Download Brainstem

Brainstem
Brainstem
脑
脊髓
Brainstem
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Telencephalon
Diencephalon
Cerebellum
Brain stem
Ventral view
Lateral view
10 pairs of the cranial nerves are attached to
the brain stem
The brainstem
 Midbrain
 Pons
 Medulla oblongata
Medulla oblongata
External structure
 Pyramid: contain pyramidal tract
(corticospinal tract)
Decussation of pyramid: formed
by crossing fibers of corticospinal tract
 Olive: produced by underlying inferior
olivary nucleus
 Anterolateral sulcus: rootlets of
hypoglossal nerve emerge from it
 Posterolateral sulcus: rootlets of
glossopharyngeal, vagus and accessory
nerves emerge from it
ventral aspect
Pons
Basilar part
Basilar sulcus : basilar artery
Middle cerebellar peduncle
Trigeminal nerve
Bulbopontine sulcus: from medial
to lateral, the abducent, facial and
vestibulocochlear nerves appear
Pontocerebellar trigone : the
junction of medulla, pons and cerebellum,
containing facial, vestibulocochlear and
glossopharyngeal N.
ventral aspect
Midbrain
 Cerebral peduncle
Crus cerebri
 Interpeduncular fossa
Oculomotor nerves emerge
Posterior perforated substance
ventral aspect
Medulla oblongata
 Lower portion
– Gracile tubercle produced by
underlying gracile nucleus
– Cuneate tubercle
produced by
underlying cuneate nucleus
– Inferior cerebellar peduncle
 Upper portion: forms the lower half
of rhomboid fossa
dorsal aspect
Pons
Superior cerebellar peduncle
Superior medullary velum
Upper portion of the rhomboid
fossa
dorsal aspect
Roof of the fourth ventricle
• Anterior part:
formed by superior
cerebellar peduncle and
superior medullary velum
• Posterior part:
formed by inferior medullary
velum and choroid plexus of
fourth ventricle
• Three apertures
– Median aperture of fourth
ventricle
– Two lateral apertures of
fourth ventricle
Fourth ventricle
Position
• Situated ventral to
cerebellum, and
dorsal to pons and
upper part of
medulla
Midbrain
Corpora quadrigemina
Superior colliculus constitute
centers for visual reflexes
Inferior colliculus associated
with auditory pathway
Trochlear n.
dorsal aspect
Rhomboid fossa
floor of the fourth ventricle
Boundaries
• Inferolateral: gracile and
cuneate tubercles, inferior
cerebellar peduncle
• Superolateral: superior
cerebellar peduncle
• Lateral recess
Features
• Median sulcus, Sulcus limitans
• Medial eminence
Facial colliculus: nucleus of abducent n.
• Lateral triangle area
Vestibular area: vestibular nuclei
Acoustic tubercle: cochlear nucleus
Locus ceruleus
• Striae medullares
Medial:
Hypoglossal triangle : nucleus of
hypoglossal n.
Vagal triangle: dorsal nucleus of vagal n.
Lateral: Vestibular area (vestibular nuclei)
• Area postrema
Internal structure
 Gray matter
-Nuclei of cranial nerves
-Non-cranial nerve nuclei
 White matter
-Accending tract
-Descending tract
 Reticular formation
The characteristics of internal structure of brain stem
(1) the gray matter is formed by series of isolated nuclei.
(2) the position of the white matter and gray matter are
rearranged as the opening of the forth ventricle.
(3) In addition to nuclei of cranial nerves, brain stem has noncranial nerve nuclei.
(4) has expansion area of reticular formation which contains
many important nuclear groups of vital centers in medulla,
such as center of heart beat, blood pressure and
respiratory.
Compared with spinal cord, the gray matter and white
matter in brain stem are changed their positions as the
fourth ventricle appears
Nuclei of cranial nerves
Special somatic sensory
general somatic sensory
Special visceral sensory
General visceral sensory
General visceral motor
Special visceral motor
General somatic motor
Seven types of cranial nuclei
1. General somatic motor nuclei
Innervate skeletal muscle
involved in the movement of
eye and tongue (muscle of
extraocular and tongue)
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Nucleus of oculomotor n.
