Parapharyngeal space
The parapharyngeal space, also known as the prestyloid parapharyngeal space, is a deep compartment of the head and neck around which most other suprahyoid fascial spaces are arranged. It consists largely of fat, neurovascular structures, and, in some definitions, the retromandibular part of the deep lobe of the parotid gland.
On this page:
Terminology
Two naming conventions exist in the literature. In the first definition, familiar to most head and neck surgeons, the parapharyngeal space is divided into prestyloid and poststyloid (retrostyloid) compartments 1-3,10. In the second definition, introduced by some radiologists, the prestyloid parapharygeal space is simply termed the parapharyngeal space, and the poststyloid pharapharygeal space is termed the carotid space 4-6. The latter facilitates differential diagnosis and is used in this article.
Other terms for the parapharyngeal space include the lateral pharyngeal space, pharyngomaxillary space, and even less commonly pterygomaxillary space, pterygopharyngeal space, peripharyngeal space, pterygomandibular space, and pharyngomasticatory space 1.
Gross anatomy
The parapharyngeal space is shaped like an inverted pyramid, with its base at the skull base, with its apex inferiorly pointing towards the greater cornu of the hyoid bone 2.
Contents
- fat (main component)
- vessels
- internal maxillary artery, depending on its course
- ascending pharyngeal artery, depending on its course
- pterygoid venous plexus, in its portion surrounded by fat (the rest is within the masticator space)
- nerve
- small branch of the mandibular division of the trigeminal nerve (cranial nerve V3) supplying the tensor veli palatini muscle
- salivary tissue
Lymph nodes and muscle are not included in the radiological definition of the parapharyngeal space.
Boundaries
The parapharyngeal space has complex fascial margins occupying the space between the muscles of mastication and the muscles of deglutition 1-6:
- superior: base of skull
- inferior: greater cornu of the hyoid bone, although some state the space functionally ends higher, with the styloglossus muscle at the level of the angle of the mandible 1
- medial: middle layer of the deep cervical fascia covering the superior pharyngeal constrictor and levator and tensor veli palatini muscles
- lateral: superficial layer of the deep cervical fascia extending between styloid process and mandibular ramus, covering the parotid and lateral pterygoid muscle, although some state the fascia creates the stylomandibular tunnel through which part of the deep lobe of the parotid protrudes into the parapharyngeal space 1
- anterior: pterygomandibular raphe and superficial layer of the deep cervical fascia covering the medial pterygoid muscle
- posterior: an extension of tensor veli palatini muscle fascia termed the tensor-vascular-styloid fascia 1,10-12; or an extension of the fascia of the stylopharyngeus, styloglossus, and levator veli palatini muscles 13,14
Relations
- posteromedial to the masticator space, particularly medial pterygoid muscle
- anteromedial to the parotid space
- posterolateral to the pharyngeal mucosal space
- anterolateral to the prevertebral space, retropharyngeal space, and danger space
- anterior to the carotid (poststyloid parapharyngeal) space
- overlaps with the infratemporal fossa 5
Radiographic features
CT/MRI
The parapharyngeal space appears triangular in the axial plane with density/signal consistent with fat.
Knowledge about the displacement patterns of fat within the parapharyngeal space will aid in the localization of lesions within adjacent deep spaces of the head and neck. A lesion arising in the:
- masticator space displaces the parapharyngeal fat posteromedially
- parotid space displaces the parapharyngeal fat anteromedially
- pharyngeal mucosal space displaces the parapharyngeal fat posterolaterally
- retropharyngeal space, danger space, and prevertebral space displace the parapharyngeal fat anterolaterally
- carotid (poststyloid parapharyngeal) space displaces the parapharyngeal fat anteriorly
In contrast, a lesion primarily involving the parapharyngeal space will displace the carotid space posteriorly and the pharynx medially.
