Download Brainstem: Pons

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11
Brainstem: Pons
Introduction
External Features
Internal Structure
• Structure of the basilar part
• Structure of the tegmental part
Transverse Section Through the Lower Pons
INTRODUCTION
Pons, in a literal sense, means ‘the bridge’. It acts as a conduit
for the passage of impulses from one side of the cerebellum to the other and also between the medulla, below, and
midbrain, above. Physiologically, the centre of respiration
is present in the pons. Pons also has nuclei of origin for the
following cranial nerves: Trigeminal (V), abducent (VI),
facial (VII) and vestibulocochlear (VIII).
EXTERNAL FEATURES
Pons is a part of the brainstem, situated between the medulla, below, and midbrain, above (see Figs 10.1–10.4). It
lies in front of the cerebellum. It is about 2.5 cm long and
presents a ventral and a dorsal surface.
The ventral surface is convex and is bounded by upper
and lower borders. This surface presents transversely running ridges (fibres). Laterally, these ridges come closer to
form a bundle, the middle cerebellar peduncle. The point
of junction between the anterior surface of the pons and
the middle cerebellar peduncle is marked by the emergence
of the trigeminal nerve. The trigeminal nerve emerges in
the form of a large sensory root and a small motor root.
The ventral surface also presents a shallow groove in the
midline, known as the basilar groove. This groove lodges
the ‘basilar artery’. The ventral surface of the pons is in
relation to ‘dorsum sellae’ and ‘basiocciput’. These are the
bony landmarks present on the basilar surface (internal
aspect) of the skull.
On the ventral aspect, three cranial nerves are seen to
emerge from the pontomedullary junction (i.e. lower border of pons). The abducent nerve emerges just above the
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• Arrangement of grey matter
• Arrangement of white matter
Transverse Section Through the Upper Pons
• Arrangement of grey matter in tegmentum
• Arrangement of white matter in tegmentum
• Tumours of the pons
pyramid and facial and vestibulocochlear nerves emerge
above the olive (see Figs 10.1–10.4).
The posterior surface of the pons is formed by the upper part of the floor of the fourth ventricle. This surface is
limited laterally by the superior cerebellar peduncles. The
posterior surface of the pons is related to the cerebellum.
INTERNAL STRUCTURE
A transverse section passing through the pons is divided
into ventral (basilar) and posterior (tegmentum) parts
(Fig. 11.1).
The basilar (ventral) part contains transversely and vertically running white fibres and scattered masses of grey matter (pontine nuclei). The transverse fibres run laterally to
form the middle cerebellar peduncle while the vertical fibres
run downwards to form the pyramid of medulla. The structure of the basilar part is the same throughout the pons (at
all levels).
The tegmentum of the pons is a direct upward continuation of the medulla except for the pyramidal tracts (which
run through the basilar part of pons). This part consists of
many ascending and descending tracts and nuclei for the
cranial nerves.
Structure of the Basilar Part
The basilar part of the pons consists of descending longitudinal fibres, transverse pontine fibres and pontine nuclei.
The descending fibres enter the pons as a compact bundle
but soon they break up into many bundles due to the presence of pontine nuclei and transversely running pontine
fibres (Fig. 11.2).
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Tegmental part
Middle
cerebellar peduncle
Basilar part
Nucleus of trapezoid body
Trapezoid body
Pontine nuclei
Descending longitudinal fibres
Figure 11.1 Schematic diagram showing the transverse section through the lower part of the pons. The basilar part of the pons lies ventral to the
trapezoid body while the tegmental part lies dorsal to it.
Descending Longitudinal Fibres
The descending longitudinal fibres consist of corticospinal,
corticonuclear and corticopontine fibres.
• Corticospinal fibres: These fibres traverse the pons and
converge again to form pyramids in medulla.
• Corticonuclear fibres: These fibres descend along with the
corticospinal to form pyramids in medulla. However,
many corticonuclear fibres terminate in the contralateral
(and some ipsilateral) motor nuclei of cranial nerves and
reticular formation of pons.
• Corticopontine fibres: These fibres arise from the frontal,
parietal, temporal and occipital cortices and terminate on
pontine nuclei of the same side.
Pontine Nuclei
The pontine nuclei are small masses of grey matter scattered
between longitudinal (vertical) and transversely arranged
fibres. The pontine nuclei give rise to transverse fibres of
the pons. These fibres are known as pontocerebellar because they terminate in the cerebellum (cerebellar cortex).
