zill anatomy web pages - internal morphology of the spinal cord and brain...

98Internal M

orphology of the Spinal Cord and Brain in Stained Sections

Medial motor nuclei

Anterolateral system

Anterior corticospinal tract

Gracile fasciculus

Posterior spinocerebellar tract

Rubrospinal tract

Reticulospinal fibers

Cuneate fasciculus

Cuneate nucleus

Anterior spinocerebellar tract

Spinal trigeminal nucleus (pars caudalis)GelantinosaMagnocellular

Tectospinal tract

Medial longitudinal fasciculus

Accessory nucleus

Spinal trigeminal tract

Central gray

Spino-olivary fibers

Pyramid

Vestibulospinal tract andreticulospinal tract

Gracile nucleus

Post. column/med. lemniscus sys. (proprioception/vibratory sense, discriminative touch)

Corticospinal fibers (somatomotor)

Anterolateral system (pain/thermal sense, touch from body)

Spinal trigeminal and/or ventral trigeminothalamic fibers (pain/thermal sense, touch from head)

Sensory

Motor

Cranial nerve nuclei

Pyramidal decussation


5-8 Transverse section of the medulla through the decussation of thepyramids (motor decussation, pyramidal decussation, crossing of corti-cospinal fibers). This is the level of the spinal cord–medulla transition.The corticospinal fibers have moved from their location in the lateral fu-niculus to the motor decussation and will cross to form the pyramid onthe opposite side.

The Medulla O

blongata With M

RI and CT

99

Anatomical orientation Clinical orientation MRI, T2-weighted imageMRI, T1-weighted image CT cisternogram

5-9 Transverse section of the medulla through the dorsal column nu-clei (nucleus gracilis and nucleus cuneatus), caudal portions of the hy-poglossal nucleus, caudal end of the principal olivary nucleus, and middleportions of the sensory decussation (crossing of internal arcuate fibers).

100Internal M


Lateral reticular nucleus

Posterior longitudinal fasciculus

Dorsal motor nucleus of vagus

Degenerated corticospinal fibers

Medial longitudinal fasciculusTectospinal tractMedial lemniscus

Gracile fasciculus


Rubrospinal tract

Restiform body

Internal arcuate fibers

Cuneate fasciculus

Accessory cuneate nucleus

Hypoglossal nucleus

Solitary nuclei and tract

Principal olivary nucleus


Spinal trigeminal nucleus (pars caudalis)

Posterior spinocerebellar tract

Hypoglossal nerve

Fascicles of hypoglossal nerve

Nucleus ambiguus

Cuneate nucleus

Central gray


Pyramid

Medial accessory olivary nucleus

Arcuate nucleus

Gracile nucleus

Preolivary sulcus

Retroolivary sulcus(postolivary sulcus)






Sensory

Motor


Ventral trigeminothalamic tract

Vestibulospinal fibers and reticulospinal fibers

The Medulla O

blongata With M

RI and CT

101


5-10 Transverse section of the medulla through rostral portions ofthe sensory decussation (crossing of internal arcuate fibers), obex, and thecaudal one-third of the hypoglossal and principal olivary nuclei.

102Internal M






Sensory

Motor








Rubrospinal tract

Restiform body(+ juxtarestiform body=inferior cerebellar peduncle)


Cuneate fasciculus

Hypoglossal nucleus


Posterior accessory olivary nucleus


Spinal trigeminal nucleus (pars interpolaris)


Retroolivary sulcus(postolivary sulcus)

Hypolossal fibers

Nucleus ambiguus

Cuneate nucleus

Level of obex

Preolivary sulcus

Pyramid


Arcuate nucleus


Nucleus raphe, obscurus

Area postrema

Gracile nucleus

Olivocerebellar fibers

Reticular formation


Ventral trigeminothalamic tract Central tegmental tract and amiculum of olive

The Medulla O

blongata With M

RI and CT

103


104Internal M







Rubrospinal tract


Spinal trigeminal nucleus(pars interpolaris)

Dorsal motor nucleus of the vagus

Hypoglossal nucleusSolitary nuclei and tract

Central tegmental tractand amiculum of olive

Inferior (spinal)vestibular nucleus

Vagus nerve


Posterior accessoryolivary nucleus

Nucleus ambiguus


Restiform body( + Juxtarestiform body =

Inferior cerebellar peduncle)

Medial vestibular nucleus

Hypoglossal nervePyramid


Arcuate nucleus

Nucleus raphe, pallidus

Sulcus limitans



Reticular formation







Sensory

Motor


5-11 Transverse section of the medulla through rostral portions ofthe hypoglossal nucleus and the middle portions of the principal olivary nu-cleus. The fourth ventricle has flared open at this level, and the resti-form body is enlarging to become a prominent structure on the dorso-lateral aspect of the medulla.

The Medulla O

blongata With M

RI and CT

105


106Internal M






Sensory

Motor


Reticulospinal fibers


Nucleus prepositus

Degenerated corticospinal fibersVentral trigeminothalamic tract


Solitary nuclei

Nucleus ambiguus

Rubrospinal tract


Pontobulbar nucleus

Anterior (ventral)cochlear nucleus

Posterior (dorsal)cochlear nucleus

Solitary tract

Inferior (or spinal) vestibular nucleus

Stria medullares of fourth ventricle


Central tegmental tractand amiculum of olive


Cochlear nerve

Posterior accessory olivary nucleus


Glossopharyngeal nerve

Cerebellum



Pyramid

Reticular formation

Restiform body


Arcuate nucleusMedial longitudinal fasciculus

Tectospinal tractMedial lemniscus

Inferior salivatory nucleus


Spinal trigeminal nucleus (pars oralis)



5-12 Transverse section of the medulla through the posterior (dor-sal ) and anterior (ventral ) cochlear nuclei and root of the glossopharyngealnerve. This corresponds to approximately the rostral third to fourth ofthe principal olivary nucleus.

The Medulla O

blongata With M

RI and CT

107


108Internal M


Secondary cochlear fibers


Superiorcerebellarpeduncle

Superior medullary velum


Mediallemniscus



Superior vestibular nucleus

Secondary cochlear fibers

Superior olive


Facial nucleus

Solitary tract

Facial nerve


Abducens nucleus

Inferiorcerebellar peduncleRestiform body

Juxtarestiform body

Central tegmental tract


Vestibular root ofVIIIth nerve

Lateral vestibular nucleus

Superior olive


Pontobulbar nucleus (or body)


Spinal trigeminal nucleus(pars oralis)

Tectospinal tract

Pyramid

Reticular formation


Nucleus raphe, magnus



Rubrospinal tract


Pontine nuclei





Sensory

Motor


5-13 Transverse section of the medulla–pons junction through therostral pole of the principal olivary nucleus and through the facial motornucleus. This plane is just caudal to the main portions of the abducensnucleus. Pontine nuclei at this level may also be called arcuate nuclei.

The Medulla O

blongata With M

RI and CT

109


5-14 Semidiagrammatic representation of the internal distributionof arteries in the medulla oblongata. Selected main structures are la-beled primarily on the left side of each section and the general patternof arterial distribution overlies these structures on the right side. Thegeneral distribution patterns of arteries in the medulla as illustratedhere may vary from patient to patient. For example, the territoriesserved by adjacent vessels may overlap to differing degrees at theirmargins or the territory of a particular vessel may be smaller or largerthan seen in the typical pattern.

