Human Brain Divisions
cerebrum, brainstem, diencephalon, cerebellum
What protects the brain?
skull, meninges, and BBB
Ventricles of the
... [Show More] brain
cavities within the brain filled with cerebrospinal fluid; 2 lateral, 3rd ventricle, 4th ventricle
Meninges
3 layers of connective tissue that cover and protect the CNS organs and enclose CSF.
Dura Mater
thick, outermost layer of the meninges surrounding and protecting the brain and spinal cord
pia mater
the delicate innermost membrane enveloping the brain and spinal cord.
CSF
special fluid formed in walls of ventricles from blood plasma by permeating through the choroid plexus; cushions the brain and spinal cord by providing buoyancy, allowing the brain to float.
BBB
diffusion barrier that prevents most particles from entering CNS tissue; brain and spinal cord separate from general blood circulation. Formed by impermeable brain capillaries, due to astrocytes due to need for stable chemical environment.
Cerebrum
largest part of the brain, 83%; includes median longitudinal fissure, left and right cerebral hemispheres, gyri, sulci, and fissures
corpus callosum
A bridge of white nerve fibers that connect cerebral hemispheres
Cerebral cortex
outer region of the cerebrum, containing sheets of nerve cells; gray matter of the brain
Deep sulci
frontal, parietal, temporal, occipital
Frontal sulci
controls higher level executive fx like reasoning and decision making; controls motor fx and control over voluntary muscle actions
parietal lobe
A region of the cerebral cortex whose functions include processing information about touch; receive sensory info from receptors in mouth for taste and in skn four touch, pain, and pressure.
Occipital
interprets visual input
Temporal
sensory areas for hearing and smelling
Association areas
act mainly to integrate more than 1 type of sensory info for purposeful action
Primary motor cortex
the section of the frontal lobe responsible for voluntary movement
Primary sensory cortex
regions of the cerebral cortex that initially process information from the senses
Broca's area
controls language expression - an area, usually in the left frontal lobe, that directs the muscle movements involved in speech; speech production
Wernicke's Area
located in temporal lobe; speech comprehension
Conciousness
state of being awake/aware, located in the cerebrum.
Cerebrum controls:
Cerebrum controls activities of the lower parts of the brain, can override functioning of lower parts of brain (i.e. via biofeedback, meditation, etc.), initiates voluntary motor activities and controls actions of cerebellum by acting on sensory input via thalamus.
Brainstem
medulla oblongata, pons, midbrain
medulla oblongata
Part of the brainstem that controls vital life-sustaining functions such as heartbeat, breathing, blood pressure, and digestion; vasoconstriction, reflex centers for vomiting, coughing, sneezing, hiccuping and swallowing, tracts that ascend or descend between SC and brains higher centers
vasoconstriction
the constriction of blood vessels, which increases blood pressure.
Pons
Contains axon bundles traveling between cerebellum and rest of CNS; fx with medulla to regulate breathing rate and has reflex centers concerned with head movements in response to auditory and visual stimuli
Midbrain
Acts as a relay center for tracts passing between the cerebrum, SC or cerebellum; reflex-centers for higher levl fxs involved in visual, auditory, and tactile responses.
Superior and inferior colliculi
located at the rostral end of the brainstem, control reflexes for head, neck in response to sudden visual or auditory stimulus
Diencephalon
thalamus, hypothalamus, epithalamus
maintains homeostasis, regulates basic body fx like hinger, sleep, thirst, body temp, water balance, and BP
Controls pituitary gland by regulating hormones of endocrine
link between nervous and endocrine systems
Thalamus
the brain's sensory switchboard, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla; filters out unimportant sensory info and directs it to appropriate regions of cerebruum for interpretation.
Epithalamus
contains the pineal gland (melatonin for sleep-wake cycle)
Cerebellum
Mini-Brain
composed of thin outer cortex of gray matter and internal white matter
Maintain balance, certain eye movements, normal muscle tone, and posture
keeps joints and bones in place
Anterior and posterior lobes
receive info from body trunk and influence motor activities of trunk, shoulders, and pectoral girdle muscles
Vermis
intermediate portion/ coordinates limb movements
cerebellar peduncles
fiber tracts that communicate with other parts of the brain
The Limbic System
neural system (including the hippocampus, amygdala, and hypothalamus) located below the cerebral hemispheres; associated with emotions and drives.
involves both concious and unconcious parts of brain
our "feeling brain" because stimulation of different areas of limbic causes rage and anger, pain, pleasure, and sorrow
cingulate gyrus
plays role in expressing emotions via gestures and resolves mental conflict; connects different lobes of cerebrum
Hippocampus
involved in retrieval and storage of memories
Amygdala
small portion of limbic that's involved in emotions such as rage and anger
Fornix
bundle of nerve fibers that serve as a connection to hippocampus
Mamillary bodies
contains fibers that project into thalamus and assist with memory of smell
Basal Ganglia
masses of gray matter that lie deep within each hemisphere of cerebrum
part of limbic system
responsible for working with the cerebellum to regulate planning motor movements and motor learning
overall effect is to have an inhibitory effect of cerebral cortex to slow down and control precise movements
Parkinson's disease
Apraxia
inability to perform particular purposive actions, as a result of brain damage. Results in rigid movements and difficulty in executing a motor plan.
