ANATOMY OF
THE MEDULLA
OBLONGATA
Ahmed Elnabawy Ahmed
Nasr
Contact Information
Dr. Ahmed Elnabawy Ahmed
Official Email : Ahmed.elnabawy@nmu.edu.eg
Mobile (Optional): 01025330333
Learning Outcomes
At the end of the lecture, the students should be able to:
Identify the external and internal features of the medulla oblongata
Relate the deep nuclei of the medulla to vascular lesions of the medulla
the medulla lies in the clivus
medulla anterior view you can see
anterior median fissure
2anterior lateral sulcus
2 posterior lateral sulcus
the pyramids ﺑﻴﻤﺮ ﺑﻴﻬﺎcorticospinal tract
EXTERNAL FEATURES
Ventral Surface
Three elevations
1. Pyramid ❑ contains the corticospinal tract.
❑ In the lower part, 85% of the corticospinal fibers cross
to opposite side forming pyramidal decussation.
2. Olive ❑ formed by inferior olivary nucleus
3. Inferior ❑ connects the medulla with the cerebellum
cerebellar
peduncle
Three Fissures Exit of the last 4 cranial nerves
1 IX
❑ in the midline
2 XII X
Anterior medial sulcus
3 XI
Preolivary fissure ❑ between the pyramid and olive Hypoglossal nerve
Postolivary fissure ❑ between the olive and inferior cerebellar peduncle
Glossopharyngeal, vagus and cranial accessory nerves
Dorsal Surface
Lower Part of the Medulla
Three elevations
1. Gracile tubercle ❑ medial - formed by gracile nucleus
2. Cuneate tubercle ❑ middle - formed by cuneate nucleus
3. Tuberculum cinereum ❑ lateral - formed by spinal trigeminal
nucleus
3
an elevation on the lateral aspect of the 21
medulla oblongata produced by the
spinal trigeminal tract and its nucleus.
Dorsal Surface
Upper Part of the Medulla (lower part of the floor of the 4th ventricle)
Three trigones sulcus limitans (inferior fovea)
Hypoglossal trigone ❑ medial, formed by hypoglossal nucleus 12
Vagal trigone ❑ middle, formed by dorsal motor
nucleus of vagus 10
Vestibular trigone ❑ lateral, formed by the medial &
inferior vestibular nuclei. 8
Stria medullaris
Area postrema (vomiting center) Ves Vg
at the lower angle of the 4th ventricle (obex). H
Stria medullaris of the 4th ventricle Opex
INTERNAL FEATURES
NUCLEAR GROUPS IN THE MEDULLA
1. Gracile and cuneate nuclei
❑ Receive gracile and cuneate tracts.
❑ second-order neuron for
kinesthesia, discriminative touch
and sense of vibration from the
same side of the body.
❑ Their axons cross to the opposite
side in sensory decussation and
form medial lemniscus.
2. Cerebellar relay nuclei
1. Inferior olivary nuclear complex
2. Arcuate nucleus
3. Accessory (lateral) cuneate nucleus
middle cerebellar
peduncle
4. Reticular formation
5. Vestibular nuclei Vestibular
nuclei
Reticular
formation
Arcuate n.
Inferior olivary nuclear complex
Accessory cuneate n.
3. Cranial nerves nuclei 4 motor + 4 sensory
2 MOTOR NUCLEI (not parasympathetic)
❖In the floor of fourth ventricle
Hypoglossal (hypoglossal trigone)
nucleus ❖Supplies all muscles of the tongue
except palatoglossus.
❖Supplies all muscles of the pharynx, all
muscles of the larynx and all muscles of
the palate except tensor palati muscle.
❖It is divided into three parts:
Nucleus 1.Upper part: Gives fibers to
ambiguus Glossopharyngeal IX
Stylopharyngeus
2.Middle part: Gives fibers to vagus
give fibers to last 3.Lower part: Gives fibers to cranial X ❑ Muscles of the
4 cranial nerves pharynx except
accessory nerve, which join the vagus stylopharyngeus.
nerve. ❑ Muscles of the larynx.
XI ❑ Muscles of the palate
except tensor palati.
2 PARASYMPATHETIC NUCLEI
Inferior
❖Supplies the parotid gland via
salivatory glossopharyngeal nerve.
nucleus
❖In the floor of the fourth ventricle (vagal
Dorsal
trigone).
motor
❖Supplies thoracic and abdominal
nucleus of
viscera till the left colic flexure through
the vagus vagus nerve.
2 SENSORY NUCLEI
❖ascends in the pons and descends in
the spinal cord.
Spinal ❖It mediates pain and temperature
sensations from the same side of the
trigeminal face.
nucleus
❖The axons cross to the opposite side,
form the trigeminal lemniscus, which
terminates in (VPMNT). medial
❖Upper one-third: receives taste fibers
via :
1)Facial nerve (chorda tympani): anterior
2/3
Nucleus
2)Glossopharyngeal nerve: posterior 1/3
solitarius
3)Vagus nerve: epiglottis and the most
posterior part of tongue.
❖Lower two thirds: receive general
visceral sensation.
2 VESTIBULAR
Medial and inferior vestibular nuclei
❖In the floor of the fourth ventricle
(vestibular trigone).
VASCULAR LESIONS OF THE MEDULLA
Medial Medullary Syndrome
Cause Occlusion of the anterior Spinal artery.
Clinical signs
1. Hypoglossal nerve & nucleus lesion
❖ LMN paralysis of the same side of the
tongue (hemiparalysis).
❖ Deviation of the protruded tongue
toward the affected side.
2. affection of the medial lemniscus
❖ Contralateral loss of kinesthesia, discriminative
touch and sense of vibration.
3. affection of the corticospinal tract
❖ Contralateral hemiplegia.
Lateral Medullary Syndrome
Cause Occlusion of the PICA (Posterior Inferior Cerebellar Artery)
Clinical signs
Question 1
A 61-year-old patient arrived to the emergency room complaining of
paralysis of the muscles of the left side of his body. A neurologist
assessed his condition and found that he lost the sense of vibration
from the left side of his body. The doctor examined his tongue and
noticed atrophy of the right half of the tongue and deviation of the
tongue to the right side upon protrusion. Which of the following
arteries is most likely affected?
A. paramedian pontine arteries
B. Anterior spinal artery
C. Posterior inferior cerebellar artery
D. Posterior spinal artery
E. Anterior inferior cerebellar artery
Question 1
A 61-year-old patient arrived to the emergency room was diagnosed of
occlusion of the right Posterior inferior cerebellar artery. Which of the
following signs was found in his condition?
A. Loss of pain and temperature from his left side of the face
B. Loss of pain and temperature from his right lower limb
C. Loss of pain and temperature from his right upper limb
D. Ataxia the left half of his body
E. Dropping in the right upper eye lid
