Lecture 17: Brain: Cortices, Nuclei And Tracts Flashcards
Is the cortex gray or white matter?
Gray matter
The following characteristics from the Langdon table belong to which group?
- Brain larger relative to body size
- clear development of the cerebrum beyond an olfactory function
- cerebrum larger in proportion to the rest of the brain
- neocortex
- complex limbic system
- visual processing centered in cerebral cortex
Mammals
The following characteristics from the Langdon table belong to which group?
- cerebrum extremely large relative to body size
- lateralization of the cerebrum
- areas of the left hemisphere specialized for language
- expanded limbic cortex
Humans
What are the 3 initial brain vesicles?
Prosencephalon
Mesencephalon
Rhombencephalon
When do the initial brain vesicles develop in gestation?
By the end of the fourth week of development
What are the 5 secondary brain vesicles?
Telencephalon Diencephalon Mesencephalon Metencephalon Myelencephalon
What does the telencephalon form from and what does this become?
From the prosencephalon and becomes the cerebrum
What does the diencephalon form from and what does this become?
From prosencephalon and forms the thalamus, hypothalamus and epithalamus
What does the mesencephalon form from and what does this become?
It remains as in week 4 of development
What does the metencephalon form from and what does this become?
From the rhombencephalon forms the pons and cerebellum
What does the myelencephalon form from and what does this become?
From the rhombencephalon forms the medulla oblongata
When are the 5 secondary brain vesicles differentiated by?
Week 5 of gestation
What are the 4 major regions of the brain?
Cerebrum, diencephalon, brainstem and the cerebellum
What cortices and association areas are within the frontal lobe?
- primary motor cortex
- premotor cortex
- motor speech area (Brocas)
- frontal eye fields
What cortices and association areas are within the parietal lobe?
- primary somatosensory cortex
- somatosensory association area
- part of wernickes area
- part of gnostic area
What cortices and association areas are within the temporal lobe?
- primary auditory cortex
- primary olfactory cortex
- auditory association area
- olfactory association area
- part of Wernickes area
- Part of gnostic area
What cortices and association areas are within the occipital lobe?
- primary visual cortex
- visual association areas
What cortices and association areas are within the insula lobe?
Primary gustatory cortex
What are the primary functions of the frontal lobe?
Higher intellectual functions, personality, verbal communicaiton, voluntary motor control of skeletal muscles
What are the primary functions of the parietal lobe?
Sensory interpretation of textures and shapes, understanding speech and formulating words to express thoughts and emotions (wernickes)
What are the primary functions of the temporal lobe?
Interpretation of auditory and olfactory sensations of auditory and olfactory experiences
What are the primary functions of the occipital lobe?
Conscious perception of visual stimuli, integration of eye focusing movements, correlation of visual images with previous visual experiences
What are the primary functions of the insula lobe?
Interpretation of taste and memory
What are primary motor and sensory cortical regions connected to and what is their function?
Connected to adjacent association areas that process and interpret incoming data or coordinate a motor response
Where is the premotor cortex located and what is its function?
Frontal lobe–coordinate learned skilled motor activities
Where is the somatosensory association area located and what is its main function?
Parietal lobe and integrates and interprets sensations to determine the texture, temperature, pressure and shape of objects
Where is the auditory association area located and what is its main function?
In the temporal lobe and it interprets characteristics of sound and stores memories of sounds heard in the past
Where is the visual association area located and what is its main function?
In the occipital lobe and is responsible for processing visual information by analyzing color, movement and form to identify things we see
What is wernickes area and were is this located? What does this work with?
Left hemisphere. Recognize, understand and comprehend spoken or written language. Works with Broca’s area which is the motor speech area
Where is the gnostic area located and what is an example of how this works?
Parietal, occipital and temporal lobes
E.g. Clock indicates 12:30, you smell food cooking, friend talks about hunger and you interpret it to be lunch time
What tracts in the brain gray or white matter?
Central white matter
What is the function of the association tracts?
Connect different regions of cerebral cortex within the same hemisphere
Where are commissural tracts found?
Between cerebral hemispheres
What is the function of projection tracts?
Link cerebral cortex to the caudal brain regions (i.e. Corticospinal tract)
What do arcuate fibers connect?
Connect neighboring gyro within a single cerebral lobe
What do the longitudinal fasciculi connect?
Gyro between different cerebral lobes of the same hemisphere
What are cerebral nuclei?
Paired irregular masses of gray matter buried deep within the central white matter
What is the caudate nucleus and what is this shaped like?
C-shaped
Neurons within stimulate appropriate muscles to coordinate arm and leg movements associated with walking
What is the amygdaloid body?
Expanded region at the tail of the caudate nucleus. Participates in the expression and control of moods and emotions
Where are the putamen and globus pallidus from and what is their function?