The pontine nuclei are a relay station in the corticopontocerebellar pathway, that is, between the cerebral cortex and
contralateral cerebellar hemisphere. Corticopontine fibres
from various lobes of cerebral cortex end in pontine nuclei
(Fig. 11.2).
Transverse Pontine Fibres
Transverse pontine fibres are pontocerebellar fibres that run
transversely across the midline of the pons. While running
transversely in the pons, the bundles of pontocerebellar fibres
cross the vertically running bundles of the descending fibres
(corticospinal and corticonuclear). The pontocerebellar fibres together form a bundle (on the opposite side) which is
referred to as ‘middle cerebellar peduncle’. The pontocerebellar fibres are a part of the corticopontocerebellar pathway.
Corticopontine
Midbrain
Corticonuclear fibres
Pons
Motor cranial nerve
nuclei and reticular formation
Pontocerebellar fibre
Middle cerebellar
peduncle
Pontine nuclei
Olive
Pyramid
Medulla
Corticospinal
fibres
Figure 11.2 Components of descending longitudinal fibres (i.e. corticospinal, corticonuclear and corticopontine) in the basilar part of pons. Corticospinal fibres converge to form pyramid, corticonuclear fibres end in motor nuclei of cranial nerves or in reticular formation and corticopontine fibres
end in pontine nuclei. Pontocerebellar fibres form the middle cerebellar peduncle. They originate in pontine nuclei and run transversely to cerebellum.
The basilar part of pons consists of both longitudinal and transverse and running fibres.
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129
(Pons)
(a)
(b)
Figure 11.3 Transverse sections of pons (cranial and caudal levels). (a) Illustration depicting levels of transverse section. (b) Photograph depicting
the transverse section of pons.
Photograph courtesy: Professor RK Zargar and Dr Sunita Athavale, People’s Medical College, Bhopal.
Structure of the Tegmental Part
The tegmental (dorsal) part of the pons is the upward continuation of the medullary reticular formation. The white
matter in the tegmentum consists of various ascending and
descending tracts. The grey matter consists of the cranial
nerve nuclei of V, VI, VII and VIII nerves and reticular nuclei. The posterior surface of pons forms the floor of the
fourth ventricle.
The structure of the tegmentum is different in the upper and lower parts of pons. Hence, it is customary to study
the internal structure of the tegmental part of pons at two
different levels—caudal (lower) part, transverse section
passing through the facial colliculus, and cranial (upper)
part, transverse section passing through trigeminal nuclei
(Fig. 11.3).
• The vestibular nuclei complex receives afferent fibres from
•
•
TRANSVERSE SECTION THROUGH THE LOWER PONS
The transverse section through the lower part of pons corresponds to the level of facial colliculus (Fig. 11.4).
•
Arrangement of Grey Matter
• The floor of the fourth ventricle, at this level, is lined by
grey matter and shows the presence of two cranial nerve
nuclei—abducent and vestibular. Also, seen are the cranial nerve nuclei of trigeminal nerve (spinal nucleus of
the trigeminal nerve) and facial nerve, at deeper levels.
• The abducent nerve nucleus lies beneath the facial colliculus and lateral to the medial longitudinal bundle. The
facial colliculus is formed due to a complicated loop
formed by the fibres of the facial nerve winding around
the abducent nucleus. This nucleus gives origin to the
abducent nerve, which is the motor nerve for the lateral
rectus muscle of eye.
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•
the vestibular division of the vestibulocochlear nerve.
The efferents from this nuclei form the vestibulocerebellar tract, vestibulospinal tract, medial longitudinal bundle and lateral lemniscus. The vestibular nuclei convey
impulses concerned with equilibrium and orientation in
three-dimensional space.
There are two cochlear nuclei which are designated as
‘ventral’ and ‘dorsal’. The ventral and dorsal nuclei lie on
the ventral and dorsal aspects of the inferior cerebellar
peduncle, respectively. These two nuclei are relay stations in the pathway of hearing or in the auditory pathway. These nuclei receive the afferents from the cochlear
nerve.
The motor nucleus of the facial nerve is present in the
reticular formation, medial to the nucleus of the spinal
tract of the trigeminal nerve and dorsal to the superior
olivary nucleus. This nucleus gives origin to the motor
fibres of facial nerves for the innervations of muscles of
facial expression.
