The Central Nervous System Key Words

integumentary

Aside from the nervous system, which other organ system develops out of the ectoderm?

mesencephalon

Which primary vesicle of the embryonic nervous system does not differentiate into more vesicles at the secondary stage?

thalamus, hypothalamus, retina

Which adult structure(s) arises from the diencephalon?

craniofacial bone

Which non-nervous tissue develops from the neuroectoderm?

neural crest

Which structure is associated with the embryologic development of the peripheral nervous system?

**brain stem**

region of the adult brain that includes the midbrain, pons, and medulla oblongata and develops from the mesencephalon, metencephalon, and myelencephalon of the embryonic brain

**cephalic flexure**

curve in midbrain of the embryo that positions the forebrain ventrally

**diencephalon**

region of the adult brain that retains its name from embryonic development and includes the thalamus and hypothalamus

**forebrain**

anterior region of the adult brain that develops from the prosencephalon and includes the cerebrum and diencephalon

**hindbrain**

posterior region of the adult brain that develops from the rhombencephalon and includes the pons, medulla oblongata, and cerebellum

**mesencephalon**

primary vesicle of the embryonic brain that does not significantly change through the rest of embryonic development and becomes the midbrain

**metencephalon**

secondary vesicle of the embryonic brain that develops into the pons and the cerebellum

**midbrain**

middle region of the adult brain that develops from the mesencephalon

**myelencephalon**

secondary vesicle of the embryonic brain that develops into the medulla

**neural crest**

tissue that detaches from the edges of the neural groove and migrates through the embryo to develop into peripheral structures of both nervous and non-nervous tissues

**neural fold**

elevated edge of the neural groove

**neural groove**

region of the neural plate that folds into the dorsal surface of the embryo and closes off to become the neural tube

**neural plate**

thickened layer of neuroepithelium that runs longitudinally along the dorsal surface of an embryo and gives rise to nervous system tissue

**neural tube**

precursor to structures of the central nervous system, formed by the invagination and separation of neuroepithelium

**neuraxis**

central axis to the nervous system, from the posterior to anterior ends of the neural tube; the inferior tip of the spinal cord to the anterior surface of the cerebrum

**primary vesicle**

initial enlargements of the anterior neural tube during embryonic development that develop into the forebrain, midbrain, and hindbrain

**prosencephalon**

primary vesicle of the embryonic brain that develops into the forebrain, which includes the cerebrum and diencephalon

**rhombencephalon**

primary vesicle of the embryonic brain that develops into the hindbrain, which includes the pons, cerebellum, and medulla

**secondary vesicle**

five vesicles that develop from primary vesicles, continuing the process of differentiation of the embryonic brain

**telencephalon**

secondary vesicle of the embryonic brain that develops into the cerebrum

internal carotid artery

What blood vessel enters the cranium to supply the brain with fresh, oxygenated blood?

dura mater

Which layer of the meninges surrounds and supports the sinuses that form the route through which blood drains from the CNS?

ependymal

What type of glial cell is responsible for filtering blood to produce CSF at the choroid plexus?

third ventricle

Which portion of the ventricular system is found within the diencephalon?

disruption of blood to the brain

What condition causes a stroke?

**anastomosis**

area where vessels unite to form interconnections that normally allow blood to circulate to a region even if there may be partial blockage in another branch.

**anterior spinal artery**

blood vessel from the merged branches of the vertebral arteries that runs along the anterior surface of the spinal cord

**arachnoid granulation**

outpocket of the arachnoid membrane into the dural sinuses that allows for reabsorption of CSF into the blood

**arachnoid mater**

middle layer of the meninges named for the spider-web–like trabeculae that extend between it and the pia mater

**arachnoid trabeculae**

filaments between the arachnoid and pia mater within the subarachnoid space

**basilar artery**

blood vessel from the merged vertebral arteries that runs along the dorsal surface of the brain stem

**carotid canal**

opening in the temporal bone through which the internal carotid artery enters the cranium

**central canal**

hollow space within the spinal cord that is the remnant of the center of the neural tube

**cerebral aqueduct**

connection of the ventricular system between the third and fourth ventricles located in the midbrain

**choroid plexus**

specialized structures containing ependymal cells lining blood capillaries that filter blood to produce CSF in the four ventricles of the brain

**circle of Willis**

unique anatomical arrangement of blood vessels around the base of the brain that maintains perfusion of blood into the brain even if one component of the structure is blocked or narrowed

**common carotid artery**

blood vessel that branches off the aorta (or the brachiocephalic artery on the right) and supplies blood to the head and neck

**dura mater**

tough, fibrous, outer layer of the meninges that is attached to the inner surface of the cranium and vertebral column and surrounds the entire CNS

**dural sinus**

any of the venous structures surrounding the brain, enclosed within the dura mater, which drain blood from the CNS to the common venous return of the jugular veins

**foramen magnum**

large opening in the occipital bone of the skull through which the spinal cord emerges and the vertebral arteries enter the cranium

**fourth ventricle**

the portion of the ventricular system that is in the region of the brain stem and opens into the subarachnoid space through the median and lateral apertures

**internal carotid artery**

branch from the common carotid artery that enters the cranium and supplies blood to the brain

**interventricular foramina**

openings between the lateral ventricles and third ventricle allowing for the passage of CSF