Both from the lentiform nucleus. Putamen controls muscular movement at a subconscious level. The globes pallidus inhibits activity of the thalamus
What is the function of the claustrum?
Subconscious processing of visual information
What is the function of the diencephalon?
Provides the relay and switching centers for some sensory and motor pathways and for control of visceral activities
What is part of the 5 section brain does the epithalamus belong to and what is the posterior part of this?
Diencephalon
Posterior part is the pineal gland which secretes melatonin
What part of the epithalamus help relay signals from the limbic system and control visceral and emotional responses to odors?
Habenular nuclei
What part of the brain does the thalamus belong to? What is the main function of the thalamus?
Diencephalon
Sensory impulses from all conscious senses except olfaction converge on the thalamus
What is the function of the anterior group/nuclei of the thalamus?
Mood
What is the function of the lateral group/nuclei of the thalamus?
Mood
What is the function of the medial group/nuclei of the thalamus?
Consciousness and emotion
What is the function of the posterior group/nuclei of the thalamus?
Special sense
What is the function of the ventral group/nuclei of the thalamus?
Somatomotor and somatosensory
What is the main role of the parventricular nucleus of the hypothalamus?
Oxytocin
What is the main role of the preoptic area of the hypothalamus?
Body temp
What is the main role of the anterior nucleus of the hypothalamus?
Parasympathetic division of autonomic control center
What is the main role of the supraoptic nucleus of the hypothalamus?
ADH
What is the main role of the Suprachiasmatic nucleus of the hypothalamus?
Circadian rhythm
What is the main role of the dorsomedial nucleus of the hypothalamus?
Sympathetic division of autonomic control division
What is the main role of the mammillary body of the hypothalamus?
Olfaction and swallowing
What part of the 5 section brain does the brainstem belong to?
Mesencephalon
What part of the brain to the cerebral peduncle, substantia nigra, tegmentum, and tectum belong to?
Brainstem–mesencephalon
What is the cerebral penduncle?
Motor tracts
What is the function of the substantia nigra?
Inhibitory signals to skeletal muscle
What is the function of the tegmentum?
Posture
What is another name for the tectum and what is its main function?
Corpora quadrigemina
Visual and auditory relay
What does the pons regulate and what nuclei does this house?
Regulate rate and depth of breathing, house nuclei for V, VI, VII, and VIII
What is the main functions of the medulla and what nuclei does this house? What general bodily functions is this associated with?
Corticospinal tracts and sensory relay (the olive). Nuclei for VIII, IX, X, XI, XII
Also cardiac, vasomotor, respiratory and those related to coughing, gagging, sneezing, salivation, swallowing and vomiting
What is the main function of the oilvary nucleus of the medulla?
Proprioception
What is the function of the cerebellum?
Coordinates and fine tunes skeletal muscle movements and ensured that skeletal muscle contraction follows the correct pattern leading to smooth coordinated movements. Performs indirectly with voluntary and involuntary motor pathways
Where is the limbic system found?
Ring around the diencephalon
The limbic system is composed of various structure that collectively process and experience emotions. What all collectively makes up the limbic system?
- parahippocampal gyrus
- hippocampus
- amygdaloid body
- olfactory bulb
- fornix
- various nuclei in the diencephalon
What cranial nerve is associated with the first (manidbular) pharyngeal arch?
Trigeminal (CN V) nerve
What cranial nerve is associated with the second (hyoid) pharyngeal arch?
Facial nerve (CN VII)
What cranial nerve is associated with the third pharyngeal arch?
Glossopharyngeal nerve (CN IX)
Which cranial nerves are associated with the fourth and sixth pharyngeal arch?
Superior laryngeal branch of vagus (CN X)
Recurrent laryngeal branch of vagus
What is characteristic of al sympathetic fibers?
They are postganglionic arising from the superior cervical ganglion of the sympathetic trunk. They travel on vessels to structures that they innervate
What is the only names sympathetic nerve that is of concern for us?
Deep petrosal
What is characteristic of the parasympathetic fibers?
They are preganglionic fibers that arise from the nuclei in the brain stem and synapse at 4 ganglia in the head
What are the 4 ganglia that parasympathetic fibers synapse at?
Ciliary, pterygopalatine, optic and submandibular
What cranial nerves carry preganglionic parasympathetic fibers?
III, VII, IX and X
What is the function of CN I? What is special about this nerve?
Sensation of olfaction or smell
Only type of nervous tissue to regenerate
What is the pathway for CN I?
Travels through the foramina in cribiform plate of ethmoid bone and synapses in the olfactory bulbs, located in the anterior cranial fossa
What are the 2 modalities of the trigeminal CN V?
