brain and cranial nerves -ANAT

what are the 3 brain surface structures?

gyrus: ridges on brain surface

sulcus: grooves between gyri

fissures: deep sulci between gyri

what does gray matter and white matter consist of

gray matter: cell bodies, dendrites, and unmyelinated axons of neurons

white matter: myelinated axons of neurons

what are the neuronal tracts and what 3 fibers do they contain?

neuronal tracts: axons in the white matter are grouped in bundles/fibers.

association fibers: connect different parts of the same hemisphere 

commissural fibers: connect corresponding areas of the two hemispheres 

projection fibers: link cerebral cortex to lower brain regions and spinal cord

whats the cerebrum 

it is the main part of the brain located in the front area of the skull, it has 2 cerebral hemispheres which are divided by the longitudinal fissure 

what are the layers of the cerebrum and what matter does it contain?

Cerebral cortex: superficial layer of the cerebrum which is composed of gray matter

Cerebral Medulla: deep layer of cerebrum, composed of white matter

whats the corpus callosum ?

it is a bundle of axons that connect the right and left cerebral hemispheres

what are the 5 lobes and what 2 sulci are there on the cerebrum ?

the 5 lobes are frontal, parietal, occipital, temporal, insula

Central sulcus divides the frontal and parietal lobes 

Lateral sulcus divides the frontal/parietal lobes from the temporal lobe 

what is the frontal lobe responsible for and where is it?

it is the most anterior lobe of the brain, it gives voluntary motor functions, decision making and planning, as well as personality

what are 2 important areas in the frontal lobe and explain what it is in charge of ?

precentral sulcus: it is the location of the primary motor cortex which controls majority of motor functions

broca’s area: controls muscles used for speech and only present on one side (usually left side)

whats the function and location of the parietal lobe ?

it gives general sensory info for touch, pain, and temperature 

what are the 2 important areas for the parietal lobe, and explain them?

postcentral gyrus: contains primary somatosensory cortes, processes touch, pain and temp

wernicke’s area: comprehension of written/spoken language, partially in the temporal lobe

it is after the frontal lobe, before the occipital lobe

whats the function and location of the temporal lobe ?

it functions in giving primary auditory perception, olfaction, and emotional association. It is on the bottom.

whats the functions and location of the occipital lobe 

it is the most posterior lobe of the brain. it functions by processing visual info, and stores visual memory 

whats the insula and where is it? (hidden one!)

it is located deep the to lateral sulcus, it gives memory and interpretation of taste

what are the 3 regions of diencephalon?

epithalamus, thalamus and hypothalamus

whats the thalamus

it relays both motor and sensory info to and from the cerebrum, it contains specific nuclei from various functions

whats the epithalamus

it is the structure behind the thalamus, contains the pineal gland which secretes melatonin for circadian rhythm (sleep)

whats the hypothalamus 

it contains main nuclei with a variety of functions including appetite, and temperature, it is important for maintaining homeostasis. It connects the nervous system to the endocrine system through the pituitary gland (pituitary hormones control several other hormone glands) 

whats the limbic system

it is a group of structures on the cerebrum and diencephalon. It is our “emotional brain”, which allows us to generate emotions, and connects emotions to senses

what 3 regions are in the brainstem

the midbrain, pons and medulla oblongata

what consists of the midbrain ?

midbrain: superior most portion of brainstem 

cerebral aqueduct: it essentially the central midbrain 

here are some posterior structures… 

corpora quadrigemina: consists of the paired superior colliculi and inferior colliculi

superior colliculi: is the visual reflex center, which tracks moving objects, movement of eyes and head in response to visual stimulus 

inferior colliculi: auditory reflex center, movement of body in response to sound 

what is the pons ?

it is the middle portion of the brainstem, it acts as a respiratory center for the body, controls the skeletal muscles used for breathing, and works with the medulla oblongata 

what makes up the medulla oblongata and what are the 3 vital centers?

it is the most inferior portion of the brainstem (continuous with spinal cord), it has multiple vital centers: cardiac center, vasomotor center, and respiratory center

explain the cardiac center, vasomotor center, and respiratory center

cardiac center: regulate heart rate and strength of contraction

vasomotor center:regulate blood vessel diameter

respiratory center: rate of respiration (works with Pons)

what is the cerebellum?

it is the 2nd largest part of the brain, and contains two cerebellar hemispheres (which are connected by vermis), it functions in fine tune skeletal movements, provides feedback to cerebrum, and maintains equilibrium and posture 

what are the effects of alcohol on cerebellum?

loss of gait: cant walk straight or smooth

loss of balance and posture: cant stand on one foot

Inability to detect proprioceptive info: cant close eyes or touch nose

what is the cerebellar cortex and arbor vitae? 

cerebellar cortex: outer gray matter 

arbor vitae: inner white matter (looks like tree) 

what are cranial meninges and what are the 3 layers ?

they are a series of protective coverings on the brain that extend from the brain to the skull. there are 3 layers: pia mater, arachnoid mater and dura mater.

what is meningitis?

it is an infection or inflammation of meninges

whats the pia mater, arachnoid mater and dura mater ?

