The Brain Flashcards
CNS includes?
the brain + the spinal cord
The brain includes?
-cerebrum, brainstem & cerebellum
What is the spinal cord?
-cylindrical bundle of nerves that extends from foramen magnum (upper border of atlas) to first or second lumbar vertebrae
What is the narrowing of the cord called?
the Conus Medullaris
Spinal nerves continue along what?
Cauda Equina
How many enlargements of the spinal cord? What are they?
- 2
- cervical & lumbar regionals
- enlarges the motor & sensory nerves that come in & out of the spinal cord to supply the arms & legs respectively
After the apex of the conus medullaris? What is it called & what does it do?
from apex of conus medullaris there is a CT filament called the filum terminale that anchors the cord to the first coccygeal segment
What are the 5 parts that make up the spinal cord?
- white matter
- grey matter
- central canal
- dorsal horns
- ventral horns
What is white matter?
myelinated, outer layer of spinal cord
What is grey matter?
unmyelinated, inner H-shaped portion of spinal cord
What is the central canal?
filled with CSF, runs longitudinally along length of spinal cord, continuous with ventricular system of brain
What are the dorsal horns?
sensory nerve tracts
What are the ventral horns?
motor neurons
What does the brainstem include?
- midbrain
- pons
- medulla oblongata
What is the medulla oblongata good for?
several centers for autonomic function:
-respiration, cardiac center, vasomotor center, reflex centers for vomiting, swallowing, coughing, sneezing
part of it forms the fourth ventricle
What does the medulla oblongata contain?
- pyramids (corticospinal tracts)
- decussation of the pyramids (where motor fibers from L hemisphere cross to the right and vice versa)
- nuclei for CN IX, X, XI & XII
What is the pons? What does it contain?
- ‘bridge’
- contains fiber tracts connecting the medulla & cerebellum with upper portions of the brain
- contains respiratory centers that work with those in the medulla
- contains nuclei for CN V (motor) VI, VII, part of VIII
What is the midbrain? What does it contain?
- cerebral peduncles
- substantia nigra
- corpora quadrigemina
- nuclei for CN III, IV & V (sensory)
- cerebral aqueduct passes through midbrain
What are the cerebral peduncles?
-connecting tracts from pons to cerebellum
What is the substantia nigra?
-dopamine producing regions associated with reward, addiction & movment
What are the corpora quadrigemina?
-the masses that make up the superior & inferior colliculi
What is the cerebellum responsible for?
- balance/posture, learning of motions, cognitive functions & motor coordination
- does not initiate motions, but responsible for fine tuning motions
- damage to the cerebellum will result in lack of coordination in gait, speech, etc.
What are the parts of the cerebrum?
- hemispheres (connected by corpus collosum)
- sulci (valleys) & gyri (hills)
- lobes: frontal, parietal, occipital, temporal
Cerebral hemispheres include…
- cerebral cortex
- basal ganglia
Cerebral cortex is a site for?
-site for sensorimotor integration & perceptive qualities of our experiences
What is a gyrus?
-convolution of cortex
What is a sulcus/fissure? What are the 3 fissues/sulci?
- gap between gyri
- longitudinal fissure: divides brain into L & R halves
- lateral (sylvian) sulcus: separates temporal from frontal lobes
- central sulcus: separates frontal from parietal lobes
What are the lobes of the brain? What do they do?
- frontal: primary, motor activity, behavior, speech production
- parietal: primary somatosensory & proprioception; association of somatosensory, vision, audition; formation of egocentric space & sense of self
- occipital: vision
- temporal: audition, olfaction, memory
What is the homunculus?
- ‘little human’
- image of the body imprinted on the brain; two types: sensory & motor
- sensory homunuclus is represented on postcentral gyrus of parietal lobe
- motor homunculus represented on the precentral gyrus of the frontal lobe
What sensory information is received in the thalamus? Where is it integrated and relayed to?
- all sensory stimuli, except for olfaction are received here
- integrated & relayed through thalamocortical radiations to specific cortical areas
What does the hypothalamus comprise? What is the chief region for? What does it regulate? What does it produce?
- comprises the wall & floor of the 3rd ventricle
- chief region for integration of autonomic NS
- regulates H2O balance, BT & thirst
- produces antidiuretic hormone & oxytocin
What are the 12 cranial nerves?
CN I= olfactory CN II= optic CN III= oculomotor CN IV= trochlear CN V= trigeminal CN VI= abducens CN VII= facial CN VIII= vestibulocochlear CN IX= glossopharyngeal CN X= vagus CN XI= accessory CN XII= hypoglossal
What is CN I for? How do you test it?
