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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3643_Библиотеки_им_академика_М_И_Перельмана.pdf
30
Fig. 1.10 Variations of the vagus nerve in the neck. The normal posi-
tion of the vagus nerve in the neck is between the ICA (and CCA) and
the IJV, on a slightly more posterior plane than the vessels. Sometimes,
however, the vagus nerve may depict a different position. Such variations are surgically relevant, and the surgeon must be aware on modifi ed
anatomical relationships, in order to avoid any damage of the nerve.
During locoregional anesthesia when the anesthesiologist tries to infi ltrate the area of the carotid sinus and glomus, inadvertent block of the
vagus nerve may ensue. Panel ( a ), vagus nerve in anterior, medial, and
superfi cial position crossing the carotid bifurcation. Panel ( b ), vagus
nerve crossing the carotid bifurcation. Note that in this case, the IJV is
also in abnormal position, i.e., anterior and medial to the ECA and
CCA. Successive images demonstrating the surgical approach, with
mobilization of the carotid bifurcation and of the vagus nerve, allowing
the endarterectomy and insertion of the synthetic patch
ICA
CCA
X
IJV
a
H. Muresian
31
IJV
ICACCA
X
ECA
ICA
IJV
CCA
X
ICA
IJV
CCA
X
b
Fig. 1.10 (continued)
1 The Cerebral Circulation
32
CCA
ICA
ECA
IJV
XI
V3
Fig. 1.11 Accessory nerve in
pre-jugular position. The
accessory nerve ( XI ) may depict
a pre-jugular position and may
be damaged more easily when
exposing the carotid bifurcation
during removal of cervical lymph
nodes. In the case illustrated, the
pre-jugular accessory nerve can
be further damaged while
approaching the suboccipital
vertebral artery ( V3 )
H. Muresian
33
VII
IX
X
XII
XI
XII
X
XI
VII
IX
VII
XII
XI
X
IX
XII
a
b
c
Fig. 1.12 The retromandibular space. Schematic reconstruction as in
Fig.
1.6 . Panel ( a ), inferior view of the cranial base, with the mandible
removed. The IJV ( blue ) and the ICA ( red ) are surrounded by numerous
nerves. The vagus ( X ) and glossopharyngeal ( IX ) nerves exit the cranial
cavity in a pre-jugular position and the accessory nerve ( X ) retro-
jugular. The hypoglossal nerve ( XII ) exits through a separate canal
(hypoglossal canal) and passes between the ICA and the IJV. The styloid muscles separate the facial nerve ( VII ) from the remainder. The
facial nerve crosses the retromandibular space to reach the parotid
gland. Panel ( b ), lateral view with the mandible in place. Note the nar-
row space between the mastoid process and the mandible and the deeper
position of the ICA. Panel ( c ), with mobilization of the mandible
( double-headed arrow ), the retromandibular space can be enlarged,
usually no more than 2 cm as the facial nerve can be easily elongated
and damaged. Exposure of the distal ICA usually requires division of
the styloid muscles
1 The Cerebral Circulation
34
SCA
VA
V3
V4
SCA
VA
ITA
Inf Thyr
V3
SCA
VA
V3
VA
PICA
AICA
SCA
VA
BA
PCA
a
b
Fig. 1.13 The vertebral artery (1). Angiographic aspect of the verte-
bral artery (VA). Panel ( a ), the origin is usually in the fi rst portion of the
subclavian artery ( SCA ) opposite the internal thoracic ( ITA ). More dis-
tal to the VA origin, are the thyrocervical trunk and suprascapular arteries. The fi rst portion ( V1 ) is on a deeper plane, between the anterior
scalene and longus colli muscle. The artery enters the transverse foramen of the cervical vertebra C
6
(although numerous variations of
entrance are described). The C2–C1 and suboccipital curves of the VA
are well visible (V3 and V4). InfThyr inferior thyroid artery. Panel ( b ),
the distal segments of the VA as these appear on angiogram. Anterior
and lateral projections. VA vertebral artery, BA Basilar artery, PICA pos-
terior inferior cerebellar artery, AICA anterior inferior cerebellar artery,
SCA superior cerebellar artery, PCA posterior cerebral artery
H. Muresian
35
ICA
ECA
CCA
IJV
X
VA
Thyr
OHi
Fig. 1.14 The vertebral artery (2). Intraoperative aspect of the fi rst seg-
ment of the VA, from origin in the SCA to the entrance in the transverse
osseous canal at the level of C
6
. The carotid artery and bifurcation were
dissected both inferior and superior to the omohyoid muscle OHi (the
pretracheal/visceral layer of the cervical fascia was divided). The VA
was approached between the CCA and the IJV (retracted together with
