Brain Stem
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The brain
Telencephalon Diencephalon Cerebellum Brain stem
The brain stem Guiqiong He Department of Anatomy Chongqing Medical University
Introductio Located between the cerebrum n and the SC
Provides a pathway for tracts running between higher and lower neural centers.
Microscopically, it consists of deep gray matter surrounded by white matter fiber tracts. Produce automatic behaviors necessary for survival. Consists of the midbrain, pons, and medulla oblongata.
Each region is about an inch in length.
midbrain
pons
Medulla oblongata
Medulla oblongata Ventral surface
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
Retroolivary sulcus: rootlets of glossopharyngeal, vagus and accessory nerves emerge from it
¶ IX, X, XI, XII cranial n. attach to the medulla oblongata
Medulla oblongata Dorsal surface
Lower portion
Gracile tubercle: produced by underlying gracile nucleus
Cuneate tubercle: marks the site of cuneate nucleus
Inferior cerebellar peduncle
Obex
Upper portion: forms the lower half of rhomboid fossa
Pons Ventral surface
Basilar part
Basilar sulcus
Bulbopontine sulcus: from medial to lateral, the abducent, facial and vestibulocochlear nerves appear
Middle cerebellar peduncle Trigeminal nerve
Pontocerebellar trigone: the junction of medulla, pons and cerebellum ¶ V, VI, VII, VIII cranial n. attach to the pons
Pons Dorsal surface
Superior cerebellar peduncle
Superior medullary velum
Midbrain Ventral surface
Crus cerebri
Interpeduncular fossa: oculomotor nerves emerge from medial of crus cerebri
Posterior perforated substance
¶ III cranial n. attach to the ventral surface of the midbrain
Midbrain Dorsal surface
Superior colliculus: constitute centers for visual reflexes
Inferior colliculus: associated with auditory pathway
Brachium of superior colliculi
Brachium of inferior colliculi trochlear nerves
¶ IV cranial n. attach to the posterior surface of the midbrain
Fourth ventricle Central canal →fourth ventricle →mesencephalic aqueduct→third ventricle
Position
Situated ventral to cerebellum, and dorsal to pons and cranial half of medulla
Boundaries
Inferolateral: gracile and cuneate tubercles, inferior cerebellar peduncle Superolateral: superior cerebellar peduncle Lateral recess
Features
Median sulcus
Sulcus limitans
Vestibular area: overlies vestibular nuclei
Acoustic tubercle: overlying dorsal cochlear nucleus
Medial eminence Striae medullares
Facial colliculus: overlies nucleus of abducent n. and genu of facial nerve
Hypoglossal triangle: overlying hypoglossal nucleus
Vagal triangle: overlies dorsal nucleus of vagus nerve
Funiculus separans
Area postrema
Locus ceruleus
Roof
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
Tela choroidea and choroid plexus
Internal structures Somatic sensory nuclei.
Gray matter
Cranial nerve nuclei Non-cranial nerve nuclei (eg. relay nuclei)
Visceral sensory nuclei.
Visceral motor nuclei. Somatic motor nuclei.
Cranial nerve nuclei i.General somatic motor nuclei
Nucleus of oculomotor n.
Nucleus of trochlear n.
Nucleus of abducent n.
Nucleus of hypoglossal n.
Summary of general somatic motor nuclei Nucleus
Site
Cranial n. Function
Nucleus of
Midbrain
Ⅲ
Supreior, inferior,and medial recti, inf. obliquus, levator palpebrae superioris
Nucleus of trochlear n.
Midbrain
Ⅳ
Superior obliquus
Nucleus of abducent n.
Pons
Ⅵ
Lateral rectus
Nucleus of hypoglossal n.
Medulla
Ⅻ
Muscles of tongue
Oculomotor n.
ii. Special visceral motor nuclei
Motor nucleus of trigeminal n.
Nucleus of facial n.
Nucleus ambiguus
Accessory nucleus
Summary of special visceral motor nuclei Nucleus
Site
Cranial n.
Function
Motor nucleus of trigeminal n.
Pons
Ⅴ
Masticatory muscles
Nucleus of facial n.
Pons
Ⅶ
Facial m., platysma, posterior belly of digastric, stylohyoid, stapedius
Ⅸ,Ⅹ.Ⅺ
Skeletal m. of pharynx, larynx and upper part of esophagus
Nucleus ambiguus Medulla
Accessory nucleus
MedullaⅪ cervical cord
Sternocleidomastoid, trapezius
iii. General visceral motor nuclei
Accessory oculomotor nucleus
Superior salivatory nucleus
Inferior salivertory nucleus
Dorsal nucleus of vagus n.
