颈静脉孔区解剖

CHAPTER 12 J UGULAR F ORAMEN

The jugular foramen is located between the temporal and the occip-ital bones. It can be regarded as a hiatus between the temporal and the occipital bones (1). The right foramen is usually larger than the left. The foramen is configured around the sigmoid and inferior petrosal sinuses. The jugular foramen is divided into three compartments: two venous compartments and a neural or intrajugular compartment. The venous compartments consist of a larger posterolateral venous channel, the sigmoid part, which receives the ?ow of the sigmoid sinus, and a smaller anteromedial venous channel, the petrosal part, which receives the drainage of the inferior petrosal sinus. The petrosal part forms a characteristic venous con?uens by also receiving tributaries from the hypoglossal canal, petroclival ?ssure, and vertebral venous plexus. The petrosal part empties into the sigmoid part through an opening between the glossopharyngeal and the vagus nerves in the medial wall of the jugular bulb. The intrajugular or neural part, through which the glossopharyngeal, vagus, and accessory nerves course, is located between the sigmoid and petrosal parts. The junction of the sigmoid and petrosal parts of the foramen, when viewed from above, is the site of bony prominences on the opposing surfaces of the temporal and occipital bones, called the intrajugular processes, which are joined by a ?brous, or, less commonly, an osseous bridge, the intrajugular sep-tum, separating the sigmoid and petrosal part of the foramen. The glossopharyngeal, vagus, and accessory nerves penetrate the dura on the medial margin of the intrajugular process of the temporal bone to reach the medial wall of the jugular bulb and internal jugular vein. The jugular foramen is dif?cult to access surgically. The dif?culties in exposing this foramen are created by its deep location and the sur-rounding structures, such as the carotid artery anteriorly, the facial nerve laterally, the hypoglossal nerve medially, and the vertebral artery inferiorly, all of which block access to the foramen and require careful management.

The structures that traverse the jugular foramen are the sigmoid sinus and jugular bulb, the inferior petrosal sinus, meningeal branches of the ascending pharyngeal and occipital arteries, the glossopharyn-geal, vagus, and accessory nerves with their ganglia, the tympanic branch of the glossopharyngeal nerve (Jacobson’s nerve), the auricular branch of the vagus nerve (Arnold’s nerve), and the cochlear aqueduct. Tumors involving the jugular foramen can extend as follows: 1) along the eustachian tube into the nasopharynx and through the foramina at the base of the cranium, 2) along the carotid artery to the middle fossa, 3) through the intracranial ori?ce of the jugular foramen or along the hypoglossal canal to the posterior fossa, 4) through the tegmen tym-pani to the ?oor of the middle fossa, 5) through the round window and the internal acoustic meatus to the cerebellopontine angle, and 6) through the extracranial ori?ce of the jugular foramen to the upper cer-vical region.

Surgical Approaches

The most common operative approaches used to access various aspects of the foramen and adjacent areas are the postauricular transtemporal, retrosigmoid, and far lateral approaches. Postauricular Transtemporal Approach