PIA MATER: “soft mother”, innermost layer which adheres directly to the brain 

ARACHNOID MATER: middle layer superficial to pia mater 

• subarachnoid space: space between arachnoid and pia maters (contains cerebrospinal fluid) 

• arachnoid trabeculae: web of elastic fibers that extend into subarachnoid space 

DURA MATER: tough, superficial-most layer 

• periosteal layer: next to skull 

• meningeal layer: lies deep to periosteal layer 

• subdural space: between dura and arachnoid maters 

• subdural hematoma: blood accumulates in subdural space 

what are dural venous sinuses?

Within the dura mater there are separations between the periosteal and meningeal layers that drain blood and CSF from the brain

whats the cranial dura septa? and what are the 2 structures of it?

they are just extensions of the dura mater and meningeal dura mater, that leads into the cranial cavity

falx cerebri: extends into the longitudinal fissure, separating the right and left hemispheres of the brain

tentorium cerebelli: between the cerebrum and cerebellum

whats the ventricular system and what are the 4 types 

the ventricular system is a series of cavities in the brain that hold cerebrospinal fluid 

There are 2 lateral ventricles )one in each hemisphere) 

Third ventricle: located between the two thalami 

Cerebral aqueduct: located in the midbrain 

Fourth ventricle: located between the pons and cerebellum 

what is the central canal

it starts in the medulla oblongata and runs through the spinal cord (small hole in middle of spinal cord and long canal in the brainstem).

what is the cerebrospinal fluid and its functions?

it is a clear filtrate that circulates in ventricles and subarachnoid space, complete volume is replaced approximately every 8 hours.

functions

• buoyancy: keeps brain afloat

• reduces brain weight by 97%

• protection: slows movement of skull

* similar to tofu being in a liquid *

how is CSF produced ?

it is produces by the choroid plexus: 

• capillaries located in each ventricle that filters plasma from the blood to form CSF

• plasma is retrieved by arachnoid villi that extend into the superior sagittal sinus 

what is CSF circulation?

1) CSF produced in ventricles and flows through ventricles

2) flows form fourth ventricle into central canal

3) CSF returned to the blood through arachnoid villi into dural venous sinus

fill in this chart

what is the olfactory CN I ?

sensory: smell 

entrance/exit: olfactory foramina in cribriform plate of ethmoid bone 

whats optic CN II?

sensory: vision

origin: retina

entrance/exit: optic canal of sphenoid bone

whats the oculomotor CN III?

motor: controls eye movement, eyelid raising, and pupil construction

innervates medial rectus, superior/inferior rectus, inferior oblique

entrance/exit: superior orbital fissure of sphenoid bone

whats the trochlear CN IV?

motor: innervates superior oblique eye muscle 

entrance/exit: superior orbital fissure of sphenoid bone 

whats the trigeminal CN V ?

motor: jaw movement/innervates muscles of mastication

sensory: touch, temp and pain

• opthalamic divison V1: cornea, nose, forehead, scalp (forehead region)

• maxillary division V2: nasal mucosa, palate, gums and cheek (maxillary region)

• Mandibular division V3: sensation to face at mandible region

origin: level of the pons

entrance/exit:

• opthalamic V1-superior orbital fissure of the sphenoid bone

• V2 maxillary branch- foramen rotundum of the sphenoid bone

• V3 mandibular branch- foramen ovale of the sphenoid bone

what is abducens CN VI?

motor: innervates lateral rectus eye muscle

origin: pons

entrance/exit: superior orbital fissure of sphenoid bone

whats facial CN VII?

sensory: taste to anterior 2/3 of tongue

motor:

• innervates muscle of facial expression 

• secretions of lacrimal and salivary glands 

entrance/exit: internal acoustic meatus of the temporal bone to the stylomastoid foramen of the temporal bone 

whats vestibulocochlear CN VIII?

sensory: hearing and equilibrium

origin: vestibule and cochlea of inner ear

entrance/exit: internal acoustic meatus of temporal bone to pons

glossopharyngeal CN IX?

origin: medulla oblongata

sensory: taste to posterior 1/3 of tongue, monitor oxygen and carbon dioxide levels in blood

motor: innervates pharynx muscle, regulate secretions of parotid gland

whats vagus CN X? (LV BUFFET!!)

Entrance/exit: jugular foramen 

sensory: taste 

motor: helps with swallowing 

what is the accessory CN XI?

entrance/exit

• spinal root enters through foramen magnum of occipital bone

• entire nerve exits through jugular foramen of the skull

motor:

• cranial root: muscles of pharynx

• spinal root: sternocleidomastoid and trapezius muscles

whats the hypoglossal CN XII ?

entrance/exit: hypoglossal canal of the occipital bone

motor: innervates intrinsic and extrinsic tongue muscles