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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6025_Библиотеки_им_академика_М_И_Перельмана
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1 Anatomy and Surgical Approaches
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1.2 Neuroanatomy
I. Spin al cord .
A. Gro ss s t r u c t u r e .
1. The spinal cord typically ends at L1–L2 (conus medullaris).
a. It may be as high as T12 or as low as L2–L3.
b. In newborn infants, the cord ends at L2–L3.
2. Length: 45 cm cord and 25 cm lum terminale (10% increase in length with
exion, mostly at C1, T1, and L1, least at C6 and T6).
3. Mean diameter (10 mm, transverse diameter greater than sagittal diameter).
4. Relationship between cord and vertebral segments (Fig. 1.2) (Table 1.3).
Fi g . 1 . 2 Th e sp in al co rd an d n er ve
root s. The spinal cord em erges from
the foramen magnum as a continuation of the medulla oblongata and
ends in a cone-shaped structure
known as t he conus medullaris. The
loca t ion of t he co n u s m ed u lla ris is
usually the L1–L2 intervertebral disk
in a d ult s. Th e ce r vica l co rd e nlarg e s
maximally at the C6 vertebra to provide C3–T2 innervat ion to the upp e r
lim bs, an d th e lum bo sacra l enlarge ment is present at T11–L1 vertebral
segm ents to provide L1–S3 cord segments to the lower extremities.
Ta b l e 1 . 3 Re la t io n s h i p b e t w e e n c o r d a n d
vert e bral se g m ent s
Co r d s e g m e n t Ve r t e b ra l s e g m e n t
C1 C1
C8 C7
T6 T5
T1 2 T8
L2 T 1 0
1 Anatomy an d Surgical Approaches 5
L5 T 1 1
S3 T12
B. In t er n al s t r u ct u re s (Fig. 1.3) (Table 1.4).
1. The peripheral white matter and central gray matter.
a. Gray matter: cell bodies of e erent neurons.
(1) Posterior horns: som atosensory.
(2) Anterior horns: som atom otor.
(3) Intermediolateral horns: visceral.
(4) Re ex som atic centers.
b. White m atter: nerve bers and glia.
(1) Posterior funiculus: posterior colum ns (fasciculus cuneatus laterally
and gracilis medially).
(2) Lateral funiculus: lateral corticospinal and lateral spinothalam ic
fascicu lu s.
(3) Anterior funiculus: anterior spinothalam ic tract.
2. Central ependymal canal: passage of cerebrospinal uid.
3. Spinal cord syndromes (Table 1.5).
C. Vas c u la rit y o f t h e sp in al co r d .
1. Cervical spine.
a. The anterior spinal artery: the major vessel for anterior and central
aspects of the cord:
(1) Two medullary feeders at the brain stem by the vertebral arteries.
(2) Other medullary feeders from the vertebral arteries and ascending
cervical arteries, particularly C2 and C6 from th e left and C2, C5, C6
from th e righ t .
b. Two posterior spinal arteries from the posterior inferior cerebellar
arteries have minimal contribution to the central gray matter.
2. Thoracolumbar spine.
a. The anterior spinal artery, two posterior spinal arteries.
1 Anatomy and Surgical Approaches
6
a
b
Fi g . 1 . 3 ( a , b ) Cro ss se ct ion o f t h e sp inal co rd wit h t h e ou t er whit e m at te r and t he inn e r g ra y m at te r.
Th e wh it e m a t t e r o f t h e sp in al co rd co nt a in s ne rve b e rs a nd g lia a nd is d ivid e d in t o t h re e co lu m n s:
posterior, lateral, and anterior. The posterior column includes the fasciculus cuneatus laterally and the
fasciculus gracilis m edially. Th e latera l colum n co n t a ins t he d e sce nding m ot o r latera l co rticospinal
and lateral spinothalamic fasciculi, and the anterior funiculus contains the ascending anterior spinothalamic tract and other descending tracts. The lateral spinothalamic tracts cross through the ventral commissure to the contralateral side of the cord. The gray matter of the spinal cord contains cell
bodies of e erent and internuncial neurons.
Ta b l e 1 . 4 Spin al cord fu n ct ion
Co m p o n e n t s N o t e s
1 Anatomy an d Surgical Approaches 7
Mot or fu nct ion Ce re b ral co rt ex
In t e rn al c ap su le
Co rt ico sp in al t ra c t
Pyramidal tract (90%
decussate at the medulla
to the contralateral lateral
corticospinal fasciculus)
An t e r io r h o r n c e lls
Se n so r y fu nct ion Fa s c i c u l u s g r a c i l i s : l o w e r l i m b s
and below midthorax
Fa s c i c u l u s c u n e a t u s : u p p e r
lim bs an d ab ove m idt h o rax
La t e r a l c o r t i c o s p i n a l f a s c i c u l u s :
tracts for the upper extremities
are medial to the lower
extremities
Se n so r y t ract s cro ss t o t he
opposite side in the medulla
oblongata and to the sensory
cortex
b. Feeders.
