Sphenoid sinus
The sphenoid sinus is the most posterior paranasal sinus.
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Summary
- location: the central body of the sphenoid bone anteroinferior to the sella turcica
- blood supply: posterior ethmoidal and sphenopalatine arteries
- innervation: posterior ethmoidal nerve and the orbital branch of the pterygopalatine ganglion
Gross anatomy
The sphenoid sinuses are paired spaces formed within the body of the sphenoid bone, communicating with the roof of the nasal cavity via the sphenoethmoidal recess in its anterior wall. The two sinuses are separated by a septum which may or may not be in the midline. It usually lies anteroinferior to the sella.
A large sinus can show a number of ridges and depressions related to closely adjacent structures. These can include the pituitary gland, optic nerve, and internal carotid artery.
Relations
- superiorly: cavernous sinus, sella turcica, and its contents
- inferiorly: nasal cavities
- anteriorly: nasal cavities, posterior ethmoid air cells
- posteriorly: contents of the middle cranial fossa
- laterally: cavernous sinus, cranial cavity
Types of pneumatization
- conchal
- lateral recess
- presellar
- sellar (which can be incomplete or complete)
Arterial supply
- posterior ethmoidal artery
- nasal branches of the sphenopalatine artery
Venous drainage
- superior ophthalmic veins via posterior ethmoidal veins
Lymphatic drainage
Lymph drainage occurs via afferent vessels leading into the retropharyngeal nodes
Innervation
- parasympathetic: orbital branches of the pterygopalatine ganglion
- sensory: posterior ethmoidal nerve from the nasociliary nerve, a branch of the ophthalmic division of the trigeminal nerve
Variant anatomy
With respect to optic nerve relationship:
- type 1: adjacent to sphenoid sinus
- type 2: indenting the sinus
- type 3: traversing the sinus
- type 4: adjacent to posterior ethmoid sinus
Development
Pneumatization starts at around 2 years of age and it develops more slowly than the other paranasal sinuses.
Practical points
It is important to look for and report the type of pneumatization of this sinus and to report the relationship with adjacent neurovascular structures, especially dehiscence.
See also
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
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cranial vault
- muscles of the head and neck
- muscles of the tongue (mnemonic)
- muscles of mastication
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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
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- deep cervical fascia
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deep spaces of the neck
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- perivertebral space
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- pterygopalatine fossa
- retropharyngeal space
- suprasternal space (of Burns)
- visceral space
- surgical triangles of the neck
- orbit
- ear
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- nose
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- blood supply of the head and neck
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arterial supply
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common carotid artery
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- variants
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common carotid artery
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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)
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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
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ansa cervicalis
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- 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
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