Summary of general visceral motor nuclei Nucleus
Site
Cranial n.
Function
Accessory oculomotor nucleus
Midbrain
Ⅲ
Sphincter pupillae and ciliary m.
Superior salivatory nucleus
Pons
Ⅶ
Submandibular, sublingual and lacrimal glands
Inferior salivertory nucleus
Medulla
Ⅸ
Parotid gland
Dorsal nucleus of vagus n.
medulla
Ⅹ
Many cervical, thoracic and abdominal viscera
iv. Visceral sensory nuclei ( general and special )
Nucleus of solitary tract
Summary of visceral sensory nuclei ( general and special )
Nucleus
Site
Cranial n.
Function
Nucleus of solitary tract
Medulla
Ⅶ,Ⅸ,Ⅹ
Taste and visceral sensation
v. General somatic sensory nuclei
Mesencephalic nucleus of trigeminal n.
Pontine nucleus of trigeminal n.
Spinal nucleus of trigeminal n.
Summary of general somatic sensory nuclei Nucleus
Site
Mesencephalic nucleus of trigeminal n. Pontine nucleus of trigeminal n.
Midbrain
Ⅴ
Proprioception of head
Pons
Ⅴ
Tactile sensation of head
Ⅴ
Pain and temperature sense of head
Spinal nucleus of Medulla trigeminal n.
Cranial n. Function
vi. Special somatic sensory nuclei
Cochlear nuclei
Vestibular nuclei
Summary of 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
Non-cranial nuclei (relay Gracile nucleus nuclei)
Cuneate nucleus
Inferior olivary nucleus
Superior olivery nucleus
Pontine nucleus
Nucleus of inferior colliculus
Gray matter layers of superior colliculus
Red nucleus
Substantia nigra
Pretectal area
Summary of non-cranial nerve nuclei Nucleus
Site
Gracile nucleus
Medulla (underneath gracile tubercle)
Cuneate nucleus
Medulla (underneath cuneate tubercle)
Superior olivery nucleus
Pons
Pontine nucleus
pons
Nucleus of inferior colliculus
Midbrain
Gray matter layers of superior colliculus
Midbrain
Red nucleus
Midbrain
Substantia nigra
Midbrain
Pretectal area
Midbrain
White matter Ascending tracts
Medial lemniscus Spinal lemniscus Trigeminal lemniscus Lateral lemniscus
Medial lemniscus
Spinal lemniscus
Trigeminal lemniscus
Descending tracts
Corticospinal tract Rubrospinal tract Tectospinal tract Vestibulospinal tract Reticulospinal tract
Lateral lemniscus
Reticular formation of brain stem
Ascending reticular activating system (ARAS) Motor central and vital centres
Reticulospinal tract Cardiovascular center and respiratory center
Serotonergic rapheal nuclei
The characters of internal structure of brain stem
Medulla oblongata Lower part (closed part) Two decussations–
Decussations of medial lemniscus Decussations of pyramid
Medulla oblongata Upper part (open part)
Appearance of inferior olivary nuculeus and inferior cerebellar peduncle Enlargement of central canal to form the fourth ventricle floor
Pons
Tegmentum of pons directed upward continuation of medulla oblongata
Basilar part contain both longitudinal and transverse fibers intermixed with pontine nuclei
Midbrain
Rectum of midbrain:
includes superior and inferior colliculi
Cerebral peduncle
Tegmentum
contain ascending tracts, central gray matter, recticular formation and so on
Substentia nigra Crus cerebri :
Pyramidal tract
middle three-fifths of the crus:
Frontopontine tract: medial one-fifth:
pariatotempopontine tract: lateral one-fifth
Medulla Nuclei in the medullaOblongata are associated w/ autonomic control, cranial nerves, and motor/sensory relay. Autonomic nuclei:
Cardiovascular centers
Respiratory rhythmicity centers
Cardioinhibitory/cardioacce leratory centers alter the rate and force of cardiac contractions Vasomotor center alters the tone of vascular smooth muscle
Receive input from the pons
Additional Centers
Emesis, deglutition, coughing, hiccupping, and sneezing
Medulla Oblongata Sensory & motor nuclei of 5
cranial nerves:
Auditory/Vestibular (8), Glossopharyngeal (9), Vagus (10), Accessory (11), and Hypoglossal (12)
Relay nuclei
Nucleus gracilis and nucleus cuneatus pass somatic sensory information to the thalamus Olivary nuclei relay info from the spinal cord, cerebral cortex, and the brainstem to the cerebellar cortex.
