General Human Anatomy Exam 3 Study Guide

Comprehensive vocabulary flashcards covering the Nervous Tissue, Brain and Nerves, Spinal Cord and Nerves, Autonomic Divisions, and Special Senses sections of the General Human Anatomy Exam 3 Study Guide.

Neuron

A specialized excitable cell of nervous tissue distinguished from other cells by its unique structures, including a cell body, dendrites, and an axon.

Neurotransmitter

A chemical messenger released by a presynaptic cell into the synapse to transmit signals across to a postsynaptic cell.

Synapse

The specialized junction where communication occurs between a presynaptic cell and a postsynaptic cell.

Presynaptic cell

The neuron or cell that transmits a signal across a synapse by releasing neurotransmitters.

Postsynaptic cell

The cell that receives the signal on the opposite side of a synapse via neurotransmitter receptors.

Cell body

The central biosynthetic core of a neuron located primarily within the grey matter of the central nervous system.

Dendrites

Branching neuronal processes that receive incoming signals and convey them toward the cell body, located in the grey matter.

Axon

A long, slender neuronal projection that conducts outgoing nerve signals away from the cell body toward axon terminals.

Axon terminal

The distal endpoint of an axon that forms synapses and releases neurotransmitters to communicate with target cells.

Myelin sheath

A lipid-rich insulating layer enclosing an axon, which gives white matter its characteristic white appearance and increases conduction speed.

Node of Ranvier

A periodic unmyelinated gap along the length of an axon between segments of the myelin sheath.

Grey matter

Nervous tissue composed predominantly of neuronal cell bodies, dendrites, and unmyelinated parts of neurons.

White matter

Nervous tissue composed predominantly of myelinated axons, appearing white due to the high lipid content of the myelin sheath.

Sensory neuron

A functional category of neuron that transmits incoming sensory signals from peripheral receptors toward the central nervous system.

Interneuron

A neuron located entirely within the central nervous system that integrates and relays signals between sensory and motor neurons.

Motor neuron

A neuron that conducts motor impulses outward from the central nervous system to effector targets such as muscles and glands.

Oligodendrocytes

Glial cells located in the central nervous system that produce and wrap the myelin sheath around CNS axons.

Ependymal cells

Glial cells located in the central nervous system that line the brain ventricles and central canal, functioning in the production and movement of cerebrospinal fluid.

Microglia

Glial cells resident in the central nervous system that act as phagocytes to clear cellular debris and defend against pathogens.

Astrocytes

Abundant glial cells located in the central nervous system that anchor neurons, regulate extracellular chemistry, and help form the blood-brain barrier.

Schwann cells

Glial cells located in the peripheral nervous system that form the myelin sheath around PNS axons.

Satellite cells

Glial cells located in the peripheral nervous system that surround and support neuronal cell bodies within ganglia.

Dural venous sinuses

Venous channels situated between layers of the dura mater in the brain through which blood and drained cerebrospinal fluid circulate.

Cerebrospinal fluid

The clear liquid that circulates through the brain ventricles, central canal, and subarachnoid space to cushion and nourish CNS tissue.

Choroid plexus

A specialized vascular network of ependymal cells and capillaries located within the ventricles that produces cerebrospinal fluid.

Arachnoid villi

Finger-like extensions of the arachnoid mater that project into the dural venous sinuses to reabsorb cerebrospinal fluid back into venous circulation.

Ventricles

Fluid-filled internal cavities of the brain through which cerebrospinal fluid flows.

Medulla oblongata

The most inferior part of the brainstem, responsible for vital autonomic reflex centers governing heart rate, blood pressure, and breathing.

Pons

The brainstem structure located superior to the medulla oblongata that relays signals between the cerebrum, cerebellum, and spinal cord.

Superior colliculi

Paired visual reflex centers in the midbrain tectum that coordinate visual tracking and head turning toward visual stimuli.

Inferior colliculi

Paired auditory reflex centers in the midbrain tectum that process and route sound information and initiate startle responses.

Cerebellum

The brain structure posterior to the brainstem that coordinates voluntary movements, posture, balance, and fine motor skills.

Thalamus

The major sensory relay station in the diencephalon that filters and projects incoming sensory inputs to the appropriate primary cortical regions.

Hypothalamus

The diencephalic control center located below the thalamus that regulates the autonomic nervous system, endocrine function, body temperature, and homeostasis.