Related pathology
Lesions involving the (prestyloid) parapharyngeal space include 7:
- tumors 8,9
- salivary gland tumors (most common), most commonly pleomorphic adenoma
- neurogenic tumors, such as trigeminal schwannoma
- lipoma
- parapharyngeal abscess or phlegmon/cellulitis
- developmental lesions
- cystic hygroma/lymphangioma
- second branchial cleft cyst (atypical location)
Related Radiopaedia articles
Anatomy: Head and neck
- skeleton of the head and neck
-
cranial vault
- scalp (mnemonic)
- fontanelle
-
sutures
- calvarial
- facial
- frontozygomatic suture
- frontomaxillary suture
- frontolacrimal suture
- frontonasal suture
- temporozygomatic suture
- zygomaticomaxillary suture
- parietotemporal suture (parietomastoid suture)
- occipitotemporal suture (occipitomastoid suture)
- sphenofrontal suture
- sphenozygomatic suture
- spheno-occipital suture (not a true suture)
- lacrimomaxillary suture
- nasomaxillary suture
- internasal suture
- basal/internal
- skull landmarks
- frontal bone
- temporal bone
- parietal bone
- occipital bone
- skull base (foramina)
-
facial bones
- midline single bones
- paired bilateral bones
- cervical spine
- hyoid bone
- laryngeal cartilages
-
cranial vault
- muscles of the head and neck
- muscles of the tongue (mnemonic)
- muscles of mastication
-
muscles of facial expression
- occipitalis muscle
- circumorbital and palpebral muscles
- nasal muscles
- buccolabial muscles
- elevators, retractors and evertors of the upper lip
- levator labii superioris alaeque nasalis muscle
- levator labii superioris muscle
- zygomaticus major muscle
- zygomaticus minor muscle
- malaris muscle
- levator anguli oris muscle
- risorius muscle
- depressors, retractors and evertors of the lower lip
- depressor labii inferioris muscle
- depressor anguli oris muscle
- mentalis muscle
- compound sphincter
- orbicularis oris muscle
- incisivus superior muscle
- incisivus inferior muscle
- muscle of mastication:
- elevators, retractors and evertors of the upper lip
- muscles of the middle ear
- orbital muscles
- muscles of the soft palate
- pharyngeal muscles
- suprahyoid muscles
- infrahyoid muscles
- intrinsic muscles of the larynx
- muscles of the neck
- accessory muscles of the neck
- deep cervical fascia
-
deep spaces of the neck
- anterior cervical space
- buccal space
- carotid space
- danger space
- deep cervical fascia
- infratemporal fossa
- masticator space
- parapharyngeal space
- stylomandibular tunnel
- parotid space
- pharyngeal (superficial) mucosal space
- perivertebral space
- posterior cervical space
- pterygopalatine fossa
- retropharyngeal space
- suprasternal space (of Burns)
- visceral space
- surgical triangles of the neck
- orbit
- ear
- paranasal sinuses
- nose
- oral cavity
- pharynx
- larynx
- viscera of the neck
- blood supply of the head and neck
-
arterial supply
-
common carotid artery
- carotid body
- carotid bifurcation
- subclavian artery
- variants
-
common carotid artery
- venous drainage
-
arterial supply
- innervation of the head and neck
-
cranial nerves
- olfactory nerve (CN I)
- optic nerve (CN II)
- oculomotor nerve (CN III)
- trochlear nerve (CN IV)
-
trigeminal nerve (CN V) (mnemonic)
- trigeminal ganglion
- ophthalmic division
- maxillary division
- mandibular division
- abducens nerve (CN VI)
- facial nerve (CN VII)
-
vestibulocochlear nerve (CN VIII)
- vestibular ganglion (Scarpa's ganglion)
- glossopharyngeal nerve (CN IX)
-
vagus nerve (CN X)
- superior laryngeal nerve
- recurrent laryngeal nerve (inferior laryngeal nerve)
- (spinal) accessory nerve (CN XI)
- hypoglossal nerve (CN XII)
- parasympathetic ganglia of the head and neck
- greater occipital nerve
- third occipital nerve
-
cervical plexus
- muscular branches
- longus capitis
- longus colli
- scalenes
- geniohyoid
- thyrohyoid
-
ansa cervicalis
- omohyoid (superior and inferior bellies separately)
- sternothyroid
- sternohyoid
- phrenic nerve
- contribution to the accessory nerve (CN XI)
- cutaneous branches
- muscular branches
- brachial plexus
- pharyngeal plexus
-
cranial nerves
- lymphatic drainage of the head and neck
- embryological development of the head and neck