2. Objectives:
(1) External features of Pons
(2) Internal features of Pons– cross sections
(1) At the level of Facial Colliculus
(2) At the level of Motor & Sensory Nucleus of
trigeminal nerve
(3) Blood supply with Applied aspects
3. Connects the medulla &
midbrain
Function
Transmit information
between spinal cord
& higher brain
regions via neural
circuits
Relay motor
information
between cerebral
cortex &
cerebellum
4. PONS
PONS
M
C
P
Length – 2.5 cm
External features ..
1. Dorsal & ventral surfaces…
- transvereslystriated
2. Basilar sulcus (vertical) ..
Lodges Basilar Artery.
3. Dorsal surface forms upper part of floor
of 4th Ventricle.
5. Laterally .. Continuous with Middle
Cerebellar Peduncle - trigeminal nerve
6. Superior border - 3rd ,4th
7. Inferior border .. With 6th, 7th & 8th C.N.
BASILAR GROOVE
7. Lower
part
Upper part
Internal features
• By 2 sections.
• (1) At lower part of medulla
Fascial Colliculus
• (2) At upper part
At motor & Sensory Nucleus
of Trigeminal nerve
8. • The pons is divisible into - ventral part (basilar) &
dorsal part (Tegmentum).
Ventral (basilar) part
- The basilar (ventral) part has a uniform structure throughout
length of pons.
- contains transverse and vertical fibres & Pontine nuclei.
(i) Transverse fibres are the pontocerebellar fibres- cross the
midline to enter the opposite middle cerebellar peduncle.
(ii) The vertical fibres -
- Some of them descend from cerebral cortex to end in
the pontine nuclei. (corticopontine)
- Corticospinal fibres that descend through the pons in
to the medulla .
- Corticonuclear fibres end in the motor nuclei of
cranial nerves mainly of opposite side.
Internal = Basilar & Tegmental Part
-The basilar (Ventral) part - Uniform structure throughout
-Tegmentum (dorsal) part - Differs in upper & lower part of
pons.
13. Ventral(Basilar)PartPons
GREY MATTER
Pontine nuclei:
Afferents - Corticopontine fibres of the same side.
Efferents - Pontocerebellar fibres that cross the midline & pass
through the middle cerebellar peduncle to enter
the cerebellum. (Cortico-ponto-cerebellar pathway)
Middle cerebellar
peduncle
14. WHITE MATTER
Longitudinal fibres:- Corticospinal and Corticonuclear (pyramidal) tracts.
Transverse fibres:- Pontocerebellar
Going to opposite half of cerebellum
through middle cerebellar peduncle
Ventral(Basilar)PartPons
15. Tegmentum of pons (dorsal part)
Differs in upper & lower part of pons
16. C.S. at Facial Colliculus
Abducent
Nucleus
Motor Nucleus
of Facial Nerve
Internal genu -
Facial Colliculus
Neurobiotaxis ?
17. C.S. at Facial Colliculus
Superior
salivatory
Nucleus
Lacrimatory
Nucleus
Nucleus Tractus
Solitarius –
Upper End
18. C.S. at Facial Colliculus
Vestibular
Nucleus
Spinal Nucleus &
Spinal Tract of V
19. Superior Olivary Nuclear Complex
Principal
Superior
Olivary
Nucleus
Accessory
Superior Olivary
Nucleus
Retro - Olivary
Nucleus
32. Sensory Nuclei Of Vth Nerve
Spinal Nucleus
Pain & Temperature
Mesencephalic - Proprioceptive
Principal Sensory
Touch & Pressure
From- Ipsilateral Face
1st Order Neuron
54. Alternating Trigeminal Hemiplegia
1. 5th Nerve
- Ipsilateral loss of pain and
tepmperature sensation from the
face (facial hemianesthesia)
- LMN paralysis of masticatory
muscles
2. Pyramidal Tract
Contralateral Hemiplegia