The postauricular transtemporal approach, the most common approach selected for a lesion in the jugular foramen, accesses the region from laterally, through the mastoid, and from below, through the neck. A C-shaped postauricular skin incision provides the exposure for a mastoidectomy and the neck dissection. The external auditory canal is either preserved or transected, depending on the anterior extent of the pathological abnormality. The neck dissection is com-pleted initially to gain control of the major vessels and the branches supplying the tumor. The internal carotid artery, branches of the exter-nal carotid artery, internal jugular vein, and lower cranial nerves are exposed in the carotid sheath. A mastoidectomy with extensive drilling of the infralabyrinthine region accesses the jugular bulb. A limited mas-toidectomy con?ned to the area behind the stylomastoid foramen and mastoid segment of the facial nerve, combined with removal of the adjacent part of the jugular process of the temporal bone, will provide access to the posterior and posterolateral aspect of the jugular foramen. Three obstacles to exposure of the full lateral half of the jugular fora-men, the facial nerve, styloid process, and rectus capitis lateralis mus-cle are dealt with by transposing the facial nerve, removing the styloid process, and dividing the rectus capitis lateralis muscle. Anterior exten-sions of the pathological abnormality are reached by sacri?cing the external and the middle ear structures. Sensorineural hearing can be preserved by maintaining the footplate of the stapes in the oval win-dow to avoid opening the labyrinth. Intracranial extensions of the lesion are reached by the retrosigmoid or presigmoid approaches after adding a suboccipital craniectomy. Some lesions can be removed by a transtemporal infralabyrinthine approach directed through the tem-poral bone below the labyrinth without a neck dissection, if the extracranial extension of the lesion is not prominent. The exposure can be extended by opening the otic capsule (translabyrinthine approach). Retrosigmoid Approach

A lesion located predominantly intradurally above the jugular fora-men can be resected by the retrosigmoid approach. A lateral suboccip-ital craniectomy exposes the dura behind the sigmoid sinus. The dura is opened, and the cerebellum is gently elevated away from the poste-rior surface of the temporal bone to expose the cisterns in the cerebel-lopontine angle and the intracranial aspect of the cranial nerves enter-ing the jugular foramen, hypoglossal canal, and internal acoustic meatus. Lesions can be followed into only the upper part of the fora-men by this approach.

Far Lateral Approach

An extended modi?cation of the retrosigmoid approach, the far lat-eral approach, may be selected if the tumor extends down to the fora-men magnum in front of or lateral to the lower brainstem. In this approach, the jugular foramen is opened from behind by completing a paracondylar modi?cation of the far lateral approach. In this modi?ca-tion, the rectus capitis lateralis is detached from the occipital bone at the posterior margin of the foramen and the posterior margin is removed. The dura is opened and the cerebellum elevated to expose the intracranial extension of the pathological abnormality at the lower clivus and at the foramen magnum. In another variant of the approach, depending on the location and extent of the pathological abnormality, the jugular tubercle is removed extradurally to minimize the retraction of the brainstem needed to reach the area anterior to the medulla and pontomedullary junction. Most jugular foramen tumors cannot be reached by this route because they extend forward beyond the limits of this approach to the posterior part of the foramen.

REFERENCES

1.Rhoton AL Jr: Jugular foramen. Neurosurgery47[Suppl 3]:S267–S285, 2000.

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FIGURE 12-1.Jugular foramen. Posterior view of the cranial base with the cranial nerves and arteries pre-served. The j ugular foramen is posi-tioned below the internal acoustic meatus and superolateral to the hypoglossal nerves entering the hypoglossal canal. The glossopharyn-geal, vagus, and accessory nerves enter the dural roof of the j ugular foramen. The superior cerebellar arter-ies arise at the midbrain level and pass below the oculomotor and trochlear nerves and above the trigeminal nerve. The anterior inferior cerebellar arteries arise at the pontine level and course by the abducens, facial, and vestibulocochlear nerves. The poste-rior inferior cerebellar arteries arise from the vertebral artery at the medullary level and course near the glossopharyngeal, vagus, accessory, and hypoglossal nerves.

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FIGURE 12-2.The dural roof of the left jugular foramen has been exposed below the facial and

vestibulocochlear nerves. There is a dural septum between the glossopharyngeal and vagus

nerves at the roof of the jugular foramen. The glossopharyngeal nerve is often adherent to the

rootlets of the vagus nerve in the cistern, however, at the roof of the jugular foramen, there is

consistently a dural septum separating the glossopharyngeal from the vagus nerve. The glos-

sopharyngeal nerve enters a shallow meatus, the glossopharyngeal meatus, in the dural roof of

the foramen. The glossopharyngeal dural fold passes above the glossopharyngeal nerve at the

entrance to the glossopharyngeal meatus. The vagus nerve enters the vagal meatus, which is

broader than, but not as deep, as the glossopharyngeal meatus, at the roof of the jugular fora-

men. There is also a dural fold around the upper and lateral margin of the vagal meatus. The

accessory nerve ascends to enter the lower part of the vagal meatus.