La t e r a l s p i n o t h a l a m i c
fasciculus: p ain, te m perat ure,
and light touch
An t e r io r s p in o t h a la m i c
fasciculus: cru de touch
Ta c t i le d i s c r i m in a t i o n ,
proprioception, and vibration sense
Mo s t b e rs c ro ss t h ro ug h t he
vent ral com m issure t o t he
opposite side and ascend through
the lateral spinothalamic tract
Post erior cord synd ro m e: o n ly
crude touch is spared
(1) Superior intercostal artery: branch of deep cervical artery, which is a
branch of the right subclavian artery, feeds the cord at the cervical–
thoracic junction.
(2) One to ve segm ental vessels: tenuous blood supply for the upper
thoracic cord (watershed critical zone from T4 to T10).
(3) The artery of Adamkiew icz (80% from T10 from the left, but origin
may vary from T5 to L5) supplies the thoracic cord.
(4) Anastom otic loop of the conus medullaris from aortic segm ental and
lateral sacral arteries.
3. Venous drainage (azygos and hemiazygos veins).
a. Veins of the spinal cord anteriorly and posteriorly.
b. Batson’s plexus: from basiocciput to the coccyx.
c. Clinical signi cance: metastatic dissem ination and infections
II. Sp in a l m e n in ges (Fig. 1.4).
A. Du r a m at e r : o u te r co ve r in g o f t h e sp in al co rd .
B. Le p t o m e n in x: p ia m at e r ( o u t e r lin in g o f t h e co rd ) a n d a r a ch n oid m e m b ra n e
(transparent sheet containing the cerebrospinal uid).
1 Anatomy and Surgical Approaches
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Ta b l e 1 . 5 Spin al cord synd ro m es (in com p let e co rd in jury)
Syndro m e Charac t e ris tic s Co m m o n cau s e s Re co ve ry
Ce n t ra l
cord
syndrome
(most
comm on)
An t e r io r
cord
syndrome
Great er m o t or d e cit
in u ppe r e xt re m ities
(medial tract s of the
lat e ral cort ico spin a l
fasciculus) com p are d
with the lower
extremities (lateral
tracts).
Mo t or fu n c t io n a nd
sensation to light
touch are impaired.
Th e p os t e rio r co lu m n
Ext e n s io n in j u r y
mechanism in
patients with
spondylosis
due to anterior
osteophytes and
posterior infolded
ligam en t um avu m
(pincer e ect)
Dire ct co m p re ssio n
of anterior spinal
cord or anterior
spinal artery injury
Goo d p ro g no sis (full
funct ional re cove ry
is rare )
Lo w e r e x t r e m i t y a n d
bladder function
recover before
upper extremities
Worst pro g n o sis
10–20% motor
recovery
Br o w n –
Séq u a rd
syndrome
funct ions (pressure and
proprioception) are
spared.
Pain and t e m p erat u re loss
are contralateral and one
or two levels below the
injury, whe reas m ot or and
proprioception loss are
ipsilat eral and at t he le vel
of the injury. The motor
paralysis is accid at the
leve l o f t he injury (lo wer
motor injury). Below the
from b o ny spicu les
Penet rat ing t raum a
(st ab wound to the
back)
Exc e l le n t p r o g n o s i s
99% recovery of
ambulatory function
Post e rior
cord
syndrome
(very rare)
leve l o f in jury, t he m ot o r
paralysis is spastic (upper
motor injury).
Lo s s o f p r o p r i o c e p t i o n
and vibration sense only
(posterior spinal cord).
In ju r y t o t h e
posterior spinal
artery
Ra r e a n d n o t we ll
characterized
1 Anatomy an d Surgical Approaches 9
a
b
Fi g . 1 . 4 ( a , b ) Cro ss se ct io n o f t he sp in a l co rd a n d m en in g e s. The sp in a l co rd is co ve re d b y t he pia
mater, which is the outer lining of the cord, and the transparent arachnoid mater, which contains the
cerebrospinal uid. The dura mater is the outer covering of the spinal cord. The spinal cord is anchored
to the dura by the dentate ligaments that project laterally from the lateral side of the cord to the
arachnoid and dura midway between the exiting spinal nerves.
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1 Anatomy and Surgical Approaches
C. De n t a t e liga m e n t: b et w e e n t h e d or sa l a n d ve n t ra l n e r ve r o o t s , s t ab iliz e s t h e
spinal cord within the dura.