The salivatory nuclei are usually divided into superior salivatory, inferior salivatory and lacrimatory nuclei. These
nuclei are located between the upper end of dorsal vagal
nucleus and inferior end of facial nucleus. The upper end
of the dorsal vagal nucleus is situated at the level of pontomedullary junction and the inferior end of facial nucleus is located in the lateral part of reticular formation. The
salivatory nuclei are a group of parasympathetic motor
nuclei. These nuclei send secretomotor fibres via facial
nerve (to pterygopalatine and submandibular ganglia)
and glossopharyngeal nerve (to otic ganglion). The postganglionic fibres from the ganglia supply to the salivary
and lacrimal glands.
The nucleus of the spinal tract of the trigeminal nerve
and the tract are present ventromedial to the inferior
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Facial nerve
Medial longitudinal bundle
nucleus
Tectospinal
Facial colliculus
Abducent nucleus
Vestibular nuclei
complex
Inferior cerebellar
peduncle
Cochlear nuclei
Superior salivatory
nucleus
Reticular formation
Spinal nucleus and
tract of trigeminal nerve
Middle cerebellar
peduncle
Lateral lemniscus
VIII nerve
Spinal lemniscus
Pontocerebellar
fibres
Trigeminal lemniscus
Nucleus of tractus
solitarius
Medial lemniscus
VII nerve
Trapezoid nucleus
Corticospinal and
corticonuclear
(Or corticopontine)
fibres
Trapezoid body
Rubrospinal tract
VI nerve
Pontine nuclei
Figure 11.4 Transverse section of pons at the level of facial colliculus. The facial nerve, after taking origin from the nucleus, follows an unusual course.
At first, the fibres of the facial nerve pass dorsomedially below the abducent nerve nucleus. Then they pass upwards on the medial side of the abducent
nucleus, close to midline. Fibres then curve forwards and laterally above the abducent nucleus. At this place, fibres lie deep to the floor of the fourth ventricle forming the facial colliculus. Now these fibres pass forwards, laterally and downwards through the reticular formation lying between its own nucleus
on the medial side and the nucleus of the spinal tract of the trigeminal nerve on the lateral side.
•
•
•
•
cerebellar peduncle and lateral to the nucleus of the facial
nerve.
Nucleus of tractus solitarius: At the level of the lower
pons, this nucleus lies lateral to the superior salivatory
nucleus.
The reticular nuclei are a small collection of grey matter
scattered in the network of white fibres.
Superior olivary nuclear complex: The complex of superior olivary nuclei mainly consists of the lateral superior olivary nucleus, medial superior olivary nucleus and
retro-olivary group of nuclei. These nuclei are situated
lateral to the reticular formation, in the lower pons, at the
pontomedullary junction (not shown in Fig. 11.4 as the
section is at a higher level).
The nucleus of the trapezoid body is situated in the ventral
part of tegmentum. This nucleus is placed in the auditory
pathway and its fibres constitute the lateral lemniscus.
Arrangement of White Matter
At the level of lower pons, many new features appear in the
white matter of the tegmentum. The trapezoid body is seen
as a mass of white matter in the ventral part of tegmentum, just dorsal to the basilar part. The medial and spinal
lemnisci have changed their positions. The trigeminal and
spinal lemnisci are new ascending tracts seen at this level.
Trapezoid Body
The trapezoid body is formed by the fibres of both ventral
and dorsal cochlear nuclei. These fibres cross the midline in
the ventral part of the tegmentum. Fibres of the trapezoid
body relay in the trapezoid nucleus and in the superior olivary complex. The efferents of these nuclei form the lateral
lemniscus (ascending auditory pathways).
Medial, Trigeminal, Spinal and Lateral Lemnisci
• These lemnisci are situated posterior to the trapezoid
body (Fig. 11.4).
• The medial lemniscus is the most medial and now orient-
ed transversely. The body is somatotopically represented
in such a way that fibres from the neck and upper limb lie
most medially and those of the lower limb most laterally.
The medial lemniscus is joined by the fibres of the ventral
spinothalamic tract.*
• The trigeminal lemniscus begins to form at this level and
is situated lateral to the medial lemniscus. It is formed
by the axons arising from the contralateral spinal nucleus
of the trigeminal nerve. This tract conveys the exteroceptive impulses (pain, touch, temperature) from the area of
supply of the trigeminal nerve (face, nose, mouth, tongue,
conjunctiva, etc.)