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FIGURE 12-3.The left sigmoid and infe-rior petrosal sinuses have been unroofed. The glossopharyngeal, vagus, and acces-sory nerves are exposed at the roof of the jugular foramen. The jugular foramen has three parts: sigmoid, petrosal, and intra-jugular. The sigmoid sinus descends and turns forward to pass through the sigmoid part of the jugular foramen. The inferior petrosal sinus descends and passes through the petrosal part of the j ugular foramen. The glossopharyngeal, vagus, and accessory nerves exit the cranium through the intrajugular part of the fora-men, which is located between the sigmoid and petrosal parts. Two bundles of hypoglossal rootlets enter a bi?d hypoglos-sal canal above the occipital condyle and join after exiting the hypoglossal canal.

FIGURE 12-4.The jugular bulb has been removed to expose the j ugular fossa on the lower surface of the tem-poral bone. The glossopharyngeal nerve enters the j ugular foramen above and medial to the vagus nerve. The tympanic branch (Jacobson’s nerve) of the glossopharyngeal nerve arises in the medial part of the jugular fossa, ascends to cross the promontory in the tympanic cavity, and gives rise to the lesser petrosal nerve. The auric-ular branch (Arnold’s nerve) of the vagus nerve arises in the intrajugular part of the foramen and passes later-ally across the anterior margin of the j ugular fossa. The bone above the hypoglossal canal has been drilled to expose a bi?d hypoglossal canal. The two bundles of hypoglossal rootlets j oin at the extracranial end of the hypoglossal canal and descend in the carotid sheath with the glossopharyn-geal, vagus, and accessory nerves.J UGULAR F ORAMEN

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FIGURES 12-5 AND 12-6.Inferior view of the temporal bone and jugular foramen. Figure 12-5,the internal jugular vein is exposed below the jugular foramen and descends on the medial side of the facial nerve and styloid process. The glossopharyngeal, vagus, accessory, and hypoglossal nerves descend in the carotid sheath with the internal carotid artery and internal jugular vein. The occipital condyle has been drilled to expose the passage of the hypoglossal nerve behind the vertebral artery and through the hypoglossal canal. The mandibular head, which sits in the mandibular fossa, is exposed anterolateral to the jugular foramen. The middle meningeal artery and branches of the third trigemi-nal division are exposed below the greater sphenoid wing in the infratemporal fossa. Bone has been removed to expose the eustachian tube and the petrous segment of the internal carotid artery. The Vidian nerve, which arises from the union of the greater and deep petrosal nerves, continues forward in the Vidian canal. The rectus capitis lateralis muscle attaches to the occipital bone behind the jugular foramen. The auriculotemporal branch of the third trigeminal division conveys autonomic ?bers from the lesser petrosal nerve to the otic ganglion, which provides auto-nomic innervation to the parotid gland.

FIGURE 12-6.The rectus capitis lateralis muscle has been resected and the part of the occipital bone forming the posterior margin of the jugular foramen has been removed to expose the lower part of the sigmoid sinus as it hooks forward to form the j ugular bulb. The venous plexus in the hypoglossal canal has been removed. The infe-rior petroclival vein, which courses along the extracranial surface of the petroclival ?ssure, has been removed to expose the petrous apex articulating with the lateral edge of the clivus along the petroclival

?ssure.