110Internal M


Abbreviations

FCu Cuneate fasciculusFGr Gracile fasciculus ML Medial lemniscus

NuCu Cuneate nucleusNuGr Gracile nucleus

Py PyramidRB Restiform body (� juxtarestiform body �

inferior cerebellar peduncle)RetF Reticular formation

Vascular Syndromes or Lesions of the Medulla Oblongata

Medial Medullary Syndrome: Results from oc-clusion of branches of anterior spinal artery.

Deficits Structure Damaged

• Contralateral hemiplegia • Pyramid (cortico-of arm and leg spinal fibers)

• Contralateral loss of • Medial lemniscusposition sense, vibratory sense and discriminative touch

• Deviation of tongue to • Hypoglossal nerve in ipsilateral side when medulla or hypo-protruded; muscle glossal nucleusatrophy and fasciculations

Comment: The medial medullary syndrome is rarecompared to the more common occurence of the lateralmedullary syndrome. Nystagmus may result if the lesioninvolves the medial longitudinal fasciculus or the nu-cleus prepositus hypoglossi. The lesion may involveventral trigeminothalamic fibers, but diminished painand thermal sense from the contralateral side of the faceis rarely seen. The combination of a contralateral hemi-plegia and ipsilateral deviation of the tongue is called aninferior alternating hemiplegia when the lesion is at thislevel.

Lateral Medullary Syndrome: Results from oc-culsion of posterior inferior cerebellar artery orbranches of PICA to dorsolateral medulla (PICA syn-drome, Wallenberg syndrome). In many cases the lat-eral medullary syndrome frequently results from occlu-sion of the vertebral artery with consequent loss of flowinto PICA.


• Contralateral loss of • Anterolateral system pain and thermal fibers sense on body

• Ipsilateral loss of pain • Spinal trigeminal and thermal sense on face tract and nucleus

• Dysphagia, soft palate • Nucleus ambiguus, paralysis, hoarseness, roots of 9th and 10thdiminished gag nervesreflex

• Ipsilateral Horner • Descending syndrome (miosis, hypothalamospinal ptosis, anhidrosis, fibersflushing of face)

• Nausea, diplopia, • Vestibular nuclei tendency to fall to (mainly inferior and ipsilateral side, medial)nystagmus, vertigo

• Ataxia to the • Restiform body and ipsilateral side spinocerebellar fibers

Comment: In addition to the above, involvement ofthe solitary tract and nucleus may (rarely) cause dysageu-sia. Dyspnea and tachycardia may be seen in patients withdamage to the dorsal motor nucleus of the vagus. It is alsopossible that damage to respiratory centers in the reticu-lar formation or to the vagal motor nucleus may result in hiccup (singultus). Bilateral medullary damage maycause the syndrome of “Ondine’s curse,” an inability tobreathe without willing it or “thinking about it.”

Tonsillar Herniation: Although the cerebellar ton-sil is not part of the medulla, the herniation of this struc-ture (tonsillar herniation) down through the foramenmagnum has serious consequences for function of themedulla. The coneing of the cerebellar tonsils into, andthrough, the foramen magnum may compress themedulla resulting in cardiac and respiratory arrest. This isdue to a combination of pressure on the medulla and theocclusion of small vessels serving cardiac and respiratorycenters in the lateral area of the medulla. Patients expe-riencing a sudden herniation of the cerebellar tonsilsmay lose consciousness rapidly and die.

Syringobulbia: A cavitation within the brainstem(syringobulbia) may exist with syringomyelia, be inde-pendent of syringomyelia, or in some cases both may ex-ist and communicate with each other. The cavity in sy-ringobulbia is usually on one side of the midline of themedulla. Signs and symptoms of syringobulbia may in-clude weakness of tongue muscles (hypoglossal nucleus ornerve), weakness of pharyngeal, palatal, and vocal muscula-ture (ambiguus nucleus), nystagmus (vestibular nuclei),and loss of pain and thermal sensation on the ipsilateral sideof the face (spinal trigeminal tract and nucleus or cross-ing of trigeminothalamic fibers).

Arterial Patterns W

ithin The Medulla O

blongata With Vascular Syndrom

es111

Rostral

Caudal

Rostral

Caudal

Posterior spino-cerebellar tract

Posterior spino-cerebellar tract

Spinal trigeminal tractand nucleus

Rubrospinaltract

Lateral cortico-spinal tract

Anterolateralsystem

Inferior olivary complex(principal nucleus)

Corticospinal fibers







Nucleus prepositus

Fourth ventricle



Hypoglossal nucleus

Inferior olivary complex


Posterior (dorsal) cochlear nucleus

Hypoglossal nerve

Nucleus ambiguus

Hypoglossal nucleus

Nucleus ambiguus



Pyramidal decussation

Medial decussation

Medial lemniscus (ML)

Vestibular nuclei

Pyramid (Py)Py

RB

RetF

RetF

ML

NuCu

NuGr

FCuFGr

Posterior spinal artery (and arterial vasocorona in spinal cord)

Anterior inferior cerebellar artery

Anterior spinal artery

Vertebral artery

Posterior inferior cerebellar artery

Vertebral artery plus paramedian branches of caudal portions of basilar artery

112Internal M






Sensory

Motor


Tela choroidea

Globose nucleus, GNu(posterior interposed cerebellar nucleus)


Lateral recess offourth ventricle

Restiform body

Tonsil of cerebellum

Dentate nucleus, DNu(lateral cerebellar nucleus)

Inferior (spinal)vestibular nucleus

Medial longitudinal fasciculusTectospinal tract

Inferior medullary velum

Emboliform nucleus(anterior interposedcerebellar nucleus)

Hilum of dentate nucleus


Choroid plexus

Nucleus prepositus

Fastigial nucleus, FNu(medial cerebellar nucleus)

Nodulus

Uvula



FNuDNu

GNu

DNu



5-15 Transverse section through the dorsal aspects ofmedulla at the level of the cochlear nuclei and the cerebellar nuclei.The plane corresponds to about the middle of the dentate nucleus

and caudal portions of the globosus and emboliform nuclei. For ad-ditional details of the medulla at this level see figure 5-12 on page106.

The Cerebellar N

uclei113

114Internal M


Globose nucleus, GNu(posterior interposed cerebellar nucleus)


Restiform body


Dentate nucleus(lateral cerebellar nucleus)

Facial nerve



Superior cerebellar peduncle(brachium conjunctivum)

Abducens nerve Facial nerve


Abducens nucleus



FNu

ENu

GNu

Facial motor nucleus

Juxtarestiform body

Emboliform nucleus, ENu(anterior interposed cerebellar nucleus)

Fastigial nucleus, FNu(medial cerebellar nucleus)

Inferiorcerebellarpeduncle





Sensory

Motor


5-16 Transverse section through dorsal portions of pons at thelevel of the abducens nucleus (and facial colliculus) and through rostralportions of the cerebellar nuclei. For additional details of the pons at thislevel see Figure 5-17 on page 116.

