Nervous Tissue, Brain, and Spinal Cord Anatomy

Flashcards covering the histological classification of nervous tissue, neuroglia, nerve coverings, brain and spinal cord anatomy, meningeal layers, ventricular circulation, and anatomical lab model identification keys.

What term defines a collection of neuron cell bodies in the central nervous system (CNS) versus the peripheral nervous system (PNS)?

In the CNS, a collection of cell bodies is called a nucleus, whereas in the PNS, it is called a ganglion.

What term defines a collection of axons in the central nervous system (CNS) versus the peripheral nervous system (PNS)?

In the CNS, a collection of axons is called a tract, whereas in the PNS, it is called a nerve.

What are the two principal cell types found in nervous tissue, and what is their primary functional characteristic?

Neurons, which are excitable, and neuroglia, which are supportive.

Which four types of neuroglia are found exclusively in the central nervous system (CNS)?

Astrocytes, microglial cells, ependymal cells, and oligodendrocytes.

What are the primary functions of astrocytes and microglial cells in the central nervous system?

Astrocytes regulate the environment and anchor neurons to blood vessels; microglial cells function as phagocytes.

What is the primary function of ependymal cells in the central nervous system?

Ependymal cells produce cerebrospinal fluid (CSF).

What is the primary function of oligodendrocytes in the CNS, and which PNS neuroglial cell performs an equivalent function?

Oligodendrocytes form myelin sheaths around axons in the CNS; Schwann cells form myelin sheaths in the PNS.

What are the two neuroglial cell types found in the peripheral nervous system (PNS) and their functions?

Satellite cells protect neuron cell bodies, and Schwann cells form the myelin sheath around axons.

What are the three structural classifications of neurons?

Bipolar, pseudo-unipolar, and multipolar.

What are the three functional classifications of neurons and the direction of their transmission?

Sensory (afferent) neurons transmit input toward the CNS; motor (efferent) neurons transmit output to effectors (muscles and glands); and interneurons (association neurons) integrate signals within the CNS.

What are the three connective tissue coverings of a peripheral nerve from outermost to innermost?

Epineurium surrounds the whole nerve, perineurium surrounds nerve fascicles, and endoneurium surrounds individual axons within a fascicle.

What are the four major brain divisions and their primary functions?

The cerebrum performs higher mental functions, interprets sensory stimuli, and plans/initiates movement; the diencephalon processes, integrates, and relays information, maintains homeostasis, and regulates biological rhythms; the cerebellum monitors and coordinates movement; and the brainstem maintains homeostasis, controls reflexes, monitors movement, and relays information.

How are gray matter and white matter organized within the cerebrum?

The cerebrum has outer gray matter (cerebral cortex), inner gray matter (basal nuclei), and deep cerebral white matter composed of myelinated axons/tracts.

What are the three types of white matter tracts in the cerebrum?

Association fibers, commissural fibers (such as the corpus callosum), and projection fibers.

How are gyri, sulci, and fissures defined on the surface of the cerebrum?

A gyrus is an elevated ridge, a sulcus is a shallow groove, and a fissure is a deep groove.

What deep groove separates the left and right cerebral hemispheres?

The longitudinal fissure.

What five lobes make up the cerebral cortex?

Frontal, parietal, temporal, occipital, and insula.

What structures comprise the diencephalon?

Thalamus, epithalamus (including the pineal gland), hypothalamus, infundibulum, pituitary gland, subthalamus, and mammillary body.

In the cerebellum, what names are given to the internal white matter and the external gray matter?

The internal branching white matter is the arbor vitae, and the outer gray matter is the cerebellar cortex.

What three regions compose the brainstem from superior to inferior?

Midbrain, pons, and medulla oblongata.

What are the layers of the cranial meninges and their spaces from superficial to deep?

Dura mater (periosteal and meningeal layers), subdural space, arachnoid mater, subarachnoid space (containing CSF), and pia mater.

What four ventricles make up the brain ventricular system, and what connects the third and fourth ventricles?

Two lateral ventricles, the third ventricle, and the fourth ventricle; the cerebral aqueduct connects the third ventricle to the fourth ventricle.

How is cerebrospinal fluid (CSF) formed by the choroid plexuses?

CSF forms as a filtrate containing glucose, oxygen, vitamins, and ions produced across capillary walls and ependymal cells lining the ventricles.

What are the four steps of cerebrospinal fluid (CSF) circulation?

1. The choroid plexus of each ventricle produces CSF. 2. CSF flows through the ventricles and enters the subarachnoid space via the median and lateral apertures. 3. CSF flows through the subarachnoid space. 4. CSF is absorbed into the dural venous sinuses via arachnoid granulations.

At what anatomical landmarks does the spinal cord begin and end, and how many pairs of spinal nerves does it give rise to?

It begins at the foramen magnum and terminates at the $L2$ vertebral level, giving rise to $31$ pairs of spinal nerves.

What are the conus medullaris, cauda equina, and filum terminale?

The conus medullaris is the tapered terminal end of the spinal cord; the cauda equina is the collection of nerve roots extending inferiorly through the vertebral canal; and the filum terminale is an extension of pia mater anchoring the spinal cord to the coccyx.

What structures anchor the spinal cord within the dural sheath and vertebral canal?

The filum terminale and denticulate ligaments.

How do spinal meninges differ from cranial meninges regarding the epidural space?

The spinal cord possesses an epidural space filled with fat superficial to the dura mater, whereas the cranial dura mater is fused directly to the periosteum of the skull.

How are gray matter and white matter distributed in a cross section of the spinal cord?

Inner gray matter forms dorsal, lateral, and ventral horns; outer white matter forms funiculi (dorsal, lateral, and ventral) carrying ascending sensory and descending motor tracts.

On the Denoyer-Geppert giant brain model, which numbers designate the precentral gyrus (motor area) and postcentral gyrus (sensory area)?

Number 10 corresponds to the precentral gyrus (somatomotor cortex), and number 11 corresponds to the postcentral gyrus (somatosensory cortex).

On the Verimp Atlay cranial meninges model, what are layers 1 through 6 overlying the cranial cavity?

1. Skin, 2. Subcutaneous tissue, 3. Epicranial aponeurosis, 4. Subaponeurotic space, 5. Pericranium, and 6. Skull.

On the 3B VH410 cerebral ventricles model, what structure is designated by number 4?

The interventricular foramen (foramen of Monro).