pons

Question 1

what does the pons extend from

Answer 1

Extends from the cranial end of the medulla to the cerebral peduncles of the
midbrain

Question 2

what are the ventral relations of the pons

Answer 2

clivus but separated from it by the meninges, basilar artery and
basilar plexus of veins

Question 3

what is the pons related to laterally

Answer 3

connected to the cerebellum by middle cerebellar peduncle

Question 4

what does the pons form

Answer 4

Dorsally it forms the cranial half of the floor of the 4th ventricle

Question 5

what does the basilar part contain

Answer 5

It is occupied by a number of longitudinal and transverse fibres
 Nuclei pontis
 The longitudinal fibres (corticospinal, corticobulbar and corticopontine) reach the
pons through the crus cerebri of the midbrain
 Corticospinal fibres extend down to enter the pyramid
 Some of the corticonuclear fibres mainly end in the contralateral cranial nerve
nuclei and few end ipsilaterally, and rest of the corticonuclear fibres extend down
to the pyramid of the medulla
 Corticopontine fibres synapse with the nuclei pontis at various levels in the pons
 The transverse fibres are the axons arising from pontine nuclei (pontocerebellar)
and going to the cerebellum through the contra-lateral middle cerebellar
peduncle

Question 6

what does the tegmental part contain

Answer 6

 It is traversed by a number of ascending and descending tracts
 Presence of salivatory nuclei, cranial nerve nuclei (5th, 6th, 7th and 8th) and reticular formation

Question 7

Cross-section through the caudal part of pons or at the level of fascial colliculus
It shows the presence of:

Answer 7

Medial lemniscus – Tract of Gall and Burdach
Spinal lemniscus – carry pain and temperature from opposite side of the body
Trigeminal lemniscus – conveys pain and thermal sensations from the face and
forehead
Lateral lemniscus – concerned with hearing

Question 8

how is lateral leminiscus formed

Answer 8

Contralateral ventral and dorsal
cochlear nuclei
 Both contralateral and ipsilateral
fibers from trapezoid body and
superior olivary nuclear complex

Question 9

what does Superior olivary nuclear complex consists of:

Answer 9

• Principal superior olivary nucleus
• Accessory superior olivary nucleus
• Retro-olivary nucleus

Question 10

Further dorsally the tegmentum contains:

Answer 10

• Motor nucleus of VII nerve – facial colliculus
• Superior olivary nucleus
• Nucleus solitarius
• Nucleus of spinal tract of trigeminal nerve
• Motor nucleus of facial nerve:

Question 11

what does the Superior salivatory nucleus and lacrimatory nucleus do

Answer 11

provides preganglionic
secretomotor fibers to the submandibular, sublingual, lacrimal glands and to the glands
of the nasal cavity and palate (VII nerve)

Question 12

what does the Inferior salivatory nucleus do

Answer 12

provide preganglionic secretomotor fibers to the parotid
gland (IX nerve)

Question 13

what does the Upper end of nucleus of tractus solitarius do

Answer 13

It
receives taste fibers from the anterior two-third of the tongue and soft palate through
VII nerve, from the posterior one-third of the tongue by IX nerve and posterior most
part of the tongue by X nerve

Question 14

what does the The spinal nucleus of V do

Answer 14

receives exteroceptive senses (stimuli originating from
outside the body - vision, hearing, touch, taste, smell) from X, IX, and possibly VII
nerve

Question 15

what does the Central tegmental tract contain

Answer 15

• Descending fibers from the red nucleus and periaqueductal grey matter to the
  inferior olivary nuclear complex
• Ascending fibers from the brain stem reticular nuclei to the intra-laminar nuclei of
  thalamus and other parts of diencephalon (limbic system)

Question 16

what does the The medial longitudinal bundle do

Answer 16

for

adjustment of balance

Question 17

what does the Tectospinal tract do

Answer 17

establishes a spino-visual reflex

Question 18

what is the blood supply of the pons

Answer 18

• Numerous pontine branches from the basilar artery
• Anterior inferior cerebellar artery

———–Clinical correlation
Millard-Gubler syndrome (Medial inferior pontine syndrome)
* Results from lesion in the basilar or ventral part of the pons
* Emerging fibres of abducent nerves
The characteristic features of this syndrome are:
* Ipsilateral medial squint due to the involvement of abducent nerve
* Contralateral hemiplegia due to the involvement of corticospinal tract

Question 19

what is Pontocerebellar angle syndrome

Answer 19

The structures mainly affected include:
* 5th, 7th and 8th cranial nerves

This syndrome occurs due to the pressure exerted on the lateral region of the caudal part of
the pons by acoustic neuroma
Acoustic neuroma develops from the Schwann cells surrounding the cochlear nerve near its
attachment to the brainstem

Question 20

what are the signs and symptoms of Pontocerebellar angle syndrome

Answer 20

• Tinnitus (is noise or ringing in the ears), progressive deafness and vertigo due to
  damage to 8th cranial nerve
• Ipsilateral facial palsy due to the involvement of facial nerve
• Ipsilateral loss of pain and temperature due to the involvement of spinal tract and
  nucleus of 5th cranial nerve