The Cerebellar N

uclei115

116Internal M




Superiorcerebellarpeduncle




Juxtarestiform body

Trapezoid bodyand nuclei



Trigeminal nerve

Principal sensory nucleus

Trigeminal motor nucleus


Mesencephalic tractand nucleus

Facial nerve, internal genu

Restiform body


Superior salivatory nucleus, SSNu

Pontocerebellar fibers

Facial nerve



Superior olive

Lateral lemniscus

Abducens nucleus



Spinal trigeminal nucleus(pars oralis)

Superior vestibular

nucleus

Abducens nerve

SSNu

Reticular formation

Medial lemniscus



Tectospinal tract


Rubrospinal tract

Pontine nuclei

Pontine nuclei





Sensory

Motor


5-17 Transverse section of the caudalpons through the facial motor nucleus, abducensnucleus (and facial colliculus), and the in-tramedullary course of fibers of facial and ab-ducens nerves.

The Pons With M

RI and CT

117


118Internal M



Superior salivatory nucleus

Facial nerve, Internal genu(Fac, G)






Abducens nucleus

Trapezoid body

Mesencephalic nucleusand tract

Trigeminal nerve

Facial nerve


Lateral lemniscus

Superior olive

Abducens nerve


Pontine nuclei

Medial lemniscus

Reticular formation

Superior cerebellar peduncle

Pontine nuclei


Spinal trigeminal nucleus and tract (rostral end)

Fac,G




Rubrospinal tract


Principal sensory nucleus(caudal part)

Trigeminal motor nucleus(caudal part)

Middle cerebellar peduncle

Mesencephalic nucleusand tract






Sensory

Motor


5-18 Transverse section of the pons through the rostral pole of thefacial nucleus and the internal genu of the facial nerve and rostral portionsof the abducens nucleus.

The Pons With M

RI and CT

119


120Internal M



Mesencephalic nucleus

Trigeminal nerve

Nucleus ceruleus

Lateral lemniscus

Rubrospinal tract





Principal sensory nucleus


Middle cerebellar peduncle(brachium pontis)


Lateral lemniscus

Superior olive

Reticulotegmental nucleus

Nucleus raphe, pontis

Pontine nuclei

Pontine nuclei

Lateral lemniscus, nucleus

Medial lemniscus

Reticular formation



ASCT


Anterior spinocerebellar tract(ASCT)

Mesencephalic tract

Central grey (periventricular grey)





Sensory

Motor




Tectospinal tract

5-19 Transverse section of the pons through the principal sensorynucleus and motor nucleus of the trigeminal nerve.

The Pons With M

RI and CT

121


5-20 Transverse section of the rostral pons through the exit of thetrochlear nerve and rostral portions of the exit of the trigeminal nerve.

122Internal M


Nucleus raphe, dorsalis

Nucleus centralis, superior Lateral lemniscus andnuclei of lateral lemniscus



Rubrospinal tract





Tectospinal tractAnterolateral system

Medial lemniscus


Dorsal trigeminothalamic tract

Middle Cerebellar peduncle(brachium pontis)

Trigeminal nerve

Basilar pons

FrenulumCerebral aqueduct

Central gray (Periaqueductal gray)

Trochlear nerve, exit

Pontine nuclei

Reticular formation

Mesencephalic nucleus and tract

Locus ceruleus





Sensory

Motor


The Pons With M

RI and CT

123


5-21 Semidiagrammatic representation of the internal distri-bution of arteries in the pons. Selected main structures are labeledon the left side of each section; the general pattern of arterial dis-tribution overlies these structures on the right side. Some patientsmay have variations of the general distribution patterns of arteriesto the pons as shown here. For example, the adjacent territoriesserved by vessels may overlap to differing degrees at their marginsor the territory of a particular vessel may be smaller or larger thanseen in the general pattern.

124Internal M


Vascular Syndromes or Lesions of the Pons

Medial Pontine Syndrome: Results from occlu-sion of paramedian branches of basilar artery.


• Contralateral hemiplegia • Corticospinal of arm and leg fibers in basilar

pons• Contralateral loss or • Medial

decrease of position lemniscusand vibratory senseand discriminative touch (arm and leg)

• Ipsilateral lateral rectus • Abducens nerve muscle paralysis fibers or

nucleus• Paralysis of conjugate gaze • Paramedian

toward side of lesion pontine reticular formation (pontine gaze center)

Comment: The combination of corticospinal deficitson one side of the body coupled with a cranial nerve mo-tor deficit on the opposite is called a middle alternatinghemiplegia when the lesion is at this level. Diplopia will re-sult (abducens nerve lesion) on gaze toward the side of thelesion. Involvement of the abducens nucleus may also re-sult in an inability to adduct the contralateral medial rec-tus muscle (damage to abducens internuclear neurons).

At caudal levels the lesion may extend lateral to involvethe lateral lemniscus (hypacusis), parts of the middle cere-bellar peduncle (some ataxia), the facial motor nucleus (ip-silateral facial paralysis), the spinal trigeminal tract and nu-cleus (ipsilateral loss of pain and thermal sensation from theface), and the anterolateral system (contralateral loss of painand thermal sensation from the body). At rostral pontine lev-els the lesion may extend into the medial lemniscus or mayinvolve only the arm fibers within this structure (cortralat-eral loss of vibratory sense, proprioception, and discriminativetouch), the motor nucleus of the trigeminal nerve (ipsilat-eral paralysis of masticatory muscles), or may damage the an-terolateral system and rostral portions of the spinaltrigeminal tract and nucleus (loss of pain and thermal sensa-tion from the body [contralateral] and from the face [ipsilateral]).

Lateral Pontine Syndrome: Results from occlu-sion of long circumferential branches of basilar artery.

Deficit Structure Damaged

• Ataxia, unsteady gait, • Middle and fall toward side of lesion superior cerebellar

peduncles (caudal and rostral levels)

• Vertigo, nausea, • Vestibular andnystagmus, deafness, cochlear nerves tinnitus, vomiting and nuclei(at caudal levels)

• Ipsilateral paralysis of • Facial motor facial muscles nucleus (caudal

levels)• Ipsilateral paralysis of • Trigeminal motor

masticatory muscles nucleus (midpontine levels)

• Ipsilateral Horner • Descendingsyndrome hypothalamospinal

fibers• Ipsilateral loss of pain • Spinal trigeminal

and thermal sense tract and nucleusfrom face

• Contralateral loss of pain • Anterolateral and thermal sense system from body

• Paralysis of conjugate • Paramedianhorizontal gaze pontine reticular

formation (at mid to caudal levels)

Comment: The various combinations of thesedeficits may vary depending on whether the lesion is lo-cated in lateral pontine areas at caudal levels versus lateralpontine areas at rostral levels. As noted above lesions lo-cated in lateral portions of the pontine tegmentine mayalso extend medial at either caudal or rostral levels andgive rise to some of the deficits discussed above in the sec-tion on medial pontine syndrome.

