Lecture Exam Five (14.3 The Hindbrain and Midbrain)

The brain stem consists of these three structures

(1) Medulla oblongata

(2) Pons

(3) Midbrain

The embryonic hindbrain differentiates into these two subdivisions

(1) Myelencephalon

(2) Metencephalon

The myelencephalon becomes this adult structure

Medulla oblongata

These are the pair of ridges on the anterior surface of the medulla oblongata

Pyramids

This is a prominent bulge lateral to each pyramid of the medulla oblongata

Olive

These are the two pairs of ridges that are continuous with the spinal cord located on the posterior side of the medulla oblongata

(1) Gracile fasciculi

(2) Cuneate fasciculi

The first order sensory fibers of the gracile and cuneate fasciculi synapse with second order neurons whose fibers decussate forming this specific structure within the medulla

Medial lemniscus

This is the largest group of descending fibers filling the pyramids on the anterior surface of the medulla oblongata

Corticospinal tracts

These carry motor signals from the cerebral cortex on the way to the spinal cord to stimulate our skeletal muscle

Corticospinal tracts

Signals pass through this group of descending fibers any time you carry out a body movement below the neck

Corticospinal tracts

This small group of descending fibers control the neck muscle

Tectospinal tract

This is a major relay center within the medulla oblongata for signals going from many levels of the brain and spinal cord to the cerebellum

Inferior olivary nucleus

This is a loose network of nuclei extending throughout the medulla, pons, and midbrain

Reticular formation

This center within the reticular formation of the medulla regulates the rate and force of the heartbeat

Cardiac center

This center within the reticular formation of the medulla regulates blood pressure and flow by dilating and constricting blood vessels

Vasomotor center

These two centers within the reticular formation of the medulla regulates the rhythm and depth of breathing

Respiratory centers

This embryonic structure becomes the pons and cerebellum

Metencephalon

This is a broad anterior bulge rostral to the medulla

Pons

These are the two pairs of thick stalks located on the posterior surface of the pons

Cerebral peduncles

This is the main function of the cerebral peduncles of the pons

Connect the cerebellum to the pons and midbrain

This embryonic structure becomes the midbrain

Mesencephalon

This is a short segment of the brainstem that connects the hindbrain and forebrain

Midbrain

This is the part of the midbrain posterior to the cerebral aqueduct

Tectum

The tectum exhibit these four bulges

Superior and inferior colliculi

This pair of colliculi control the extrinsic muscles of the eyes

Superior colliculi

These are other visual control centers located between the superior colliculi and thalamus that control pupillary diameter and focusing of the lens

Pretectal nuclei

This pair of colliculi receive signals from the inner ear and relay them to other parts of the brain (especially the thalamus)

Inferior colliculi

This pair of colliculi mediate the reflexive turning of the head in response to a sound

Inferior colliculi

These structures mainly make up the area anterior to the cerebral aqueduct in the midbrain

Cerebral peduncles

These are the three main components of the cerebral peduncles within the midbrain

(1) Tegmentum

(2) Substantia nigra

(3) Cerebral crus

The tegmentum is dominated by this structure named for its pink color due to its high density of blood vessels

Red nucleus

Connections of the tegmentum go mainly from the __________ to collaborate with fine ___________ control.

cerebellum, motor

This is a dark gray to black nucleus that is pigmented with melanin within the cerebral peduncles of the midbrain

Substantia nigra

This component of the cerebral peduncle is a motor center that relays inhibitory signals to the thalamus and basal nuclei to suppress unwanted body movement

Substantia nigra

This is a bundle of nerve fibers that connect the cerebrum to the pons and carry the corticospinal nerve tracts

Cerebral crus

This is a loosely organized web of gray matter that runs vertically through all levels of the brainstem and the upper spinal cord

Reticular formation

These are the five functions of the nuclei within the reticular formation

(1) Somatic motor control

(2) Cardiovascular control

(3) Pain modulation

(4) Sleep and consciousness

(5) Habituation

This tract within the reticular formation adjusts muscle tension to maintain tone, balance, and posture, especially during body movements

Reticulospinal tract

The reticular formation also relays signals from the eyes and ears to this specific structure so it can integrate the information into its role of motor coordination

Cerebellum

True or False : The reticular formation includes cardiac and vasomotor centers similar the ones present within the medulla oblongata

True

This is a process in which the brain learns to ignore repetitive, inconsequential stimuli while remaining sensitive to others

Habituation

This narrow wormlike structure connects the right and left cerebellar hemispheres of the cerebellum

Vermis

The white matter of the cerebellum exhibits this branching or fern-like pattern

Arbor vitae

These densely spaced cells of the cerebellum are the most abundant type of neuron in the entire brain

Granule cells

These cells of the cerebellum are the most distinctive neurons and have a tremendous profusion of dendrites

Purkinje cells

These three pairs of stalks connect the cerebellum to the brainstem

Cerebral peduncles

The three pairs of cerebral peduncles include a pair of inferior peduncles connected to the ________________, a pair of middle peduncles to the _________, and a pair of superior peduncles to the ___________.

medulla oblongata, pons, midbrain

Most spinal input enters the cerebellum by way of the ____________ peduncles; most input from the rest of the brain enters by way of the ___________ peduncles; and cerebellar output travels mainly by way of the __________ peduncles.

inferior, middle, superior

True or False : There is an increase in cerebellar activity when a person is required to judge the elapsed time between two stimuli

True