*According to some authors, the ventral spinothalamic tract joins the lateral spinothalamic tract to form the spinal lemniscus.
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Brainstem: Pons
• The spinal lemniscus is formed by the fibres of lateral
•
•
•
•
spinothalamic and spinotectal tracts. It lies lateral to the
trigeminal lemniscus.
The lateral lemniscus begins in the lower half of pons. It is
a part of the auditory pathway. It lies most laterally in the
lemniscal band, that is, lateral to the spinal lemniscus.
The ventral spinocerebellar tract is situated dorsolateral
to the lateral lemniscus.
The spinal nucleus and tract of trigeminal nerve are situated lateral to the facial nerve nucleus.
The lateralmost area of the tegmentum is occupied by the
inferior cerebellar peduncle.
TRANSVERSE SECTION THROUGH THE UPPER PONS
The transverse section through the upper part of pons
corresponds to the level of trigeminal nuclei (Fig. 11.5).
This level passes through the motor and principal sensory
nuclei of the trigeminal nerve. The dorsal part of the tegmentum now contains the cavity of the fourth ventricle,
which is bounded dorsolaterally on either side by a superior cerebellar peduncle and roofed by the superior medullary velum.
Arrangement of Grey Matter in Tegmentum
131
Below this level, the nucleus is continuous with the spinal
nucleus of the trigeminal nerve. This nucleus is the relay
station for the sensation of touch (pain and temperature
being carried by the spinal nucleus). Fibres arising from
this nucleus ascend in the trigeminal tract and after crossing to the opposite side terminate in thalamus.
• Motor nucleus of the trigeminal nerve: This nucleus lies
medial to the sensory nucleus in the floor of the fourth
ventricle, within the reticular formation. It gives origin to
the motor root of the trigeminal nerve.
• Nucleus of lateral lemniscus: This small nucleus is present
medial to lateral lemniscus. This nucleus is considered as
a relay station in the auditory pathway and is associated
with the trapezoid nucleus.
Arrangement of White Matter in Tegmentum
At the upper level of pons, the trapezoid body is usually not
seen. However, some fibres of the trapezoid body may be
visible just ventral to the medial lemniscus.
• The medial, trigeminal and spinal lemnisci are in the
same position.
• The lateral lemniscus is more prominent at this level.
• The ventral spinocerebellar tract now joins the superior
cerebellar peduncle.
• The superior cerebellar peduncle is situated at the dorso-
The following nuclei are seen in tegmentum:
lateral position of the section.
• Principal (superior) sensory nucleus of the trigeminal nerve:
It is situated lateral to the motor nucleus (Fig. 11.5).
• The medial longitudinal bundle, tectospinal tract and ru-
brospinal tracts are seen in the paramedian position.
Superior medullary velum
Superior cerebellar peduncle
Ventral spinocerebellar tract
Principal sensory
nucleus of V nerve
Cavity of the fourth ventricle
Motor nucleus
of V nerve
Central tegmental tract
LL
Nucleus of
lateral lemniscus
Tegmental part of pons
MLB
TST
Middle cerebellar peduncle
RST
SL
TL
ML
Sensory root of V nerve
Motor root of V nerve
V
Corticospinal fibres
V
Basilar part of pons
Trapezoid body
Pontine nuclei
Figure 11.5 Transverse section of pons at the level of trigeminal nucleus (upper pons).
LL—lateral leminsicus, ML—medial lemniscus, MLB—medial longitudinal bundle, RST—rubrospinal tract, SL—spinal lemniscus, TL—trigeminal lemniscus, TST—tectospinal tract.
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CLINICAL ASPECT
Vascular Lesions of the Pons
Vascular lesions of the pons may result due to occlusion
or haemorrhage of pontine arteries which are branches
from the basilar artery.
Pontine Haemorrhage
Pontine haemorrhage is usually fatal. This condition results in hemiplegia on the opposite side of the lesion due
to damage to corticospinal fibres and results in facial paralysis on the same side due to involvement of the facial
nerve and nucleus. (But if the haemorrhage is extensive
and bilateral, then paralysis of face and limbs is also bilateral.) Similarly, due to the involvement of sympathetic
fibres in the reticular formation the patient suffers from
hyperpyrexia and shows the pinpointed pupil. Hyperpyrexia is due to damage to sympathetic fibres through
which the hypothalamic heat regulating centre exerts its
effect. The pinpointed pupil results due to over-activity
of parasympathetic fibres in the absence of sympathetic
fibres. Damage to reticular formation leads to deep coma
as it controls consciousness. If the vital centres of reticular
formation controlling respiration and circulation are also
damaged, then sudden death may occur.