**jugular veins**

blood vessels that return “used” blood from the head and neck

**lateral apertures**

pair of openings from the fourth ventricle to the subarachnoid space on either side and between the medulla and cerebellum

**lateral ventricles**

portions of the ventricular system that are in the region of the cerebrum

**lumbar puncture**

procedure used to withdraw CSF from the lower lumbar region of the vertebral column that avoids the risk of damaging CNS tissue because the spinal cord ends at the upper lumbar vertebrae

**median aperture**

singular opening from the fourth ventricle into the subarachnoid space at the midline between the medulla and cerebellum

**meninges**

protective outer coverings of the CNS composed of connective tissue

**occipital sinuses**

**orthostatic reflex**

sympathetic function that maintains blood pressure when standing to offset the increased effect of gravity

**pia mater**

thin, innermost membrane of the meninges that directly covers the surface of the CNS

**sigmoid sinuses**

dural sinuses that drain directly into the jugular veins

**straight sinus**

dural sinus that drains blood from the deep center of the brain to collect with the other sinuses

**subarachnoid space**

space between the arachnoid mater and pia mater that contains CSF and the fibrous connections of the arachnoid trabeculae

**superior sagittal sinus**

dural sinus that runs along the top of the longitudinal fissure and drains blood from the majority of the outer cerebrum

**third ventricle**

portion of the ventricular system that is in the region of the diencephalon; sends messages to and receives messages from the lateral ventricles

**transverse sinuses**

dural sinuses that drain along either side of the occipital–cerebellar space

**ventricles**

remnants of the hollow center of the neural tube that are spaces for cerebrospinal fluid to circulate through the brain

**vertebral arteries**

arteries that ascend along either side of the vertebral column through the transverse foramina of the cervical vertebrae and enter the cranium through the foramen magnum

myelinated axons

Which structure predominates in the white matter of the brain?

nerve

Which term describes a bundle of axons in the peripheral nervous system?

parietal

Which lobe of the cerebral cortex is responsible for generating motor commands?

hypothalamus

What region of the diencephalon coordinates homeostasis?

pons

What level of the brain stem is the major input to the cerebellum?

anterior horn

What region of the spinal cord contains motor neurons that direct the movement of skeletal muscles?

cerebral cortex

Brodmann’s areas map different regions of the ________ to particular functions.

**ascending pathway**

fiber structure that relays sensory information from the periphery through the spinal cord and brain stem to other structures of the brain

**association area**

region of cortex connected to a primary sensory cortical area that further processes the information to generate more complex sensory perceptions

**chief sensory nucleus**

component of the trigeminal nuclei that is found in the pons

**decussate**

to cross the midline, as in fibers that project from one side of the body to the other

**dorsal column system**

ascending tract of the spinal cord associated with fine touch and proprioceptive sensations

**fasciculus cuneatus**

lateral division of the dorsal column system composed of fibers from sensory neurons in the upper body

**fasciculus gracilis**

medial division of the dorsal column system composed of fibers from sensory neurons in the lower body

**medial lemniscus**

fiber tract of the dorsal column system that extends from the nuclei gracilis and cuneatus to the thalamus, and decussates

**mesencephalic nucleus**

component of the trigeminal nuclei that is found in the midbrain

**multimodal integration area**

region of the cerebral cortex in which information from more than one sensory modality is processed to arrive at higher level cortical functions such as memory, learning, or cognition

**nucleus cuneatus**

medullary nucleus at which first-order neurons of the dorsal column system synapse specifically from the upper body and arms

**nucleus gracilis**

medullary nucleus at which first-order neurons of the dorsal column system synapse specifically from the lower body and legs

**primary sensory cortex**

region of the cerebral cortex that initially receives sensory input from an ascending pathway from the thalamus and begins the processing that will result in conscious perception of that modality

**sensory homunculus**

topographic representation of the body within the somatosensory cortex demonstrating the correspondence between neurons processing stimuli and sensitivity

**spinal trigeminal nucleus**

component of the trigeminal nuclei that is found in the medulla

**spinothalamic tract**

ascending tract of the spinal cord associated with pain and temperature sensations

**anterior corticospinal tract**

division of the corticospinal pathway that travels through the ventral (anterior) column of the spinal cord and controls axial musculature through the medial motor neurons in the ventral (anterior) horn

**Betz cells**

output cells of the primary motor cortex that cause musculature to move through synapses on cranial and spinal motor neurons

**Broca’s area**

region of the frontal lobe associated with the motor commands necessary for speech production

**cerebral peduncles**

segments of the descending motor pathway that make up the white matter of the ventral midbrain

**cervical enlargement**

region of the ventral (anterior) horn of the spinal cord that has a larger population of motor neurons for the greater number of and finer control of muscles of the upper limb

**corneal reflex**

protective response to stimulation of the cornea causing contraction of the orbicularis oculi muscle resulting in blinking of the eye

**corticobulbar tract**

connection between the cortex and the brain stem responsible for generating movement

**corticospinal tract**

connection between the cortex and the spinal cord responsible for generating movement

**executive functions**

cognitive processes of the prefrontal cortex that lead to directing goal-directed behavior, which is a precursor to executing motor commands

**extrapyramidal system**

pathways between the brain and spinal cord that are separate from the corticospinal tract and are responsible for modulating the movements generated through that primary pathway

**frontal eye fields**

area of the prefrontal cortex responsible for moving the eyes to attend to visual stimuli