Anatomy-Medulla Flashcards
What tract are these fibers from?
Lateral cortical spinal tract. This is where they first cross at the spino-medullary junction.
After analysis of the posterior column pathway in this image, which section is higher up in the medulla?
The bottom image. Note that as the fibers from the nucleus gracilis and nucleus cuneatus decussate to the medial lemniscus, the medial lemniscus grows and the posterior column axons shrink.
Where in the medulla would you find pain, temperature and light touch sensory nerve fibers of the face? How are these somatotopically arranged?
Spinal Vth nucleus. These travel up to the brainstem from C1-C2 region and come from V1, V2 and V3. Note the soma topic arrangement below “with the eyes in front”.
Where in the medulla would you find pain, temperature and light touch sensory nerve fibers of the ear?
The ear is innervated by CNs VII, IX and X for pain, thermal and light touch sensation. The ganglia are located separately, but they all fall into the spinal Vth tract.
Where do the secondary fibers from the spinal Vth tract go?
Trigemino-thalamic pathway forms a track through the brainstem on its way to the thalamus. The secondary fibers cross where they enter the brainstem.
What symptoms would a patient present with who has a spinal Vth tract in the spinal Vth nucleus? What if it were lesioned near the thalamus?
Ipsilateral loss of pain, temp and light touch sensation because it is the secondary fibers that cross over on their way to the thalamus. If there was a lesion beyond the 1st synapse, then you would have symptoms contralateral to the side of the lesion.
What medullary structure is associated with CN XII?
Hypoglossal nucleus. The fibers leave through the olive and pyramids.
What medullary structure is associated with unconscious proprioception in the upper extremity?
Accessory cuneate nucleus.
What medullary structure is replaced by the inferior salivary nucleus?
DMX. CN IX is what innervates the parotid gland.
Label the different nuclei of the medulla as they move from the midline to the lateral edge:
Medial motor: Hypoglossal -> tongue (XII). Nucleus ambiguus -> pharyngeal arches 3,4,6 (XI, X, XI). Inferior salivatory & DMX -> parasympathetic (IX, X). Lateral sensory: taste & visceral -> solitary nucleus (IX, X). Pain, temp, light touch -> spinal Vth (V, VII, IX, X)
Single tongue muscle not innervated by the hypoglossal nerve?
Palatoglossus. This in innervated by X.
What muscles have motor innervation by CN X on its way out of the medulla?
Soft palate, pharynx and larynx via the pharyngeal branch, superior laryngeal external branch and recurrent laryngeal branch. These are found in the nucleus ambiguus.
What region of the body has pain, temp, light touch innervation from CN X? Where in the medulla is the nucleus?
Skin of the external ear and epiglottis -> Superior ganglion -> Spinal Vth nucleus.
What regions of the body have visceral sensory fibers from CN X? Where in the medulla do these go?
Carotid body, thoracic viscera, abdomen viscera and larynx -> inferior ganglion -> solitary nucleus.
What region of the body has taste innervation from CN X? Where in the medulla is the nucleus?
Epiglottis -> Inferior ganglion -> Solitary nucleus
What is the single solitary muscle innervated by CN IX?
Stylopharyngeus. Note that it courses right on top of it.
Where does CN IX provide sensory innervation?
GSA: ear & posterior 1/3 of tongue (spinal Vth). SVA: posterior 1/3 of tongue taste (rostral nucleus solitarius). GVA: pharynx & carotid sinus (caudal nucleus solitarius)
What supplies blood to these three regions of the medulla?
Note that you see pyramids and prominent posterior columns. This tells you that you are at the base of the medulla. Here, the anterior supply comes from the anterior spinal artery, the middle supply from the vertebral artery and the posterior supply from the posterior spinal artery.
A patient comes to see you in the ED complaining of loss of voluntary movement on his left side. Physical exam reveals deviation of the tongue toward the right side. Occlusion of what medullary artery would cause a patient to present with these symptoms?
This patient has inferior alternating hemiplegia. This happens as a result of occlusion of the anterior spinal artery and infarction of the pyramidal portion of the medulla. This creates a contralateral motor deficit because the lesion is before the pyramidal decussation and an ipsilateral paralysis of the tongue because the hypoglossal motor fibers do not decussate, but do travel between the olive and pyramids.
What arteries supply the regions of the medulla indicated below?
Note that you are up a little higher, with more prominent medial lemnisci. The PICA will supply the posterior portion of the medulla and the vertebral the anterior portion.
A patient presents to the ED complaining of loss of pain sensation on the right side of his body and left side of his face, a droopy left eyelid, constricted left pupil, dysphagia, dysphonia, left-sided ataxia and nystagmus. Where is the lesion in this patient?
This patient has Wallenberg’s Syndrome.The lesion hit the spinothalamic tract (contralateral loss of pain sensation), the autonomics (Horner’s), nucleus ambiguus (arch 3,4,6 muscles of soft palate, pharynx & larynx), spinal Vth (ipsilateral loss of pain sensation in face), inferior cerebellar peduncle (ipsilateral ataxia) and the inferior vestibular nucleus (nystagmus).