Located btwn the diencephalon and the pons.
2 bulging cerebral peduncles on the ventral side. These contain:
Descending fibers that go to the cerebellum via the pons Descending pyramidal tracts
Running thru the midbrain is the hollow cerebral aqueduct which connects the 3rd and 4th ventricles of the brain. The roof of the aqueduct ( the tectum) contains the corpora quadrigemina
2 superior colliculi that control reflex movements of the eyes, head and neck in response to visual stimuli 2 inferior colliculi that control reflex movements of
Midbrain
•Cranial nerves 3&4 (oculomotor and trochlear) exit from the midbrain •Midbrain also contains the headquarters of the reticular activating system
Midbrain
On each side, the midbrain contains a red nucleus and a substantia nigra
Red nucleus contains numerous blood vessels and receives info from the cerebrum and cerebellum and issues subconscious motor commands concerned w/ muscle tone & posture Lateral to the red nucleus is the melanin-containing substantia nigra which secretes dopamine to inhibit the excitatory neurons of the basal nuclei.
Damage to the substantia
Pons
Literally means “bridge” Wedged btwn the midbrain & medulla. Contains:
Sensory and motor nuclei for 4 cranial nerves
Respiratory nuclei:
Trigeminal (5), Abducens (6), Facial (7), and Auditory/Vestibular (8) Apneustic & pneumotaxic centers work w/ the medulla to maintain respiratory rhythm
Nuclei & tracts that process and relay info to/from the cerebellum Ascending, descending, and transverse tracts that interconnect other portions of the CNS
Medulla Oblongata Most inferior region of the brain stem. Becomes the spinal cord at the level of the foramen magnum. Ventrally, 2 ridges (the medullary pyramids) are visible.
These are formed by the large motor corticospinal tracts. Right above the medullaSC junction, most of these fibers cross-over (decussate).
What brainstem structures are visible here?
Telencephalon Diencephalon Cerebellum Brain stem
The brain stem Guiqiong He Department of Anatomy Chongqing Medical University
Introductio Located between the cerebrum n and the SC
Provides a pathway for tracts running between higher and lower neural centers.
Microscopically, it consists of deep gray matter surrounded by white matter fiber tracts. Produce automatic behaviors necessary for survival. Consists of the midbrain, pons, and medulla oblongata.
Each region is about an inch in length.
midbrain
pons
Medulla oblongata
Medulla oblongata Ventral surface
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
Retroolivary sulcus: rootlets of glossopharyngeal, vagus and accessory nerves emerge from it
¶ IX, X, XI, XII cranial n. attach to the medulla oblongata
Medulla oblongata Dorsal surface
Lower portion
Gracile tubercle: produced by underlying gracile nucleus
Cuneate tubercle: marks the site of cuneate nucleus
Inferior cerebellar peduncle
Obex
Upper portion: forms the lower half of rhomboid fossa
Pons Ventral surface
Basilar part
Basilar sulcus
Bulbopontine sulcus: from medial to lateral, the abducent, facial and vestibulocochlear nerves appear
Middle cerebellar peduncle Trigeminal nerve
Pontocerebellar trigone: the junction of medulla, pons and cerebellum ¶ V, VI, VII, VIII cranial n. attach to the pons
Pons Dorsal surface
Superior cerebellar peduncle
Superior medullary velum
Midbrain Ventral surface
Crus cerebri
Interpeduncular fossa: oculomotor nerves emerge from medial of crus cerebri
Posterior perforated substance
¶ III cranial n. attach to the ventral surface of the midbrain
Midbrain Dorsal surface
Superior colliculus: constitute centers for visual reflexes
Inferior colliculus: associated with auditory pathway
Brachium of superior colliculi
Brachium of inferior colliculi trochlear nerves
¶ IV cranial n. attach to the posterior surface of the midbrain
Fourth ventricle Central canal →fourth ventricle →mesencephalic aqueduct→third ventricle
Position
Situated ventral to cerebellum, and dorsal to pons and cranial half of medulla
Boundaries
Inferolateral: gracile and cuneate tubercles, inferior cerebellar peduncle Superolateral: superior cerebellar peduncle Lateral recess
Features
Median sulcus
Sulcus limitans
Vestibular area: overlies vestibular nuclei
Acoustic tubercle: overlying dorsal cochlear nucleus
Medial eminence Striae medullares
Facial colliculus: overlies nucleus of abducent n. and genu of facial nerve
Hypoglossal triangle: overlying hypoglossal nucleus
Vagal triangle: overlies dorsal nucleus of vagus nerve
Funiculus separans
Area postrema
Locus ceruleus
Roof
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
Tela choroidea and choroid plexus
Internal structures Somatic sensory nuclei.