The occlusion of the pontine branches of the basilar
artery may result in various syndromes. These are described in Table 11.1.
Tumours of the Pons
Tumours of the pons arise from neuroglial cells (mostly astrocytes). Astrocytoma occurs in childhood. In this lesion,
cranial nerves of the same side are affected (cranial nerves V,
VI, VII and VIII). However, involvement of the corticospinal tract leads to hemiparesis on the opposite side.
Table 11.1
Syndromes Associated with Occlusion of Pontine Branches of Basilar Artery
Syndrome
Site of Damage
Clinical Features
Raymond’s syndrome
(Due to occlusion of pontine branches of
the basilar artery)
Corticospinal and other descending motor
fibres
Damage to abducent nerve fibres (Fig. 11.6)
Hemiplegia/hemiparesis on the opposite side
of the body (UMN type of lesion)
Paralysis of the lateral rectus muscle of eye
ball. This results in medial squint
Millard–Gubler syndrome
(It is a more dorsolaterally located lesion
than Raymond’s. In this syndrome,
axons and nucleus of the VI nerve are
spared.)
Damage to corticospinal fibres
Damage to fibres of the VII cranial nerve
and its nucleus (Fig. 11.7)
Hemiparesis on the opposite side of the body
(UMN type of lesion)
Paralysis of the same side of face (LMN type
of paralysis)
Foville’s syndrome
Lesion of abducent nerve nucleus
(It is a more dorsally and medially located Facial nucleus and its axons (Fig. 11.8)
lesion as compared to the Millard–
Transient ischaemia of the corticospinal
Gubler syndrome; Fig. 11.8.)
tract
LMN type of paralysis of lateral rectus muscle
resulting in medial squint on the same side
of the lesion
LMN type of paralysis of facial muscles on the
same side
Hemiparesis of a brief duration on the opposite side of the body
Facial nerve
nucleus
Facial nerve
Abducent nerve
Abducent nerve
Descending fibres
Figure 11.6 Raymond’s syndrome. This syndrome results in hemiplegia on the opposite side of the body due to involvement of corticospinal
fibres. This also results in medial squint on the same side due to damage to
the abducent nerve.
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Figure 11.7 Millard–Gubler syndrome. This results in hemiparesis on
the opposite side of the body and paralysis of the face on the same side.
Hemiparesis results due to damage to only few corticospinal fibres. The
abducent nerve is spared.
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133
Facial nerve
Abducent nerve
Figure 11.8 Foville’s syndrome. This results in medial squint and facial paralysis on the same side of the body.
SUMMARY
External Features of Pons
Pons lies between the medulla and midbrain and is situated
in front of the cerebellum. It presents ventral and dorsal surfaces. The ventral surface of pons is convex and presents a
shallow groove in midline—the basilar groove. On each side,
the ventral surface is continuous with the middle cerebellar
peduncle and shows the attachment of V cranial nerve. The
posterior surface of pons is formed by the upper part of the
floor of the fourth ventricle. Three cranial nerves (VI, VII
and VIII) emerge from the pontomedullary junction.
Tegmentum, at the level of facial colliculus (lower pons),
shows the following features:
Arrangement of Grey Matter in Tegmentum
•
•
•
Internal Structure of Pons
A transverse section passing through pons is divided into
basilar and tegmental parts (Fig. 11.1).
•
•
The structure of the basilar part of pons consists of descending fibres (corticospinal, corticonuclear and corticopontine) and transverse pontine fibres (pontocerebellar).
The pontine nuclei are small masses of grey matter scattered between longitudinally and transversely arranged
fibres.
The structure of the tegmental part of pons consists of
ascending and descending tracts, cranial nerve nuclei of V
to VIII nerves and reticular formation.
The structure of basilar part of pons remains constant
throughout the pons. However, the structure of tegmentum
differs in upper and lower parts of pons.
•
•
The floor of the fourth ventricle, at this level, shows the presence of abducent and vestibular nerve nuclei (Fig. 11.3).
