P3-2, Ex. 17, Gross Anatomy of the Brain & Cranial Nerves

fornix

A long projection of the hippocampus that connects to other nuclei in the limbic system

frontal lobe

A region of the cerebral cortex that has specialized areas for movement, abstract thinking, planning, memory, and judgement, while functionally containing the primary motor cortex, the premotor and prefrontal cortices.

occipital lobe

A region of the cerebral cortex that processes visual information

interthalamic adhesion

A small, midline mass of gray matter that connects the right and left thalamic bodies

projection fiber tracts

CNS nerve fibers that carries up-and-down communication between the cerebrum and lower CNS areas

association fiber tracts

CNS nerve fibers that provides for back-and-forth communication between different parts of the same cerebral hemisphere

(+) Patients with unresponsive wakefulness syndrome (UWS) often reflexively respond to visual and auditory stimuli. Explain how this phenomenon relates to the unaffected parts of their brain involved in sensory input.

In UWS, the major relay station for the cerebral cortex, the thalamus, has been affected and sensory input to the cortex has been decreased if not eliminated completely. Since some visual and auditory inputs are relayed through the corpora quadrigemina they remain unaffected by the damage in the thalamus and may still function.

(+) A brain hemorrhage within the region of the right internal capsule results in paralysis of the left side of the body. Explain why the left side (rather than the right side) is affected.

Most of the descending fibers from the cerebral cortex decussate in the medullary pyramids and are therefore contralateral in their effector sites. Therefore a stroke in the right hemisphere will affect motor function on the left side of the body.

(+) Explain why trauma to the brain stem is often much more dangerous than trauma to the frontal lobes.

The brain stem controls many of the body's autonomic functions such as respiration, heart rate, and vasomotor tone (i.e., blood pressure), while the frontal lobe is more involved with cognitive thought and personality. Trauma to the brain stem is life threatening while trauma to the frontal lobes, while serious, would not be as detrimental in the short term.

(+) Patients with unresponsive wakefulness syndrome (UWS) have lost awareness of self and their environment. In many cases, there is no damage to the cerebral cortex or the brain stem. If signal transmission to the cerebral cortex is affected, what part of the brain is most likely to have been damaged?

The thalamus.

olfactory bulb

a brain structure located above the nasal cavity beneath the frontal lobes

pons

a brain structure that relays information from the cerebellum to the rest of the brain

tentorium cerebella

a dural fold separating the cerebrum from the cerebellum

falx cerebri

a dural fold that attaches the cerebrum to the crista galli of the skull

choroid plexus

a highly vascular portion of the lining of the ventricles that secretes CSF

cerebral aqueduct

a narrow tube interconnecting the third and fourth ventricles of the brain, located in the center of the mesencephalon

hypothalamus

a neural structure lying below the thalamus; site of regulation of body temperature and water balance; helps govern the endocrine system via the pituitary gland, and is linked to emotion; most important autonomic center

abducens nerve (VI)

a primarily motor nerve that provides somatic motor fibers to superior oblique muscle that moves the eyeball (SO4)

lateral ventricles

a set of paired ventricles (the first and second ventricles) lying within the cerebral hemispheres

midbrain

a small part of the brain above the pons that integrates sensory information and relays it upward

subarachnoid space

a space in the meninges beneath the arachnoid membrane and above the pia mater that contains CSF

central canal

a tiny, CSF-containing channel found within the spinal cord and inferior medulla oblongata

anterior commisure

additional inter-hemisphere connection, between anterior cortex, esp of temporal lobes

central sulcus

anatomically separates the frontal lobe and precentral gyrus from the parietal lobe and postcentral gyrus; is the functional separation between the primary motor cortex and the primary somatosensory cortex

cerebellum ('little brain') (hindbrain)

brain region most involved in producing smooth, coordinated skeletal muscle activity.

cerebral aqueduct

canal that connects the third and fourth ventricles

The convolutions (gyri) of the cerebral cortex are important because they increase the _______________

cerebral surface area

medulla oblongata

contains autonomic centers, which regulate blood pressure, heart rate, and respiratory rhythm, as well as coughing, sneezing, and swallowing centers

facial (VII)

cranial nerve involved in Bell's palsy (facial paralysis)

trigeminal (V)

cranial nerve involved in chewing food (mastication)

trigeminal (V)

cranial nerve involved in feeling a toothache

vestibulocochlear (VIII)

cranial nerve involved in listening to music and in seasickness

oculomotor (III)

cranial nerve involved in raising the eyelids and in pupillary constriction

optic (II)

cranial nerve involved in reading the newspaper

accessory (XI)

cranial nerve involved in rotating the head

facial (VII)

cranial nerve involved in secretion of saliva and in tasting well-seasoned food

vagus (X)

cranial nerve involved in slowing the heart and in increasing motility of the digestive tract

olfactory (I)

cranial nerve involved in smelling a flower

longitudinal fissure

deep sulcus that separates the two cerebral hemispheres

embryologic forebrain

embryologic precursor to the adult cerebral hemispheres and the diencephalon, which includes the thalamus, optic chiasma, and hypothalamus

embryologic hindbrain

embryologic precursor to the medulla oblongata, pons, and cerebellum

transverse cerebral fissure

fissure that structurally separates the occipital lobe of the cerebrum or cerebral cortex from the cerebellum

temporal lobe

functionally contains the primary auditory cortex that translates sounds from the cochlea into different perceptions (e.g., meanings and memories) and also has Wernicke's area for the understanding of speech

basal nuclei (basal ganglia)

gray matter areas located deep within the white matter of the cerebral hemispheres that collectively contain the caudate nucleus and putamen

thalamus

important synapse site for afferent fibers traveling to the sensory cortex

function of the basal nuclei (basal ganglia)

