Jugular foramen
Encyclopedia
The jugular foramen is a large aperture
in the base of the skull
. It is located behind the carotid canal
and is formed in front by the petrous
portion of the temporal
, and behind by the occipital
; it is generally larger on the right than on the left side.
An alternative imaging based subclassification exist, using the jugular spine, which is a bony ridge partially separating the jugular foramen, into two parts.
Aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are,...
in the base of the skull
Base of the skull
The base of skull is the most inferior area of the skull, composed of the endocranium and lower parts of the skull roof.-Bones:*Ethmoid bone*Sphenoid bone*Occipital bone*Frontal bone*Parietal bone*Temporal bone**Petrous portion of the temporal bone...
. It is located behind the carotid canal
Carotid canal
On the interior surface of the temporal bone, behind the rough surface of the apex, is the large circular aperture of the carotid canal, which ascends at first vertically, and then, making a bend, runs horizontally forward and medialward.-Contents:...
and is formed in front by the petrous
Petrous portion of the temporal bone
The petrous portion of the temporal bone or pyramid is pyramidal and is wedged in at the base of the skull between the sphenoid and occipital bones. Directed medially, forward, and a little upward, it presents for examination a base, an apex, three surfaces, and three angles, and contains, in its...
portion of the temporal
Temporal bone
The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebrum.The temporal bone supports that part of the face known as the temple.-Parts:The temporal bone consists of four parts:* Squama temporalis...
, and behind by the occipital
Occipital
The word occipital, in zoology, pertains to the occiput .Occipital is a descriptor for several areas of animal & human anatomy.*External occipital protuberance* Internal occipital crest* Greater occipital nerve...
; it is generally larger on the right than on the left side.
Contents
The jugular foramen may be subdivided into three compartments, each with their own contents.- The anterior compartment transmits the inferior petrosal sinusInferior petrosal sinusThe inferior petrosal sinuses, within the human head, are beneath the brain and allow blood to drain from the center of the head.They drain on either side inferiorly from the cavernous sinus and join with the sigmoid sinus to form the internal jugular vein, which continues inferiorly to drain...
. - The intermediate transmits the glossopharyngeal, vagus, and accessory nerveAccessory nerveIn anatomy, the accessory nerve is a nerve that controls specific muscles of the shoulder and neck. As part of it was formerly believed to originate in the brain, it is considered a cranial nerve...
s (aka cranial nerves number IX, X, and XI respectively). - The posterior transmits the sigmoid sinusSigmoid sinusThe sigmoid sinuses , within the human head, are two areas beneath the brain which allow blood to drain inferiorly from the posterior center of the head. They drain from the transverse sinuses and converge with the inferior petrosal sinuses to form the internal jugular vein...
(becoming the internal jugular vein) and some meningeal branches from the occipitalOccipitalThe word occipital, in zoology, pertains to the occiput .Occipital is a descriptor for several areas of animal & human anatomy.*External occipital protuberance* Internal occipital crest* Greater occipital nerve...
and ascending pharyngeal arteries.
An alternative imaging based subclassification exist, using the jugular spine, which is a bony ridge partially separating the jugular foramen, into two parts.
- The smaller, anteromedial, "pars nervosa" compartment contains CN IX, Jacobson nerve (or the tympanic nerveTympanic nerveThe tympanic nerve is a branch of the glossopharyngeal nerve found near the ear.-Path:It arises from the petrous ganglion, and ascends to the tympanic cavity through a small canal, the fossula petrosa/tympanic canaliculus, on the under surface of the petrous portion of the temporal bone on the...
, a branch of CN IX), and receives the venous return from inferior petrosal sinusInferior petrosal sinusThe inferior petrosal sinuses, within the human head, are beneath the brain and allow blood to drain from the center of the head.They drain on either side inferiorly from the cavernous sinus and join with the sigmoid sinus to form the internal jugular vein, which continues inferiorly to drain...
. - The larger, posterolateral, "pars vascularis" compartment contains CN X, CN XI, Arnold's nerve (or the auricular branch of CN X involved in the Arnold's reflex, where external auditory meatus stimulation causes cough), jugular bulb, posterior meningeal artery (branch of vertebral arteryVertebral arteryThe vertebral arteries are major arteries of the neck. They branch from the subclavian arteries and merge to form the single midline basilar artery in a complex called the vertebrobasilar system, which supplies blood to the posterior part of the circle of Willis and thus significant portions of the...
), and meningeal branch of ascending pharyngeal arteryAscending pharyngeal arteryThe ascending pharyngeal artery, the smallest branch of the external carotid, is a long, slender vessel, deeply seated in the neck, beneath the other branches of the external carotid and under the Stylopharyngeus...
.