Branchial motor
General sensory
What are the divisions of the trigeminal nerve CN V?
1=ophthalmic nerve
2=maxillary
3= mandibular
Where does the ophthalmic nerve of the trigeminal pass through?
Superior orbital fissure
Where does the maxillary nerve of the trigeminal nerve pass through?
Passes through the foramen rotundum
Where does the mandibular nerve of the trigeminal pass through?
The foramen ovale
What is the only branch of the trigeminal nerve that supplies motor function?
Mandibular
**all three parts have somatic sensory functions
The facial nerve (CN VII) has 4 modalities with varying functions. What are these modalities?
- Branchial motor
- visceral motor
- general sensory
- special sensory
In regards to facial (CN VII) nerve, what is the function of the somatic (branchial) motor component?
Muscles of facial expression
In regards to facial (CN VII) nerve, what is the function of the visceral (parasympathetic) motor modalities?
Stimulates the lacrimal, sublingual and submandibular gland
In regards to facial (CN VII) nerve, what is the function of the special sensory modalities?
Taste from the anterior 2/3rds of the tongue
In regards to facial (CN VII) nerve, what is the function of the general sensory modalities?
Supplies a small area of skin behind the ear and possibly supplements CN V3 (acoustic meatus and external tympanic)
What are the 2 branches of the vestibulocochlear nerve (CN VIII) and what are their functions?
Cochlear branch- conducts impulses for hearing
Vestibular branch-conducts impulses for equilibrium
What are the 5 modalities of the glossopharyngeal nerve (CN IX)?
Branchial motor Visceral motor Visceral sensory General sensory Special sensory
In regards to the glossopharyngeal nerve (CN IX), what is the function of the branchial motor modality?
To supply the stylopharyngeus
In regards to the glossopharyngeal nerve (CN IX), what is the function of the visceral motor modality?
Supplies the otic ganglion, which sends fibers to stimulate the parotid gland
In regards to the glossopharyngeal nerve (CN IX), what is the function of the visceral sensory modality?
Carries sensation from the carotid body and from the carotid sinus
In regards to the glossopharyngeal nerve (CN IX), what is the function of the general sensory modality?
General sensation from the posterior 1/3rd of the tongue, skin of external ear, and the internal surface of the tympanic membrane
In regards to the glossopharyngeal nerve (CN IX), what is the function of the special sensory modality?
Taste from the posterior 1/3rd of tongue
What are the 4 modalities of the vagus nerve?
Branchial motor
Visceral motor
Visceral sensory
General sensory
In regards to the vagus nerve, what is the function of the branchial motor modality?
To striated muscle of the pharynx, tongue and larynx
In regards to the vagus nerve, what is the function of the visceral motor modality?
To smooth muscle and glands of pharynx, larynx and thoracic and abdominal viscera
In regards to the vagus nerve, what is the function of the visceral sensory modality?
From the larynx, trachea, esophagus, and thoracic and abdominal viscera, stretch receptors in the walls of the aortic arch, chemoreceptors in the aortic bodies adjacent to the arch
In regards to the vagus nerve, what is the function of the general sensory modality?
From the skin at the back of the ear and in the external acoustic meatus, part of the external surface of the tympanic membrane and the pharynx
What is the main modality of the accessory nerve (CN XI)?
Branchial motor component that supply sternomastoid and trapezius
What is the main modality and function of the hypoglossal nerve (CN XII)?
Somatic motor that supplies all intrinsic and extrinsic muscles of the tongue except the palatoglossus
What is the main modality and main function of the optic nerve (CN II)?
Special sensory conveys visual information from the retina
Where is visual stimulus information processed and interpreted?
Processed by the thalamus and then interpreted by visual association areas in the cerebrum
What are the two modalities of the oculomotor nerve?
Somatic motor and visceral motor
In regards to the oculomotor nerve (CN III), what is the function of the somatic motor component?
Supplies the four extrinsic eye muscles that move the eyeball
In regards to the oculomotor nerve (CN III), what is the function of the visceral (parasympathetic) motor component?
Innervates sphincter pupillae muscle of the iris to make pupil constrict and contracts ciliary muscles to make the lens of eye more spherical
What is the main component of the trochlear nerve (CN IV) and what is its function?
Somatic motor and it supplies one extrinsic muscle of eye to move the eye inferiorly and laterally
What is the main component of the abducens nerve (CN VI) and what is its function?
