Fig. 2.1
Anatomy of the intracranial end of the left jugular bulb and its adjacent area. (a) Osseous structures related to the jugular foramen. The jugular foramen sits between the internal auditory canal and hypoglossal canal. The foramen is separated into two parts by the intrajugular processes of the temporal and occipital bones. The petrosal part is the smaller medial part where the pyramidal fossa opens into its superior margin. The sigmoid part is the lateral part where the sigmoid sulcus ends. The petroclival fissure terminates at the anteromedial edge of the foramen. (b) The neurovascular relationships of the intracranial end of the jugular foramen and its adjacent area. The foramina for the cranial nerves lie in the anterior wall of the posterior fossa dura. The glossopharyngeal, vagus, and accessory nerves enter into the jugular foramen. The trigeminal nerve enters Meckel’s cave. The abducens nerve pierces the dura covering the clivus. The facial and vestibulocochlear nerves enter the internal auditory canal. The hypoglossal nerve enters the hypoglossal canal. (c) The dura covering the petrous surface of the temporal bone has been removed. The endolymphatic sac sits on the posterior surface of the petrous bone anterior to the sigmoid sinus. The neural part of the jugular foramen is located between the petrosal and sigmoid parts of the jugular foramen. (d) Neurovascular relationships of the intracranial end of the jugular foramen and its adjacent area were shown after removal of the jugular bulb. The glossopharyngeal nerve enters the glossopharyngeal meatus. The vagus and accessory nerves enter the vagal meatus. They are separated by the dural septum. (e) The terminal part of the sigmoid sinus and jugular bulb have been removed and the superior margin of the sigmoid part of the jugular foramen and jugular process of the temporal bone have been drilled to expose the course of glossopharyngeal, vagus, and accessory nerves in the foramen. The vagal rootlets form the vagal superior ganglion in the foramen where Arnold’s nerve arises. (f) Translocating the vagus nerve laterally shows the course of the glossopharyngeal nerve. The superior ganglion of the vagus nerve has been retracted to expose the tympanic branch of the glossopharyngeal nerve. The branch originates from the glossopharyngeal nerve at the external orifice of the jugular foramen. (g) Anatomical structures buried in the temporal bone were shown from the posterior cranial fossa. The jugular process and rectus capitis lateralis muscle are obstacles to accessing the jugular bulb. (h) Removal of the jugular process and rectus capitis lateralis muscle exposes the posteroinferior surface of the jugular bulb and posterior surface of the internal jugular vein. A. artery, Ac. acoustic, Aqued. aqueduct, Asc. ascending, Aur. auricular, Br. branch, CN cranial nerve, Cap. capitis, Coch. cochlear, Cond. condylar, Cond. Condyle, Depress. depression, Endolymph. endolymphatic, Fiss. fissure, Glossophar. glosopharyngeal, Hypogloss. hypoglossal, Inf. inferior, Int. internal, Intrajug. intrajugular, Jug. jugular, Lat. lateralis, M. muscle, Marg. marginal, Meat. meatal, meatus, Occip. occipital, Petro-occip. petro-occipital, Pet. petrosal, Post. posterior, Proc. process, Rec. rectus, Sept. septum, Sig. sigmoid, Sup. superior, Trig. trigeminal, Temp. temporal, Tymp. tympanic, V. vein, Vert. vertebral, Vest. vestibular
Fig. 2.2