The ventral and dorsal and cochlear nuclei are located on
the dorsal and ventral aspects of the inferior cerebellar
peduncle, respectively.
The motor nucleus of the facial nerve is present in the
area of reticular formation. The facial nerve follows an
unusual course before it comes out at the pontomedullary junction.
Nucleus of the spinal tract of trigeminal nerve is located
ventromedial to the inferior cerebellar peduncle.
Nucleus of tractus solitarius and superior salivatory nucleus are situated ventromedial to facial nucleus.
Arrangement of White Matter
•
•
•
The trapezoid body is seen at the junction of basilar and
tegmental parts. Posterior to the trapezoid body, four lemnisci (medial, trigeminal, spinal and lateral) are arranged
from medial to lateral side.
The medical longitudinal bundle, tectospinal tract and
rubrospinal tract are situated at the paramedian position
(Fig. 11.3).
The inferior cerebellar peduncle is present in the lateralmost area of tegmentum.
Multiple Choice Questions
1. Which of the following statements about pons is false?
a. It lies in front of cerebellum
b. The posterior surface of pons is formed by the upper
surface of the roof of the fourth ventricle
c. The posterior surface of pons is limited laterally by
superior cerebellar peduncles
d. The posterior surface of pons is related to cerebellum
(Refer to pages 127 and 128)
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2. Which of the following statements about pons is false?
a. The ventral surface of pons is bounded by upper and
lower borders
b. The ventral surface of pons is convex
c. There is a shallow basilar groove in midline, which
lodges the basilar plexuses of veins
d. Laterally, the ventral surface is continuous with the
middle cerebellar peduncle
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e. The ventral surface of pons is in relation to basisphenoid (clivus) bone
(Refer to page )
3. All the following statements about the transverse section
of pons are true except
a. The section is divided into basilar and tegmental
parts
b. The basilar part contains transversely and vertically
running white fibres
c. The basilar part does not contain grey matter (nuclei)
d. Transverse fibres run laterally to form the middle
cerebellar peduncle
e. Vertical fibres run downwards to form the pyramid
(Refer to pages 129 and 130)
4. Which of the following descending fibres are present in
the basilar part of the pons?
a. Corticospinal
b. Corticonuclear
c. Corticopontine
d. All of the above
(Refer to page 129)
5. Which of the following statements about the corticopontocerebellar pathway is false?
a. It arises from frontal, temporal, parietal and occipital
lobes
b. It terminates on pontine nuclei of the same side
c. Fibres arising from pontine nuclei constitute transverse fibres (pontocerebellar) of the pons
d. Pontocerebellar fibres enter the cerebellum on the
same side through the middle cerebellar peduncle
e. Pontine nuclei are a relay station in the corticopontocerebellar pathway
(Refer to page 129)
6. The efferents of the vestibular nuclear complex form the
following except
a. Vestibulocerebellar tract
b. Vestibulospinal tract
c. Medial longitudinal bundle
7.
8.
9.
10.
d. Lateral lemniscus
e. Medial lemniscus
(Refer to page 130)
The trapezoid body is formed by
a. Fibres of both dorsal and ventral cochlear nuclei
b. Efferents arising from superior olivary nuclei
c. Efferents arising from the nucleus of the trapezoid
body
d. All of the above
(Refer to page 131)
Which of the following lemnisci are present in the white
matter of tegmentum at the upper level of pons?
a. Medial lemniscus
b. Spinal lemniscus
c. Trigeminal lemniscus
d. Lateral lemniscus
e. All of the above
(Refer to page 132)
The following statements about pontine haemorrhage
are true except
a. It occurs due to occlusion or haemorrhage of pontine
arteries
b. Corticospinal fibres are damaged leading to hemiplegia on the opposite side of the body
c. Facial paralysis on the opposite side of the body due
to damage to facial nucleus
d. There is hyperpyrexia due to damage to sympathetic
fibres through which the heat regulating centre exerts
its effect
e. Pinpoint pupil due to damage to sympathetic fibres
(Refer to page 132)
Which of the following facts about Raymond’s syndrome are true?
a. It results due to occlusion of pontine branches of the
basilar artery
b. Damage occurs to corticospinal fibres
c. Damage to abducent nerve fibres
d. All of the above
(Refer to page 132)
Answers
1. b;
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2. c;
3. c;
4. d;
5. d;
6. e;
7. d;
8. e;
9. c;
10. d.
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