Basic Neuroanatomy Flashcards
2 major divisions of the nervous system
- Central Nervous System (CNS): Brain and spinal cord
- Peripheral Nervous System (PNS): everything outside brain and spinal cord
2 divisions of the PNS
- Somatic nervous system (SNS)
- Autonomic Nervous system (ANS)
Somatic nervous system
- interacts with external environment; controls voluntary muscles
- Has afferent nerves that carry sensory signals in from the skin, skeletal muscles, joints, eyes, ears, etc. into CNS (body -> brain)
- Has efferent nerves that carry motor signals from CNS out to skeletal muscles (brain -> body)
Autonomic nervous system
- Regulates internal environment; controls internal organs
- Has afferent nerves that carry sensory signals from internal organs to the CNS
- Has efferent nerves that carry motor signals from the CNS to internal organs (2 types)
2 types of efferent nerves in Autonomic Nervous System
- Sympathetic nerves:
- Mobilize energy resources in threatening situations (ie. Via adrenal glands) to help you take action
- Parasympathetic nerves:
- Conserve energy; facilitates immune function, digestion, etc.
- We usually receive input from these systems at the same time (not true that only one or the other is activated)
Term for clusters of cell bodies in CNS vs. PNS
- In CNS: “Nucleus”
- In PNS: “Ganglia”
Term for bundles of axons in CNS vs. PNS
- In CNS: “tract”
- In PNS: “nerve”
Alternate term for “axons”
“Fibers”
Basic neuroanatomical directional terms
- Anterior/rostral (front)
- Posterior/caudal (back)
- Dorsal/superior (top)
- Ventral/inferior (bottom)
Directions in the NS/Brain
- Medial (vertical slice through middle)
- Lateral (either to the left or right of that vertical slice; left lateral or right lateral)
Planes the brain is cut on
- Coronal (frontal) section (like a slice encompassing your whole face)
- Horizontal section (like a slice cutting horizontally through the top of your head)
- [Mid-]sagittal section (like a vertical slice between your eyes)
spinal cord
- Different sections (from top to bottom): cervical, thoracic, lumbar, sacral, coccygeal)
- On spinal cord, most of sensory info comes from dorsal side; on ventral side is where motor information is exiting
- 2 different areas of each piece of spinal cord:
- Inner H-shaped core of grey matter: composed largely of cell bodies and unmyelinated axons
- Surrounding area of white matter: composed of unmyelinated axons
Major divisions of the brain
- Forebrain (incl. telencephalon & diancephalon)
- Midbrain (incl. mesencephalon)
- Hindbrain (incl. metacephalon & myelencephalon)
myelencephalon
- AKA: Medulla
- Composed largely of tracts carrying signals between the rest of the brain and the body
- Contains reticular formation (~100 nuclei involved in myriad functions)
- Important for basic life functions
metencephalon
- Houses many fiber tracts & reticular formation
- Fibers and pontine nuclei create large bulge: “pons”
- Contains cerebellum (10% of brain volume but 50% of its neurons)
mesencephalon
composed of tectum and tegmentum
tectum
- composed of 2 pairs of bumps; inferior colliculi and superior colliculi (on dorsal side)
- Inf: responds to auditory stimuli
- Sup: responds to visual stimuli
tegmentum
- contains:
- Top of the reticular formation
- Fibers of passage
- Periaqueductal grey (resp. for old evolutionary behaviours - ie. Rats running away from threats)
- Substantia nigra (provides dopamine to other areas of brain, important for movement)
- Red nucleus (resp. For organism-specific behaviours - ie. eats squeaking vs. Dogs barking); on ventral side
diancephalon
- Composed of thalamus and hypothalamus
- Thalamus: comprises many different types of nuclei, including sensory relay nuclei. Includes Corticothalamic loop: allows us to be awake and aware
- Hypothalamus: plays important role in several behaviours due partly to its effect on pituitary gland
telencephalon
- Largest division of brain
- Cerebral cortex is its most prominent constituent; also contains corpus callosum
location and function of corpus callosum
- Located in telencephalon
- Connects the cerebral hemispheres together (along with other cerebral commissures)
appearance of cerebral cortex
- Highly convoluted (increases surface area while maintaining a small volume), unlike many smooth-brained mammals
- Large furrows are called fissures or sulci; ridges between fissures are called gyri
- Largest fissure is the longitudinal fissure (goes through centre of the brain, separates left and right hemisphere)
- Interindividual cortical variability – lots of variation amongst individuals, but similarity between identical twins
Limbic system components
- Fornix
- Left and right cingulate cortex
- Hippocampus
- Amygdala
- Mammillary body
- Septum
Basal ganglia components
- Striatum (Caudate and putamen); made up of nucleus accumbens
- Thalamus
- Amygdala
- Globus pallidus
Lobes of cerebral cortex
- Two major landmarks: Central fissure and lateral fissure
- Four lobes: Occipital, Temporal, Parietal, and Frontal.
anatomical features that protect the brain
- skull
- meninges
- ventricles
3 layers of meninges
- Dura matter
- Arachnoid matter
- Pia matter
types of ventricles
- Lateral ventricles
- Third ventricle
- Cerebral aqueduct
- Fourth ventricle (close to medulla and pons)
- Central canal
