Lecture 3 Flashcards
OVERVIEW
OVERVIEW
The brain has ____ billion neurons and ___ trillion neuroglia.
- 100
- 1
What is the order of brain development?
- ectoderm
- neural fold
- neural tube
- 3 primary vesicles
- 5 secondary vesicles
What are the 5 secondary vesicles and what structures are located in them?
- Telencephalon= cerebral hemispheres, basal ganglia, limbic system
- Diencephalon= thalamus, hypothalamus, epithalamus
- Mesencephalon (midbrain)= cerebral peduncles, corpus quadrigemina
- Metencephalon= cerebellum, pons
- Myelencephalon= medulla oblongata
Ascending sensory signals going to the telencephalon have to cross the others, what does this result in?
Other structures have the potential to modify the signals (descending motor signals act the same way)
List the correct order of the protective coverings of the brain.
- SCALP= skin, connective tissue, aponeurosis, lipid, periosteum
- cranial bones= skull
- epidural space
- dura mater
- subdural space
- arachnoid mater
- subarachnoid space
- pia mater
Which of the spaces has interstitial fluid?
Which space has CSF?
- subdural space
- subarachnoid space
What are the 3 folds of the dura mater that hold the brain in place and their location?
Falx Cerebri -sagittal between cerebral hemispheres Falx Cerebelli -sagittal between cerebellar hemispheres Tentorium Cerebelli -transverse between cerebrum and cerebellum
Are there sinuses associated with these folds?
Yes, allowing blood to drain
The brain is a fuel hog, it is __% of the total body weight, but uses __% of the bodies O2 and glucose when it is resting.
- 2%
- 20%
What does the brain normally use as a fuel source?Is it able to store it?
- glucose
- no
What are the 3 parts of the BBB?
- tight junctions
- continuous endothelial cell basement membrane
- astrocytes (neuroglia)
The BBB is selective for the passage of _____ soluble substances but allows free passage of ______ soluble substances into the brain.
- water
- lipid (hydrophobic)
What are the 3 organs that don’t have the BBB?
What are they collectively called?
- hypothalamus, pituitary, pineal gland
- circumventricular organs
BRAIN STEM OVERVIEW
BRAIN STEM OVERVIEW
What are the 3 parts of the brain stem?
- myelencephalon (medulla oblongota)
- pons
- mesencephalon (midbrain)
The medulla oblongota contains both ________ ascending and ________ descending tracts.
- sensory
- motor
The medulla oblongata pyramids are paired ventral surface ridges that contain what tracts?
motor descending
What does the decussation of pyramids seperate and what is its function?
- seperates the spinal cord from the medulla
- function is carrying the corticospinal tracts which carry motor impulses from the motor cortex to the spinal cord (this is where cross over to control the opposite side of the body occurs)
What are the paired bulges lateral to pyramids which contain the inferior olivary nuclei? What is its function?
- olives
- links brain and spinal cord motor signals to the cerebellum for the perception of time
- proprioception, hearing
The dorsal medulla contains the fasciculus gracilis and the fasciculus cuneatus which do what?
- fasciculus gracilis-carries sensory information from the lower limbs
- fasciculus cuneatus-carries sensory information from the upper limbs and torso
What is the decussation of the medial lemniscus?
the crossover of ascending sensory input to the contralateral brain hemisphere
The medulla oblongata has nuclei perform vital body functions but also has nuclei for what cranial nerves?
CN8-CN12
What is the overall function of the medulla oblongata?
- nuclei for vital centers and cranial nerves(including respiration, cardiac function, vasodilation, and reflexes like vomiting, coughing, sneezing, and swallowing)
- signal propogation via ascending and descending tracts
The pons has nuclei for ascending and descending tracts, but also has nuclei for what cranial nerves?
CN5-CN7
What is the function of the pons?
information relay for cerebellar hemispheres
What are the structures found in the midbrain?
- cerebral peduncles
- corpora quadrigemina (superior and inferior colliculi)
- nuclei for CN3 and CN4
- red nucleus and substantia nigra
The midbrain contains cerebral peduncles which contain what?
