WEEK 11 Anatomy
NEURON STRUCTURE AND FUNCTION
Q: What are the three main structural components of a neuron?
A: Dendrites, soma (cell body), and axon.
Q: What is the function of dendrites?
A: To receive neural signals from other neurons.
Q: What is the function of the soma (cell body)?
A: To integrate incoming signals and maintain cellular function.
Q: What is the function of the axon?
A: To conduct electrical impulses away from the soma.
Q: What is the role of axon terminals?
A: To transmit signals to other neurons or target tissues via synaptic release.
Q: What are the two major structural types of neurons?
A: Multipolar neurons and unipolar (pseudounipolar) neurons.
Q: What is a multipolar neuron?
A: A neuron with one axon and multiple dendrites; common in the CNS.
Q: What is a unipolar (pseudounipolar) neuron?
A: A neuron with one process that branches into peripheral and central axons; found in sensory ganglia.
NERVOUS SYSTEM FUNCTIONAL DIVISIONS
Q: What are the two major functional divisions of the nervous system?
A: The somatic nervous system and the autonomic nervous system (ANS).
Q: What does the somatic nervous system control?
A: Voluntary skeletal muscle activity.
Q: What does the autonomic nervous system regulate?
A: Involuntary functions such as heart rate, digestion, and respiratory rate.
AUTONOMIC NERVOUS SYSTEM
Q: Where are sympathetic preganglionic neuron cell bodies located?
A: In the lateral horn of the spinal cord grey matter at T1–L2.
Q: Through what nerves do sympathetic preganglionic axons exit the CNS?
A: Spinal nerves at T1–L2 levels.
Q: Where are parasympathetic preganglionic neuron cell bodies located?
A: In cranial nerve nuclei in the brainstem and sacral spinal cord grey matter.
Q: Through what do parasympathetic axons exit the CNS?
A: Cranial nerves and pelvic splanchnic nerves.
Q: What is the effect of sympathetic activation on the heart?
A: Increases heart rate and contractility.
Q: What is the effect of parasympathetic activation on the heart?
A: Decreases heart rate.
Q: What is the effect of sympathetic activation on the GI tract?
A: Decreases motility and secretion.
Q: What is the effect of parasympathetic activation on the GI tract?
A: Increases motility and secretion.
CRANIAL NERVES AND NUCLEI
Q: What is the function of cranial nerve IX (Glossopharyngeal)?
A: Sensation from the pharynx and posterior tongue; taste; motor to stylopharyngeus; parasympathetic to parotid gland.
Q: What is the function of cranial nerve X (Vagus)?
A: Sensory and motor to thoracic and abdominal viscera; regulation of heart, lungs, and digestive tract.
Q: What extraocular muscle does the lateral rectus control, and what nerve innervates it?
A: Moves eye laterally; innervated by CN VI (abducens).
Q: What extraocular muscle does the medial rectus control, and what nerve innervates it?
A: Moves eye medially; innervated by CN III (oculomotor).
Q: What does the levator palpebrae superioris muscle do, and what innervates it?
A: Elevates the upper eyelid; innervated by CN III (oculomotor).
Q: What is the function of the vestibular nuclei?
A: Process balance and spatial orientation from the inner ear.
Q: Where is the oculomotor nucleus located and what does it control?
A: Midbrain; controls most extraocular muscles.
Q: What is the function of the Edinger-Westphal nucleus?
A: Parasympathetic control of pupil constriction and lens accommodation.
Q: What is the function of the trochlear nucleus?
A: Innervates superior oblique muscle (CN IV) for downward and lateral eye movement.
Q: What does the trigeminal motor nucleus control?
A: Muscles of mastication.
Q: What is the function of the abducens nucleus?
A: Controls lateral rectus muscle via CN VI.
Q: What does the facial motor nucleus control?
A: Facial expression muscles via CN VII.
VISUAL PATHWAY
Q: What is the pathway for visual information in the brain?
A: Retina → Optic nerve → Optic chiasm → Optic tract → Lateral geniculate nucleus → Visual cortex.
Q: What is this structure?
A: Thalamus
MOTOR NEURON PATHWAYS
Q: What is the function of upper motor neurons (UMNs) in the lateral corticospinal tract?
A: Initiate and modulate voluntary muscle contractions by acting on LMNs.
Q: Where are UMNs of the lateral corticospinal tract located?
A: Primary motor cortex; they descend through the internal capsule and decussate at the medulla.
Q: What is the function of lower motor neurons (LMNs)?
A: Directly innervate skeletal muscles to cause contraction.
Q: Where are LMNs located?
A: In the anterior horn of the spinal cord and cranial nerve nuclei in the brainstem.
INNER EAR AND VESTIBULAR APPARATUS
Q: What does the posterior semicircular canal detect?
A: Angular acceleration of the head in the coronal plane (e.g., side-bending).
Q: What does the horizontal semicircular canal detect?
A: Angular acceleration in the transverse plane (e.g., head turning).
Q: What does the anterior semicircular canal detect?
A: Angular acceleration in the sagittal plane (e.g., nodding).
Q: What is the function of the saccule?
A: Detects vertical linear acceleration.
Q: What is the function of the utricle?
A: Detects horizontal linear acceleration.