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Questions and Answers
Which structure lies between the two cerebral peduncles in the midbrain?
What landmark divides the midbrain into anterior and posterior parts?
What is the function of the superior colliculi in the vision process?
Which part of the midbrain is referred to as Tectum?
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What structures make up the anterio-lateral part of the midbrain?
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Which part of the midbrain contains other important nuclei and tracts passing through it?
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What are the two structures that make up the cerebral peduncles in the midbrain?
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How are the superior and inferior colliculi together referred to?
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What is the role of the brainstem in relation to the cerebral hemispheres and the cervical spinal cord?
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Which region of the brainstem is considered the narrowest?
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What is considered equivalent to brain death by some experts?
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Which region of the brainstem is widest?
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Which part of the brainstem is located closest to the spinal cord?
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What are some clinical outcomes of brainstem disorders?
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In an adult, how long is the brainstem on average?
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Study Notes
Brain Stem
- Located at the base of the brain, between the deep structures of the cerebral hemispheres and the cervical spinal cord
- Approximately 3 inches in length in an adult person
- Divided into three regions: midbrain, pons, and medulla oblongata
Midbrain
- Superior (rostral) region of the brainstem
- Divided into anterior (anterolateral) and posterior parts by the cerebral aqueduct
- Posterior part: tectum
- Anterior part: two cerebral peduncles, comprising the tegmentum and crura cerebri
- Substantia nigra lies between the cerebral peduncles, plays a role in motor planning and eye movement coordination
- Nuclei of cranial nerves III and IV located here
Pons
- Middle and largest part of the brainstem
- Lies between the midbrain and medulla oblongata, ventral to the cerebellum
- Connected to the cerebellum via the middle cerebellar peduncle
- Nuclei of cranial nerves V-VIII located here
- Ventral part characterized by the bulge of transverse pontocerebellar fibres, with the basilar artery located in the midline
Medulla Oblongata
- Lowest and smallest part of the brainstem
- Continues down as the spinal cord
- Point of junction with the spinal cord (cervico-medullary junction) marked by the foramen magnum of the skull externally and the obex of the floor of the fourth ventricle internally
- External surfaces: anterior, posterior, and lateral
- Anterior surface: anterior median fissure, ventrolateral sulcus, posterolateral sulcus, and pyramids
- Posterior surface: forms the lower part of the floor of the fourth ventricle, with the posterior median fissure, gracile fasciculus, and cuneate fasciculus
Clinical Significance
- Even small lesions of the brainstem may have profound effects
- Brainstem disorders can result in speech disorders, vestibular disturbance, abnormal consciousness, dysphagia, and respiratory disturbance
- Complete loss of brainstem function is regarded by some experts as equivalent to brain death
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Description
Test your knowledge on the anatomy of the medulla oblongata, focusing on structures like the pyramids, Hypoglossal cranial nerve (XII), and Olives. Explore the functional roles of these structures in motor coordination and nerve transmission.