Abbreviations

BP Basilar ponsCSp Corticospinal fibersCTT Central tegmental tract

MCP Middle cerebellar peduncle (brachium pontis)

ML Medial lemniscusMLF Medial longitudinal fasciculus

RB Restiform body (�juxtarestiform body �inferior cerebellar)

RetF Reticular formationSCP Superior cerebellar peduncle

(brachium conjunctivum)

Arterial Patterns W

ithin The Pons With Vascular Syndrom

e125

Rostral

Caudal

Ventral trigeminothalamic fibers

Facial nerve

Spinal trigeminaltract

Abducens nucleus

Trochlear nerve



Abducens nerve

Basilar pons (BP)

Spinal trigeminalnucleus

Vestibular nuclei


Trigeminal nerve

Principal sensoryMotor

Mesencephalic

Trigeminal nuclei:


Lateral lemniscus

Medial longitudinal fasciculus (MLF)


Fourth ventricle

RB

MCP

ML

MLF

CSp

BP

SCP

ML

MCP

SCP

ML

CSpRetF

CTT


Paramedian branches of basilar artery

Short circumferential branches of basilar artery

Long circumferential branches of basilar artery and branches of anterior inferior cerebellar artery

Long circumferential branches of basilar artery and branches of superior cerebellar artery

126Internal M


Central gray (periaqueductal gray)

Trochlear nerve

Tectospinal tract

Nucleus centralis, superior


Parietopontine fibersOccipitopontine fibersTemporopontine fibers


Reticular formation

Inferior colliculus, external nucleus

Pontine nuclei


Nucleus ceruleus



Crus cerebri



Lateral lemniscus

Superior cerebellarpeduncle, decussation

Medial lemniscus

Rubrospinal tract


Inferior colliculus, pericentral nucleus

Inferior colliculus, central nucleus

Inferior colliculus, commissure




Cerebral aqueduct





Sensory

Motor


5-22 Transverse section of the brainstem at the pons–midbrainjunction through the inferior colliculus, caudal portions of the decussa-tion of the superior cerebellar peduncle, and rostral parts of the basilar pons.The plane of section is just caudal to the trochlear nucleus.

The Midbrain W

ith MRI and C

T127


128Internal M


CorticospinalCorticospinalfibersfibers


Central tegmental tractTectospinal tract

Substantia nigra, pars compacta

Spinotectal tract


Interpeduncular fossa



Interpeduncular nucleus

Medial lemniscus


Rubrospinal tract

Pontine nuclei

Inferior colliculus, brachium

Reticular formation

Superior cerebellarpeduncle, decussation

Corticospinalfibers

Cor

ticon

ucle

ar fi

bers

(cor

ticob

ulba

r fib

ers)

FPon

PPon

OPon

TPon


Crus cerebri

Posterior longitudinal fasciculusCentral gray (periaqueductal gray)

Cerebral aqueduct

Superior colliculus

Frontopontine fibers (FPon)

Parietopontine fibers (PPon)Occipitopontine fibers (OPon)Temporopontine fibers (TPon)

Spinothalamic tract

Trochlear nucleus

Anterolateralsystem




Sensory

Motor



5-23 Transverse section of the midbrain through the trochlear nu-cleus and decussation of the superior cerebellar peduncle. The section also in-cludes caudal parts of the superior colliculus and the rostral tip of the basi-lar pons.

The Midbrain W

ith MRI and C

T129

Anatomical orientation Clinical orientation MRI, T2-weighted imageMRI, T1-weighted image CT cisternogramg gg g g

130Internal M





Sensory

Motor



LegLeg

TrunkTrunk

ArmArm

Pallidonigral fibersNigrostriatal fibers

Corticonigral fibers

Spinothalamic tract




Posterior (dorsal)tegmental decussation

Red nucleus

Substantia nigrapars compacta (SNpc)


Superior cerebellar peduncle, decussation

Anterior (ventral) tegmental decussation

Medial geniculate nucleus

Superior colliculus

Rubrospinal tract

Oculomotor nerve

Interpeduncular nucleus

Substantia nigrapars reticulata (SNpr)


Reticular formation



Mediallemniscus

Corticospinalfibers

Cortic

onuc

lear

fibe

rs

(cor

ticob

ulba

r fib

ers)

SNpc

SNpr

PPon

OPon

TPon

FPon

Leg

Trunk

Arm

Crus cerebri

Central gray (periaqueductal gray)

Cerebral aqueduct



Spinotectal tract

Oculomotor nucleus



5-24 Transverse section of the midbrain through the superior col-liculus, caudal parts of the oculomotor nucleus, and caudal parts of the rednucleus. The plane of section is caudal to the Edinger-Westphal nucleus but

includes rostral portions of the decussation of the superior cerebellar pe-duncle, which, at this level, are intermingled with the caudal part of thered nucleus. Leg � lower extremity; Arm � upper extremity.

The Midbrain W

ith MRI and C

T131


132Internal M





Sensory

Motor



LegLeg

TrunkTrunkArmArm

Optic tract


Cerebellorubral fibers andcerebellothalamic fibers


Brachium, inferior colliculus

Peripeduncular nucleus


Habenulopeduncular tract

Lateralgeniculate

nucleus

Superior colliculus, commissure



Oculomotor nerve

Oculomotor nuclei

Mediallemniscus

Corticonigral fibersPallidonigral fibersNigrostriatal fibers

Edinger-Westphal nucleus

Mesencephalic tract and nucleus

Superior colliculus, brachium

Spinothalamic tract

Medial geniculate nucleus

Pulvinar nuclear complex


Corticonuclear fibers(corticobulbar fibers)

Substantia nigra,pars reticulata (SNpr)

Substantia nigra,pars compacta (SNpc)

Red nucleus

SNpc

SNpr

PPon

OPon

TPon

FPon

Leg

TrunkArm

Central grey (periaqueductal grey)

Cerebral aqueduct



Spinotectal tract

Superior colliculus


5-25 Transverse section of the midbrain through the superior col-liculus, rostral portions of the oculomotor nucleus, including the Edinger-Westphal nucleus, and the exiting fibers of the oculomotor nerve. The

plane of this section is also through caudal portions of the dien-cephalon including the pulvinar nuclear complex and the medial and lat-eral geniculate nuclei. Leg � lower extremity; Arm � upper extremity.

The Midbrain W

ith MRI and C

T133

Anatomical orientation Clinical orientation MRI, T2-weighted imageMRI, T1-weighted image MRI, T1-weighted image

MRI, T2-weighted image

Anatomical orientation Clinical orientation MRI, T2 weighted imageMRI, T1 weighted image MRI, T1

MRI, T2-

134Internal M





Sensory

Motor




Parietopontine fibersOccipitopontine fibers

Temporopontine fibers

Optic tract

(OpTr)


Brachium of superior colliculus

Spinothalamic tract

Lateral geniculatenucleus (LGNu)

Nucleus of Darkschewitsch

Supraoptic nucleus

Peripeduncular nucleus

Superior colliculus

Pulvinar nuclear complex (Pul)

Pretectalnuclei

Posterior commissure

Medialgeniculate

nucleus (MGNu)

Pineal

Subthalamic nucleus

Mammillothalamic tract (MtTr)

Fornix (F)

Medial lemniscus



Ventral trigeminothalamic tract

Red nucleus(RNu)

Corticospinalfibers

Corticonuclear fibers(corticobulbar fibers)

Frontopontine fibers

Habenulopeduncular tractHypothalamus

Third ventricle

Cerebral aqueduct

Transition fromcrus cerebri (CC) tointernal capsule

Cerebellorubral fibers andCerebellothalamic fibers

Nucleus of Cajal


5-26 Slightly oblique section through the midbrain–diencephalonjunction. The section passes through the posterior commissure, the ros-tral end of the red nucleus, and ends just dorsal to the mammillary body.At this level, the structure labeled mammillothalamic tract probably also

contains some mammillotegmental fibers. Structures at the midbrain-thalamus junction are best seen in an MRI angled to accommodate thatspecific plane. To make the transition from drawing to stained sectionto MRI easy, selected structures in the MRI are labeled.

