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Sign in with Apple. The rectus capitis lateralis muscle is the muscle most intimately related to the jugular foramen.
It extends vertically behind the internal jugular vein from the transverse process of the atlas to the jugular process of the occipital bone. On the posterior neck are the trapezius muscle, splenius capitis, and semispinalis capitis. Beneath the semispinalis capitis muscle, three muscles arise between the inferior nuchal line and the margin of the foramen magnum: the rectus capitis posterior major and minor and the superior oblique muscle.
The suboccipital triangle, an area defined by the opposing margins of the rectus capitis posterior major and the superior and inferior oblique muscles, is the site at which the vertebral artery courses along the upper posterior surface of the atlas. Postauricular exposure of the jugular foramen.
A, the detail shows the site of the scalp incision. The C-shaped retroauricular incision provides access for the mastoidectomy, neck dissection, and parotid gland displacement.
The scalp flap has been reflected forward to expose the sternocleidomastoid and the posterior part of the parotid gland. B, the more superficial muscles and the posterior belly of the digastric have been reflected to expose the internal jugular vein and the attachment of the superior and inferior oblique to the transverse process of C1.
A mastoidectomy has been completed to expose the facial nerve, sigmoid sinus, and capsule of the semicircular canals. C, enlarged view of the mastoidectomy. The jugular bulb is exposed below the semicircular canals. The chorda tympani arises from the mastoid segment of the facial nerve and passes upward and forward.
The tympanic segment of the facial nerve courses below the lateral canal. D, enlarged view of the caudal part of the exposure shown in C. The facial nerve and styloid process cover the extracranial orifice of the jugular foramen. The facial nerve crosses the lateral surface of the styloid process.
The stylomastoid artery arises from the postauricular artery. The rectus capitis lateralis attaches to the jugular process of the occipital bone behind the jugular foramen. The postauricular transtemporal approach accesses the region from laterally, through the mastoid, and from below, through the neck Fig. 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 completed initially to gain control of the major vessels and the branches supplying the tumor. The internal carotid artery, branches of the external 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 mastoidectomy confined 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 foramen, the facial nerve, styloid process, and rectus capitis lateralis muscle are dealt with by transposing the facial nerve, removing the styloid process, and dividing the rectus capitis lateralis muscle.
Anterior extensions of the pathological abnormality are reached by sacrificing the external and the middle ear structures. Sensorineural hearing can be preserved by maintaining the foot plate of the stapes in the oval window to avoid opening the labyrinth. Intracranial extensions of the lesion are reached by the retrosigmoid or presigmoid approaches after adding a suboccipital craniectomy.
The lesion can be removed by a transtemporal infralabyrinthine approach directed through the temporal bone below the labyrinth without the neck dissection, if the extracranial extension of the lesion is not prominent. The exposure can be extended by opening the otic capsule translabyrinthine approach. E, the external auditory canal has been transected and the middle ear structures have been removed, except the stapes, which has been left in the oval window.
The lateral edge of the jugular foramen has been exposed by completing the mastoidectomy, transposing the facial nerve anteriorly, and fracturing the styloid process across its base and reflecting it caudally. The rectus capitis lateralis has been detached from the jugular process of the occipital bone. The petrous carotid is surrounded in the carotid canal by a venous plexus.
F, a segment of the sigmoid sinus, jugular bulb, and internal jugular vein have been removed. The lateral wall of the jugular bulb has been removed while preserving the medial wall and exposing the opening of the inferior petrosal sinus into the jugular bulb. Removing the venous wall exposes the glossopharyngeal, vagus, accessory, and hypoglossal nerves, which are hidden deep to the vein.
The main inflow from the petrosal confluens is directed between the glossopharyngeal and vagus nerves. G, the medial venous wall of the jugular bulb has been removed.
