Parapharyngeal Space

Parapharyngeal space (spatium parapharyngeum) is space lateral and dorsolateral to pharynx, medially continues into retropharyngeal space.

Boundaries:
 * superiorly – base of skull
 * inferiorly – carotid triangle
 * ventromedially – pharynx
 * dorsally – prevertebral muscles (longus colli and capitis), scaleni mm., sternocleidomastoid m.
 * ventrolaterally – digastric m. (post. belly), stylohyoid m., stylohyoid lig., stylopharyngeal m., styloglossus m., med. pterygoid m., sup. constrictor of pharynx m.

Parapharyngeal space is divided by styloid septum, which runs from stylohyoid lig. and styloid muscles to the wall of pharynx, into prestyloid and retrostyloid part.

Prestyloid part of parapharyngeal space
Prestyloid part of parapharyngeal space (paratonsilar space)is the very most ventral part of parapharyngeal space. It's very narrow space.

It contains: glossopharyngeal nerve, ascendent palatine artery,...

It‘s lower part is close to submandibular gland (which is close to palatine tonsilla – so infections can easily spread to prestyloid and then to restrostyloid space)

Retrostyloid part of parapharyngeal space
It contains: internal carotid artery, ascendent pharyngeal artery, internal jugular vein, glossopharyngeal nerve, vagus nerve, accessory nerve, hypoglossal nerve, sympathetic trunk (inside deep cervical fascia)