Corpus callosum

The large commissural tract of white matter connecting the left and right cerebral hemispheres, facilitating interhemispheric communication.

Primary motor cortex

The cortical region in the frontal lobe responsible for planning and executing voluntary motor commands.

Primary somatosensory cortex

The cortical region located in the parietal lobe that directly receives incoming general sensory signals such as touch, pressure, and temperature.

Primary visual cortex

The primary cortical area located in the occipital lobe that receives raw visual signals originating from the retina via the optic nerve pathway.

Primary auditory cortex

The primary cortical area located in the temporal lobe that directly receives sound information conveyed through the vestibulocochlear nerve pathway.

Primary gustatory cortex

The primary cortical area responsible for processing incoming taste sensory signals.

Primary olfactory cortex

The primary cortical area responsible for processing incoming smell sensory signals.

Primary cortex vs. association areas

Primary cortex areas directly receive raw sensory input or initiate motor output, whereas association areas integrate, interpret, and give meaning to that information based on memories and contextual processing.

Prefrontal cortex

The anterior portion of the frontal lobe dedicated to complex decision-making, executive function, working memory, and social behavior.

Amygdala

A limbic system structure involved in processing emotion, emotional memories, and fear responses.

Hippocampus

A limbic structure essential for consolidating short-term memory into long-term memory and spatial navigation.

Cingulate gyrus

A limbic cortex fold located superior to the corpus callosum that participates in emotional processing, behavioral regulation, and autonomic responses.

Association fibers

Nerve fibers that connect different cortical regions within the same cerebral hemisphere.

Commissural fibers

Nerve fibers that connect corresponding cortical regions between the left and right cerebral hemispheres, exemplified by the corpus callosum.

Projection fibers

Nerve fibers that connect the cerebral cortex with lower brain regions, the brainstem, or the spinal cord.

Olfactory nerve (CNI)

a sensory cranial nerve dedicated to mediating the sense of smell.

Optic nerve (CNII)

a sensory cranial nerve that carries visual photons and signals from the retina to the brain.

Oculomotor nerve (CNIII)

Cranial nerve III, a predominantly motor nerve that innervates extrinsic eye muscles to control eye movements, pupil constriction, and eyelid elevation.

Trochlear nerve (CNIV)

a motor cranial nerve that innervates the superior oblique extrinsic eye muscle.

Trigeminal nerve (CNV)

a mixed nerve providing general sensory innervation to the face and motor innervation to the muscles of mastication.

Abducens nerve (CNVI)

a motor nerve that innervates the lateral rectus muscle to abduct the eye.

Facial nerve (CNVII)

a mixed nerve controlling muscles of facial expression, taste sensation from the anterior tongue, and parasympathetic control of salivary and lacrimal glands.

Vestibulocochlear nerve (CNVIII)

a sensory nerve that transmits hearing and balance signals inward from the inner ear apparatus.

Glossopharyngeal nerve (CNIX)

a mixed nerve mediating taste and sensation from the posterior tongue, swallowing movements, and salivary secretion.

Vagus nerve (CNX)

an extensive mixed nerve providing extensive parasympathetic motor innervation to thoracic and abdominal organs as well as visceral sensory feedback.

Accessory nerve (CNXI)

Cranial nerve XI, a motor nerve that innervates the trapezius and sternocleidomastoid muscles to move the head and neck.

Hypoglossal nerve (CNXII)

a motor cranial nerve that innervates the intrinsic and extrinsic muscles of the tongue for speech and swallowing.

Innervate

To supply an organ, muscle, or tissue with nerves or nerve impulses.

Meninges

The three connective tissue membranes that envelop the brain and spinal cord, ordered from outermost to innermost as the dura mater, arachnoid mater, and pia mater.

Subarachnoid space

The space situated between the arachnoid mater and the pia mater that contains cerebrospinal fluid and major blood vessels.

Epidural space

The space located between the dura mater and the surrounding vertebral wall containing adipose tissue and blood vessels.

Anterior root

The motor root of a spinal nerve that carries motor axons emerging from the anterior horn of the spinal cord to peripheral effectors.

Posterior root

The sensory root of a spinal nerve that carries incoming sensory axons from peripheral receptors into the posterior horn of the spinal cord.

Anterior ramus

The larger branch of a spinal nerve that carries both sensory and motor axons to innervate the anterior and lateral trunk and the upper and lower limbs.

