Ethmoidal air cells
The ethmoidal air cells, also known less commonly as the ethmoidal sinuses, form one of the four pairs of paranasal sinuses. They are located within the single, midline ethmoid bone.
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Summary
- location: between the orbit and the nasal cavity, within the ethmoid labyrinth of the ethmoid bone
- blood supply: supraorbital, anterior and posterior ethmoidal and sphenopalatine arteries
- innervation: anterior and posterior ethmoidal and supraorbital nerves
Gross anatomy
A collection of air cells (3-18 in number) separated by bony septa within each side of the lateral mass, or labyrinth, of the ethmoid bone.
They are separated into anterior and posterior groups by the basal lamella, the lateral attachment of the middle turbinate to the lamina papyracea. Historically the ethmoid sinuses were subdivided into 3 groups of air cells: the anterior, middle and posterior ethmoidal air cells. The middle group are now incorporated into the anterior group.
The anterior ethmoidal air cells drain to the hiatus semilunaris and middle meatus via the ethmoid bulla, which forms parts of the ostiomeatal complex. The posterior ethmoidal air cells drain to the superior meatus via the sphenoethmoidal recess 2.
Some of the ethmoidal air cells have been given specific names, because of their importance in surgical procedures or involvement in head and neck pathologies:
- frontal recess cells, including the agger nasi cells
- ethmoid bulla
- Haller cells
- Onodi cells
Arterial supply
From the ophthalmic branch of the internal carotid artery, the supraorbital, anterior and posterior ethmoidal arteries supply the ethmoid air cells with the sphenopalatine artery (a branch of the maxillary artery) also contributing. Thus, the ethmoid air cells are supplied by branches of both the internal and external carotid arteries.
Lymphatic drainage
Lymph from the ethmoid air cells drains to the submandibular and retropharyngeal group of nodes.
Innervation
The posterior ethmoidal air cells, along with the sphenoid sinus, are supplied by the posterior ethmoidal nerve, whereas the anterior ethmoidal nerve supplies the anterior ethmoidal air cells. Both these nerves are extraconal branches of the nasociliary nerve, a branch of the ophthalmic division of the trigeminal nerve.
Development
They are present at birth, and they develop rapidly from 0-4 years of age. They further mature from 8-12 years of age through puberty.
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
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