread of infections via lymphatic channels or along neurovascular sheaths. Clinically, the parapharyngeal space is significant for harboring a variety of neoplasms, with 70–80% being benign, including pleomorphic adenomas from salivary tissue (40–50% of cases) and neurogenic tumors like schwannomas (14–41%), while malignant lesions such as squamous cell carcinomas or sarcomas account for 20–30%. Infections, often odontogenic or from pharyngeal sources, can involve the space, leading to deep neck abscesses that require prompt imaging and surgical intervention due to risks of airway compromise or vascular erosion. Diagnostic evaluation relies heavily on cross-sectional imaging like CT and MRI to delineate compartments and guide surgical access, which is typically approached via transcervical or transparotid routes to preserve neurovascular integrity.

Anatomy

Boundaries and Relations

The parapharyngeal space is an inverted pyramid-shaped potential space in the suprahyoid neck, with its base at the skull base superiorly—specifically involving the jugular foramen and carotid canal—and its apex extending inferiorly to the hyoid bone. Medially, it is bounded by the superior constrictor muscle of the pharynx and the overlying buccopharyngeal fascia, which forms part of the middle layer of the deep cervical fascia. Laterally, the space is limited by the medial aspect of the mandible, the deep lobe of the parotid gland, and the medial pterygoid muscle, with the superficial layer of the deep cervical fascia covering the medial pterygoid muscle contributing to this boundary. Anteriorly, it is delimited by the pterygomandibular raphe and the fascia of the medial pterygoid muscle. Posteriorly, the boundary consists of the prevertebral fascia and the alar fascia, adjacent to the retropharyngeal space. The parapharyngeal space communicates posteriorly with the retropharyngeal space, anteriorly with the masticator space, and inferiorly with the , providing potential pathways for the spread of pathology between these regions. It is primarily enclosed by the pharyngobasilar medially and the laterally, which help define its fascial confines.

Divisions

The parapharyngeal space is primarily divided into an anterior prestyloid compartment and a posterior poststyloid compartment by the styloid process along with its attached muscles—the , stylohyoid, and stylopharyngeus—and the surrounding fascial condensations that form a thin diaphragm-like structure. This division creates distinct spatial zones that influence the distribution and containment of pathological processes within the space. The prestyloid compartment is largely composed of and maintains open communication with the deep lobe of the via the stylomandibular , while notably lacking major neurovascular elements. In contrast, the poststyloid compartment houses critical neurovascular structures and is characterized by the arrangement of its contents, including fat anterior to the , the sheath itself in a central position, and additional fat posteriorly. Key fascial planes, collectively referred to as the tensor-vascular-stylomandibular system, play a crucial role in delineating these compartments; this system extends from the anteriorly to the styloid process and continues inferiorly via the , providing a barrier that generally limits the spread of infections or tumors across compartmental boundaries. However, this fascial layer is often thin and serves as only a minimal impediment to pathological extension. Anatomical variations include occasional incomplete or absent fascial separations between compartments, which can facilitate atypical patterns of dissemination.

Contents

The parapharyngeal space is divided into prestyloid and poststyloid compartments, with each housing distinct anatomical structures that contribute to its overall function in supporting neurovascular and lymphatic elements of the head and neck. The prestyloid compartment primarily contains loose areolar and , which provides cushioning and fills the space between adjacent structures. It also includes the medial extension of the deep lobe of the and minor or ectopic salivary tissue, along with small lymphatic nodes that facilitate local drainage. Vascular elements in this compartment feature branches of the , which supply nearby musculature and glands. Neural components are limited but include branches of the innervating the . In contrast, the poststyloid compartment, also known as the carotid space, encompasses the , which encloses the , , and (cranial nerve X). Additional neurovascular structures include IX (glossopharyngeal), XI (accessory), and XII (hypoglossal), the sympathetic chain with its , and the pharyngeal plexus. The (CN IX) provides motor innervation to the via its pharyngeal branches, aiding in pharyngeal elevation during . Lymph nodes corresponding to levels II and III are present, along with occasional fat pads and glomus tissue. Vascular supply here includes the ascending pharyngeal and occipital arteries. Lymphatic drainage from the parapharyngeal space primarily routes to the , particularly levels II and III, which influences patterns of in head and neck malignancies by serving as an initial nodal station.

