View
110
Download
5
Category
Preview:
DESCRIPTION
Midbrain, Pons, Midbrain Nuclei, Pons Nuclei, Fiber tracts in midbrain, Fiber tracts in Pons
Citation preview
SGD Group 4 October, 2012 y
Embryology: developed from Mesencephalon
MIDBRAIN BOUNDARIES
Lateral
Superior Brachium Inferior Brachium
Posterior
Tectum
Suprior colliculi Inferior colliculi
Anterior
Crura Cerebri
Medial
Tegmentum
MIDBRAIN By: MATHET
Crura Cerebri
-surrounds the interpeduncular fossa
On the medial side is the OCULOMOTOR NERVE
Its floor is perforated by many blood vessels in the region called posterior perforated substance
Superior Brachium
- links lateral geniculate to superior colliculus
Inferior Brachium
- links medial geniculate to inferior colliculus
SGD Group 4 October, 2012
Posterior side
Anterior Side
Tectum or quadrigeminal plate
Divides into:
Superior colliculi
- Visual reflex
Inferior colliculi
- Lower auditory refle
Tegmentum -contains all descending and ascending tracts from spinal cord Contains:
1. Oculomotor nuclei 2. Mesencephalic
Reticular formation 3. Red nucleus
Structures that divides each boundaries: Cerebral aqueduct – separates tectum from tegmentum Substantia nigra
- Separates tegmentum from crura cerebri
SGD Group 4 October, 2012 Nuclei of the Midbrain Location Afferent
Connection Efferent Connection
Function
Inferior Colliculus (Large Nucleus of Gray Matter)
Tectum Cochlea Major brainstem auditory relay transmitting impulses from lateral lemniscus to medial geniculate body
Parabigeminal nucleus Ventrolateral to inferior colliculus
Functions with superior colliculus in processing visual information
Trochlear nucleus Posterior to medial longitudinal fasciculus
Superior oblique muscle
Works with trochlear nerve in movement of superior oblique muscle
Mesencephalic nucleus of CN V Lateral to cerebral aqueduct
Proprioreceptors on Teeth, periodontum, temporomandibular joints; Muscles spindles of muscles of mastication
Proprioception (Deep pressure);(Stretch)
Substantia nigra Between tegmentum and crus cerebri
Muscle tone
Superior colliculus Tectum Retina Visual reflex
Oculomotor nucleus
Lateral somatic columns - Dorsal cell nucleus - Intermediate cell nucleus - Ventral cell nucleus - Medial cell nucleus Caudal central nucleus Visceral nuclei
- Edinger Westphal nucleus
- Anterior median nucleus
Nucleus of Perlia
Posterior to medial longitudinal nucleus
Motor neurons of Extraocular muscles, Pupillary sphincter and lens thru ciliary ganglion
Innervates inferior rectus muscle Innervates inferior oblique muscle Innervates medial rectus muscle Innervates superior rectus muscle Innervate levator palpebral muscle Accommodation of lens; Pupillary light reflex Ocular convergence
Accessory Motor Nuclei Interstitial nucleus of Cajal
Nucleus of Darkshewitsch
Nuclei of Posterior
Commissure
Relationship with other nuclei Nucleus prepositus Rostral interstitial
nucleus of MLF
Lateral to Middle longitudinal fasciculus (MLF) Ventrolateral border of central gray matter Dorsolateral and dorsal to central gray matter
Slow rotatory and vertical eye movements and smooth pursuit eye patterns Upward eye movement Downward eye movement
Red nucleus Between cerebral aqueduct and substantia nigra
Acts in close conjunction with the motor cortex and cerebellum in controlling motor behavior
Source: Snell Neuroanatomy and Carpenters Human Neuroanatomy
SGD Group 4 October, 2012
Locations of each Midbrain nuclei
SGD Group 4 October, 2012 Fiber Tracts of the Midbrain Origin Termination Function
(Motor Tracts)
Corticospinal Tract Anterior Corticospinal Tract Lateral Corticospinal Tract
Pyramidal cells of Layer V of cerebral Cortex
Nucleus proprius of Lamina IV, Dorsal horn cells of Lamina V and VI and Intemediate zone cells of Lamina VII
Controls movement of torso, upper limbs and lower limbs
Corticonuclear Tract/ Corticobulbar Tract
Motor cortex of Frontal Lobe
Motor neurons of brainstem motor nuclei
Controls muscles of head, face and neck
Temporopontine Tract Temporal Lobe Pontine nuclei Carries information to the cerebellum about the type and strength of motor impulse generated in the cortex
Frontopontine Tract Frontal Lobe Pontine nuclei
Medial longitudinal fasciculus Medial Vestibular nucleus, Superior Colliculus
Trochlear , Abducens and Occulomotor nuclei
Carries information of the direction that the eye would move; Integrates movements directed by gaze centers (frontal eyefield) and information about head movement
Decussation of Rubrospinal Tract Red nucleus Lamina V, VI and VII of spinal cord
Control of muscle tone on flexor muscle groups
