Physiology
Groups of nerves coming together for a common purpose
Plexus
Decussates laterally & anteriorly
Corticospinal tract
Home to the spinal reflex arc
Spinal cord
Latin for “bridge,” and its function is to provide a bridge among the medulla, midbrain, and cerebellum.
Pons
Function: Sense of smell
Damage: Anosmia - loss of the sense of smell
CN I- Olfactory
An area of skin that is innervated by a single spinal nerve, and it represents the distribution of the cutaneous region served by the nerve.
Dermatome
Carry sensory information from the body, like pain, for example, up the spinal cord to the brain.
Ascending/sensory tracts
Responsible for direct voluntary activation of the muscles of the body.
Precentral gyrus
Extends through medulla, pons, and midbrain. It is a vitally important set of nuclei that forms the “oldest” part of the brainstem and reflects an early evolutionaly effort at complex processing.
Reticular formation
Damage to the this nerve can have a significant impact upon speech production and mastication.
CN V- Trigeminal
Counteracts stress responses by slowing heart rate, constricting pupils, and lowering blood pressure
Parasympathetic nervous system
Innervates the nuclei of the cranial nerves V, VII, IX, X, XI, and XII.
Corticobulbar tracts
An important structure involved in placing memory into long-term storage, navigation in space, and the sense of smell.
Hippocampus
Important auditory relay related to localization of sound in space as well as integration of body sense with auditory sense.
Inferior colliculi
Function: Somatic sense of the tongue, taste on ⅓ of tongue; Motor innervation of parotid gland, stylopharyngeus, and superior pharyngeal constrictor
CN IX- Glossopharyngeal
Mediate senses that arise from the outside environment, such as cold, heat, pressure, and painful stimuli presented to the body
Exteroceptors
Almost all of the afferent fibers entering the cerebrum arise from what structure?
Thalamus
A horizontal dural shelf that separates the cranium into superior (cerebral) and inferior (cerebellar) regions.
Tentorium cerebelli
A lesion to this part of the brainstem could have profound effects on the function of the entire body because nearly all motor and sensory fibers pass through the crus cerebri.
Midbrain
Damage causes paralysis of the trapezius or sternocleidomastoid.
CN XI- Accessory
Photoreceptors become hyperpolarized when stimulated and produce _____________ rather than an all-or-none action potential, so we can actually see shades of a color.
Graded potential
Lesions here would cause dysregulation of muscle tone and reflexes, disinhibition of the basal ganglia control network, and loss of skilled motor function.
Extrapyramidal system
The final relay for sensory information directed toward the cerebral cortex.
Thalamus
An important nucleus of the X vagus nerve and is found lateral to the hypoglossal and dorsal vagal nuclei that mediates taste, gag reflex, and cough.
Nucleus solitarius
(VE) visceral efferent = Motor innervation of facial muscles
(SVA) special visceral afferent = Taste, anterior ⅔ of tongue
(GSA) general somatic afferent = Tactile sense of external auditory meatus and epithelial of pinna
(GVE) general visceral efferent = Lacrimal glands for tearing; sublingual and submandibular glands for saliva; mucous membrane of nose and mouth
CN VII- Facial