Anatomy of the extracranial end of the jugular bulb and its adjacent area. (a) Osseous structures related to the jugular foramen from inferior. The foramen sits behind the carotid canal and styloid process, lateral to the anterior part of the occipital condyle and medial to the styloid foramen. The jugular process forms the posterior surface of the bulb. (b) The anatomy of the jugular foramen from inferior. The muscular structures have been removed, and the mastoid process, jugular process, and occipital condyle have been drilled to show the course of the sigmoid sinus. The hypoglossal canal and posterior condylar canal have been skeletonized to show their courses in the occipital condyle and jugular tubercle, respectively. The internal carotid artery courses just anterior to the internal jugular vein. (c) The clivus has been drilled to expose the inferior petrosal sinus. The sinus, which courses along the intracranial surface of the petroclival fissure, and the inferior petroclival vein, which courses along the extracranial surface of the fissure, empty into the petrosal confluence before emptying into the internal jugular vein. The lateral condylar vein has been partially removed to expose the course of CN XII and the venous plexus of the hypoglossal canal. The posterior condylar vein empties into the medial surface of the sigmoid sinus. (d) The occipital condyle and hypoglossal canal have been drilled to expose the course of the hypoglossal nerve. The alar ligament and dura covering the posterior cranial fossa have been removed. The ascending pharyngeal artery sends the jugular and hypoglossal branches. A. artery, Asc. ascending, CN cranial nerve, Car. carotid, Cond. condyle, condylar, Conf. confluence, Fiss. fissure, For. foramen, Hypogl. hypoglossal, Inf. inferior, Int. internal, Jug. jugular, Lat. lateral, Max. maxillary, Occip. occipital, Occipitomast. occipitomastoid, Pet. petrosal, petrous, Petrocliv. petroclival, Pharyng. pharyngeal, Post. posterior, Proc. process, Sig. sigmoid, Sphenopet. sphenopetrosal, Stylomast. stylomastoid, Vag. vaginal, V. vein, Vert. vertebral
Fig. 2.3
(a) The removal of the temporal bone, parotid gland, temporomandibular joint, and pterygoid muscles clearly exposes the neurovascular relationships around the jugular foramen. (b). The translocation of the internal carotid artery anteriorly and internal jugular vein posteriorly exposes the course of the lower cranial nerves after they exit the jugular foramen and hypoglossal canal. (c) Translocation of the jugular bulb leaving the medial wall of the bulb shows the relationship between the sinuses and cranial nerves. (d) Removal of the posterior fossa dura and medial wall of the jugular bulb clearly shows the intracranial, foraminal, and extracranial courses of the lower cranial nerves. Red and black asterisks indicate the ganglion of the glossopharyngeal and vagal nerves, respectively. A. artery, Ac. acoustic, AICA. anterior inferior cerebellar artery, Asc. ascending, Auriculotemp. auriculotemporal, Br. branch, Car. carotid, CN cranial nerve, Cond. condylar, Chor. choroid, Ext. external, Fibrocart. fibrocartilage, For. foramen, Flocc. Flocculus, Gass. gasserian, Gang. ganglion, Inf. inferior, Int. internal, Jug. jugular, Lt. left, Max. maxillary, Meat. meatus, N. nerve, Occip. occipital, Pet. petrosal, Plex. plexus, Post. posterior, Pharyng. pharyngeal, Sig. sigmoid, Sternocleidomast sternocleidomastoid, Symp. Sympathetic, Temp. temporal, Transver. transverse, V. vein, Vert. vertebral
Fig. 2.4
Postauricular transtemporal approach. (a) High cervical exposure. (b) Infralabyrinthine mastoidectomy. (c) The removal of the mastoid tip exposes the insertion of the rectus capitis lateralis muscle into the jugular process. (d) Removal of the jugular process and the rectus capitis lateralis exposes the posteroinferior surface of the jugular bulb. (e) Enlarged view of the dotted area in (c) after the Fallopian bridge technique was performed. (f) View of the presigmoid approach. (g) View of the retrosigmoid approach. (h) Removal of the external auditory canal and infracochlear drilling exposes the internal carotid artery medial to the jugular bulb. A. artery, A.I.C.A. anterior inferior cerebellar artery, Aur. auricular, Aque. aqueduct, Cap. capitis, Car. carotid, Chor. chorda, choroid, CN cranial nerve, Coch. cochlear, Cond. condylar, Endolymph. endolymphatic, Flocc. flocculus, For. foramen, Gl. gland, Gr. greater, groove, Inf. inferior, Int. internal, Jug. jugular, Lat. lateral, lateralis, Lev. levator, N. nerve, M. muscle, Mast. mastoid, Mid. middle, Obl. oblique, Occip. occipital, Occipitomast. occipitomastoid, Pet. petrosal, Plex. plexus, Post. posterior, Proc. process, Rec. rectus, Scap. scapula, Sig. sigmoid, Suboccip. suboccipital, Sup. superior, Surf. surface, Stylomast. stylomastoid, Temp. temporalis, Triang. triangle, Tymp. tympani, M. muscle, Transv. transverse, V. vein