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FIGURE https://www.360docs.net/doc/0f2176233.html,teral view of the left tympanic cavity and mastoid area. The tympanic part of the temporal bone, which forms the lower and anterior margin of the external meatus, has been removed, but the tympanic sulcus and osseous ring to which the tympanic membrane attaches has been preserved. The carotid ridge separates the carotid canal and jugular foramen. Meningeal branches of the ascending pharyngeal and occipital arteries enter the jugular fora-men. The glossopharyngeal, vagus, and accessory nerves pass through the jugular foramen on the medial side of the jugular bulb. The malleus, incus, and stapes are exposed in the tympanic cavity. The stylomastoid branch of the occipital artery joins the facial nerve at the stylomas-toid foramen. The surface of the temporal and occipital bones surrounding the jugular foramen and carotid canal has an irregular surface that serves as the site of attachment of the upper end of the carotid sheath. The mastoid segment of the facial nerve and the stylomastoid foramen are situated lateral to the jugular bulb. The chorda tympani arises from the mastoid segment of the facial nerve and courses along the deep surface of the tympanic membrane and crosses the upper part of the handle of the malleus.

FIGURE https://www.360docs.net/doc/0f2176233.html,teral view of the left tympanic cavity, mastoid area, and adjacent part of the infratempo-ral fossa. The tympanic segment of the facial nerve passes below the lat-eral semicircular canal and turns downward to form the mastoid seg-ment, which exits the stylomastoid foramen. The stylomastoid foramen and the mastoid segment are posi-tioned lateral to the j ugular bulb. The semicircular canals are located above the j ugular bulb. The third trigeminal division exits the fora-men ovale to enter the infratemporal fossa. The chorda tympani arises from the mastoid segment of the facial nerve, courses along the deep surface of the tympanic membrane, crosses the upper part of the handle of the malleus, exits the cranium by passing through the petrotympanic fissure, and joins the lingual branch of the mandibular nerve in the infratemporal fossa.J UGULAR F ORAMEN

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FIGURE 12-9.The ?oor of the mid-dle fossa and the tympanic ring have been removed to expose the j ugular bulb and petrous carotid. The jugular bulb is positioned below the semicir-cular canals. The junction of the ver-tical and horizontal segments of the petrous carotid is positioned below the cochlea. The malleus and medial wall of the tympanic cavity have been preserved. The eustachian tube extends downward and medially across the anterior surface of the petrous carotid. The third trigeminal division has been elevated out of the foramen ovale.

FIGURE 12-10.A short segment of the Eustachian tube has been removed to expose more of the horizontal segment of the petrous carotid. The greater petrosal nerve courses along the ?oor of the middle fossa on the upper surface of the petrous carotid.The deep petrosal nerves arise from the sym-pathetic nerves accompanying the internal carotid artery. The deep and greater petrosal nerves join to form the vidian nerve, which passes forward through the vidian canal to j oin the maxillary nerve and pterygopala-tine ganglion in the pterygopalatine fossa.The pharyngobasilar fascia has been opened to expose the upper part of the longus capi-

tis muscle.

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FIGURE 12-11.The internal carotid artery has been displaced forward out of the carotid canal to expose the carotid nerves, which arise in the cervical sympathetic ganglia and ascend with the artery. The glossopharyngeal, vagus, accessory, and hypoglossal nerves exit the cra-nium on the medial side of the internal carotid artery and jugular vein. The hypoglossal nerve passes forward along the lateral surface of the internal carotid artery, and the accessory nerve descends posteriorly across the lateral surface of the internal jugular vein. The vagus nerve descends in the carotid sheath. The glossopharyngeal nerve descends along the medial side of the internal carotid artery.

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FIGURE 12-12.The j ugular bulb, positioned below the

vestibule and semicircular canals, has been removed. The

vertical segment of the petrous carotid has been removed

while preserving the horizontal segment. The cochlea,

which has been opened, is located above the lateral genu of

the petrous carotid artery. The tympanic segment of the

facial nerve passes between the lateral semicircular canal

and oval window. The mastoid segment of the nerve

descends lateral to the jugular fossa.