D. Sep t um p osticu m bet w ee n th e p ia and arachn oid on t he d orsa l aspect fro m
low er cervical to con us regions.
E. Ep id u r a l sp a c e : sp ace b et w e e n t h e b on e a n d d u r a .
1. Space: 2 mm at L3–L4, 4 mm at L4–L5, 6 mm at L5–S1.
2. Plica mediana dorsalis durae matris: a median fold at the lum bosacral region.
F. Te r m i n a t i o n o f t h e d u r a / a r a c h n o i d e n v e l o p e v a r i e s f r o m S1 – S 2 t o S2 – S 3 , a n d
the dura invests the lum terminale and attaches to the coccyx.
III. Sp in al n er ves.
A. Th ir t y- on e p air s o f sp in a l n e r ve s : 8 ce r vica l, 1 2 t h o ra cic, 5 lu m b a r, 5 sa cr al,
1 coccygeal.
B. Th e s p in a l r oot n e r ve co n sis t s o f m o t o r a n d s e n so r y r oo t le t s , t h e d or sa l r o ot
ganglion, and the spinal nerve.
1. Sympathetic connections by preganglionic (white) rami and unmyelinated
postganglionic (gray) rami.
2. Branches: sinuvertebral nerve to the annulus of the disk, and dorsal ramus
for facet s an d p ost er io r m uscle s .
a. The sinuvertebral nerve reenters the spinal canal through the foramen
to lie anterior to the nerve root and cranial to the disk. The sinuvertebral
nerves innervate the posterior longitudinal ligament, the posterior part
of the annulus, and the ventral part of the dura. The sinuvertebral nerves
typically ascend to innervate the superior disk as well.
b. The dorsal primary rami gives medial (innervates facet joints above and
below, segmental muscles, and interspinous ligament), lateral (innervates
iliocostalis m u scle), and occasion ally interm ediate (innervates
longissim us m u scle) branches.
C. Th e C1 n e r ve e m er ge s a b ove t h e C1 ve r t eb r a , a n d t h e C8 e m e r ge s a bo ve t h e T1
vertebra. In th e th oracic an d lum bar regions, the sp in al nerves em erge beneath
the pedicles bearing the same number.
D. Sp in al ner ves in t he in t er vertebra l foram ina:
1. Cervical spine: no intervertebral foramen for C1 and C2, but C3–C8 escape
through corresponding foramina occupying ~ 75% of space.
2. Thoracic spine: thoracic spinal nerves are small and occupy 20% of the
foram en a n d e xit b elow t h e p e d icle.
3. Lumbar spine: large lumbar nerves occupy 33% of the foramen and exit
obliquely below the pedicle.
4. Sacrum: anterior rami emerge through the anterior sacral foramina, and
posterior rami through the posterior sacral foramina.
E. De r m at om e s a n d m yo t o m es (Fig. 1.5) (Table 1.6).
F. D y n a m i c s :
1. L5 or S1 nerve roots may glide up to 1 cm during exion–extension.
2. The spinal cord and nerve roots generally stretch in exion and relax in
extension, but the spinal canal and foramen enlarge in exion and narrow in
extension.
G. Ca ud a e qu in a:
1. Lumbar and sacral roots are organized in a speci c pattern.
2. Fifty percent compression of the thecal sac leads to dysfunction.
1 Anatomy an d Surgical Approaches 11
b
a
Fi g . 1 . 5 ( a – c ) An t e r io r a n d p o s t e r io r d e r m a t o m e s .
H. Nerve root an om alies (Kadish and Sim m ons) (Fig. 1.6):
1. Type I: intradural anastomosis.
2. Type II: anomalous origin of nerve roots.
3. Type III: extradural anastomosis.
4. Type IV: extradural division.
I. Vascu lat u re of t h e n er ve root :
1. Proximal and distal radicular arteries anastomose in the proximal third of
c
the root in the foramen, which may be a vascular-de cient area.
2. Intrinsic vasculature: interfascicular and intrafascicular vessels with
com pensat ing coils and ar teriovenous anastom osis allow considerable
interfascicu lar m otion and stretch of the root.
3. A thin pia mater allows exchange of metabolites with cerebrospinal uid.
4. Mechanical compression causes vascular compression, which manifests in
neuroischemic claudication clinically.
J. Pl e x u s :
1. Cervical and brachial plexus.
a. The anterior rami of C1–C4 form the cervical plexus.