Clinical Relevance

Infections and Inflammatory Conditions

Infections of the parapharyngeal space represent a subset of deep neck infections that can arise from contiguous spread of adjacent inflammatory processes, posing significant risks due to the space's proximity to vital neurovascular structures. These infections are typically polymicrobial, involving aerobic and anaerobic such as species, , and anaerobes like and . Common etiologies include odontogenic infections originating from dental abscesses, particularly involving the second and third molars, as well as or and, less frequently, of the parotid or minor salivary glands. Odontogenic sources account for a substantial proportion of cases, often spreading from the masticator space, while pharyngitis-related infections typically involve the prestyloid compartment. Sialadenitis contributes rarely but can lead to suppuration extending into the parapharyngeal space, as documented in isolated case reports. Pathophysiologically, infections propagate through fascial planes connecting the parapharyngeal space to neighboring compartments, such as the masticator space via the or the retropharyngeal space inferiorly. Prestyloid involvement often results in medial bulging of the pharyngeal wall and lateral displacement of the , whereas poststyloid extension may compromise the , leading to vascular complications. These planes facilitate rapid dissemination, potentially involving multiple spaces. Clinically, patients present with acute symptoms including due to involvement of masticatory muscles, , neck swelling, and systemic signs like fever and . In poststyloid cases, complications such as airway obstruction from or —characterized by internal jugular vein and septic emboli—can occur, exacerbating morbidity. The parapharyngeal space's anatomical communications with adjacent regions, as outlined in the boundaries and relations, enable this spread from primary sites like the or oral cavity. Recognition of parapharyngeal space infections has increased since the early , attributed to advancements in cross-sectional that allow earlier detection of deep space involvement. These infections remain rare but life-threatening, with historical mortality rates reaching up to 20% in untreated or advanced cases, primarily from , mediastinitis, or vascular rupture. Management centers on prompt intravenous broad-spectrum antibiotics, such as amoxicillin-clavulanate or clindamycin combined with a beta-lactam, targeting polymicrobial flora for 2-3 weeks, alongside surgical incision and drainage for formation. In select cases of localized abscesses without airway compromise or vascular involvement, antibiotic-only treatment may suffice, as supported by recent studies showing successful outcomes and shorter hospital stays. Minimally invasive options, such as ultrasound-guided transoral drainage, have been reported in recent cases (as of 2025), providing precise access and quick recovery while avoiding external incisions. Early intervention is critical to avert descending spread to the , which carries a high mortality if neglected. Airway protection via may be required in severe presentations.

Neoplastic Conditions

Neoplastic conditions of the parapharyngeal space are rare, comprising less than 1% of all head and neck tumors, with approximately 80% being benign and predominantly originating from or neurogenic tissues. These tumors often arise within the space's compartmental structure, influencing their clinical behavior and displacement patterns relative to vascular structures like the . Prestyloid compartment tumors primarily consist of salivary gland neoplasms, with from the deep lobe of the accounting for about 50% of cases; these lesions typically displace the medially and posteriorly. In contrast, poststyloid compartment tumors are frequently neurogenic, including schwannomas and neurofibromas arising from IX-XII or the sympathetic chain (approximately 25% of cases), or vascular such as paragangliomas and tumors (about 15%); these displace the anteriorly. Malignant neoplasms, representing 20-30% of cases, often include squamous cell carcinoma metastases to lymph nodes within the space or direct extensions from adjacent sites like the nasopharynx, alongside sarcomas or malignant salivary gland tumors. Patients may present with an asymptomatic neck mass, though cranial nerve involvement can cause palsies such as hoarseness from vagus nerve (CN X) compression; growth patterns reflect compartmental origins, with MRI demonstrating fatty tissue displacement that aids in localizing the tumor source. Post-2020 studies have emphasized molecular markers like (SDH) mutations in paragangliomas, particularly SDHB variants, which correlate with increased metastatic potential and poorer prognosis, guiding risk stratification in these vascular tumors.

