Martini Chap. 14

What is the average length of an adult spinal cord?

About 18 inches (45 cm)

What is the maximum width of a section of the spinal cord?

About 14 mm (0.55 in)

What divides the spinal cord into left and right portions?

The anterior median fissure and posterior median sulcus

What are the enlargements of the spinal cord?

Cervical enlargement (supplies nerves to shoulder girdles and upper limbs) and lumbar enlargement (innervates pelvis and lower limbs)

What is the conus terminalis?

The tapered end of the spinal cord around L2/L3

What is the function of the filum terminale?

Provides longitudinal support to the spinal cord

How many cervical vertebrae are there?

Seven cervical vertebrae but eight cervical nerves

What are the three layers of spinal meninges?

Pia mater, arachnoid mater, and dura mater

What is the function of the dura mater?

Outermost covering of the spinal cord, providing toughness and fibrous protection

What is the epidural space?

The region between the dura mater and the walls of the vertebral canal containing blood vessels and adipose tissue

What is the role of the arachnoid trabeculae?

Extends between the arachnoid membrane and the pia mater, supporting the structure

What is contained in the subarachnoid space?

Cerebrospinal fluid (CSF)

What do the posterior gray horns contain?

Somatic and visceral sensory nuclei

What do the anterior gray horns contain?

Somatic motor nuclei

What are nerve plexuses?

Networks formed by the ventral rami of spinal nerves that innervate specific body regions

What is a reflex arc?

The wiring behind a reflex, starting at a receptor and ending at a peripheral effector

What is the difference between innate and acquired reflexes?

Innate reflexes are formed during development, while acquired reflexes are learned motor patterns

What is a monosynaptic reflex?

A reflex arc where a sensory neuron directly synapses on a motor neuron

What is an example of a monosynaptic reflex?

The stretch reflex

What is a polysynaptic reflex?

A reflex arc involving one or more interneurons between the sensory receptor and the peripheral effector

What are the three primary brain vesicles?

Prosencephalon, mesencephalon, and rhombencephalon

What are the secondary brain vesicles derived from the primary vesicles?

Telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon

What separates the two lateral ventricles?

The septum pellucidum

What connects the third ventricle to the fourth ventricle?

The mesencephalic aqueduct (aqueduct of Sylvius)

What is the flow of cerebrospinal fluid (CSF) through the ventricles?

Lateral ventricles -> foramen of Monro -> third ventricle -> cerebral aqueduct -> fourth ventricle -> central canal

What are the two layers of the dura mater in the cranial cavity?

Outer (endosteal) layer and inner (meningeal) layer

What is the function of dural folds?

Provide additional stabilization and support to the brain

What are dural sinuses?

Large collecting veins located between the two layers of a dural fold

What are the three largest dural folds?

Falx cerebri, tentorium cerebelli, and falx cerebelli.

What is the function of the falx cerebri?

It projects between the cerebral hemispheres in the longitudinal fissure and contains the superior and inferior sagittal sinuses.

What does the tentorium cerebelli do?

It separates and protects the cerebellar hemispheres from the cerebrum.

What is the role of the falx cerebelli?

It divides the two cerebellar hemispheres, located inferior to the tentorium cerebelli.

What is the choroid plexus?

A structure consisting of specialized ependymal cells and permeable capillaries that produces cerebrospinal fluid (CSF).

How much cerebrospinal fluid does the choroid plexus produce daily?

About 500 mL per day.

What is the total volume of cerebrospinal fluid at any moment?

Approximately 150 mL.

How often is the entire volume of CSF replaced?

About every 8 hours.

How does CSF enter the subarachnoid space?

Through two lateral apertures and a median aperture after circulating through the ventricles.

What are arachnoid granulations?

Clusters of arachnoid villi that drain CSF into the venous sinuses.

What does the central sulcus separate?

The anterior frontal lobe from the posterior parietal lobe.

What is the primary motor cortex located?

In the precentral gyrus, which is in front of the central sulcus.

What is the primary somatosensory cortex located?

In the postcentral gyrus, which is behind the central sulcus.

What is the function of association areas in the cortex?

To interpret data from primary areas, allowing recognition of sensations.

What does Wernicke's area control?

The ability to interpret spoken and written language.

What is hemispheric lateralization?

The phenomenon where each hemisphere of the brain is responsible for specific functions.

What is the dominant hemisphere for most people?

The left hemisphere, which contains language-based skills and analytical tasks.

What is the role of the right hemisphere?

To analyze sensory information and relate the body to the sensory environment.

What are the components of the basal ganglia?