Spinal Cord
a major part of the central nervous system which conducts sensory and motor nerve impulses to and from the brain
extends from brainstem to 1st lumbar vertebrae and terminates at the conus medullaris
Cauda equina
collection of spinal nerves below the end of the spinal cord
vertebral column
Protects spinal cord, meninges, and csf
spinal dura mater
single-layer sheath that is separated from vertebral column via epidural space
Filium terminale
extension of pia mater, anchors spinal cord to coccyx
Spinal tap
placement of a needle through an intervertebral space into the subarachnoid space to withdraw CSF
less risk to damage at L1
central canal/vertebral foramen
opening that runs length of spinal cord and filled with CSF
White matter in SC
composed of myelinated and unmyelinated nerve fibers, organized into columns.
Tracts of SC
a bundle of nerve axons, cross-over to opposite side of SC
What makes L-side control the R-side and vice versa
Dorsal root
the sensory branch of each spinal nerve; cell bodies of afferent neurons
dorsal root ganglion
contains cell bodies of sensory neurons
Ventral root
axons of motor neurons
gray commissure
connects masses of gray matter; encloses central canal; this cross-bar
Anterior/ventral horns
contain somatic motor neurons with axons that serve as efferent paths from receptors by way of dorsal roots of SC
Posterior/dorsal horns
one of the afferent paths from receptors by way of dorsal roots of SC
Lateral horns
(only in thoracic and superior lumbar regions) - sympathetic neurons
Spinal Nerves
31 pairs of nerves arising from the spinal cord
Roots
two short branches that lie within vertebral column
Dorsal root
contains axons of sensory neurons, impulses toward cord
Ventral root of SC
contains axons of efferent motor neurons, impulses away from cord
Dorsal ramus
Contains nerves that serve dorsal portions of trunk
Ventral ramus
nerves that serve the remaining ventral part of upper and lower limbs
Plexus
some ventral rami merge with adjacent ventral rami, a network of interconnecting nerves
Major plexus
cervical, brachial, lumbar, sacral
Spinal nerve path
signal passes through dorsal roots into SC and to the brain for processing
command signal sent down the SC to appropriate level and out ventral root of SC
signal carried via spinal nerve to appropriate destination to muscle fiber to enable voluntary muscular contraction.
Dermatomes
an area of the skin supplied by nerves from a single spinal root
Cervical plexus
C1-C5
Phrenic nerve: most important, supplies both motor and sensory fibers to diaphragm (irritation causes hiccups)
if severed, paralysis which requires a ventilator
Brachial plexus
C5-T1
innervates the pectoral girdle and upper limbs
Axillary nerve
deltoid and teres minor, long head of triceps brachii, sensory part of shoulder joint
Radial nerve
Supplies triceps brachii of arm, as well as 12 muscles in forearm controlling wrist and finger extension; sensory info to associated joints and overlying skin
wraps elbow joint and radial nerve of humerus then follows radial nerve in forearm
Median nerve
supplies flexor muscles of forearm and skin of first 3.5 fingers
Ulnar nerve
supplies part of flexor muscles of forearm, wrist, and hand, skin of 1/2 ring finger, and pinky
Musculocutaneous nerve
flexor muscles of arm, including biceps brachii, and brachialis
Lumbar plexus
L1-L4
anterior and posterior division of branch into nerves to supply pelvis and lower extremities
Femoral nerve
major nerve of lumbar plexus, supplies hip flexors and knee extensors and sensation of skin of anterior thigh
lateral femoral cutaneous nerve
a cutaneous nerve that innervates the skin on the lateral part of the thigh.
L3
saphenous nerve
Supplies impulses to the skin of the inner side of the leg and foot.
Sacral plexus
L4-S4
Sciatic nerve: arises from sacral plexus, largest nerve in the body
supplies trunk and posterior surface of thigh (branches: common fibular nerve, tibial nerve)
Autonomic NS
the part of the PNS that controls the glands and muscles of the internal organs, like the heart
Made up of motor neurons that control internal organs automatically and w/o conscious intervention. [Show Less]