Diagnostic and Surgical Approaches

(MRI) is the preferred modality for evaluating parapharyngeal space due to its superior contrast, allowing delineation of planes and tumor margins. On T1-weighted images, the prestyloid compartment appears hyperintense due to content, and the "fat crescent sign"—a thin rim of preserved surrounding a prestyloid mass—helps distinguish benign salivary tumors from poststyloid lesions. Computed tomography (CT) complements MRI by assessing bony erosion, vascular encasement, and calcifications, particularly useful for detecting skull base involvement or displacement. serves as an initial tool for vascular assessment, identifying hypervascular lesions like paragangliomas through color Doppler flow. Diagnostic features rely on compartment-specific displacement patterns; for instance, prestyloid lesions cause a lateral bulge of the pharyngeal wall, while poststyloid tumors bow the styloid process anteriorly. (FNA) provides cytologic evaluation with high accuracy, achieving approximately 90-92% sensitivity for detecting malignancy in salivary-origin tumors, though nondiagnostic rates can reach 20-30% due to vascularity or . Surgical approaches are selected based on tumor location and size. The transcervical approach is most common, offering direct access to poststyloid lesions while preserving neurovascular structures. For prestyloid salivary tumors, the transparotid approach facilitates preservation and tumor delivery. Larger or midline lesions may require mandibulotomy for adequate exposure, though it increases morbidity. Preoperative endovascular is standard for hypervascular tumors, reducing intraoperative blood loss by occluding feeding vessels. As of 2024, mixed reality integrated with surgical navigation has been utilized to assist in tumor resections, enabling 3D visualization and precise intraoperative guidance with low deviation and minimal blood loss in reported series. Common complications include cranial nerve injuries, with the hypoglossal nerve (CN XII) among the lower at risk during poststyloid dissection, alongside CN X and XI deficits causing or shoulder weakness; vascular complications such as carotid rupture occur in less than 5% of cases but can be catastrophic. A multidisciplinary team involving otolaryngology () and is essential for preoperative planning and intraoperative management to minimize these risks. Recent advances include transoral robotic surgery (TORS), introduced around 2010 and gaining traction since 2015 for selected benign tumors, providing minimally invasive access with improved visualization and reduced external scarring. Positron emission tomography-computed tomography (PET-CT) enhances malignancy staging by detecting metabolic activity and distant metastases, particularly in squamous cell or adenoid cystic carcinomas extending to the parapharyngeal space.

References

  1. https://radiopaedia.org/articles/parapharyngeal-space?lang=us
  2. https://emedicine.medscape.com/article/849385-overview
  3. https://ajronline.org/doi/10.2214/ajr.177.6.1771465
  4. https://www.kenhub.com/en/library/anatomy/the-para-and-retropharyngeal-spaces
  5. https://www.imaios.com/en/e-anatomy/anatomical-structures/parapharyngeal-space-1541093000
  6. https://iowaprotocols.medicine.uiowa.edu/protocols/tumors-parapharyngeal-space
  7. https://entokey.com/3-parapharyngeal-space-anatomy-and-dissection/
  8. https://radiologykey.com/the-parapharyngeal-space-prestyloid-parapharyngeal-space/
  9. https://www.ijhns.com/doi/pdf/10.5005/jp-journals-10001-1059
  10. https://www.thieme-connect.com/products/ejournals/pdf/10.1055/a-2419-9782.pdf
  11. https://radiopaedia.org/articles/stylopharyngeus-muscle?lang=us
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  36. https://emedicine.medscape.com/article/849385-treatment
  37. https://karger.com/orl/article/72/6/332/261556/Transoral-Robotic-Surgery-for-Parapharyngeal-Space
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