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1 Anatomy and Surgical Approaches
Ta b l e 1 . 6 Myo t o m e a n d d e rm at om e d ist rib ut ion
Nerve
ro o t Mo t o r Se nso ry Re ex
C4 Dia p hra g m an d t ra p eziu s Ba se o f n e ck No ne
C5 De lt oid an d b ice ps Up p e r o ut e r a rm Bice ps b ra ch ii
C6 Wrist e xt e nso rs Thu m b Brach io ra d ia lis
C7 Tr i c e p s a n d w r i s t e xo r s Lo n g n g e r Tr i c e p s b r a c h i i
C8 Fin g e r e xo rs Lit t le n g e r None
T1 In t rin sic m u s c le s o f t h e h a n d Me d ia l fo re arm No ne
L1 Tr a n s v e r s u s a b d o m i n i s I n g u i n a l r e g i o n N o n e
L2 I l i o p s o a s U p p e r t h i g h N o n e
L3 Q u a d r i c e p s A n t e r i o r a n d m e d i a l
None
thigh
L4 T i b i a l i s a n t e r i o r A n t e r i o r k n e e , m e d i a l
Pat ellar t e ndon
le g , ankle, a n d fo ot
L5 E x t e n s o r h a l l u c i s l o n g u s F i r s t w e b s p a c e H a m s t r i n g
S1 Gast ro cn e m iu s Po st erior t h ig h,
Ac h i lle s t e n d o n
small toe
S2 Bla d d e r sp hin c t e r Po st erior t h ig h and
le g
Bu lb o c a ve r n o s u s
(S2–S3)
S3– S5 An a l sph inct e r (S3 ) Pe rin e um , a n us An a l t o n e (cau d a
equina syndrome)
Fi g . 1 . 6 Th e fo ur t yp es o f n e r ve ro ot a no m a lie s.
1 Anatomy an d Surgical Approaches 13
b. The anterior rami of C5–T1 form the brachial plexus.
(1) Branches: suprascapular (C5–C6), subscapular (C5–C6), subclavius
(C5–C6), long thoracic (C5–C7), musculocutaneous (C5–C6), median
(C5–T1), axillary (C5–C6), radial (C5–T1), medial cutaneous nerve of arm
and forearm (C8–T1), medial cutaneous (C8–T1), ulnar (C8–T1).
2. Lumbosacral and coccygeal plexus.
a. Lumbosacral trunk (L4, L5) and S1, S2, S3, and S4 anterior rami.
b. Sciatic (L4–S3) and pudendal (S2–S4) nerves.
c. Branches: superior gluteal (L4–S1), inferior gluteal (L5–S2), nerve to
the obturator internus, nerve to the quadratus femoris (L5–S2), and the
posterior cutaneous nerve of the thigh (S1–S3).
d. Anterior coccygeal plexus: S5 and coccygeal anterior rami to become
anterior caudal nerve.
IV. Au to n om ic syst e m s (sym pat h et ic an d para sym pat hetic syst em s).
A. Sy m p a t h et ic ce n te rs .
1. C8 to L4 spinal cord.
2. Sympathetic trunk and ganglions: cervical to sacral.
3. Cardioaccelerator center, sweat glands, vasomotor, bronchopulmonary,
abdominal splanchnic, anorectal/bladder continence, and ejaculation center.
4. Loss of sympathetic system.
a. Peripheral vasodilation (hypotension), bradycardia, inability to perspire,
and hypothermia due to spinal cord injury (injury of the preganglionic
ber and intermediolateral cell column).
b. Horner’s syndrome: drooping of upper eyelid (ptosis), enophthalmos,
contraction of the pu pil (m iosis), absen ce of sweating (an h idrosis) (injur y
to cervical or rst thoracic sympathetic chain).
c. Urogenital problem s: retrograde ejaculation due to improper closing of
the bladder neck (injury to the hypogastric plexus).
d. Autonomic dysre exia.
(1) Spinal cord injury above sympathetic splanchnic visceral out ow (T6).
(2) Hypertension, sweating, headache, ushing (return of re ex).
B. Pa ra sy m p a t h et ic s y s t e m s : b r a i n s t e m a n d s a c r a l s p in al c o rd ( v is ce ra l a n d p e n ile
erection functions).
1.3 Surgical Anatomy
I. Ce r vical sp in e (Fig. 1.7).
A. Bon y a n at o m y (Fig. 1.8).
1. Atlas: no vertebral body, anterior tubercle (longus colli attachment),
posterior tubercle (rectus minor and suboccipital membrane attachment),
and large transverse processes with transverse foramen (superior and
inferior oblique muscle at tachm ent).
a. The posterior neural arch fuses at 3 years, and anterior neural arch (two
sites) fuses at 7 years.
b. The atlas has large transverse processes, where the superior and inferior
oblique m uscles attach. The transverse foramen is located within the
transverse process, through which the vertebral artery passes.
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