What are the tonsillar pillars?

Tonsillar Pillars: Anatomical Definition

The tonsillar pillars are two muscular folds of tissue that form the anterior and posterior boundaries of the tonsillar fossa, where the palatine tonsils are located. 1

Anatomical Structure

Anterior Tonsillar Pillar (Palatoglossal Arch)

• The anterior pillar is formed by the palatoglossus muscle and creates the front boundary of the tonsillar fossa 1
• This structure provides critical structural support to the soft palate, and loss of its integrity (such as after tonsillectomy) can lead to palatal collapse against the posterior pharyngeal wall 2
• Deficiency of anterior tonsillar pillar support predisposes patients to obstructive sleep apnea syndrome by allowing passive collapse of the soft palate 2

Posterior Tonsillar Pillar (Palatopharyngeal Arch)

• The posterior pillar is formed by the palatopharyngeus muscle and defines the back boundary of the tonsillar fossa 1
• The palatopharyngeus muscle is a major defining element that forms the medial wall of the lateral palatal space and contributes to the continuity between the soft palate and lateral pharyngeal wall 3, 1
• This muscle has three components of pharyngeal origins and two heads of velar insertions, with the bulk of muscle fibers extending to the posterior tonsillar pillars with a mean length of 27.58 ± 6.73 mm and section area of 34.1 ± 10.50 mm² 3
• The palatopharyngeus consists of two functional divisions: longitudinal fasciculi (which elevate the pharynx and depress the soft palate) and transverse fascicle/Passavant's ridge (which functions as a nasopharyngeal sphincter) 1

Anatomical Relationships

• The glossopharyngeal (IX) nerve is consistently identified deep to the superior constrictor musculature at the intersection of the posterior tonsillar pillar with the base of tongue 4
• The palatine tonsils themselves are lymphoepithelial organs strategically positioned between these pillars at the junction of the oral cavity and oropharynx 5
• The pillars receive blood supply dominantly from branches of the ascending pharyngeal artery and tonsillar artery, with partial supply from ascending palatine and dorsal lingual arteries 3
• Nerve supply to the palatopharyngeus muscle comes from branches of the pharyngeal plexus, with concentration at the level 10-25 mm below the hard palate 3

Clinical Significance

• Understanding tonsillar pillar anatomy is essential for tonsillectomy procedures, as the peritonsillar space between the tonsil capsule and muscular wall (formed by these pillars) must be dissected 5
• Preservation of anterior pillar integrity during tonsillectomy is critical to prevent postoperative airway collapse and sleep-disordered breathing 2
• The posterior pillar serves as an important anatomical landmark during transoral robotic surgery for tonsillar tumors 4