Functional Anatomy of Brainstem

Functional Anatomy of Brainstem : 

Functional Anatomy of Brainstem Prof. Saeed Shafi

Slide 2: 

http://www.mrcophth.com/cranialnerveexamination/facialnerve.html

Slide 3: 

To identify the external features of Brainstem Pyramid, Olive, Faciculus gracilus, Faciculus cuneatus on external surface of medulla. Vagal, Hypoglosssal & Vestibular triangles, Obex, area postrema, Facial Colliculus in floor of 4th ventricle. Basal Pons, Isthmus of Pons &Lateral lemniscus Basis pedunculi & Substantia nigra Tectum of midbrain / superior &inferior colliculi

Slide 4: 

To know the internal structure of brainstem Descending tracts Ascending tracts Cranial nerve nuclei Medulla Pons Midbrain Inferior olivary nuclear complex Pontine nuclei Named Nuclei Red nucleus of midbrain Substantia nigra Reticular formation (polysynaptic neurons and nuclei)

Morphology of Medulla Oblongata : 

Morphology of Medulla Oblongata Medulla is 3 cm long Upper limit clearly marked by lower border of basal pons Inferior limit at rootlets of 1st cervical spinal nerve

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Dorsal surface of Medulla : 

Dorsal surface of Medulla On dorsal surface junction of medulla and pons is marked by a line passing through inferior edge of middle cerebellar peduncles (ICP) Closed part of medulla Fasciculus gracilis Fasciculus cuneatus Open part of medulla Floor of 4th ventricle

CN attached to Medulla : 

CN attached to Medulla Hypoglossal attached to venterolateral sulcus between pyramid and olive) 9th, 10th, 11th CN to dorsal olivary sulcus 7th & 8th at junction of Medulla and Pons well laterally Abducent at junction of base of pyramid and basal pons

Cranial nerve nuclei : 

Cranial nerve nuclei Medulla –Hypoglossal nucleus, Nucleus ambiguous, DMN of Vagus, Vestibular nuclear complex, Auditory nuclei, Spinal trigeminal nucleus, Tractus solitarius nucleus Pons – Abducent nerve nucleus, facial nucleus, trigeminal nuclei (Chief sensory nucleus, motor nucleus) Midbrain – 3rd & 4th nerve nuclei, mesencephalic nucleus of trigeminal

Named Nuclei in Brain stem : 

Named Nuclei in Brain stem Inferior olivary nuclear complex Pontine nuclei Inferior Salivatory Nucleus Superior Salivatory Nucleus Red nucleus of midbrain Substantia nigra Reticular formation nucli

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Brainstem Ascending tracts Dosral Column Tracts / Posterior Column Tracts Fasciculus Gracilis Medial Lemniscus Fasciculus Cuneatus Spinocerebellar Tracts Spinotectal Tracts Spinothalamic Tracts Spinal Lemniscus Spinoreticular Lateral Lemniscus Trigeminal lemniscus

Descending tracts of Brainstem : 

Descending tracts of Brainstem Corticospinal Tract Corticonuclear Cortico-pontocerebellar Rubrospinal Reticulospinal Vestibulospinal Medial longitudinal fasciculus Tectospinal

Medullary Nuclei : 

Medullary Nuclei 1. Inferior olivary nuclear complex (inferior olivary nucleus, medial accessory olivary nucleus, dorsal accessory olivary nucleus) Afferents by Central tegmental tract from corpus striatum & red nucleus Cortico-olivary fibers Spino-olivary fibers Efferent by Olivo-cerebellar fibers through ICP Olivo-spinal

Medullary Nuclei : 

Medullary Nuclei 2. Gracile Nuclus Cuneate Nucleus Arcuate nucleus 5. Lateral cuneate nucleus

Cranial Nerve Nuclei in Medulla : 

Cranial Nerve Nuclei in Medulla Hypoglossal nucleus Nucleus ambiguus Dorsal motor nucleus of vagus Nucleus of solitary fasciculus Ventibulo-cochlear nuclear complex Nucleus of the trigeminal spinal tract

Cranial Nerve Nuclei in Medulla : 

Cranial Nerve Nuclei in Medulla Ventibulo-cochlear nuclear complex Dorsal cochlear nucleus Ventral cochlear nucleus Superior vestibular nucleus Medial vestibular nucleus Lateral vestibular nucleus Inferior vestibular nucleus

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NA

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PONS : 

PONS Basal Pons Tegmentum Only cranial nerve attached to pons is trigeminal

Internal structure : 

Internal structure Pontine nuclei Cranial nerves Nuclei (5th, 6th, 7th) & Fiber tracts ML, SL, LL Corticopontine fibers Pontocerebellar fibers Corticospinal fibers

Slide 26: 

Motor nucleus Chief sensory nucleus Mesencephalic nucleus Spinal nucleus 5thCN Nuclei in Pons

Slide 27: 

5th CN

Slide 28: 

7th CN

Slide 29: 

Superior salivary nucleus lies along side the facial nucleus. It is parasympathetic in function. It provides axons which pass out in nervous intermedius part of facial nerve and reach to pterygopalatine and Submandibular ganglia. Its lower part is called inferior salivatory nucleus. Its fibers joins to the glossopharyngeal nerve to reach to otic ganglion.

MIDBRAIN : 

MIDBRAIN It connect Diencephalon to the Pons & Cerebellum. It is the shortest segment of brainstem. Not more than 1.5 cm in length. Topographically it lies in posterior fossa . Its upper part passing through tentorial notch.

Midbrain : 

Midbrain Crus cerebri Substancia Nigra Cerebral peduncle Tegmentum Tectum is the roof of midbrain

Aqueduct of midbrain : 

Aqueduct of midbrain Passes through the tegmentum. Connects the third and fourth ventricle.

Slide 34: 

3rd & 4th cranial nerves leave midbrain. Occulomotor nerve leaves through the medial surface of crus on the ventral surface. Trochlear nerve leaves the dorsal surface of midbrain just below the inferior colliculi.

Internal structure : 

Internal structure Each crus contains corticospinal , cortico nuclear and corticopontine fibers.

Slide 38: 

4th CN

Cerebellar Peduncles : 

Cerebellar Peduncles Inferior cerebellar peduncle Posterior spinal cerebellar tracts Olivocerebellar tract Vestibulo-cerebellar tract Cuneocerebellar tract Cerebelovestibular Middle cerebellar peduncle Pontocerebellar Superior cerebellar peduncle Anterior spinocerebellar Dentatorubrocerebellar Cerebellospinal fibers

COMPONENTS OF CRANIAL&SPINAL NERVES : 

COMPONENTS OF CRANIAL&SPINAL NERVES Afferent components Special somatic afferent Optic nerve Cochlear Vestibular General Somatic Afferent Dorsal gray horn of spinal cord Graycile and nuclei Special Visceral afferent Taste Olfaction General Visceral afferent (for visceral reflexes) Dorsal grayhorn / nucelus and tractus solitarius

Efferent components : 

Efferent components General somatic efferent Motor horn of spinal cord Occulumotor trochlear abducents hypoglossal nuclei Special visceral efferent Supply muscles of branchail arches origin Trigeminal motor nucleus Fascial motor nucleus Nucleus Ambiguos Accessory nucleus General visceral efferent Preganglionic neurons of ANS, adinger westphal nucelus, lacrimtary nucleus, salivartory nuclei, dosral motor nucleus of vagus Special somatic efferent Centrifugal fibers of 8th nerve and optic nerve.