Download File

Chapter 3
Brainstem Anatomy,
Topography, and Functional
Levels
The brainstem: midbrain, pons, medulla oblongata
Midbrain
Tentorial notch
clivus
foramen
magnum
anterior
posterior
3rd ventricle
Cerebral aqueduct
4th ventricle
central canal
Medulla oblongata:
Contains centers associated with:
equilibrium
audition
deglutition
coughing
vomiting
salivation
tongue movements
respiration
circulation
Pons:
Contains centers associated with:
mastication
eye movements
facial expression
blinking
salivation
equilibrium
audition
Midbrain:
Contains centers associated with:
auditory reflexes
visual reflexes
pupillary reflexes
ventral surface
of medulla
Fig. 3-3
ventral surface
of pons
transverse bands
Cerebellar
angle
junction
Fig. 3-3
Basilar artery
Vertebral artery
ventral surface
of midbrain
(anterior part
of cerebral
peduncle)
Fig. 3-3
dorsal surface
of closed medulla
Fig. 3-4
Floor of 4th ventricle:
(see Fig. 3-4)
caudal part is formed by posterior surface of rostral medulla
Floor of 4th ventricle:
rostral part is formed by posterior surface of pons
motor structures
are more medial;
sensory structures
are more lateral
Fig. 5-3
Motor cranial nerves
ventral surface
of medulla
(cranial rootlets)
Fig. 3-3
ventral surface
of pons
transverse bands
Cerebellar
angle
junction
Fig. 3-3
ventral surface
of midbrain
CN’s I and II connect
to the forebrain
(anterior part
of cerebral
peduncle)
Fig. 3-3
Myelin-stained brainstem cross sections:
Rostral part of closed medulla (at dorsal column nuclei)
the dorsal
column nuclei
{
Fig. 3-6
Rostral part of closed medulla
Caudal part of open medulla (at hypoglassal and vagal nuclei)
hypoglossal nucleus
nucleus ambiguus
Fig. 3-7
Caudal part of open medulla (at hypoglossal and vagal nuclei)
Rostral part of open medulla (at lateral aperture)
acoustic
tubercle
Inferior cerebellar
peduncle
Fig. 3-8
Rostral part of open medulla (at lateral aperture)
(opens into
subarachnoid
space)
Caudal pons (at abducens and facial nuclei)
Facial nucleus
Fig. 3-9
Caudal pons (at abducens and facial nuclei)
Middle pons (at trigeminal nuclei)
Middle pons (at trigeminal nuclei)
Rostral pons (at decussation of trochlear nerves)
(emergence)
Rostral pons (at decussation of trochlear nerves)
Caudal midbrain (at inferior colliculus)
Trochlear nucleus
Caudal midbrain (at inferior colliculus)
Rostral midbrain (at superior colliculus)
CNIII fibers
Rostral midbrain (at superior colliculus)
corpora quadrigemina
(for reflex movements of eyes, head, and neck)
Inputs and outputs
of the
Brainstem
Reticular Formation
Fig. 20-2
Functions of the reticular formation:
*
1.
2.
3.
4.
5.
6.
7.
Integrates of cranial nerve reflexes
Helps in conduction and modulation of slow pain
Influences voluntary movements
Regulates autonomic nuclei
Is associated with diffuse modulating systems
Integrates basic functions (respiration, sleep)
Activates the cerebral cortex
*
Ascending Reticular
Activating System
Fig. 20-9
Fig. 20-1
Chapter 3
know the location of the brainstem and the locations where it is continuous with the
forebrain and the spinal cord
know the functional centers contained within the midbrain, pons, and medulla
know the locations of the tectum and tegmentum of the brainstem
know the anterior surface features of the medulla
know the anterior surface features of the pons
know the anterior surface features of the midbrain
know the posterior surface features of the closed medulla
know the parts of the brainstem that form the floor of the 4th ventricle
know the posterior surface features seen in the floor of the 4th ventricle
know the posterior surface features of the midbrain
know the points of attachment or emergence of the cranial nerves III-XII
know the cross section levels of the brainstem where the nuclei of the motor cranial
nerves are found