Final Unit 6 Notes

For the Cranial NN (see last slide from table 15.7), know:1.Name and number2.Locations of innervation3.Whether innervation is sensory or motor

Mesencephalon

• The substantia nigra houses neurons which produce the neurotransmitter dopamine. This chemical affects brain processes that control movement and the ability to experience pleasure and pain. Degeneration of cells in the substantia nigra leads to Parkinson’s disease.

• The tegmentum contains the red nuclei which issue involuntary motor commands to postural muscles.

• The tectal plate (or corpora quadrigemina) contains the superior colliculi (visual reflex centers) and the inferior colliculi (auditory reflex centers).

Mesencephalon

Pons• The cerebellar peduncles contain fibers

that connect the pons to the cerebellum.• The pons houses two autonomic

respiratory centers: the pneumotaxic center and the apneustic center. These centers regulate the rate and depth of breathing.

Pons

Medulla Oblongata• The medulla oblongata, the most inferior part of

the brainstem, is formed from the myelencephalon.

• All communication between the brain and spinal cord involves tracts that ascend or descend through the medulla oblongata.

• The anterior surface exhibits two longitudinal ridges called the pyramids which contain motor tracts.

• Most of the axons in the pyramids cross to the opposite side at a point called the decussation of the pyramids, so that each cerebral hemisphere controls voluntary movement on the opposite side of the body.

Medulla Oblongata• Lateral to each pyramid is an inferior olivary nucleus.

These nuclei relay ascending sensory information.The medulla oblongata contains several autonomic nuclei:• Cardiac center -- regulates heart rate and force of

contraction.• Vasomotor center -- controls blood pressure by regulating

the arterial smooth muscle.• Respiratory center -- regulates respiratory rate and is

influenced by the apneustic and pneumotaxic centers of the pons.

• Other nuclei here are involved in coughing, sneezing, salivation, swallowing, gagging, and vomiting (fun, eh?).

Medulla Oblongata

Cerebellum• Has a complex, highly folded gray matter cortex. Folds here

are folia.• Composed of left and right cerebellar hemispheres. • Along the midline is a narrow band between hemispheres

called the vermis. • Coordinates and fine-tunes all skeletal muscle movements.• Stores ‘muscle memories’ of learned movement patterns

(musical instruments, bike riding, etc).• Adjusts skeletal muscle activity to maintain equilibrium and

posture.

Cerebellum

Limbic System

• The structures of the limbic system form a ring around around the diencephalon.

• The limbic system is a collection of multiple structures that collectively process and experience emotion.

• The limbic system affects memory formation with relevance to emotional states.

Limbic SystemBrain structures recognized to be part of the limbic system:• Cingulate gyrus• Hippocampus -- It is essential in storing memories and forming

long-term memories. • Amygdaloid body (or amygdala) -- involved in several aspects of

intense emotion, especially fear. • Olfactory cortex -- particular odors can provoke emotions.• Fornix -- thin tract of white matter that connects hippocampus

with other limbic system structures.• Various nuclei in the diencephalon (habenular nuclei,

mammillary bodies, etc)

Limbic System

Cranial Nerves