Neuroanatomy: Brainstem Review

Flashcards about the anatomy of the brainstem, including its parts, functions, blood supply, and key nuclei and pathways. Also covers the medulla oblongata, pons, and midbrain.

What are the three major parts of the brainstem?

Pons, Medulla Oblongata, Midbrain

What are the main functions of the brainstem?

Links the brain via the diencephalon to the spinal cord and contains cranial nerve nuclei, other nuclei (e.g., olivary nucleus, red nucleus), reflex centers, somatosensory system, auditory system, motor system, and reticular formation.

What artery supplies blood to the brain stem and how?

Formed by the fusion of the two vertebral arteries at the medulla and supplies the pons with pontine vessels.

How is the medulla oblongata supplied with blood?

The vertebral arteries give rise to the anterior median spinal artery that supplies the midline of the medulla and spinal cord, and the posterior inferior cerebellar arteries supply the lateral medulla.

What type of white matter is found in the medulla oblongata?

Sensory (ascending) and motor (descending) tracts between cortex and spinal cord.

What type of grey matter is found in the medulla oblongata?

Nuclei of cranial nerves IX, X, XI, XII (and/or VIII), autonomic nuclei (cardiovascular, ventilation, vomiting/coughing/sneezing/swallowing), and special nuclei like the inferior Olivary nucleus.

What does the Dorsal Column-Medial Lemniscus pathway carry?

Carry proprioception and 2-point discrimination touch sense.

Describe the Dorsal Column- Medial Lemniscus pathway.

Sensory nerves ascend in dorsal columns, synapse in dorsal column nuclei (nucleus cuneatus and gracilis), and 2nd order neurons project to contralateral thalamic nuclei via the medial lemniscus.

What does the Corticospinal tract control?

Controls conscious movement of muscles.

Describe the Corticospinal tract pathway.

Neurons originate in the motor cortex, project via the internal capsule to the cerebral peduncle, and then split into lateral (90% decussate) and anterior (10% remain ipsilateral) corticospinal tracts in the anterior medulla oblongata.

What is the function of the Inferior Olivary nuclei?

Involved in controlling and learning coordinated movements; projects to contralateral cerebellar cortex via the inferior cerebellar peduncle.

What is the role of the Nucleus Ambiguous?

Control of motor supply of the aerodigestive tract and contains autonomic parasympathetic fibres that control blood pressure.

What is the function of the Nucleus Solitarius?

Input of taste information from cranial nerves VII, IX, and X; projects to the VPM nuclei of the thalamus; also involved in cardiovascular autonomic control.

What key nuclei are located in the pons?

Superior olivary nucleus (auditory system) and cranial nerve nuclei (V, VI, VII, VIII).

What tracts are found in the pons and where do they go?

Thick stalks posteriorly = middle cerebellar peduncles; the pons is a relay as the cortex projects to the pons (corticopontine fibres) then to the contralateral cerebellum (pontocerebellar); ascending and descending tracts also run through the pons.

What is the function of the Superior Olivary Nucleus?

Receives information from cochlear n., mixes sound information from L+R ear, integrates and processes information regarding localizing the source of sound, and projects information to the inferior colliculus of the midbrain to the primary auditory cortex in temporal horns.

What are the main regions of the midbrain?

Cerebral peduncles (ventral/anterior), quadrigeminal plate/tectal plate/tectum (dorsal/posterior), and tegmentum (middle region with red/rubro nuclei + substantia nigra).

What are the functions of the superior and inferior colliculi?

Superior colliculus (reflex turning of eyes and neck in response to visual, auditory, and cutaneous stimuli) and Inferior colliculus (auditory information relay point to auditory cortex).

What do the Cerebral Peduncles contain?

Descending fibers from internal capsule from motor cortex → pyramids + spinal cord; ascending sensory tracts to thalamus (lemnisci).

What pathways are part of the Tegmentum?

Rubrospinal tracts arise from red nuclei; input from cerebellum via superior cerebellar peduncles from deep cerebellar nuclei; fibres cross in the midbrain.

Describe the Vestibulo-ocular reflex.

Movement of the vestibular system results in eye movement, allowing one to keep focusing eyes despite head movement; involves vestibular nuclei, abducens nuclei, and the medial longitudinal fasciculus (MLF).

What components does the Reticular formation include?

Peri-aqueductal grey (PAG) in autoregulation of ascending pain pathways (gives descending analgesic pathways, opioid receptors) and dopaminergic neurones in substantia nigra (motor control, learning behaviour, reward/addiction).