Nucleus of trochlear n.
Nucleus of abducent n.
Nucleus of hypoglossal n.
General somatic motor nuclei
Nucleus
Site
Cranial n. Function
Nucleus of
Midbrain Ⅲ
Oculomotor n.
Nucleus of
trochlear n.
Nucleus of
abducent n.
Midbrain Ⅳ
Pons
Nucleus of
Medulla
hypoglossal n.
Supreior, inferior,and
medial rectus, inf. obliquus,
levator palpebrae superioris
Superior obliquus
Ⅵ
Lateral rectus
Ⅻ
Muscles of tongue
2. Special visceral motor nuclei
Innervate the skeletal muscle
derived from branchial arches
invlved in chewing, making facial
expression, swallowing, producing
vocal sounds and turning head
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Motor nucleus of trigeminal n.
Nucleus of facial n.
Nucleus ambiguus (IX, X)
Accessory nucleus n.
• No corresponding nucleus in
the spinal cord
Special visceral motor nuclei
Nucleus
Site
Cranial n.
Function
Motor nucleus of Pons
trigeminal n.
Ⅴ
Masticatory muscles
Nucleus of facial Pons
n.
Ⅶ
Facial muscles
Nucleus
ambiguus
Medulla
Ⅸ,Ⅹ.Ⅺ
Skeletal m. of pharynx,
larynx and upper part of
esophagus
Accessory
nucleus
MedullaⅪ
cervical cord
Sternocleidomastoid,
trapezius
3. General visceral motor nuclei
Innervate smooth muscle、
cardiac muscle and
glands (parasympathetic)
• Accessory oculomotor
nucleus (E-W nucleus)
• Superior salivatory
nucleus (VII)
• Inferior salivatory nucleus
(IV)
• Dorsal nucleus of vagus n.
General visceral motor nuclei
Nucleus
Site
Cranial
n.
Accessory
Midbrain Ⅲ
oculomotor nucleus
Superior salivatory Pons
nucleus
Ⅶ
Inferior salivertory Medulla
nucleus
Ⅸ
Dorsal nucleus of
vagus n.
Ⅹ
medulla
Function
Sphincter pupillae
and ciliary m.
Submandibular,
sublingual and
lacrimal glands
Parotid gland
Many cervical,
thoracic and
abdominal viscera
4. Visceral sensory nuclei
( general and special )
Relays the taste and general sensory
stimuli from the tongue and visceral
• Nucleus of solitary tract
Visceral sensory nuclei
( general and special )
Nucleus
Site
Cranial n. Function
Nucleus of
Medulla Ⅶ,Ⅸ,Ⅹ
solitary tract
epiglottis
Taste and visceral
sensation
5. General somatic sensory nuclei
Relays the sensation from
the skin, mucosa of the
head and face
• Mesencephalic nucleus
of trigeminal n.
• Pontine nucleus of
trigeminal n.
• Spinal nucleus of
trigeminal n.
General somatic sensory nuclei
Nucleus
Site
Cranial n.
Mesencephalic Midbrain
Ⅴ
nucleus of
trigeminal n.
Pontine nucleus Pons
Ⅴ
of trigeminal n.
Spinal nucleus Medulla
of trigeminal n.
Ⅴ
Function
Proprioception
sense
Tactile and
pressure sense
Pain and
temperature sense
6. Special somatic sensory nuclei
Receive the fiber of auditory
or equilibratory sensation.
• Cochlear nuclei
• Vestibular nuclei
Special somatic sensory nuclei
Nucleus
Site
Cranial n. Function
Cochlear
nuclei
Pons and
medulla
Ⅷ
Sense of hearing
Vestibular
nuclei
Pons and
medulla
Ⅷ
Sense of
equilibrium