Posterior ramus

The branch of a spinal nerve that carries both sensory and motor axons to innervate the deep muscles and skin of the back.

Plexus

An interconnected anatomical network of intersecting nerves formed by anterior rami of spinal nerves.

Phrenic nerve

A major branch of the cervical plexus that innervates the diaphragm to drive respiration.

Brachial plexus

A network of nerve fibers that gives rise to the axillary, musculocutaneous, radial, median, and ulnar nerves to innervate the shoulder, arm, and hand.

Axillary nerve

A nerve arising from the brachial plexus that innervates the deltoid and teres minor muscles and the skin over the shoulder.

Musculocutaneous nerve

A nerve arising from the brachial plexus that innervates the anterior arm flexor muscles and the lateral forearm skin.

Radial nerve

A nerve arising from the brachial plexus that innervates the posterior extensor muscles of the arm and forearm as well as the dorsal hand skin.

Median nerve

A nerve arising from the brachial plexus that innervates most anterior forearm flexor muscles and the lateral palm and fingers.

Ulnar nerve

A nerve arising from the brachial plexus that innervates intrinsic hand muscles, the flexor carpi ulnaris, and the medial hand and digits.

Femoral nerve

A major nerve of the lumbar plexus that innervates the anterior thigh muscles and skin of the anterior thigh and medial leg.

Obturator nerve

A nerve of the lumbar plexus that innervates the adductor muscles of the medial thigh compartment.

Sciatic nerve

The largest nerve of the sacral plexus, which branches into the tibial nerve and common fibular nerve to innervate the posterior thigh, leg, and foot.

Somatic motor division

The voluntary motor pathway of the nervous system that transmits conscious motor signals from the CNS to skeletal muscles via upper and lower motor neurons.

Upper motor neurons

Neurons in the somatic motor pathway whose cell bodies are located in the cerebral cortex (primary motor cortex) or brainstem.

Lower motor neurons

Neurons in the somatic motor pathway whose cell bodies reside in the anterior horn of the spinal cord or cranial nerve nuclei, with axons exiting the CNS to synapse on skeletal muscles.

Enteric nervous system

The specialized, semi-autonomous division of the nervous system that directly regulates motility, secretion, and blood flow in the gastrointestinal tract.

Autonomic nervous system

The involuntary division of the nervous system that regulates visceral target organs (heart, airways, pupils, and digestion) through sympathetic and parasympathetic two-neuron pathways.

Parasympathetic tone

The continuous baseline background activity of motor fibers dominating organ states at rest (e.g., slowing heart rate and promoting digestion).

Sympathetic tone

The continuous baseline background activity of sympathetic motor fibers maintaining vascular tone and increasing activity during stress or exercise.

Special senses

Senses that rely on specialized, complex receptor organs localized within the head: taste, smell, hearing, balance, and vision.

General senses

Widely distributed somatic and visceral senses that utilize simple receptors throughout the body to detect touch, pressure, vibration, temperature, pain, and proprioception.

Chemoreceptors

Receptors that detect and respond to chemical molecules dissolved in solution, utilized in taste and smell.

Photoreceptors

Receptors located in the retina (rods and cones) that detect and transduce photons of light.

Mechanoreceptors

Receptors that respond to physical mechanical displacement, distortion, pressure, or vibrations, utilized in touch, balance, and hearing.

Thermoreceptors

Receptors that detect changes in temperature.

Nociceptors

Specialized sensory receptors that respond to potentially tissue-damaging, noxious stimuli to signal pain.

Receptive field

The specific physical area monitored by a single sensory receptor cell within which a stimulus activates that neuron.

First-order neurons

Primary sensory neurons that detect stimuli and transmit action potentials from peripheral receptors into the spinal cord or brainstem.

Second-order neurons

Interneurons in the spinal cord or brainstem that receive signals from first-order neurons, typically decussate, and relay them to the thalamus.

Third-order neurons

Sensory neurons located in the thalamus that project axons to the primary somatosensory cortex for conscious perception.

Lingual papillae

Epithelial projections on the tongue surface that house taste buds capable of sensing $5$ distinct flavors: sweet, sour, salty, bitter, and umami.

Spiral organ

The receptor organ of hearing situated inside the cochlea that contains hair cells positioned between the basilar membrane and tectorial membrane.