Psychology Study Material: Brain Stem and Cerebellum: Medulla Oblongata
Get unlimited access to the best preparation resource for competitive exams : get questions, notes, tests, video lectures and more- for all subjects of your exam.
Brain Stem and Cerebellum
Located underneath the limbic system the brain stem, containing four structures, is found in all vertebrates.
It contains four structures:
- Medulla
- Pons
- Reticular formation
- Thalamus
Responsible for basic survival functions such as breathing, heartbeat, and blood pressure.
Medulla/Medulla Oblongata
- Located at the top of the spinal cord and continuous with it.
- Damage to Medulla can be fatal as it is the centre responsible for vital functions i.e.. , respiration, heartbeat, and blood pressure.
- Contains ascending & descending tracts that communicate between the spinal cord & various parts of the brain.
- At medulla, nerves ascending from the body and descending from the brain cross over; hence the left side of the body is connected to the right side of the brain and vice versa.
Contains 3 vital centres:
- Cardio inhibitory centre: regulates heart rate.
- Respiratory centre: regulates the basic rhythm of breathing.
- Vasomotor centre: regulates the diameter of blood vessels.
Pons
- Pons = Latin word for bridge
- Bridge connecting spinal cord with brain and parts of brain with each other.
- The pons seems to serve as a relay station carrying signals from various parts of the cerebral cortex to the cerebellum.
- Nerve impulses coming from the eyes, ears and touch receptors are sent on the cerebellum.
- The pons also participates in the reflexes that regulate breathing.
- It has parts that are important for the level of consciousness and for sleep.
Reticular Formation
- The reticular formation is a region running through the middle of the hindbrain and into the midbrain.
- A dense network of nerve cells.
- It keeps the brain alert even during sleep.
- It makes the cerebral cortex attend to new stimulation by arousing it.
- Long fibrous tracts of reticular formation run into the thalamus.
- Needed for arousal from sleep & to maintain consciousness.
- Serious damage to reticular formation may result into a coma.
Thalamus
- The pair of egg-shaped structures located at the top of the brainstem.
- Incoming sensory information is channelled to the appropriate area of the cerebral cortex by thalamus, so that it is processed there.
- Thalamus acts like a relay station … . the brain՚s sensory switchboard: it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla.
- It receives information from the sensory neurons and routes it to the higher brain regions that deal with vision, audition, taste and touch.
Cerebellum
- “Cerebellum” comes from the Latin word for “little brain” . The cerebellum is located behind the brain stem.
- Cerebellum is somehow similar to the cerebral cortex: the cerebellum is divided into hemispheres and has a cortex that surrounds these hemispheres.
- It carries 10% of the weight of the brain.
- It contains as many neurons as in the rest of the brain.
- Its function is to coordinate body movements i.e.. coordination, maintenance of posture & balance.
- Damage to cerebellum results into jerky and uncoordinated body movements.