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FIGURE 12-13.Posterior view of the nerves in the jugular foramen with the venous struc-tures removed. The posterior wall of the j ugular foramen and hypoglossal canal have been opened. The glossopharyngeal nerve enters the jugular foramen caudal to the cochlear aqueduct. The vagus nerve enters the jugular foramen behind the glossopharyngeal nerve. The auricu-lar branch of the vagus nerve (Arnold’s nerve) arises at the level of the superior ganglion and passes across the anterior wall of the jugular bulb. The accessory nerve is formed by multiple rootlets that arise from the medulla and cervical spinal cord and collect together to form a bun-dle that blends into the lower margin of the vagus nerve at the level of the jugular foramen. The vagal and accessory rootlets cross the surface of the jugular tubercle. The glossopharyngeal nerve expands at the site of the superior and inferior ganglia. The superior ganglion of the vagus nerve is located at the level of or just below the dural roof of the foramen, and the infe-rior ganglion is located below the foramen at the level of the atlanto-occipital joint.

FIGURE 12-14–12-21.Postauri-cular approach to the j ugular fora-men. Figure 12-14, the C-shaped retroauricular incision (lower left) provides access for the mastoidec-tomy, neck dissection, and re?ecting the parotid gland forward. The scalp flap and superficial muscles have been re?ected forward to expose the posterior part of the parotid gland, the posterior belly of the digastric muscle, the internal j ugular vein

and longissimus capitis, and the superior and inferior oblique muscles.J UGULAR F ORAMEN

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FIGURE 12-15.A mastoidectomy has been completed to expose the facial nerve, sigmoid sinus, j ugular bulb, and the osseous capsule of the semicircular canals. The facial nerve and styloid process block access to the extracranial orifice of the j ugular foramen. The facial nerve crosses the lateral surface of the styloid process. The stylomastoid artery arises from the postauricular artery and joins the facial nerve at the stylomastoid fora-men. The superior and inferior oblique and levator scapulae muscles attach to the transverse process of C1.

FIGURE 12-16.The tympanic membrane and the posterior part of the tympanic sulcus and ring have been removed while preserving the ossicles. A cuff of tissues around the facial nerve has been preserved at the stylomastoid foramen to avoid dissec-tion directly on the surface of the nerve and also to preserve the vascu-lar supply to the nerve from the sty-lomastoid artery. It will be necessary to resect the tympanic ring if the pathology must be followed into the Eustachian tube or along the petrous carotid artery. Some hearing will be preserved if the stapes remains in the oval window.J UGULAR F ORAMEN

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FIGURE 12-17.The external audi-tory canal has been transected and the middle ear structures have been removed, except the stapes, which has been left in the oval window. The lat-eral edge of the jugular foramen has been exposed by completing the mas-toidectomy, transposing the facial nerve anteriorly, and fracturing the styloid process across its base and re?ecting it caudally. The rectus capi-tis lateralis muscle has been detached from the jugular process of the occip-ital bone. The petrous carotid is sur-rounded in the carotid canal by a venous plexus.

FIGURE 12-18.The dura behind the sigmoid sinus has been opened to expose the facial and vestibulo-cochlear nerves entering the internal acoustic meatus and the glossopha-ryngeal and vagus nerves entering the j ugular foramen. The vertebral artery is exposed medial to the

nerves.

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FIGURE 12-19.A segment of the sigmoid sinus, j ugular bulb, and internal j ugular vein have been removed. The lateral wall of the jugular bulb has been removed while preserving the medial wall and the opening of the inferior petrosal sinus into the lower part of the bulb. The glossopharyngeal, vagus, accessory, and hypoglossal nerves are exposed below the j ugular bulb. The likeli-hood of preserving these nerves in exposing a jugular foramen lesion is greatly enhanced if the medial venous wall can be preserved. The main inflow from the inferior pet-rosal sinus is directed between the glossopharyngeal and vagus nerves.