Gray matter
Cranial nerve nuclei Non-cranial nerve nuclei (eg. relay nuclei)
Visceral sensory nuclei.
Visceral motor nuclei. Somatic motor nuclei.
Cranial nerve nuclei i.General somatic motor nuclei
Nucleus of oculomotor n.
Nucleus of trochlear n.
Nucleus of abducent n.
Nucleus of hypoglossal n.
Summary of general somatic motor nuclei Nucleus
Site
Cranial n. Function
Nucleus of
Midbrain
Ⅲ
Supreior, inferior,and medial recti, inf. obliquus, levator palpebrae superioris
Nucleus of trochlear n.
Midbrain
Ⅳ
Superior obliquus
Nucleus of abducent n.
Pons
Ⅵ
Lateral rectus
Nucleus of hypoglossal n.
Medulla
Ⅻ
Muscles of tongue
Oculomotor n.
ii. Special visceral motor nuclei
Motor nucleus of trigeminal n.
Nucleus of facial n.
Nucleus ambiguus
Accessory nucleus
Summary of special visceral motor nuclei Nucleus
Site
Cranial n.
Function
Motor nucleus of trigeminal n.
Pons
Ⅴ
Masticatory muscles
Nucleus of facial n.
Pons
Ⅶ
Facial m., platysma, posterior belly of digastric, stylohyoid, stapedius
Ⅸ,Ⅹ.Ⅺ
Skeletal m. of pharynx, larynx and upper part of esophagus
Nucleus ambiguus Medulla
Accessory nucleus
MedullaⅪ cervical cord
Sternocleidomastoid, trapezius
iii. General visceral motor nuclei
Accessory oculomotor nucleus
Superior salivatory nucleus
Inferior salivertory nucleus
Dorsal nucleus of vagus n.
Summary of general visceral motor nuclei Nucleus
Site
Cranial n.
Function
Accessory oculomotor nucleus
Midbrain
Ⅲ
Sphincter pupillae and ciliary m.
Superior salivatory nucleus
Pons
Ⅶ
Submandibular, sublingual and lacrimal glands
Inferior salivertory nucleus
Medulla
Ⅸ
Parotid gland
Dorsal nucleus of vagus n.
medulla
Ⅹ
Many cervical, thoracic and abdominal viscera
iv. Visceral sensory nuclei ( general and special )
Nucleus of solitary tract
Summary of visceral sensory nuclei ( general and special )
Nucleus
Site
Cranial n.
Function
Nucleus of solitary tract
Medulla
Ⅶ,Ⅸ,Ⅹ
Taste and visceral sensation
v. General somatic sensory nuclei
Mesencephalic nucleus of trigeminal n.
Pontine nucleus of trigeminal n.
Spinal nucleus of trigeminal n.
Summary of general somatic sensory nuclei Nucleus
Site
Mesencephalic nucleus of trigeminal n. Pontine nucleus of trigeminal n.
Midbrain
Ⅴ
Proprioception of head
Pons
Ⅴ
Tactile sensation of head
Ⅴ
Pain and temperature sense of head
Spinal nucleus of Medulla trigeminal n.