the vagus nerve X). The bony canal is covered by the origins of the
longus colli ( LC ) and anterior scalene ( AntSc ) muscles. Thyr thyroid
gland. Note the close relationship between the CCA and the VA, allowing the reimplantation of the VA into the CCA
1 The Cerebral Circulation
36
Fig. 1.15 The vertebral artery (3). Panel ( a ), demonstration of the dis-
tal (“upper”) segments of the VA, as it winds around the lateral masses
of the atlas ( C
1
) and perforates the posterior atlanto-occipital membrane
( yellow ring ) and the dura mater ( white ring ). Note the close proximity
with the odontoid process of axis ( C
2
), the lateral masses of the atlas
and the articular surfaces of the latter, with the occipital bone. The spinous process of axis is also the most prominent, allowing for a good
radiological identifi cation. Note also that the spinous processes of the
cervical vertebrae are bifi d. There is also a natural asymmetry of the
two VAs. Panel ( b ), anterior view of the same fi rst three cervical verte-
brae and the VAs. Note the orientation of the transverse foramina of the
axis with the superior part of the orifi ce oriented laterally. The transverse processes of the atlas are far more lateral than those of the remainder cervical vertebrae, being palpable just underneath the mastoid
processes (and offering a good landmark for surgery and for regional
anesthesia). Panel ( c ), the same fi rst three cervical vertebrae – posterior
aspect. Surgical approach to these segments of the VAs is cumbersome,
as the artery is on a deeper plane, covered by the suboccipital muscles.
Panel ( d ), anatomical relationships of the VA and cervical nerves. The
transverse processes of the cervical vertebrae contain the sulcus of the
cervical nerve, immediately posterior to the VA. Inadvertent puncture
of the VA may occur with cervical plexus block due to the very narrow
space between the two structures. In the same way, the subarachnoid
space may also be entered. Panel ( e ), suboccipital segments of the VAs
and anatomical relationships. The uppermost portion of the VA is covered by the suboccipital muscles. The VA can be exposed in the “vertebral artery trigone” delimitated by the following muscles: inferior
oblique ( ObI ), superior oblique ( ObS ), rectus capitis posterior major
( RCPM ). In the median portion, the rectus capitis posterior minor
( RCPm ) is partially covered by RCPM. In the area of the triangle, the
VA is also covered by the posterior atlanto-occipital membrane. The
fi rst two cervical nerves are just posterior to the VA (C
1
and C 2 ). MAST
mastoid process
BA
V3
V4
Lat. mass
C
1
C
2
C
3
*
a
H. Muresian
37
BA
C
1
C
2
C
3
V2
V3
V4
Left VA
*
c
BA
Left VA
Right VA
C
1
C
2
C
3
V3
V2
V4
b
Fig. 1.15 (continued)
1 The Cerebral Circulation
38
VA
MAST.
RCPm
RCPM
ObS
ObI
C
1
C
2
V3
C
2
C
3
C
1
Left VA
Right VA
CERVICAL
NERVE
CERVICAL
NERVE
SULCUS
d
e
Fig. 1.15 (continued)
H. Muresian
39
Ophtalmic
PCommA
Ant. Choroid.
MCAACA
Styloid process
Mastoid process
ICA
Cervical
Petrous
Cavernous
Cisternal
Cerebral
Ant
Post
LR
Fig. 1.16 The segments of the
internal carotid artery. The
drawing illustrates an anterior
view of the left ICA and the
major curves described by the
vessel. Numerous classifi cations
of the ICA segments have been
elaborated during time, serving
various purposes (see text for
details). We present here only the
major portions, as the more distal
three are frequently subdivided
especially for neurosurgical and
endovascular purposes. ACA
anterior cerebral artery, MCA
middle cerebral artery, Ant
Choroid anterior choroidal artery,
PComm A posterior
communicating artery
Fig. 1.17 The segments of the vertebral artery. The left panel illus-
trates the normally appearing angiographic image of the VA and its
segments: V0 the very origin, V1 the pretransversal (extraosseous) seg-
ment, V2 the intraosseous segment, V3 the atlanto-occipital loop, and
V4 the suboccipital segment eventually fusing into the basilar artery
( BA ). The remainder two images demonstrate the concomitant
visualization of the two VAs in a case with vertebral steal due to occlusion of the brachiocephalic trunk. Note the equal caliber of the two
VAs. The case was selected in order to demonstrate the numerous muscular branches of the VA and anastomoses with branches of the SCA
and carotid arteries (usually not so well visible)
1 The Cerebral Circulation