The intrajugular ridge extends forward from the intrajugular process, which divides the jugular foramen between the sigmoid and petrosal parts. The glossopharyngeal, vagus, and accessory nerves enter the dura on the medial side of the intrajugular process, but only the glossopharyngeal nerve courses through the foramen entirely on the medial side of the intrajugular ridge.
The vagus nerve also enters the dura on the medial side of the intrajugular process, but does not course along the medial side of the intrajugular ridge. H, the intrajugular process and ridge have been removed to expose the passage of the glossopharyngeal, vagus, and accessory nerves through the jugular foramen. The tip of a right-angle probe identifies the junction of the cochlear aqueduct with the pyramidal fossa, just above where the glossopharyngeal nerve penetrates the dura.
A pathological abnormality located predominantly intradurally can be resected by the retrosigmoid approach Fig. A lateral suboccipital craniectomy exposes the dura behind the sigmoid sinus. The dura is opened, and the cerebellum is gently elevated away from the posterior surface of the temporal bone to expose the cisterns in the cerebellopontine angle and the intracranial aspect of the cranial nerves entering the jugular foramen, hypoglossal canal, and internal acoustic meatus.
An extended modification of the retrosigmoid approach, the far-lateral approach, the subject of another chapter in this issue, may be selected if the tumor extends down to the foramen magnum in front of or lateral to the lower brainstem 10, 30, 32, In this approach, the jugular foramen is opened from behind. 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.
Several variations, depending on the location and extent of the pathological abnormality, include drilling the jugular tubercle extradurally and removing bone above without disturbing the condyle 21, The extradural reduction of the jugular tubercle aids in minimizing the retraction of the brainstem needed to reach the area anterior to the medulla and pontomedullary junction.
The preauricular subtemporal-infratemporal approach, reviewed in detail in the chapter on the temporal bone see Figs. It may be selected for tumors that extend along the petrous portion of the internal carotid artery, through the eustachian tube, or through the cancellous portion of the petrous apex A preauricular hemicoronal scalp incision is extended down to at least the level of the tragus and possibly into the cervical region, depending on the extent of the pathological finding and whether a neck dissection is needed.
The zygomatic arch is removed or reflected downward with the temporalis muscle, taking care to preserve the frontal branch of the facial nerve. A frontotemporal bone flap, which may include the superior or lateral orbital rim, is elevated, and the glenoid fossa and the mandibular condyle with the joint capsule are either dislocated inferiorly or removed.
The dura is elevated, and the bone of the middle fossa medial to the glenoid fossa is removed until the carotid canal is opened. The eustachian tube and the tensor tympani muscle, which course anterior to the carotid canal, are sacrificed during this procedure, taking care to protect the lower cranial nerves as they exit the jugular foramen.
The styloid process is divided at its base, and the internal carotid artery is reflected anteriorly to gain access to the clivus and anterior aspect of the jugular foramen. Tumors are the most common lesions to affect the jugular foramen; the majority are chemodectomas glomus jugulare tumor , neurinomas, and meningiomas, with a small percentage of other tumors, such as chondrosarcomas and chordomas 12, The glomus jugulare tumor arises either in the adventitia of the jugular dome or from the intumescences along the tympanic branch of the glossopharyngeal nerve or the auricular branch of the vagus nerve in the jugular foramen 9.
Tumors of the same nature that arise in the tympanic cavity or in the mastoid on branches of these nerves are referred to as glomus tympanicum tumors. Small glomus jugulare tumors remain confined within the jugular foramen. However, the tumor can extend as follows: 1 along the eustachian tube into the nasopharynx and through the foramina at the base of the skull, 2 along the carotid artery to the middle fossa, 3 through the intracranial orifice of the jugular foramen or along the hypoglossal canal to the posterior fossa, 4 through the tegmen tympani to the floor of the middle fossa, 5 through the round window and the internal acoustic meatus to the cerebellopontine angle, and 6 through the extracranial orifice of the jugular foramen to the upper cervical region.