The Midbrain W

ith MRI and C

T135

Anatomical orientation Clinical orientation MRI, T2-weighted image

OpTr

OpTr

LGNuMGNu

Pul

F, MTTr

CC

RNu

Pul

MRI, inversion recovery

5-27 Semidiagrammatic representation of the internal distributionof arteries in the midbrain. Selected main structures are labeled on theleft side of each section; the typical pattern of arterial distribution over-lies these structures on the right side. The general distribution patternsof the vessels to the midbrain as shown here may vary somewhat frompatient to patient. For example, the adjacent territories served byneighboring vessels may overlap to differing degrees at their marginsor the territory of a particular vessel may be larger or smaller than seenin the general pattern.

136Internal M


Abbreviations

BP Basilar ponsCC Crus cerebri

DecSCP Decussation of the superior cerebellar peduncle

IC Inferior colliculusLGNu Lateral geniculate nucleus

MGNu Medial geniculate nucleusML Medial lemniscus

RNu Red nucleusSC Superior colliculus

SCP Superior cerebellar peduncleSN Substantia nigra

Vascular Syndromes or Lesions of the Midbrain

Medial Midbrain (Weber) Syndrome: May re-sult from occlusion of paramedian branches of P1 seg-ment of posterior cerebral artery.


• Contralateral hemiplegia • Corticospinal fibers of arm and leg in crus cerebri

• Ipsilateral paralysis of • Oculomotor nerveeye movement: eye oriented down and out and pupil dilated and fixed

Comment: This combination of motor deficits atthis level of the brainstem is called a superior alternatinghemiplegia. This pattern consists of ipsilateral paralysis ofeye movement and contralateral hemiplegia of the upper andlower extremities. Damage to the corticonuclear (cor-ticobulbar) fibers in the crus cerebri may result in a par-tial deficit in tongue and facial movement on the con-tralateral side. These cranial nerve deficits are seen as adeviation of the tongue to the side opposite the lesion onattempted protrusion and a paralysis of the lower half of thefacial muscles on the contralateral side. Although parts ofthe substantia nigra are frequently involved, akinesia ordyskinesia are not frequently seen.

Central Midbrain Lesion (Claude syndrome)


• Ipsilateral paralysis of • Oculomotor nerveeye movement: eye oriented down and out and pupil dilated and fixed

• Contralateral ataxia • Red nucleus and and tremor of cerebellothalamiccerebellar origin fibers

Comment: The lesion in this syndrome may ex-tend laterally into the medial lemniscus and the dorsallyadjacent ventral trigeminothalamic fibers. If this was thecase, there could conceivably be a loss or diminution of

position and vibratory sense and of discriminative touchfrom the contralateral arm and partial loss of pain andthermal sensation from the contralateral face.

Benedikt syndrome: This results from a largerlesion of the midbrain that essentially involves both ofthe separate areas of Weber and Claude. The maindeficits are contralateral hemiplegia of arm and leg (cor-ticospinal fibers), ipsilateral paralysis of eye movementwith dilated pupil (oculomotor nerve), and cerebellartremor and ataxia (red nucleus and cerebellothalamicfibers). Slight variations may be present based on the ex-tent of the lesion.

Parinaud syndrome: This syndrome is usuallycaused by a tumor in the pineal region, such as germi-noma, astrocytoma, pineocytoma/pineoblastoma, orany of a variety of other tumors that impinge on the su-perior colliculi. The potential for occlusion at the cere-bral aqueduct in these cases also indicates that hydro-cephalus may be a component of this syndrome. Thedeficits in these patients consist of a paralysis of upwardgaze (superior colliculi), hydrocephalus (occlusion of thecerebral aqueduct), and eventually a failure of eye move-ment due to pressure on the oculomotor and trochlearnuclei. These patients may also exhibit nystagmus due toinvolvement of the medial longitudinal fasciculus.

Uncal Herniation: Herniation of the uncus occursin response to large and rapidly expanding lesions in thecerebral hemisphere, this being a supratentorial location.Uncal herniation is an extrusion of the uncus through thetentorial notch (tentorial incisura) with resultant pressureon the oculomotor nerve and the crus cerebri of the mid-brain. Initially the pupils, unilaterally or bilaterally, maydilate or respond slowly to light, followed by weakness ofoculomotor movement. As herniation progresses thepupils will be fully dilated, eye movements regulated bythe oculomotor nerve may be slow or absent, and the eyeswill deviate slightly laterally due to the unopposed actionsof the abducens nerves. There is usually weakness on thecontralateral side of the body due to compression of cor-ticospinal fibers in the crus cerebri. However, if pressureis sufficient the entire midbrain may shift so that there canbe contralateral as well as ipsilateral weakness due topressure on the same side and pressure on the oppositeside of the crus cerebri. This hemiplegia ipsilateral to the

herniation and ipsilateral to the oculomotor deficits is called the Kernohanphenomenon. As damage from the pressure on the midbrain extends downand into the upper pons the pupils are dilated and fixed, eye movementis largely absent, respiration is decreased, and the patient will becomedecerebrate (upper and lower extremities extended, toes pointed in-ward, fingers flexed, forearm pronated, head and neck extended).

Arterial Patterns W

ithin The Midbrain W

ith Vascular Syndromes

137

Rostral

Caudal

Anteromedial (paramedian) branches of basilar bifurcation and P1 segment

Lateral branches of quadrigeminal (level of inferior colliculus), quadrigeminal and posterior medial choroidal arteries (level of superior colliculus)

Anterolateral (short circumferential) branches of the quadrigeminal and medial posterior choroidal arteries

Quadrigeminal and superior cerebellar arteries (level of inferior colliculus), quadrigeminal and posterior medial choroidal arteries (level of superior colliculus)

Thalamogeniculate artery

Lateral lemniscus


Anterolateralsystem

Periaqueductal gray

Cerebral aqueduct


Trochlear nucleus

Mesencephalic nucleusOculomotor nerve

Ventral trigeminothalmicfibers


Oculomotor nucleus

Edinger-Westphal nucleus

Ventral trigeminothalamicfibers

MLSCP

CC

ML

DecSCP

SN

CC

ML

SC

RNu

LGNu

MGNu

SN

CC

IC

BP


Interpeduncular fossa

138Internal M


Caudatenucleus

Hippocampalformation

Tapetum

Stria terminalis

Superior cerebellar peduncle

Fornix, crus

Medial longitudinal striaof indusium griseum

Hippocampal commissures

Caudate nucleus, body

Optic radiations

Corpus callosum,splenium

Pineal

Superior cisternInferior colliculus

Pulvinar

Cerebellum

Fimbria of hippocampus

Lateral ventricle,inferior horn

Trochlear nerve

Caudate nucleus, tail

Cingulate gyrus

Cingulum

Choroid plexus

Atrium of lateral ventricle

Lateral longitudinal stria

5-28 Coronal section of forebrain through the splenium of the corpuscallosum and crus of fornix, and extending into the inferior colliculus and exitof the trochlear nerve. Many of the structures labeled in this figure can beeasily identified in the T1-weighted MRI adjacent to the photograph.

