Transcript 06. medulla
1. Traversed by:
Central Canal.
2. Retains:
Some of the Features
of the Spinal Cord.
3. Has:
Motor Decussation.
Ventral Horn
Much Attenuated.
Dorsal Horn
Replaced by
Caudal Part of the
Trigeminal Sensory
Nucleus (Nucleus of the
Spinal Tract of the
Trigeminal Nerve).
It is the Brain Stem
continuation of:
Substantia Gelatinosa of
the dorsal horn of the
A large nucleus.
Lies:
Medial to the Spinal Tract of the
Trigeminal Nerve.
Extends:
Through the whole length of the
brain stem.
Receives:
Pain and Temperature from:
Face, Forehead and the Mucous
Membrane of the Mouth and Nose.
Lies:
Superficial to its Nucleus.
Between:
Cuneate Nucleus and the
Spino-cerebellar tract.
Formed of:
Descending fibers that
Terminate in the
Trigeminal Nucleus Caudal
to the Level of the Pons.
It is:
Motor Decussation.
Formed of:
Pyramidal Fibers
(75-90%) cross to the
opposite side.
They descend in the
Lateral White Column of
the Spinal Cord as the
Lateral Corticospinal
Tract.
Replaced by:
Spinocerebellar
(Anterior &
Posterior)
Lateral Spino
Thalamic Tracts.
Small part appear
Deep to the
corresponding
Gracile and Cuneate
Tracts.
1. Traversed by:
Central Canal.
2. Has:
Sensory
Decussation.
3. Pyramids:
Prominent
Larger in size.
Their Axons Form:
Internal Arcuate
Fibers.
Sensory
Decussation:
Formed by Crossed
Internal Arcuate
Fibers.
Composed Of:
Ascending Internal Arcuate
Fibers after their crossing.
Lies:
Adjacent to the middle line.
Ventral to the Central Canal.
Found in:
Medulla, Pons and Midbrain.
Terminates in:
Thalamus.
Lie:
Antero lateral to the
pyramids.
Considered:
The Inferior Extension
of the Pontine Nuclei.
Their Axons Form:
External Arcuate Fibers.
Connected to:
Cerebellum through the
Inferior Cerebellar
Formed Of:
A diffuse mixture of
Nerve Fibers and Small
Groups of Nerve Cells.
Position:
Posterolateral to:
Pyramids.
Ventral to:
Spinal Tract and Nucleus
of the Trigeminal Nerve.
Lateral to the Cuneate
nucleus.
Receives
Unconscious Fibers
from the Cervical
Region.
Connected to:
Cerebellum through the
Inferior Cerebellar
Peduncle.
Its Posterior Surface
Forms:
Lower Part of the Floor
of the 4th Ventricle.
On Each Side of the
Midline.
Dorsal to
Medial aspect of the
Pyramids.
Structure:
A convoluted mass of gray matter.
Has a hilum directed Medially.
Lies:
Postero lateral to the pyramids.
Lateral to the Medial Leminiscus.
Receives Fibers From:
Motor and Sensory Cerebral
Cortices.
Red nucleus of the mid brain.
Corpus Striatum.
Concerned With:
(Restiform Body)
Lies in:
Dorso Lateral part of the
Medulla.
Connects:
Medulla and Cerebellum.
Carries:
Olivocerebellar.
Vestibulocerebellar.
Dorsal spinocerebellar.
Dorsal and Ventral
Nuclei
Lie:
Dorsal and Lateral to
the Inferior Cerebellar
Peduncle.
Receive Afferents
From:
Cochlear Nerve.
1. Hypoglossal Nucleus
A longitudinal column just
lateral to the midline.
2. Dorsal Motor Nucleus of
the Vagus
Lateral to the hypoglossal
nucleus.
Contains:
Preganglionic
Parasympathetic fibers as
far as the distal 1/3 of the
transverse colon.
3. Vestibular Nuclei (Complex)
Consist of
Medial, Lateral, Inferior and
Superior Nuclei.
Lie
In the Lateral Part of the Floor
of 4th Ventricle.
Inferior Vestibular Nucleus is
Lateral to the Inferior Fovea.
Receive Afferents From
Vestibular Nerve.
Lie
Dorsal to the Inferior
Olivary Nucleus.
Function
Gives Motor Fibers to
Constrictors of the
Pharynx.
Intrinsic Muscles of the
Larynx.
Lies
Close to the midline.
Ventromedial to the
hypoglossal nucleus.
Dorsal to the medial
lemniscus.
Identified Also in
Pons, Midbrain and
Upper Levels of the
Spinal Cord.
Receives Afferents from
Vestibular Nerve.
Consists of
Short Ascending and
Descending fibers.
They connect
Vestibular and Cochlear
Nuclei with the Cranial
Nuclei (111, 1v and v1)
It serves
Coordination of Head
and Eye Movements in
Response to VestibuloCochlear Stimuli.
Composed Of the Following
Tracts:
Spinothalamic (Lateral &
Anterior).
Trigeminothalamic.
Position
Deeply Placed.
Lateral to the medial
leminiscus.
Dorsal to the Inferior
Olivary Nucleus.
Composed of
Medial part (well formed in
the medulla) .
Lateral part (well formed in
the pons) .
Solitary Tract is in Between.
Function
Lateral Nucleus Receives
Taste Fibers from the Back
of the Tongue.
Medial Nucleus Receives
(GVA) fibers.
Position
The Most Caudal Point of
the Floor of the 4th
Ventricle.
Function
Site of Action of Centrally
Acting Emetics.
At Its Site
Blood Brain Barrier is Lost
for Certain Chemicals.
Deeply placed.
Posterior to the
Olivary Nucleus.
At this level of the
medulla:
It represents as a
Small part of the
system.
Descending:
Pyramids.
Tectospinal.
Ascending:
Medial leminiscus.
Spinal leminiscus.
Trigemino thalamic.
Ventral
spinocerebellar.
Thrombosis of branches of the
anterior spinal artery.
Manifested by :
(1) Contralateral hemiplegia of
the flaccid type (involvement of
the pyramidal fibers only).
(2) Contralateral loss of
proprioceptive sensation and fine
touch (affection of medial
lemniscus).
(3) Ipsilateral lower motor lesion
of the hypoglossal nerve
(affection of hypoglossal
Thrombosis of the Inferior
CerebellarArtery.
Manifested by
(1) Ipsilateral cerebellar
ataxia.
(2) Loss of Pain and
Temperature From the
Ipsilateral half of the Face.
(3)Loss of Pain and
Temperature from the
Contralateral Half of the
(4) Ipsilateral paralysis
of the muscles of the
Palate, Pharynx and
Larynx.
(5) Ipsilateral loss of
Taste from the
Posterior Third of the
Tongue.
(6) Ipsilateral Horner’s
syndrome