- olfactory n.
- smell
- testing done by waving a nonirritating scent under pts nose
What is CN II for? How do you test it?
- optic n.
- sense of sight, transmits retinal images back to the occipital lobe of the brain
- tested in office w/Snellen chart & fundoscopic examination
What is CN III for? What does it innervate? How do you test it?
- occulomotor n.
- innervates superior, inferior & medial rectus, inferior oblique muscles that control the movements of the eye as well as the levator palpebrae superioris muscle of the eyelid & the muscles that control pupillary constriction
- have pt. follow a moving object, look at alignment of the eyes, shine a light in their eyes & look for pupillary constriction
What is CN IV for? What does it innervate? How do you test it?
- trochlear n.
- innervates the superior oblique muscle of the eye
- observe the alignment of the eye & have pt. follow moving object with their eyes
What is CN V for? It provides sensory innervation to what and motor innervation to what? How do you test it?
- trigeminal n.
- provides sensory innervation to most of the face & motor innervation to the muscles of mastication, corneal reflex
- testing done by lightly touching the face and cornea w/cotton swab & observing bite strength
What is CN VI for? What does it innervate? How do you test it?
- abducens n.
- innervates lateral rectus muscle of eye
- look at alignment of the eyes, have pt. follow a moving object with their eyes
What is CN VII for? What does it innervate? What are the 2 notable branches? How do you test it?
- facial n.
- motor innervation to muscles of facial expression & parasympathetic motor innervation to lacrimal gland & most of sinuses
- 2 notable branches: n. to stapedius muscle (innervates stapedius muscle of inner ear) & chorda tympani which provides special sense innervation from anterior 2/3 of tongue
- testing done by observing the ability of the patient to make various facial expressions: cotton swab dipped in flavored substance & place on anterior 2/3 of tongue
- corneal reflex tests the afferent (sensory) path of CN V, but efferent response is activated by CN VII
What is CN VIII? What are the 2 major divisions? How do you test it?
- vestibulocochlear n.
- splits into 2 major divisions:
- vestibular n. which determines head position/acceleration information from inner ear
- cochlear n. processes sensation of sound information from inner ear
- test by using a tuning fork (Weber & Rinne tests) for cochlear part, to test vestibule part move head & observe eyes for nystagmus
What is CN IX? What does CN IX provide innervation to & what kind? How do you test?
- glossopharyngeal
- provides sensory info for carotid bodies/sinus, posterior 1/3 of tongue, pharynx & middle ear as well as taste for posterior 1/3 of tongue
- provides motor innervation to stylopharyngeus muscle & parotid gland
- testing of this nerve usually done by assessing ability to taste on posterior 1/3 of tongue & determining if sensation is intact on arches of palate
What is CN X? What does CN X do? What does it provide innervation to? What kind?
- vagus
- provides efferent parasympathetic innervation to all organs below the neck down to proximal 1/2 of transverse colon (with exception of adrenal glands)
- provides motor innervation to several muscles important to speech such as muscles of larynx, cricothyroid & pharyngeal constrictors
- test by asking the to say “Ahhh” and observing the uvula; if both are working the uvula should stay midline; if pt. can speak normally vagus is intact
What is CN XI? What does CN XI do? How do you test?
- accessory
- motor innervation to sternocleidomastoid & trapezius muscles
- test by asking pt to contract those muscles against resistance
What is CN XII? What does CN XII innervate? What kind? How do you test?
- hypoglossal
- motor innervation to all muscles of tongue except for palatoglossu muscle
- test by asking pt to stick tongue out straight, if deviates that indicates a dysfnction
Most simplistic, what are each of the cranial nerves and what is each responsible for?
CN I: olfactory= smell
CN II: optic= sight
CN III: oculomotor= eye movements, pupil constriction
CN IV: trochlear= superior oblique muscle
CN V: trigeminal= sensory to face, motor to muscles of mastication
CN VI: abducens= lateral rectus muscle
CN VII: facial= muscles of facial expression, taste
CN VIII: vestibulococchlear= hearing, balance
CN IX: glossopharyngeal= taste, secremotor to parotid, stylopharyngeus muscle
CN X: vagus= motor to laryngeal/pharyngeal muscles, parasympathetic to everything north of splenic flexure
CN XI: accessory= sternocleidomastoid & trapezius
CN XII: hypoglossal= muscles of tongue