The Diencephalon and Basal N

uclei With M

RI139

140Internal M





Sensory

Motor



Optic radiationsRetrolenticular limb

Choroid plexus

Lateral longitudinal striaof indusium griseum

External medullary lamina

Insula

Cingulum

Hippocampalformation

Inferior pulvinarnucleus

Fornix, body

Trochlear nucleus


Hippocampus,fimbria of

Lateral ventricle, body


Stria terminalis (StTer)

Medial geniculate

nucleus

Corpus callosum,body

Medialnucleus

Superior cistern

Lateralnucleus

Pulvinarnuclearcomplex

Lateral geniculate

nucleus

StTer and bednucleus


Alveus ofhippocampus


Superior colliculus, brachium


Medial longitudinal stria

Cingulate gyrus

Internal capsule

Sublenticular limb

5-29 Coronal section of the forebrain through the pulvinar andthe medial and lateral geniculate nuclei. The section extends into up-per portions of the midbrain tegmentum. Many of the structures la-

beled in this figure can be easily identified in the T1-weighted MRIadjacent to the photograph.


uclei With M

RI141

142Internal M


Ventral posteromedialnucleus of thalamus

Ansa lenticularis

Pulvinarnuclearcomplex

Hypothalamus

Globus pallidus:Lateral segmentMedial segment

Lateralnucleus Pineal

Thirdventricle

Dorsomedialnucleus ofthalamus

Internal capsule,posterior limb

Ventral posterolateralnucleus of thalamus

Medialnucleus

Subthalamicnucleus

Zona incerta

Lenticular fasciculus

Thalamic fasciculus

Mammillothalamic tract

Habenular nucleus

Habenular commissure

Column of fornixAnterior commissure

Centromedian nucleus of thalamus

Habenulopeduncular tract




Sensory

Motor



5-30 Slightly oblique section of the forebrain through the pulvinar, ventral pos-teromedial, and ventral posterolateral nuclei. The section extends rostrally through thesubthalamic nucleus and ends in the caudal hypothalamus just dorsal to the mammillarybodies as seen by the position of the (postcommissural) fornix.


uclei With M

RI143

144Internal M



Extreme capsule

Lateral dorsal nucleus of thalamus

Subthalamic nucleus

Internal medullary lamina

External medullary lamina andthalamic reticular nucleus


Thalamic fasciculus

Zona incerta

Corpus callosum, body

Alveus of hippocampus

Fornix, body

Cerebellothalamic fibers

Basilar pons

Cruscerebri

Posterior cerebral artery


Claustrum

External capsule

Globus pallidus:

Lateral segmentMedial segment

Optic tract




Stria terminalis (StTer)

Choroid plexus


PutamenDorsomedial

nucleusVentral lateral

nucleus

Insula

Rednucleus

Substantia nigra

StTer

Hippocampal formation

Crus cerebri



Stria medullaris thalami

Cingulum

Cingulate gyrus

5-31 Coronal section of the forebrain through the lateraldorsal nucleus, massa intermedia, and subthalamic nucleus. Many

of the structures labeled in this figure can be easily identifiedin the T1-weighted MRI adjacent to the photograph.


uclei With M

RI145

146Internal M


Extreme capsule

Dorsomedial nucleus of thalamus

Subthalamic nucleus



Choroid plexus

Thalamic fasciculus


Zona incerta


Alveus of hippocampus

Fornix, body


Claustrum

External capsule

Globuspallidus

lat.

med.

Optic tract

Amygdaloidnuclear

complex



Stria terminalis

Anterior nucleus


Putamen

Ventral lateralnucleus

Third ventricle

Insula


Posterior hypothalamus

Mammillary body





CingulumCingulate gyrus


5-32 Coronal section of the forebrain through the ante-rior nucleus of the thalamus and mammillary body. Many of the

structures labeled in this figure can be easily identified in theT1-weighted MRI.


uclei With M

RI147

148Internal M


Extreme capsule

Red nucleus

Lateral geniculatenucleus

Cerebellorubral fibers andcerebellothalamic fibers




Corticonigral fibersPallidonigral fibersNigrostriatal fibers

Anterior nucleus

Oculomotor nerve

Claustrum

External capsule

Globus pallidus,lateral segment

Thalamic fasciculus


Subthalamic nucleus

Optic tract




Stria terminalis



Putamen Dorsomedialnucleus

Ventral lateralnucleus

VL to VAtransition

Thirdventricle


Zonaincerta

Substantia nigraHippocampus

Crus cerebri


Choroid plexus

Fornix, body

5-33 Slightly oblique section of the forebrain through the anteriornucleus of the thalamus and the subthalamic nucleus. The section also in-cludes the rostral portion of the midbrain tegmentum. Many of the struc-tures labeled in this figure can be easily identified in the T1-weightedMRI adjacent to the photograph.


uclei With M

RI149

150Internal M


Extreme capsule

Basal nucleusof Meynert

Anterior nucleus

Interventricular foramen

Ventral anterior nucleus

Ansa lenticularis

Fornix, column

Lateral hypothalamicarea

Hypothalamicnuclei


SupraopticVentromedial

DorsomedialArcuate


Claustrum

External capsule

Lateral segmentMedial segment

Globus pallidus:

Optic tract

Anterior commissure

Fornix, column

Ventral amygdalofugalfibers

Amygdaloid nucleus (complex)

Caudate nucleus, head

Stria terminalis

Internal capsule,genu

Putamen


Lateral ventricle

Insula

Thirdventricle

Supraopticdecussation


Choroid plexus

Septum pellucidum

Cingulate gyrus

5-34 Coronal section of the forebrain through the inter-ventricular foramen, genu of the internal capsule, rostral tip of thedorsal thalamus, and about the middle one-third of the hypo-

thalamus. Many of the structures labeled in this figure can beeasily identified in the T1-weighted MRI adjacent to the pho-tograph.


uclei With M

RI151

152Internal M


Extreme capsule

Anterior perforatedsubstance

Anterior commissure

Basal nucleus of Meynert

Septum pellucidum


Supraoptic decussation

Infundibulum

Preoptic areaof hypothalamus

Claustrum

External capsuleGlobus pallidus,lateral segment

Insula

Diagonal band(of Broca)

Lateral olfactory stria

Lateral ventricle,anterior horn


Stria terminalis

Septal nuclei

Internal capsule,anterior limb

Amygdaloid nucleus


Putamen

Uncus

Third ventricle

Optic tract

Supraoptic nucleus


Fornix, column

Cingulum

Cingulate gyrus

5-35 Coronal section of the forebrain through the anterior commis-sure and rostral aspects of the hypothalamus. Many of the structures la-beled in this figure can be easily identified in the T1-weighted MRI.


uclei With M

RI153

154Internal M


Extreme capsule


Nucleus accumbens


Middle cerebral artery

Anterior cerebralarteries

Paraterminal gyrus

Medial olfactory stria

Claustrum

External capsuleGlobus pallidus,lateral segment

Caudate nucleus,head




Septumpellucidum

Insula

Putamen

Optic chiasm

Diagonal band (of Broca)

