The jugular foramen is located at the base of the skull and embodies the passage of the ninth to eleventh cranial nerves as well as the posterior meningeal artery, sigmoid sinus, and inferior petrosal sinus. Problems in the region of the jugular foramen can result in various neurologic syndromes such as Avellis, Jackson, Sicard, Tapia, and Villaret syndromes.
What is the jugular foramen?
The jugular foramen is an anatomical structure in the human head located in the posterior fossa at the base of the skull. It serves as a gateway into or out of the skull for three cranial nerves and three blood vessels. The nerves are cranial nerves XI-XI: the glossopharyngeal nerve, the vagus nerve, and the accessorius nerve. The blood vessels include the posterior meningeal artery, the sigmoid sinus, and the inferior petrosal sinus. Other names for the jugular foramen include zygomatic vein hole and jugular vein hole. In keeping with this, the internal jugular vein, which originates at the jugular foramen, is also known as the “jugular vein.” The orifice owes its name to this blood vessel.
Anatomy and structure
The occipital bone (Os occipitale) and the petrous bone (Pars petrosa ossis temporalis) frame the jugular foramen. The petrous bone represents part of the temporal bone (Os temporale), which in turn is part of the cranium (Neurocranium). Anatomy divides the jugular foramen into either two or three sections. In the division into three parts, the pars anterior forms the anterior part of the orifice. Through this part passes the inferior petrosal sinus, which is a blood conductor. The middle portion of the jugular foramen is represented by the pars intermedia, which serves as access to the brain for the glossopharyngeal nerve, the vagus nerve, and the accessorius nerve. The core areas of the three cranial nerves are located in the brainstem. The meningeal artery also runs here. Another blood conductor, the sigmoid sinus, runs through the posterior pars. It combines smaller blood streams that drain deoxygenated blood from the brain and merges with the internal jugular vein (internal jugular vein) immediately at the jugular foramen. As an alternative to this division into three areas, medicine also uses a dichotomy to describe the jugular foramen. In this case, the passage of the inferior petrosal sinus and the glossopharyngeal nerve forms the anterior section, whereas the posterior section contains the posterior meningeal artery, the vagus nerve, and the accessorius nerve.
Function and Tasks
The jugular foramen does not itself perform any active function, but it allows nerve fibers and blood vessels to enter the skull. The sigmoid sinus is a blood vessel that occurs once in each half of the head. Its function is to drain oxygen-depleted blood from the brain. To do this, it receives blood from other, smaller vessels: the transverse sinus as well as the superior petrosal sinus and partially the inferior petrosal sinus. The inferior petrosal sinus contains blood originating from the middle cranial fossa (fossa cranii media). This has six important openings. At the jugular foramen, the inferior petrosal sinus becomes the internal jugular vein. Furthermore, the posterior meningeal artery flows through the jugular foramen. It supplies parts of the brain with blood, which contains a lot of oxygen and is thus of central importance for the survival of the brain cells. Cranial nerves IX-XI pass through the jugular foramen. The glossopharyngeal nerve represents the ninth cranial nerve and has six major branches that innervate the tongue, tonsils, and various salivary glands, among others. In contrast, the vagus nerve or cranial nerve X supplies not only parts of the head and neck, but also areas in the chest and abdomen. The accessorius nerve forms the eleventh cranial nerve. Its ramus internus draws to the vagus nerve, while the ramus externus provides a motor connection to the sternocleidomastoid and trapezius muscles.
Diseases
Various neurologic syndromes are potentially associated with abnormalities at the jugular foramen. Avellis (Longhi) syndrome is associated with damage to the glossopharyngeal and vagus nerves secondary to lesions in the medulla oblongata. Typical symptoms are hemiparesis on the opposite (contralateral) side and paralysis of the soft palate, vocal cords and pharynx on the same (ipsilateral) side.In addition, Avellis syndrome may reduce the perception of temperature and pain in body side opposite to the damaged side. Jackson’s syndrome is also associated with paralysis of the hypoglossal nerve, which can cause discomfort in swallowing and speech, among other things. The reason for this is the impairment of the tongue. Jackson’s syndrome belongs to the oblongata syndromes, since the cause of the discomfort is also located in the medulla oblongata. Other symptoms are also possible. Sicard syndrome is a neurological condition characterized by neuralgia of the glossopharyngeal nerve. The neuralgia results in sharp or stabbing pain due to irritation in the innervation area, but may radiate to other areas. Tapia syndrome affects various cranial nerves; typically, there is paralysis of the vagus nerve, accessor nerve, and hypoglossal nerve. The tongue, pharynx, and larynx are paralyzed on the side of the body where the lesion is located. In addition, Tapia syndrome may also affect the sternocleidomastoid and trapezius muscles. Villaret’s syndrome may also result from damage to the foramen jugulare. In this case, characteristic symptoms such as sensory and swallowing disturbances and paralysis of the vocal cords, sternocleidomastoid muscle and trapezius muscle are due to nerve damage to the facial nerve, glossopharyngeal nerve, vagus nerve and accessorius nerve. The sympathetic nervous system of the neck may also be affected.