Fig. 2.5
Far-lateral approach. (a, b) Posterolateral view of the far-lateral approach. (c, d). Posteroinferior view of the far-lateral approach. Yellow and red dotted lines indicate the area for the occipital condyle and jugular process, respectively. A. artery, Atl. Occ. atlanto-occipital, Aud. auditory, CN cranial nerve, Ext. external, Flocc. flocculus, Hypogl. hypoglossal, Int. internal, Inf. inferior, Jug. jugular, Lat. lateral, P.I.C.A. posterior inferior cerebellar artery, Post. posterior, Proc. process, Sig. sigmoid, Styl. styloid, Sup. superior, Surf. surface, V. vein, Vert. vertebral
Osseous Relationships
The jugular foramen is a hiatus between the temporal bone anterolaterally and occipital bone posteromedially. The petroclival fissure, which separates the petrous portion of the temporal bone and lateral part of the occipital bone, ends at the anteromedial edge of the foramen (Figs. 2.1a and 2.2a). The inferior petrosal sinus courses along the intracranial surface of the fissure, and the inferior petroclival vein courses along its extracranial surface. The occipitomastoid suture , which separates the mastoid part of the temporal bone and squamosal portion of the occipital bone, ends at the posterolateral edge of the foramen. The jugular process, located between the lateral part of the condyle and terminal part of the occipitomastoid suture, forms the posteroinferior border of the jugular foramen (Figs. 2.1b, c, g, h and 2.2). The jugular foramen has three parts: two venous portions including the sigmoid and petrosal and a neural compartment, the intrajugular part. The two venous components, a large lateral part and small medial part, are separated by bony processes, the intrajugular processes of the temporal and occipital bones and intrajugular ridge, which extends forward from the intrajugular process of the temporal bone (Figs. 2.1a, e and 2.2a). The processes are joined by a fibrous or less commonly an osseous bridge, the intrajugular septum, separating the sigmoid and petrosal parts of the foramen [1]. The larger sigmoid part receives drainage from the sigmoid sinus, and the smaller petrous part receives drainage from the inferior petrosal sinus (Figs. 2.1a, b and 2.2a). The pyramidal fossa, a small triangular recess located on the medial side of the intrajugular process of the temporal bone, extends along the anterior surface of the petrous part of the jugular foramen (Figs. 2.1a and 2.2a). Around or in the jugular foramen, the dura of the posterior fossa is attached to the small foramina, mastoid canaliculus , tympanic canaliculus, and cochlear aqueduct. The small foramen on the lateral wall of the jugular fossa is called the mastoid canaliculus , and the auricular branch of the vagus nerve (Arnold’s nerve) passes through it (Fig. 2.1e, g). The cochlear canaliculus transmits the perilymphatic duct and cochlear aqueduct; its orifice is located just superior and lateral to where the glossopharyngeal nerve enters the intrajugular part of the jugular foramen. The tympanic canaliculus for Jacobson’s nerve, a branch of the glossopharyngeal nerve, is located on or close to the medial part of the carotid ridge. The carotid ridge separates the carotid canal from the jugular foramen and extends to the intrajugular process of the temporal bone (Figs. 2.1a, e, f and 2.2a) [2].
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