Anterior cerebral artery

Lateral olfactory stria


5-36 Coronal section of the forebrain through the head of thecaudate nucleus, rostral portions of the optic chiasm, and the nucleus

accumbens. Many of the structures labeled in this figure can be eas-ily identified in the T1-weighted MRI adjacent to the photograph.


uclei With M

RI155

156Internal M


Extreme capsule

External capsule



Gyrus rectus (straight gyrus)

Claustrum


Corpus callosum, rostrum


Putamen

Septumpellucidum

Orbital gyri

Subcallosal gyrus

Anterior cerebral arteriesOlfactory tract

Olfactory sulcus

Anterior cerebral arteries



Caudate nucleus,head

5-37 Coronal section of forebrain through the head of the caudatenucleus and the anterior horn of the lateral ventricle. Many of the structureslabeled in this figure can be easily identified in the T1-weighted MRIadjacent to the photograph.


uclei With M

RI157

5-38 Semidiagrammatic representation of the internal dis-tribution of arteries to the diencephalon, basal ganglia, and in-ternal capsule. Selected structures are labeled on the left side ofeach section; the general pattern of arterial distribution overliesthese structures on the right side. The general distribution pat-terns of arteries in the forebrain as shown here may vary frompatient to patient. For example, the adjacent territories servedby neighboring vessels may overlap to varying degrees at theirmargins or the territory of a particular vessel may be larger orsmaller than seen in the general pattern.

158Internal M


Abbreviations

APS Anterior perforated substanceBCorCl Body of corpus callosum

CC Crus cerebriCM Centromedian nucleus of thalamus

DMNu Dorsomedial nucleus of thalamusGP Globus pallidus

HyTh HypothalamusPulNu Pulvinar nuclear complex

Put PutamenSplCorCl Splenium of the corpus callosum

VA Ventral anterior nucleus of thalamusVL Ventral lateral nucleus of thalamus

Vascular Syndromes or Lesions of the Forebrain

Forebrain vascular lesions result in a wide range ofdeficits that include motor and sensory losses and a va-riety of cognitive disorders. Forebrain vessels may beoccluded by a thrombus. This is a structure (usually aclot) formed by blood products and frequently attachedto the vessel wall. Deficits may appear slowly, or waxand wane, as the blood flow is progressively restricted.

Vessels may also be occluded by embolization. A for-eign body, or embolus (fat, air, piece of thrombus, pieceof sclerotic plaque, clump of bacteria, etc.), is deliveredfrom some distant site into the cerebral circulation whereit lodges in a vessel. Since this is a sudden event deficitsusually appear quickly and progress rapidly. Interruptionof blood supply to a part of the forebrain will result in aninfarct of the area served by the occluded vessel.

Lesion in the Subthalamic Nucleus: Small vas-cular lesions occur in the subthalamic nucleus, resultingin rapid and unpredictable flailing movements of thecontralateral extremities (hemiballismus). Movementsare more obvious in the arm than in the leg. The clinicalexpression of this lesion is through corticospinal fibers,therefore it is on the contralateral side of the body.

Occlusion of Lenticulostriate Branches to In-ternal Capsule: Damage to the internal capsule mayresult in contralateral hemiplegia (corticospinal fibers) anda loss, or diminution, of sensory perception (pain, ther-mal sense, proprioception) caused by damage to thalamo-cortical fibers traversing the posterior limb to the overly-ing sensory cortex. If the lesion extends into the genu ofthe capsule, a partial paralysis of facial muscles and tonguemovement may also occur contralaterally.

Infarction of Posterior Thalamic Nuclei: Oc-clusion of vessels to posterior thalamic regions results ineither a complete sensory loss (pain/thermal sense, touch,vibratory and position sense) on the contralateral side ofthe body, or a dissociated sensory loss. In the latter case thepatient may experience pain/thermal sensory losses butnot position/vibratory losses, or vice versa. As the le-sion resolves the patient may experience intense persis-tent pain, thalamic pain, or anesthesia dolorosa.

Occlusion of Distal Branches of the Anterior(ACA) or Middle (MCA) Cerebral Arteries: Oc-clusion of distal branches of the ACA results in motor

and sensory losses in the contralateral foot, leg, and thighowing to damage to the anterior and posterior paracen-tral gyri (primary motor and sensory cortices for lowerextremity). Occlusion of distal branches of MCA resultsin contralateral motor and sensory losses of the upperextremity, trunk, and face with sparing of the leg andfoot, and a consensual deviation of the eyes to the ipsi-lateral side. This represents damage to the precentraland postcentral gyri and to the frontal eye fields.

Watershed Infarct: Sudden systemic hypoten-sion, hypoperfusion, or embolic showers may result ininfarcts at border zones between the territories servedby the ACA, MCA, and posterior cerebral artery(PCA). Anterior watershed infarcts (at the ACA–MCAjunction) result in a contralateral hemiparesis (mainlyleg) and expressive language or behavioral changes. Pos-terior watershed infarcts (MCA–PCA interface) result invisual deficits and language problems.

Anterior Choroidal Artery Syndrome: Occlu-sion of this vessel may result from small emboli or smallvessel disease. This syndrome may also occur as a com-plication of temporal lobectomy (removal of the tem-poral lobe to treat intractable epilepsy). The infarctedarea usually includes the optic tract, lower portions ofthe basal nuclei, and lower aspects of the internal cap-sule. The patient experiences a contralateral hemiple-gia, hemihypethesia, and homonymous hemianopsia. Thesedeficits are due to, respectively, involvement of corti-cospinal fibers in the posterior limb of the internal cap-sule or possibly in the crus cerebri, involvement ofthalamocortical fibers in the posterior limb of the in-ternal capsule, and involvement of the fibers of the op-tic tract.

Parkinson Disease: Parkinson disease (paralysisagitans) results from a loss of the dopamine-containingcells in the substantia nigra. Although this part of thebrain is located in the midbrain, the terminals of thesenigrostriatal fibers are in the putamen and the caudatenucleus. The classic signs and symptoms of this diseaseare a stooped posture, resting tremor, rigidity, shuffling or fes-tinating gait, and difficulty initiating or maintainingmovement (akinesia, hypokinesia, or bradykinesia). Ini-tially, the tremor and walking difficulty may appear on

one side of the body, but these signs usually spread to both sides withtime. This is a neurodegenerative disease that has, in its later stages,a dementia component.

Transient Ischemic Attack: A transient ischemic attack, com-monly called TIA, is a temporary (and frequently focal) neurologicdeficit that usually resolves within 10 to 30 minutes from the onsetof symptoms. The cause is temporary occlusion of a vessel or inade-quate perfusion of a restricted vascular territory. TIA that last 60+minutes may result in some permanent deficits. This vascular eventmay take place anywhere in the central nervous system but is morecommon in the cerebral hemisphere.