Neuromas arise either from the glossopharyngeal, vagus, or the accessory nerves, and meningiomas from arachnoid granulations in the jugular bulb or venous sinuses. Although each tumor has characteristic patterns of invasion and destruction, the basic anatomic environment is similar to that of the glomus jugulare tumor.
The approaches to the jugular foramen can be categorized into three groups: 1 a lateral group directed through the mastoid bone, 2 a posterior group directed through the posterior cranial fossa, and 3 an anterior group directed through the tympanic bone.
This categorization is based on the anatomic fact that the block of the temporal bone, excluding the squamous part, is regarded as an irregular pyramid, having its base on the mastoid surface.
The lateral approach directed through a mastoidectomy, used alone or in combination with other approaches, is the route most commonly selected for lesions extending through the jugular foramen 7, 12, Because the jugular foramen is situated under the otic capsule, the approach basic to this group is called the infralabyrinthine approach. The facial nerve is frequently transposed anteriorly to drill the bone inferior to the labyrinth.
Avoiding injury to the facial nerve is one of the key points in the lateral approaches 1. The surgical field can be widened anteriorly by sacrificing the external auditory canal and middle ear structures or medially by drilling away the otic capsule translabyrinthine approach or cochlea transcochlear approach. The postauricular transtemporal approach, when combined with a neck dissection, provides satisfactory exposure of the jugular foramen, mastoid air cells, tympanic cavity, and the extracranial structures in and around the carotid sheath.
Removal of the styloid process along with transposition of the facial nerve facilitates wide opening of the extracranial orifice of the jugular foramen and provides access to the lower part of the petrous portion of the internal carotid artery. A wider exposure for the extracranial tumor can be obtained by removing the transverse process of the atlas or dislocating or resecting the mandibular condyle. The intracranial extension of the tumor is approached either retrosigmoidally or presigmoidally after adding a lateral suboccipital craniectomy or craniotomy 4, 6, 10, 26, This group includes the retrosigmoid approach and its more extensive far-lateral and transcondylar variants.
These approaches are suited to the intracranial portion of the tumors. The conventional retrosigmoid approach provides access to the cerebellopontine angle and the intracranial orifice of the jugular foramen.
However, extensions of the tumor through the foramen magnum or medially into the clivus are beyond the reach of this approach.
The far-lateral and transcondylar modifications access these areas, providing an upward view from below by opening the posterolateral quarter of the foramen magnum and removing the posterior part of the occipital condyle.
The posterior and posterolateral margin of the jugular foramen can be accessed by removing the part of the jugular process of the occipital bone located behind the jugular foramen and the portion of the mastoid located behind the mastoid segment of the facial nerve and stylomastoid foramen. A flatter view toward the midline clivus is obtained by additional extradural drilling of the jugular tubercle, although drilling in front of these nerves risks damaging the nerves as they cross the jugular tubercle 21, The preauricular subtemporal-infratemporal approach is a major variant of this group of approaches.
It uses the pathway anterior to the external auditory canal and through the tympanic bone, which are exposed by removal or displacement of the glenoid fossa and the temporomandibular joint. The approach alone can access the anterior part of the jugular foramen after reflecting the petrous portion of the internal carotid artery anteriorly. Further extensive drilling will expose the middle to upper clivus anteriorly.
However, this approach is most often combined with a lateral approach to access an anterior extension of the pathology Fisch et al. The selection of the optimal approach requires an understanding of the nature and the extension of the lesion.
The combination of two or three approaches may be needed either in stages or in combination in one operative procedure 4, Preoperative embolization will often reduce the blood loss with a vascular tumor.
Intraoperative electrophysiological monitoring is of great help in avoiding nerve injury, in locating the neural trajectory in and around the tumor, or in predicting postoperative neural function 3, Carefully planned reconstruction is required to reduce postoperative complications, especially leakage of cerebrospinal fluid, and to achieve a satisfactory cosmetic result. Content from Rhoton AL, Jr. The posterior cranial fossa: microsurgical anatomy and surgical approaches.
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