Nervous System: Dermatomes, Reflexes, Brain Anatomy, Meninges, and Ventricular System

Vocabulary flashcards covering spinal cord trauma, dermatomes, somatic and autonomic reflexes, gross anatomical structures of the brain, meningeal protective layers, and ventricular CSF dynamics.

Dermatome

A specific area of the skin innervated by a particular spinal nerve (with the exception of C1), clinically assessed using pinpricks and light touch to identify nerve abnormalities or the level of a spinal cord injury.

Complete Spinal Cord Injury

A spinal cord injury classification in which all sensory and motor function is entirely lost below the site of the injury.

Incomplete Spinal Cord Injury

A spinal cord injury classification in which some degree of sensory or motor function remains below the site of the injury.

Paraplegia

A loss of sensory and motor function in all or part of the trunk, legs, and pelvic organs, resulting from a spinal cord injury situated between the levels of T1 and L1.

Tetraplegia (Quadriplegia)

A loss of sensory and motor function affecting the arms, legs, trunk, and pelvic organs, produced by a spinal cord injury above the C5 vertebra.

Phrenic Nerve

The nerve that exits the spinal cord above C4 to innervate the diaphragm; damage above this level can cause respiratory failure.

Reflex

A quick, involuntary, predictable response to a stimulus that employs a neural circuit bypassing conscious decision-making regions of the brain.

Reflex Arc

The neural pathway utilized by a reflex that bypasses brain regions where conscious decisions are made, routing from somatic receptors through afferent fibers, motor neurons, and back to the effector muscle.

Autonomic (Visceral) Reflexes

Reflexes governed by autonomic neurons that involve secretion from glands or the contraction of smooth muscle, such as pupillary dilation.

Somatic Reflexes

Reflexes that involve the contraction of a skeletal muscle following stimulation by a somatic motor neuron, aiding in protection and posture maintenance.

Plantar Reflex

A neurological evaluation elicited by stroking the sole of the foot in a curved line from the heel to the toes; in healthy adults, it causes the toes to flex downward and inward.

Babinski Sign

An abnormal response to the plantar reflex maneuver in adults where the great toe dorsiflexes and the smaller toes fan outward, indicating damage to the primary motor cortex or corticospinal tract.

Cerebrum

The largest portion of the brain, characterized by surface folds and divided by a deep groove into right and left cerebral hemispheres.

Gyri

The thick, raised ridges marking the surface of the cerebrum.

Sulci

Shallow grooves that divide the gyri on the cerebral surface, with deeper grooves being designated as fissures.

Longitudinal Fissure

A deep groove that divides the cerebrum into the right and left cerebral hemispheres.

Corpus Callosum

A thick bundle of nerves running along the bottom of the longitudinal fissure that connects the right and left cerebral hemispheres.

Diencephalon

The major brain region positioned between the cerebrum and the midbrain.

Cerebellum

The second largest region of the brain, situated below the cerebrum, which contains more neurons than the rest of the brain combined.

Brainstem

The remaining structural region of the brain composed of three parts: the midbrain, the pons, and the medulla oblongata.

Cerebral Cortex

The surface layer of gray matter covering the cerebrum and cerebellum, composed of neuron cell bodies and interneurons.

Nuclei (Brain)

Patches of gray matter embedded within the white matter beneath the cerebral cortex.

Dura Mater

The tough, outermost meningeal layer comprising an outer periosteal layer attached to the inner skull and an inner meningeal layer covering the brain and continuing into the spinal cord.

Dural Sinuses

Spaces formed where the dura mater separates, functioning to collect blood that has circulated through the brain before it returns to the heart.

Falx Cerebri

An inward extension of the dura mater that dips into the longitudinal fissure to separate the right and left cerebral hemispheres.

Tentorium Cerebelli

A dural extension that stretches over the top of the cerebellum, separating it from the cerebrum.

Arachnoid Mater

The delicate middle layer of the meninges situated between the dura mater and the pia mater.

Pia Mater

The innermost meningeal layer that clings tightly to the outer surface of the brain.

Traumatic Brain Injury (TBI)

A physical trauma to the brain disrupting brain function temporarily or permanently, caused by impacts, penetrating objects, acceleration-deceleration forces, or explosion blast waves.

Concussion

A form of mild traumatic brain injury often marked by confusion, amnesia, headache, dizziness, fatigue, mood disturbances, and sensitivity to light and noise.

Chronic Traumatic Encephalopathy (CTE)

A progressive degenerative brain disease resulting from repetitive head trauma in contact sports, causing symptoms of dementia such as memory loss, aggression, confusion, and depression.

Ventricles

The four internal fluid-filled chambers of the brain, consisting of two lateral ventricles, a third ventricle, and a fourth ventricle.

Cerebral Aqueduct

A narrow canal that connects the third ventricle directly to the fourth ventricle.

Central Canal

The slender channel formed by the narrowing of the fourth ventricle that extends throughout the length of the spinal cord.

Cerebrospinal Fluid (CSF)

A clear, colorless fluid that fills the ventricles and central canal, bathes the exterior of the central nervous system, provides nutrients, cushions against trauma, and assists in homeostatic monitoring of $CO_2$.

Choroid Plexus

A specialized network of blood vessels lining the floor or wall of each brain ventricle that filters blood to produce cerebrospinal fluid.

Hydrocephalus

A condition characterized by an abnormal accumulation of cerebrospinal fluid in the brain's ventricles due to a blockage in CSF circulation, leading to ventricular expansion and elevated intracranial pressure.