Arterial Patterns W

ithin the Forebrain With Vascular Syndrom

es159

Rostral

Caudal

Anterior choroidal artery

Thalamogeniculate branches of posterior cerebral artery (branch of P2)

Posteromedial branches of posterior cerebral artery (P1 segment) and branches of posterior communicating artery

Medial striate branch of anterior cerebral artery (branch of A2)

Thalamoperforating branches of posterior cerebral artery (branch of P1)

Medial posterior choroidal artery

Lateral striate branches (lenticulostriate arteries) of the middle cerebral artery

Anterolateral branches of middle and anterior cerebral artery

Anteromedial branches of anterior cerebral artery and anterior communicating artery

Retrolenticularlimb of

internal capsule

Pineal

Crus of fornix

SplCorCl

CC

CM

VL

NuDMPut

Red nucleus

Stria terminalis

Lateral dorsal nucleus

Posterior limb of internal capsule

Body of fornix

GP

VA-VL

DMNu

Put

Anterior nucleus of thalalmus

Body of caudate nucleus

Claustrum

Head of caudate nucleus

Anterior limb of internal capsule

Septum pellucidum

External capsule

Insula GP

APS

BCorCl

HyTh

Put

PulNu

Lateral geniculatenucleus

Subthalamic nucleus

Medial geniculatenucleus

Column of fornix


Tail of caudate nucleus

Mammillary bodyHypothalamus

Optic tract Amygdaloidnuclearcomplex

Optic tract

Substantia nigra


CH

APTER

6

Internal Morphology of the Brain in Stained

Sections: Axial–Sagittal C

orrelations with M

RI

Although the general organization of C

hapter 6 has been de-scribed in C

hapter 1 (the reader may w

ish to refer back to thissection), it is appropriate to reiterate its unique features at thispoint. Each set of facing pages has photographs of an axial stainedsection (left-hand page) and a sagittal stained section (right-handpage). In addition to individually labeled structures, a heavy lineappears on each photograph. T

his prominent line on the axial

section represents the approximate plane of the sagittal section

located on the facing page. On the sagittal section this line signi-

fies the approximate plane of the corresponding axial section.

The reader can identify features in each photograph and then, us-

ing this line as a reference point, visualize structures that are lo-cated either above or below

that plane (axial to sagittal compar-

ison) or

medial

or lateral

to that

plane (sagittal

to axial

comparison). T

his method of presentation provides a form

at forreconstructing and understanding three-dim

ensional relation-ships w

ithin the central nervous system.

The m

agnetic resonance image (M

RI) placed on every page

in this chapter gives the reader an opportunity to compare in-

ternal brain anatomy, as seen in stained sections, w

ith thosestructures as visualized in clinical im

ages generated in the same

plane. Even a general comparison reveals that m

any features, asseen in the stained section, can be readily identified in the adja-cent M

RI.

This chapter is also organized so that one can view structures in

either the axial or the sagittal plane only. Axial photographs appear

on left-hand pages and are sequenced from dorsal to ventral (odd-

numbered Figures 6-1 through 6-9), w

hile sagittal photographs areon the right-hand pages and progress from

medial to lateral (even-

numbered Figures 6-2 through 6-10). C

onsequently, the user canidentify and follow

structures through an axial series by simply flip-

ping through the left-hand pages or through a sagittal series by flip-ping through the right-hand pages. The inherent flexibility in thischapter should prove useful in a w

ide variety of instructional/learning situations. The draw

ings shown in the follow

ing illustratethe axial and sagittal planes of the photographs in this chapter.

Fig. 6-1

Fig. 6-3

Fig. 6-5

Fig. 6-7

Fig. 6-9

Axial P

lanes

Fig. 6-2F

ig. 6-4 Fig. 6-6

Fig. 6-8F

ig. 6-10

Sagittal

Planes

6-1

Axial section through the head of the caudate nucleusand several

key thalamic nuclei

(anterior, centromedian, pulvinar, habenular). T

heheavy line represents the approxim

ate plane of the sagittal section

shown in Figure 6-2 (facing page). M

any of the structures labeled inthis photograph can be clearly identified in the adjacent T

1-weighted

MR

I.

162Internal M

orphology of the Brain in Stained Sections

AL

Cl

StT

er

CaN

u,T

Hip,F

OpR

ad

For

Hab

Hip

Com

Sep

AntN

u

CorC

l

DM

Nu

CMP

ulNuHip

Atrium

oflateral ventricle

CP

VL

VP

L

VA

Put

CaN

u,H

Anterior horn of

lateral ventricle

IntCap:

GPl

Abbrevia

tions

AntN

uA

nterior nucleus of thalamus

Hip

Com

Hippocam

pal comm

issureC

aNu,H


IntCap

,AL

Internal capsule, anterior limb

CaN

u,TC

audate nucleus, tailIntC

ap,G

Internal capsule, genuC

IC

laustrumIntC

ap,PL

Internal capsule, posterior limb

CM

Centrom

edial nucleus of thalamus

Op

Rad

Optic radiations

CorC

IC

orpus callosumPulN

uPulvinar nuclear com

plexC

PC

horoid plexusPut

Putamen

DM

Nu

Dorsom

edial nucleus of thalamus

SepSeptum

pellucidumFor

Fornix, column

StTerStria term

inalisH

abH

abenular nucleusV

AV

entral anterior nucleus of thalamus

Hip

Hippocam

pal formation

VL

Ventral lateral nucleus of thalam

usH

ip,F

Hippocam

pus, fimbria

VPL

Ventral posterolateral nucleus

6-2

Sagittal section through the column of the fornix, anterior thalam

icnucleus, red nucleus,and m

edial portions of the pons(abducens nucleus),cerebellum

(fastigial nucleus), and medulla

(nucleus gracilis). The heavy line

represents the approximate plane of the axial section show

n in Figure6-1 (facing page). M

any of the structures labeled in this photograph canbe clearly identified in the adjacent T

1-weighted M

RI.

Axial–Sagittal C

orrelations163

AC

MB

OcN

r

Py

For,C

ol

OpN

rS

CP

,DecB

P

ML

HyN

u

LCS

p

CorC

l,G

For,B

CorC

l,Spl

LDN

uA

ntNu

HyT

h

SM

T

PoC

om

MLF

FN

u

AbdN

u

PrT

ecNu

MtT

r

NuG

rP

O

Hab

DM

Nu

SC

ICR

Nu

TroN

r

Abbrevia

tions

Abd

Nu

Abducens nucleus

MB

Mam

millary body

AC

Anterior com

missure

ML

Medial lem

niscusA

ntNu

Anterior nucleus of thalam

usM

LFM

edial longitudinal fasciculusB

PBasilar pons

MtTr

Mam

millothalam

ic tractC

orCI,G

Corpus callosum

, genuN

uGr

Nucleus gracilis

CorC

I,Spl

Corpus callosum

, spleniumO

cNr

Oculom

otor nerveD

MN

uD

orsomedial nucleus of thalam

usO

pN

rO

ptic nerveFN

uFastigial nucleus (m

edial cerebellar nucleus)PO

Principal olivary nucleusFor,B

Fornix, bodyPoC

omPosterior com

missure

For,Col

Fornix, column

PrTecNu

Pretectal nucleiH

abH

abenular nucleiPy

Pyramid

HyN

uH

ypoglossal nucleusR

Nu

Red nucleus

HyTh

Hypothalam

usSC

Superior colliculusIC

Inferior colliculusSC

P,Dec

Superior cerebellar peduncle, decussationLC

spLateral corticospinal tract

SMT

Stria medullaris thalam

iLD

Nu

Lateral dorsal nucleusTroN

rT

rochlear nerve

zill anatomy web pages - internal morphology of the spinal cord and brain...

Documents