Gross anatomical description of the medulla with associated significant clinical relevance Relevant blood supply of the Medulla Oblongata. Good revision guide

1. DETAILED ANATOMY OF THE MEDULLA
DR S.E.MBA

2. EXTERNAL FEATURES AND RELATIONS
• 3Cm long.
• Located at the caudal portion of brainstem
• Upper limit is cerebello-pontine angle
• Transverse plane that above C1 (suboccipital n)
intersects upper border of atlas dorsally and centre
of dens ventrally marks lower limit

3. • Ventral median fissure extends from foramen
coecum to caudal end of pyramid decussation
• Lateral to median fissure is pyramid
• Lat to pyramid is the ventrolateral sulcus (VLS)
• Hypoglossal nerve rootlets emerge from VLS
• Lat to VLS is olive which contains inf olivary nucleus
• inferior cerebellar peduncle connects medulla with
cerebellum and forms side wall of caudal half of
fourth ventricle
• At dorsal surface of closed part of medulla, gracile
and cuneate fasciculi continue from the spinal cord

4. • Tuberculum cinereum, lateral to cuneate fasciculus
marks the position of trigeminal spinal tract.
• Obex is apex of the V-shaped boundary of the inferior
part of the fourth ventricle, which is folded caudally
over the most rostral 1 to 2 mm of the central canal,
• The cochlear division of the vestibulocochlear nerve
ends in the dorsal and ventral cochlear nuclei, which
are situated on the base of the inferior cerebellar
peduncle. The vestibular division penetrates the brain
stem deep to the root of the inferior cerebellar
peduncle.
• Roots of glossopharyngeal , vagus and cranial division
of accessory nerves are attached to the medulla dorsal
to olive.

6. VENTRAL ASPECT LATERAL ASPECT

7. DORSAL ASPECT

10. Chiari Malformation
A 24-year-old woman
presents with a long
history of increasing
headache, blurred vision
when attempting to read
and an increasingly
unsteady gait with
intermittent falls.
Neurological
examination reveals
downbeat nystagmus
with the eyes in the
primary position,
amplified by down-gaze;
dysmetria of the lower
extremities with heel-to-
shin testing; and
hyperreflexia in both
lower extremities.
Downbeat nystagmus
consists of a rapid
downbeat
motion of the eyes
followed by a slower
upward movement.
is characteristically
associated with
conditions
involving the medulla
oblongata, particularly at
the
level of the
craniocervical junction.

11. INTERNAL STRUCTURE

13. LATERAL MEDULLARY SYNDROME (WALLENBURG SYNDROME)
1- Vestibular nuclei: vertigo, nausea, vomiting and nystagmus.
2- Cerebellar peduncle: ataxia (gait/limb)
3: Spinothalamic tract: controlateral loss of pain and temperature sensation
4: Nucleus Ambiguus: palatal and laryngeal muscles paralysis..dysphagia and dysarthria
5: Nucleus and spinal tract of V: ipsilateral analgesia and thermoanaesthesia of face
6: Descending Sympathetic fibers: ipsilateral Horner’s syndrome: …………
WHICH ARTERY? PICA

14. MEDIAL MEDULLARY SYNDROME (AVELLIS’ SYNDROME)
• Pyramidal tract: contralateral hemiparesis
• Medial lemniscus: contralateral loss of tactile discrimination
• Hypoglossal Nerve: ipsilateral paralysis of tongue, deviation to same side
WHICH ARTERY? ANTERIOR SPINAL ARTERY (MEDULLARY BRANCHES)

15. CLINICAL SIGNIFICANCE OF MEDULLA
• Raised Pressure in the Posterior Cranial Fossa and
Its Effect on the Medulla Oblongata
In patients with tumors of the posterior cranial
fossa, the intracranial pressure is raised, and the
brain––that is, the cerebellum and the medulla
oblongata––tends to be pushed toward the area of
least resistance; there is a downward herniation of
the medulla and cerebellar tonsils through the
foramen magnum. This will produce the symptoms
of headache, neck stiffness,and paralysis of the
glossopharyngeal,vagus,accessory, and hypoglossal
nerves owing to traction.

16. Thank you
For comments
mbasedy@yahoo.fr