Unit 7: Neuroanatomy & Neurophysiology - Communication and Swallowing Control

Comprehensive review flashcards covering neuroanatomy and neurophysiology concepts for speech, language, and swallowing from Unit 7.

Which major anatomical structures comprise the Central Nervous System (CNS)?

The cerebrum, cerebellum, brainstem, spinal column, thalamus, subthalamus, and basal ganglia.

Which anatomical components make up the Peripheral Nervous System (PNS)?

Spinal nerves, cranial nerves, and sensory receptors.

What is the primary difference in movement control between the Autonomic and Somatic Nervous Systems?

The Autonomic Nervous System controls involuntary movement and bodily functions, whereas the Somatic Nervous System controls voluntary movement.

How do the sympathetic and parasympathetic divisions of the autonomic nervous system differ functionally?

The sympathetic nervous system expends energy and causes vasoconstriction (fight or flight), whereas the parasympathetic nervous system conserves energy and causes vasodilation (rest and digest).

How do the pyramidal and extrapyramidal motor systems differ within the somatic nervous system?

The pyramidal system is responsible for the initiation of voluntary motor movement, while the extrapyramidal system (indirect system) controls background tone and supporting movements.

What is the neural complexity hierarchy from simplest to most complex?

Neuron (smallest organizational unit) -> Peripheral nerves -> Spinal cord -> Brainstem -> Midbrain -> Cerebral cortex (most complex).

What are the structural components of a neuron and their functions?

Dendrite (receptor region), Axon (transmits information from neuron), Myelin Sheath (insulator of axon), Neurotransmitters (substances that facilitate synapse), and Synaptic Cleft (region between neurons).

What are the active sites and physiological functions of Acetylcholine?

In the PNS, it functions as excitatory; in the CNS, it functions as modulatory and inhibitory.

What is the primary site and function of Dopamine?

It acts in the CNS with a modulatory and excitatory function.

What site and function are associated with GABA (gamma-aminobutyric acid)?

It acts within the CNS as an inhibitory neurotransmitter.

What are the functional roles of Norepinephrine, Serotonin, and Endorphins in the CNS?

Norepinephrine and Serotonin act as regulatory neurotransmitters, while Endorphins function in pain regulation.

What is the role of cerebrospinal fluid (CSF) and where does it flow?

CSF flows through the ventricles of the brain; it provides a cushion for neural tissue and facilitates nutrient delivery and waste removal.

What is the choroid plexus?

An aggregate of tissue located within each ventricle of the brain that produces cerebrospinal fluid (CSF).

What are the anatomical characteristics of the lateral, third, and fourth ventricles of the brain?

The lateral ventricles are the largest, horseshoe-shaped, and composed of four spaces; the third ventricle is an unpaired medial cavity between the left and right thalami and hypothalamus; the fourth ventricle is diamond-shaped and situated between the brainstem and cerebellum.

Which meningeal linings and structures protect the cerebral cortex?

The dura mater, arachnoid mater, and pia mater, along with cerebrospinal fluid (CSF).

What are the functional specializations of the left versus right cerebral hemispheres in most individuals?

The left hemisphere is dominant for language, speech, processing brief-duration stimuli, and detailed analysis; the right hemisphere is dominant for processing holistic spatial and tonal information, and face recognition.

How are gyri, sulci, and fissures defined in cerebral anatomy?

Gyri are the bulges of the cerebral cortex, sulci are the crevices that separate the gyri, and a fissure is a deep, distinct groove.

What structure completely separates the left and right cerebral hemispheres?

The cerebral longitudinal fissure.

What anatomical concept is represented by this distorted human figure?

The cortical homunculus, which illustrates the disproportionate amount of motor and sensory cortex dedicated to controlling body parts requiring refined motor control and high sensitivity (such as the hands, lips, and tongue).

What proportion of the cortex is occupied by the frontal lobe, and what does it control?

It occupies approximately $\frac{1}{3}$ of the cortex (the largest lobe, in the anterior-most position) and controls planning, initiation of voluntary movement, and inhibition of voluntary movement.

What is the location and function of the precentral gyrus?

Located anterior to the central sulcus, the precentral gyrus (motor strip) is the site of initiation of voluntary motor movement.

What is Broca’s area and why is it clinically significant?

Located in the dominant frontal lobe, Broca’s area is an extremely important cortical region for speech motor planning.

What is the postcentral gyrus and how does it process sensation?

Known as the sensory strip in the parietal lobe, it is the primary site of sensory input reaching consciousness; sensation from the left part of the body projects to the right hemisphere.

How do Heschl’s gyrus and Wernicke’s area differ in location and function in the temporal lobe?

Heschl’s gyrus is at the upper surface of the superior temporal lobe and acts as the primary auditory area where all auditory information projects; Wernicke’s area is located at the posterior portion of the superior temporal gyrus and is critical for receptive language processing (damage leads to Wernicke's aphasia).

What is the primary function and anatomical location of the occipital lobe?

Located at the posterior limit of the brain, it is responsible for receiving visual stimulation as well as some higher-level visual processing.

What motor functions are governed by the basal ganglia, and what results from basal ganglia lesions?

The basal ganglia control background movement and the initiation of movement patterns; lesions result in extrapyramidal dysfunction, causing hyperkinetic and hypokinetic dysarthrias.

What are the primary functional connections of the hippocampal formation?

Part of the rhinencephalon involved in memory, it communicates with the hypothalamus (related to visceral function and emotion) and the temporal lobe (associated with memory function).

What are the roles of the thalamus and the Reticular Activating System?

The thalamus serves as the final common relay for sensory information directed to the cerebral cortex (all sensations except olfaction pass through it); the Reticular Activating System arouses the cortex and focuses cortical regions to heightened awareness.