involved in the regulation, modulation, and refinement of voluntary motor activity

corpus callosum

large fiber tract connecting the cerebral hemispheres

dural venous sinuses

large veins in the dura mater that drain the cranium

optic tract

leads from optic chiasma to terminate in lateral geniculate body of the thalamus

corpora quadrigemina

located in the midbrain; contains reflex centers for vision and hearing

arachnoid mater

middle meningeal layer located inferior to the dura mater and superior to the pia mater; like a spider's cobweb in structure

hypoglossal nerve (XII)

mixed (but primarily motor in function) nerve that carries somatic motor fibers to muscles of tongue

accessory nerve (XI)

mixed (but primarily motor in function) nerve that provides somatic motor fibers to sternocleidomastoid and trapezius muscles

trigeminal nerve (V)

mixed nerve for major facial sensation; conducts sensory impulses from skin of face and anterior scalp, from mucosae of mouth and nose, and from surface of eyes; mandibular division also contains motor fibers that innervate muscles of mastication and muscles of floor of mouth

facial nerve (VII)

mixed nerve that supplies somatic motor fibers to muscles of facial expression and the posterior belly of the digastric muscle; parasympathetic motor fibers to lacrimal and salivary glands; carries sensory fibers from taste receptors of anterior tongue

glossopharyngeal nerve (IX)

mixed nerve that supplies somatic motor fibers to serve the pharyngeal muscles, and parasympathetic motor fibers to serve the salivary glands; sensory fibers carry impulses from the pharynx, tonsils, posterior tongue (taste buds), and from chemoreceptors and pressure receptors of carotid artery

vagus nerve (X)

mixed nerve with fibers that carry somatic motor impulses to pharynx and larynx and sensory fibers from same structures; very large portion is composed of parasympathetic motor fibers, which supply heart and smooth muscles of abdominal visceral organs; transmits sensory impulses from viscera

vestibulocochlear nerve (VIII)

mostly sensory nerve that consists of the vestibular branch that transmits impulses associated with sense of equilibrium from vestibular apparatus and semicircular canals; cochlear branch transmits impulses associated with hearing from cochlea; small motor component adjusts the sensitivity of the sensory receptors

gyrus

on upward projection of the cerebral cortex or an elevated ridge of cerebral tissue

cerebral hemisphere

one-half (left or right) of the cerebrum, the topmost part of the brain.

midbrain

portion of the brainstem where the cerebral peduncles are located

parietal lobe

portion of the cerebral cortex lying at the top of the head and toward the rear; receives sensory input for touch and body position

oculomotor nerve (III)

primarily motor nerve that provides somatic motor fibers to inferior oblique and superior, inferior, and medial rectus muscles, which direct eyeball, and levator palpebrae muscles of the superior eyelid; parasympathetic fibers to smooth muscle controlling lens shape and pupil size

trochlear nerve (IV)

primarily motor nerve that provides somatic motor fibers to superior oblique muscle that moves the eyeball

mamillary body

process olfactory sensations and controls reflex movements associated with eating

optic nerve (II)

purely sensory nerve that carries afferent impulses associated with vision

mamillary bodies

relay stations for olfactory pathways

cerebellum

responsible for regulation of posture and coordination of complex muscular movements

optic chiasma

site where medial fibers of the optic nerves cross

parieto-occipital sulcus

structural separation between the parietal lobe and the occipital lobe; it functionally contains the primary visual cortex

lateral sulcus

structural separation between the parietal lobe, temporal lobe, and frontal lobe

choroid plexus

structure that produces the CSF

arachnoid villi

structures instrumental in returning CSF to the venous blood in the dural venous sinuses

arachnoid villi

structures that return cerebrospinal fluid to the venous blood in the dural sinuses

precentral gyrus

the area that is structurally anterior to the central sulcus and is functionally known as the primary motor cortex

postcentral gyrus

the area that is structurally posterior to the central sulcus and is functionally known as the primary somatosensory cortex

brain stem

the connection between the brain and spinal cord that contains the midbrain, pons, & medulla oblongata

medulla oblongata

the continuation of the spinal cord within the skull, forming the lowest part of the brainstem and containing control centers for the heart and lungs

pituitary gland

the endocrine system's most influential gland, located at the base of the brain, beneath the hypothalamus; regulates growth and controls other endocrine glands

pineal gland

the gland that plays a major role in sexual development, sleep, and metabolism; secretes melatonin

lateral aperture

the inferolateral opening of the fourth ventricle that connects the ventricles with the subarachnoid space

third ventricle

the midline ventricle that conducts cerebrospinal fluid from the lateral ventricles to the fourth ventricle

pia mater

the most deep meningeal brain covering; delicate, soft, and highly vascular

dura mater

the most superior meningeal brain covering; composed of tough fibrous CT

white matter

the nervous matter composed of myelinated nerve fibers

gray matter

the nervous matter composed of neuronal cell bodies

pons

the part of the brainstem that links the medulla oblongata and the thalamus

fourth ventricle

the passageway within the pons that receives cerebrospinal fluid from the third ventricle and releases it to surround the brain and spinal cord

olfactory tract

the path along which the olfactory receptors send their electrical messages to the brain

median aperture

the superomedial opening fourth ventricle that connects to the subarachnoid space

fourth ventricle

the ventricle located between the cerebellum and the dorsal pons, in the center of the metencephalon

optic chiasma

the x-shaped crossing point of the optic nerves from the two eyes at the base of the brain

septum pellucidum

thin membrane that separates lateral ventricles

III, IV, VI

three cranial nerves involved in "rolling" the eyes

I, II, VIII

three cranial nerves that are purely or mostly sensory in function

interventricular foramen

tiny pore-like structure that connects the lateral ventricles to the third ventricle