- descending motor axon tracts from cerebral hemispheres to spinal cord, medulla, and pons
- ascending sensory axons going to the cerebrum
- PRIMARILY MOTOR
What are the parts of the corpora quadrigemina and their function?
- 2 superior colliculi- reflex movement of eye, head, and neck to visual and other stimuli
- 2 inferior colliculi- reflex movement of head and neck to auditory stimuli
The midbrain has nuclei for what cranial nerves?
CN3 and CN4
What is the function of the red nucleus and the substantia nigra?
modify motor signals (coordination)
What are the 2 main functions of the midbrain?
- relay motor impulses from cerebral cortex
- relay sensory impulses from spinal cord to thalamus
The reticular formation is composed of gray matter interspersed among areas of white matter in central portions of what?
- diencephalon
- brain stem
- spinal cord
What are the main functions of the reticular formation?
- alerting cerebral cortex to sensory signals
- the reticular activating system functions in maintaining consciousness and awakening from sleep by stimulating the cortex
- filters sensory input to remove unimportant input
CEREBELLUM (METENCEPHALON)
CEREBELLUM (METENCEPHALON)
The cerebellum is composed of _ ventricles that are connected by what?
What else is located in the cerebellum?
- 2
- vermis
- peduncles
The _______ is the gray matter of the cerebellum, and the _________ is the white matter of the cerebellum.
- cortex
- arbor vitae
What are the ridges on the cerebellum called?
folia
The cerebellar nuclei are gray matter scattered in what?
arbor vitae (white matter)
What are the 3 main functions of the cerebellum?
- coordinate cerebral control of skeletal muscle movements
- regulate muscle tone
- posture and balance
DIENCEPHALON
DIENCEPHALON
What are the 4 parts of the diencephalon?
- thalamus
- hypothalamus
- epithalamus
- subthalamus
What are the main functions of the thalamus?
- sensory relay to the correct region of the cerebral cortex
- refine motor signals with the basal nucleus
The R and L thalamus is seperated by what?
3rd ventricle
What is the overall function of the hypothalamus?
Maintain homeostasis
The hypothalamus controls ________ nervous system, _______ system, and body ___________.
- autonomic NS (heart, gut, bladder)
- endocrine (via control of pituitary)
- temperature
The hypothalamus regulates _______ behavior (limbic system), ______ and _________, and ________ rhythms and states of consciousness.
- emotional
- eating and drinking
- circadian rhythms
All of the functions of the hypothalamus are somewhat _______ _________.
unconscious involuntary
The hypothalamus has __ nuclei.
11 (dozen)
What is visible on the anterior surface of the hypothalamus?
mamillary bodies
What structure connects the pituitary to the hypothalamus
infundibulum
The epithalamus is composed of what 2 structures?
What are their functions?
- pineal gland- melatonin production to set biological clock
- habenular nuclei- emotional response to smell
The subthalamus is composed of what 3 structures?
- subthalamic nuclei (paired)
- parts of red nuclei (paired)
- parts of substantia nigra (paired)
What is the function of the subthalamus?
refines movement and is important for motor control
CIRCUMVENTRICULAR ORGANS
CIRCUMVENTRICULAR ORGANS
What are the 3 circumventricular organs? What is their function?
- hypothalamus, pituitary, pineal
- internal sensory system to maintain homeostasis
What do the circumventricular organs not have?
BBB
BASAL GANGLIA (TELENCEPHALON)
BASAL GANGLIA (TELENCEPHALON)
What is the function of the basal ganglia?
- control of skeletal muscle movement and muscle tone
- refine motor responses, making movements smoother
LIMBIC SYSTEM (TELENCEPHALON, DIENCEPHALON)
LIMBIC SYSTEM (TELENCEPHALON, DIENCEPHALON)
The limbic system is the “________” brain and functions in _______ aspects of behavior and memory-pain, pleasure, affection, and anger to determine ________.
- primitive
- emotional
- feelings
CEREBRUM (TELENCEPHALON)
CEREBRUM (TELENCEPHALON)
The cerebral cortex of the cerebrum is composed of ____ matter
gray
What are the 3 types of neurons found in the white matter of the cerebrum?
- association fibers
- commissural fibers
- projection fibers
Association fibers connect different gyri in _____ hemisphere.
same