Caudate nucleus, lentiform nucleus (globus pallidus and putamen), and amygdaloid body.

What is the function of the caudate nucleus?

To receive information from sensory, motor, and association areas of the cerebral cortex.

What is the limbic system responsible for?

Establishing emotion, linking conscious and autonomic functions, and memory storage and retrieval.

What is the fornix?

A tract of white matter that connects the hippocampus with the hypothalamus.

What does the thalamus do?

Acts as the final relay point for ascending sensory information before it reaches the primary sensory cortex.

What are the main functions of the hypothalamus?

Regulating rage, fear, pain, sexual arousal, and pleasure.

What is the tectum of the mesencephalon?

The roof of the midbrain that contains the corpora quadrigemina, processing visual and auditory sensations.

What is the function of the superior colliculus?

To receive visual inputs and process visual reflexes.

What is the function of the inferior colliculus?

To receive auditory data and control reflexive movements in response to sound.

What does the red nucleus do?

Issues subconscious motor commands affecting muscle tone and limb position.

What is the function of the nucleus in the brain?

It receives information from the cerebrum and cerebellum to issue subconscious motor commands affecting muscle tone and limb position.

What role does the substantia nigra play in the basal nuclei?

It can inhibit or stimulate the basal nuclei's direct and indirect pathways by releasing dopamine.

What are the cerebral peduncles?

Nerve fiber bundles on the anterior sides of the mesencephalon that consist of descending fibers to the cerebellum and carry voluntary motor commands from the primary motor cortex.

What is the reticular activating system (RAS)?

A component of the reticular formation that, when stimulated, increases alertness and attention.

What are the two primary functions of the cerebellum?

Adjusting postural muscles for balance and fine-tuning movements controlled at conscious and subconscious levels.

What are folia in the context of the cerebellum?

Folds of the cerebellum's surface, less prominent than the gyri of the cerebral hemispheres.

What separates the anterior and posterior lobes of the cerebellum?

The primary fissure.

What is the vermis?

A narrow band along the midline of the cerebellum that divides it into two lobes.

What are Purkinje cells?

Highly branched cells in the cerebellar cortex that contribute to its gray matter.

What is the arbor vitae?

The white matter of the cerebellum, also known as the 'tree of life.'

What do the superior cerebellar peduncles connect?

They link the cerebellum with nuclei in the midbrain, diencephalon, and cerebrum.

What is the function of the middle cerebellar peduncles?

They connect the cerebellar hemispheres with sensory and motor nuclei in the pons.

What do the inferior cerebellar peduncles permit?

Communication between the cerebellum and nuclei of the medulla oblongata.

What is the primary role of the pons?

To link the cerebellar hemispheres with the midbrain, diencephalon, cerebrum, and spinal cord.

Which cranial nerves have sensory and motor nuclei in the pons?

Cranial nerves 5 (CN V), 6 (CN VI), 7 (CN VII), and 8 (CN VIII).

What are the two respiratory centers in the pons?

The apneustic center and the pneumotaxic center.

What is the medulla oblongata's relationship with the spinal cord?

It is continuous with the spinal cord and connects the brain with the spinal cord.

What are autonomic nuclei in the medulla oblongata responsible for?

Regulating vital autonomic functions, including cardiovascular and respiratory activities.

What do the cardiovascular centers in the medulla oblongata adjust?

Heart rate, strength of heart contractions, and blood flow.

What is the role of the sensory/motor nuclei of cranial nerves in the medulla oblongata?

They provide motor commands to muscles of the pharynx, neck, and back, as well as to visceral organs.

What is the function of the nucleus gracilis and nucleus cuneatus?

They pass somatic sensory information to the thalamus.

What is a sensory receptor?

A specialized cell or dendrite that monitors specific conditions in the body or external environment.

What is the difference between sensation and perception?

Sensation is the arriving information to the CNS, while perception is the conscious awareness of that sensation.

What is a first-order neuron?

The sensory neuron that delivers sensation to the CNS.

What happens to the axon of a second-order neuron?

It crosses over to the opposite side of the CNS, which is why information is received on the opposite side of the thalamus.

What are the three primary somatic sensory pathways?

Posterior column pathway, spinothalamic pathway, and spinocerebellar pathway.

What sensations does the posterior column pathway carry?

Localized fine touch, pressure, vibration, and proprioception.

What does the spinothalamic pathway provide?

Conscious sensations of poorly localized (crude) touch, pressure, pain, and temperature.

What is the function of the spinocerebellar pathway?

To carry proprioceptive information to the cerebellum without reaching conscious awareness.