What functions are controlled by the epithalamus, hypothalamus, and subthalamus?

The epithalamus is involved with the development of gonads; the hypothalamus controls bodily functions, desires, and limbic system organization; the subthalamus controls movement.

What percentage of bodily oxygen does the cerebrovascular system consume, and what supplies it directly from the aorta?

It consumes $20\%$ of oxygen transported by the vascular system, supplied directly from the aorta by the carotid arteries.

Which cortical areas are supplied by the anterior, middle, and posterior cerebral arteries?

Anterior cerebral arteries serve medial brain surfaces; middle cerebral arteries serve the lateral cortex (including temporal lobe, motor strip, Wernicke’s area, and parietal lobe); posterior cerebral arteries serve inferior temporal and occipital lobes, upper midbrain, and diencephalon.

What is the structural and physiological significance of the Circle of Willis?

It is a series of communicating arteries that provides redundant pathways for blood flow to regions of the cerebral cortex, equalizing blood pressure and blood flow.

How do a thrombus, an embolus, and an aneurysm differ?

A thrombus is a foreign body within a blood vessel; an embolus is a foreign body that becomes released into the bloodstream; an aneurysm is the ballooning of a blood vessel that can rupture and release blood into the brain.

What is the primary role of the cerebellum?

As the largest component of the hindbrain, it coordinates motor commands with sensory inputs to control movement, specifically governing the rate, force, and range of movement.

Which cranial nerves emerge from the midbrain, pons, and medulla oblongata?

CN III and IV emerge from the midbrain; CN V, VI, and VII emerge from the pons; CN IX, X, XI, and XII emerge from the medulla oblongata.

What major anatomical transition occurs at the medulla oblongata?

Pyramidal decussation, the point at which motor commands originating in one cerebral cortex hemisphere cross over to serve the opposite side of the body.

What type of nerve pathway and sensory modality is mediated by CN I (Olfactory)?

Afferent pathway mediating the sense of smell (olfaction), via sensors embedded in the nasal cavity epithelium.

Which cranial nerves control eye movements, and what unique reflexes are mediated by CN III?

CN III (Oculomotor), CN IV (Trochlear), and CN VI (Abducens) control eye movements; CN III also provides light and accommodation reflexes associated with pupil constriction and focus.

What are the efferent and afferent innervations of CN V (Trigeminal)?

Efferent innervates muscles of mastication (pterygoids, masseter, temporalis) and tensor veli palatini; afferent mediates sensation from the face, mouth membranes, nose, teeth, gums, TMJ, and anterior $\frac{2}{3}$ of the tongue.

What are the motor and sensory distributions of CN VII (Facial)?

Efferent innervates muscles of facial expression (buccinator, zygomatic major, risorius); afferent mediates taste from the anterior $\frac{2}{3}$ of the tongue.

What are the distinct functions of the acoustic and vestibular branches of CN VIII (Vestibulocochlear)?

The acoustic branch conveys auditory information from cochlear hair cell receptors to the CNS; the vestibular branch conveys balance and spatial position information from the semicircular canals.

What are the motor and sensory functions of CN IX (Glossopharyngeal)?

Efferent innervates muscles of swallowing (superior pharyngeal constrictor) and mediates the gag reflex; afferent mediates taste from the posterior tongue and pain from the posterior tongue, upper pharynx, and tonsils.

What general viscera and structures are innervated by CN X (Vagus)?

Efferent motor fibers innervate the larynx, esophagus, intestines, pancreas, stomach, trachea, kidneys, liver, and heart; afferent fibers convey sensation from the pharynx, larynx, trachea, esophagus, thorax, and abdomen.

What does the pharyngeal branch of the Vagus nerve (CN X) innervate?

It supplies nerve fibers to the pharynx, innervates all muscles of the soft palate except the tensor veli palatini (working with CN XI), and conveys taste from the base of the tongue and sensation from the upper pharynx.

What are the efferent and afferent distributions of the Superior Laryngeal Nerve (SLN) branch of CN X?

Efferent innervates the cricothyroid muscle and secretory glands; afferent transmits laryngeal sensation.

How do the anatomical pathways of the right and left Recurrent Laryngeal Nerves (RLN) differ, and what do they innervate?

The right branch courses among the subclavian artery, trachea, and esophagus, while the left branch loops under the aortic arch to ascend between the trachea and esophagus; both provide efferent innervation to all intrinsic laryngeal muscles except the cricothyroid (for phonation, cough, vocal fold movement) and afferent tracheal sensation.

What muscles are innervated by CN XI (Accessory), and what is the pharyngeal plexus?

It innervates the sternocleidomastoid and neck strap muscles; with CN X, it forms the pharyngeal plexus to provide neural cross-coverage to palatal, laryngeal, and pharyngeal muscles.

What muscles are innervated by CN XII (Hypoglossal), and what clinical sign indicates unilateral damage?

It innervates all tongue muscles (geniohyoid, superior/inferior longitudinal, vertical, transverse) except the palatoglossus; unilateral damage causes the tongue to deviate to the ipsilateral side of the lesion upon protrusion.

What are the anatomical and functional differences between Upper Motor Neurons (UMN) and Lower Motor Neurons (LMN)?

UMNs originate in upper brain levels and descend to activate or inhibit muscle function by synapsing with LMNs; LMNs consist of motor fibers within the spinal cord or cranial nerve nuclei that communicate directly with peripheral muscle fibers.

What is the specific function of the corticobulbar tract?

It is the motor tract that serves the motor cranial nerves for speech.

Which spinal cord segments correspond to respiration and head/neck stability?

C3–C4 control respiration, and C2–C7 control head and neck stability and respiration.