Somatic motor innervates one extrinsic eye muscle for eye abduction
According to the Langdon table on vision, the following characteristics belong to what group:
- midbrain processes information from opposite eye
- six muscles coordinate the movement of each eye
Vertebrate
According to the Langdon table on vision, the following characteristics belong to what group:
- eyelids
- lacrimal gland
Tetrapods
According to the Langdon table on vision, the following characteristics belong to what group:
- eyelashes
- domination of retina by rods
- visual cortex processes information from opposite eye
Mammals
According to the Langdon table on vision, the following characteristics belong to what group:
- frontally directed vision
- visual cortex processes opposite visual field
- midbrain processes info from opposite visual field
- stereoscopic vision
- macula
- elaboration of the visual cortex
Primate
According to the Langdon table on vision, the following characteristics belong to what group:
- Domination of retina by cones
- three-color vision
Anthropoids
What accessory structure of the eye provides a superficial covering over its anterior exposed surface?
Conjunctiva
What accessory structure of the eye prevents foreign objects from coming into contact with the eye?
Eyebrows, eye lashes and eyelids
What accessory structures of the eye keep the exposed surface moist, clean and lubricated?
Lacrimal glands and ducts
What are the three tunics of the eye from outer to inner?
Fibrous (outer)
Vascular
Neural (inner)
What are the two parts of the fibrous tunic of the eye?
Cornea and sclera
What are the three parts f the vascular tunic of the eye?
Choroid, ciliary body and iris
What are the two parts of the neural tunic of the eye?
Pigmented layer and neural layer
Where does the tectospinal tract originate and what is its main function?
Brainstem and regulates positional changes of the arms, eyes, head and neck due to visual and auditory stimuli
What is characteristic of catarrhines vision?
They all have small, medium and long photopigments tuned to specific wavelengths giving short (blue), medium (green) and long (red) cones. The turnings are remarkably uniform and result in trichromatic color vision
What is characteristic of the optic disc?
Lacks photoreceptors and is called the blind spot because no image forms there
What is the macula lutea and where is this located?
Just lateral to the optic disc. It is a rounded, yellowish region of the retina–contains a pit called the fovea centralis (the area of sharpest vision). Contains the highest proportion of cones and almost no rods
What divides the anterior from the posterior cavity of the eye?
The lens
What is the anterior cavity of the eye?
Space anterior to the lens and posterior to the cornea
What subdivides the anterior chamber of the eye further into 2 chambers?
The iris.
The anterior chamber is between the iris and cornea and the posterior is between the lens and the iris
Where is aqueous humor found in the eye and what is the function?
In the anterior cavity. It removes waste products and helps maintain the chemical environment within the anterior and posterior chambers of the eye
What pathway does aqueous humor follow?
Secreted into the posterior chamber then it flows through the posterior chamber around the lens, down through the pupil and into the anterior chamber
Where is the posterior chamber of the eye located?
Posterior to the lens and anterior to the retina
What is characteristic of the vitreous humor?
Transparent, gelatinous vitreous body which completely fills the space between the lens and the retina
What are the 4 cranial nerves with parasympathetic branches?
3-oculomotor
7- facial
9-glossopharyngeal
10-vagus
What are the 4 parasympathetic ganglia in the head?
Ciliary ganglion
Pterygopalatine ganglion
Submandibular ganglion
Otic ganglion
Which ganglia does the oculomotor nerve pass through and what does the parasympathetic portion of this innervate?
Ciliary ganglion to the ciliary muscle and sphincter pupillae of iris
Which ganglia does the facial nerve pass through and what does the parasympathetic portion of this innervate?
- pterygopalatine ganglion to the lacrimal gland and the nasal, palatine, and pharyngeal glands
- submandibular ganglion to the sublingual and submandibular glands
Which ganglia does the glossopharyngeal nerve pass through and what does the parasympathetic portion of this innervate?
Otic ganglion to the parotid gland
___________ projections are responsible for the detailed operations of the brain, such as sensory interpretations, motor commands, and learning and memory
Specific
______________ projections determine how the brain will function, in a general sense, and how these functions contribute to changing states of consciousness
Nonspecific
What are the 7 principles of brain organization?
- Projections and functional systems in the nervous system can be identified as either specific or nonspecific in their targets.
- Many brain functions occur in specific locations within the brain.
- Sensory and motor connections with the body are mapped spatially onto the brain in a way that can be described by outlining images of the body itself on the cortex and nuclei.
- Functional systems were constructed through evolutionary time, sometimes by adding new layers of organization and control.
- Longitudinal systems cross the midline so that each hemisphere of the forebrain relates to the opposite side of the body.
- Many higher-level functions are handled by specific areas of the cortex that are not symmetrical, so they are preferentially lateralized to one hemisphere.
- Nervous system function is closely integrated with other body systems.
Light has just passed through the eye to the rods and cones and now a nerve impulse is being generated in the opposite direction (toward the ganglion cells of the optic nerve). What cell types will the nerve impulse run into on its way from the rods and cones to the ganglion cells?
Horizontal cells
Bipolar cells
Amacrine cells
