Jugular foramen
The jugular foramen courses anteriorly, laterally, and inferiorly as it insinuates itself between the petrous temporal bone and the occipital bone.
Gross anatomy
The jugular foramen is usually described as being divided into two parts by a fibrous or bony septum, called the jugular spine, into:
- the pars nervosa: anteromedial and smaller
- the pars vascularis: posterolateral and larger
Pars nervosa
The pars nervosa is the anteromedial portion of the jugular foramen and is smaller than the larger, posterolateral pars vascularis. It contains:
The inferior petrosal sinus drains the cavernous sinus and courses in the petro-occipital fissure adjacent to the clivus prior to its exit through the pars nervosa and subsequent drainage into the internal jugular vein beneath the foramen.
The glossopharyngeal nerve yields a tympanic branch (Jacobson nerve) which reaches and supplies the middle ear along with the inferior tympanic artery via the inferior tympanic canaliculus which is occasionally seen at CT in cross-section at the level of the caroticojugular spine.
Pars vascularis
The pars vascularis is the posterolateral portion of the jugular foramen and is larger than the smaller anteromedial portion termed the pars nervosa. It contains:
- jugular bulb: a venous expansion sitting in the jugular fossa, between the endocranial sigmoid sinus and the exocranial jugular vein
- vagus nerve (CN X)
- spinal accessory nerve (CN XI)
The vagus nerve yields an auricular branch (Arnold nerve) via the mastoid canaliculus on the lateral wall of the foramen adjacent to the mastoid segment of the facial nerve.
Alternative division into 3 parts
In this system the foramen is divided into 3 parts:
- petrous part through which the petrosal sinus passes
- intrajugular part through which the nerves pass
- sigmoid part through which the sigmoid sinus passes
The intrajugular part is positioned between the sigmoid and petrosal parts, and is the site of bony prominences called the intrajugular processes on the opposing surfaces of the temporal and occipital bones.
Radiographic features
The size of the normal jugular foramen is remarkably variable and asymmetrical. However, the normal foramen will always be well-corticated. Therefore, the bony margin (and not the size) of the foramen should guide diagnostic evaluation.
CT
CT appearance of the foramen depends upon the level and angulation of the scan. The foramen has been described as having the shape of a sitting duck on the highest axial cuts.
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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