Cranial n. Function
vi. Special somatic sensory nuclei
Cochlear nuclei
Vestibular nuclei
Summary of 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
Non-cranial nuclei (relay Gracile nucleus nuclei)
Cuneate nucleus
Inferior olivary nucleus
Superior olivery nucleus
Pontine nucleus
Nucleus of inferior colliculus
Gray matter layers of superior colliculus
Red nucleus
Substantia nigra
Pretectal area
Summary of non-cranial nerve nuclei Nucleus
Site
Gracile nucleus
Medulla (underneath gracile tubercle)
Cuneate nucleus
Medulla (underneath cuneate tubercle)
Superior olivery nucleus
Pons
Pontine nucleus
pons
Nucleus of inferior colliculus
Midbrain
Gray matter layers of superior colliculus
Midbrain
Red nucleus
Midbrain
Substantia nigra
Midbrain
Pretectal area
Midbrain
White matter Ascending tracts
Medial lemniscus Spinal lemniscus Trigeminal lemniscus Lateral lemniscus
Medial lemniscus
Spinal lemniscus
Trigeminal lemniscus
Descending tracts
Corticospinal tract Rubrospinal tract Tectospinal tract Vestibulospinal tract Reticulospinal tract
Lateral lemniscus
Reticular formation of brain stem
Ascending reticular activating system (ARAS) Motor central and vital centres
Reticulospinal tract Cardiovascular center and respiratory center
Serotonergic rapheal nuclei
The characters of internal structure of brain stem
Medulla oblongata Lower part (closed part) Two decussations–
Decussations of medial lemniscus Decussations of pyramid
Medulla oblongata Upper part (open part)
Appearance of inferior olivary nuculeus and inferior cerebellar peduncle Enlargement of central canal to form the fourth ventricle floor
Pons
Tegmentum of pons directed upward continuation of medulla oblongata
Basilar part contain both longitudinal and transverse fibers intermixed with pontine nuclei
Midbrain
Rectum of midbrain:
includes superior and inferior colliculi
Cerebral peduncle
Tegmentum
contain ascending tracts, central gray matter, recticular formation and so on
Substentia nigra Crus cerebri :
Pyramidal tract
middle three-fifths of the crus:
Frontopontine tract: medial one-fifth:
pariatotempopontine tract: lateral one-fifth
Medulla Nuclei in the medullaOblongata are associated w/ autonomic control, cranial nerves, and motor/sensory relay. Autonomic nuclei:
Cardiovascular centers
Respiratory rhythmicity centers
Cardioinhibitory/cardioacce leratory centers alter the rate and force of cardiac contractions Vasomotor center alters the tone of vascular smooth muscle
Receive input from the pons
Additional Centers
Emesis, deglutition, coughing, hiccupping, and sneezing
Medulla Oblongata Sensory & motor nuclei of 5
cranial nerves:
Auditory/Vestibular (8), Glossopharyngeal (9), Vagus (10), Accessory (11), and Hypoglossal (12)
Relay nuclei
Nucleus gracilis and nucleus cuneatus pass somatic sensory information to the thalamus Olivary nuclei relay info from the spinal cord, cerebral cortex, and the brainstem to the cerebellar cortex.
Located btwn the diencephalon and the pons.
2 bulging cerebral peduncles on the ventral side. These contain:
Descending fibers that go to the cerebellum via the pons Descending pyramidal tracts
Running thru the midbrain is the hollow cerebral aqueduct which connects the 3rd and 4th ventricles of the brain. The roof of the aqueduct ( the tectum) contains the corpora quadrigemina
2 superior colliculi that control reflex movements of the eyes, head and neck in response to visual stimuli 2 inferior colliculi that control reflex movements of
Midbrain
•Cranial nerves 3&4 (oculomotor and trochlear) exit from the midbrain •Midbrain also contains the headquarters of the reticular activating system
Midbrain
On each side, the midbrain contains a red nucleus and a substantia nigra
Red nucleus contains numerous blood vessels and receives info from the cerebrum and cerebellum and issues subconscious motor commands concerned w/ muscle tone & posture Lateral to the red nucleus is the melanin-containing substantia nigra which secretes dopamine to inhibit the excitatory neurons of the basal nuclei.
Damage to the substantia
Pons
Literally means “bridge” Wedged btwn the midbrain & medulla. Contains:
Sensory and motor nuclei for 4 cranial nerves
Respiratory nuclei:
Trigeminal (5), Abducens (6), Facial (7), and Auditory/Vestibular (8) Apneustic & pneumotaxic centers work w/ the medulla to maintain respiratory rhythm
Nuclei & tracts that process and relay info to/from the cerebellum Ascending, descending, and transverse tracts that interconnect other portions of the CNS
Medulla Oblongata Most inferior region of the brain stem. Becomes the spinal cord at the level of the foramen magnum. Ventrally, 2 ridges (the medullary pyramids) are visible.
These are formed by the large motor corticospinal tracts. Right above the medullaSC junction, most of these fibers cross-over (decussate).
What brainstem structures are visible here?
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