Sensory Tract
Lateral Lemnisci Cochlear nucleus Inferior Colliculus Principal ascending auditory pathway; connects superior olivary complex with inferior colliculus
Trigeminal Lemnisci Principal sensory nucleus of Trigeminal system
Ventroposteromedial nucleus (VPMn) of Thalamus
Conveys the nociceptive and thermal sense
Spinal Lemnisci/ spinothalamic tract Lateral Spinothalamic Tract
Anterior Spinothalamic Tract
Posterior marginal nucleus of Lamina I, nucleus propius of Lamina IV; and Dorsal horn nuclei of Lamina V
Ventral Posterolateral nucleus(VPLn) in Thalamus
Transmits pain and temperature Transmits crude touch and pressure
Medial Lemnisci/ Reil’s band/ Reil’s ribbon
Gracile nuclei and cuneate nuclei
Ventral posterolateral nucleus (VPLn) of thalamus
Constitutes the 2nd
neuron of posterior column pathway,; conveys kinaesthetic sense and discriminative tactile sense
(Source: Snell Neuroanatomy and wikipedia)
SGD Group 4 October, 2012
Posterior side: Pontine Tegmentum
Embryology: Developed from Metencephalon
Boundaries of Pons
Posterior
Pontine Tegmentum
Anterior
Basal Part (Pons Proper)
PONS By: Mathe Monje
Pontine Tegmentum - Contains:
1. Cranial nerve nuclei of CN V, VI, VII and VIII 2. Ascending and descending tracts 3. Reticular formation
Structures found: (from medial to lateral)
1. Median sulcus 2. Medial eminence 3. Sulcus limitans 4. Vestibular area
5. Substantia ferruginea – superior to medial eminence 6. Facial Colliculus – inferior to medial eminence; bulb like; Facial nucleus + Abducens nucleus 7. Superior Cerebellar peduncle – lateral limit of posterior surface of pons
Pons Proper - Consists of orderly arranged transverse and
longitudinal fiber bundles intercalated between collections of pontine nuclei
Structures found: (from medial to lateral)
1. Groove for basilar artery
2. Motor root of Trigeminal nerve (smaller)
3. Sensory Root of Trigeminal Nerve (larger)
4. Middle Cerebellar peduncle
(On the groove between pons and medulla: from medial
to lateral)
5. Abducens Nerve
6. Facial Nerve
7. Vestibulocochlear Nerve
SGD Group 4 October, 2012 Nuclei of Pons Location Afferent Connection Efferent
Connection Function
(Caudal Part)
Facial nucleus Facial Motor
Nucleus
Superior Salivatory nucleus
Posterior to lateral part of Medial lemniscus
Branchiomeric muscles of the face Lacrimal gland
Influence facial expression Influence secretion of lacrimal gland (by pterygopalatine ganglion)
Abducens Nucleus Above striae medullares and subjacent to medial eminence
Motor neurons of Lateral rectus muscles via CN VI
Together with fibers of Paramedian Pontine Reticular formation (PPRF) enables conjugate horizontal gaze/ deviation of eyes
Rostral Interstitial Nucleus of MLF
Tegmentum Together with fibers of Paramedian Pontine Reticular formation (PPRF) enables vertical eye movements
Medial Vestibular nucleus Lateral to abducens nucleus
Utricle and saccule Coordinate head and trunk Movement
Spinal nucleus of CN V Anteromedial aspect of inferior cerebellar peduncle
Receives information about deep or crude touch, pain and temperature from ipsilateral face
Pontine nuclei Pons (Obviously..hehe)
Allow modification of actions in the light of their outcome or correction of errors
Cranial Part
Motor nucleus of Trigeminal Nerve
Upper part of pons along lateral margin of 4
th ventricle
Motor neurons of Muscles of mastication
Innervates muscles of mastication , tensor tympani, myolohyoid and anterior digastric muscles
Principal Sensory Nucleus of Trigeminal Nerve
Lateral side of Motor nucleus of Trigeminal Nerve
Sensory neurons of skin of face and head , mucus membranes of nose and mouth, teeth and cranial dura
Touch, pain and thermal sense
Superior Olivary nucleus Medial Superior
Olive
Lateral Superior Olive
Medial Nucleus of
Trapezoid Body
Pons (wala na ko makta nga specific location niya)
Ipsilateral and contralateral stimulation for low frequency sounds. Ipsilateral stimulation for high frequency sounds. Contralateral stimulation Localization of sounds
Cochlear nuclei Dorsal Cochlear
nucleus
Ventral Cochlear nucleus
Dorsal aspect of Inferior Cerebellar peduncle Ventral surface of Inferior Cerebellar peduncle
Cochlea
Preserve or even enhance the timing information that is provided by each fiber of the cochlear nerve
Fiber Tracts: Spinal Tract of CN V, Lateral Lemnisci, Medial Lemnisci and Spinal Lemnisci (refer location and function on Table 2)
Source: Snell Neuroanatomy, Carpenters Human Neuroanatomy and wikipedia)
SGD Group 4 October, 2012
Caudal Part of Pons
Transverse Section at the level of Trigeminal Nuclei
Recommended