Structural Anatomy Flashcards
Neuroscience
study of nervous system
Behavioural neuroscience
study of the nervous system as it relates to behaviour
Cognitive neuroscience
the study of how cognitive processes occur in the brain, often through the lens of academic research
Neuropsychology
study of the brain in functional and dysfunctional states, often through a clinical lens
What two components make up the vertebrate nervous system?
- The peripheral nervous system
- The central nervous system
2 further branches of the PNS
1. Peripheral Nervous System
- The somatic NS
- The autonomic NS
The somatic nervous system (SNS) - interacts with…
- Peripheral Nervous System
the external environment
- Peripheral Nervous System
What 2 types of nerves does the somatic nervous system (SNS) have?
- Peripheral Nervous System
- Afferent nerves: carry sensory signals IN from the skin, skeletal muscles, joints, eyes, ears, etc into the CNS
- Efferent nerves: carry motor signals from the CNS OUT to the skeletal muscles
OVERALL:
* Afferent = arrive (bringing information in)
* Efferent = exit (putting information out)
The autonomic nervous system (ANS) - interacts with…
- Peripheral Nervous System
the internal environment
What 2 types of nerves does the somatic nervous system (SNS) have?
- Peripheral Nervous System
- Afferent nerves: carry sensory signals IN from the internal organs to the CNS
- Efferent nerves: carry motor signals OUT from the CNS to internal organs
OVERALL:
CNS <=> internal organs
The efferent nerves of the ANS are of two types:
- Peripheral Nervous System
- Sympathetic nerves, which mobilize energy in threatening situations (e.g., via adrenal glands)
- Parasympathetic nerves, which act to conserve energy or “rest and digest” (e.g., stimulate gut motility)
The central nervous system is composed into what 2 parts?
The CNS is composed of two parts as well:
- Brain
- Spinal cord (not talking about bones of spine)
inner H-shaped core of gray matter:
Spinal cord
cell bodies and unmyelinated axons
surrounding area of white matter:
Spinal cord
myelinated axons
A cluster of cell bodies is called a…
Basic terminology - CNS
…nucleus (plural: nuclei)
A bundle of axons is called a…
Basic terminology - CNS
…tract
A cluster of cell bodies is called a…
Basic terminology - PNS
…ganglion
A bundle of axons is called a…
Basic terminology - PNS
nerve
Axons are often called…
nerve fibres
Gray matter in the brain is composed of…
cell bodies + capillary blood vessels
White matter in the brain is composed of…
myelinated axons
DIRECTIONS IN THE NS:
- Dorsal
- Caudal
- Ventral
- Rostral
- Anterior
- Posterior
Dorsal
(in a 4 legged specimen)
DIRECTIONS IN THE NS:
- Towards the top
Caudal
(in a 4 legged specimen)
Towards back of head/tail
Ventral
(in a 4 legged specimen)
towards bottom
Rostral
(in a 4 legged specimen)
Towards nose/front of head
Anterior
(in a 4 legged specimen)
Towards front
Posterior
(in a 4 legged specimen)
Towards back
Directions in the NS - for humans: IN HEAD
- Dorsal: top of head (superior)
- Caudal: back of head
- Ventral: bottom of head (inferior)
- Rostral: front of head
- Posterior: back of head
- Anterior: front of head
Rostral
Directions in the NS - for humans: SPINAL CORD
Top of spinal cord (leading to brain)
Dorsal
Directions in the NS - for humans: SPINAL CORD
back of spinal cord
Caudal
Directions in the NS - for humans: SPINAL CORD
bottom of spinal cord
Ventral
Directions in the NS - for humans: SPINAL CORD
front of spinal cord
From a coronal section of the brain:
lateral <= medial => lateral
Section planes:
- Coronal: hamburger style
- Sagittal: hot dog style
- Horizontal
Laterality: 4 types
Laterality
- Unilateral
- Bilateral
- Ipsilateral
- Contralateral
Unilateral
Laterality
on one side only (only one purple square on hand)
Bilateral
Laterality
on both sides (purple box on each hand)
Ipsilateral
Laterality
on the same side (purple box on left hand and left foot)
Contralateral
Laterality
on opposite sides (purple box on left hand, and right foot)
Divisions of the brain: 18-21 day old human embryo - 3 divisions
- Hindbrain
- Midbrain
- Forebrain
Before birth, the 3 initial swellings become 5 structures
Divisions of the brain
- Telencephalon
- Diencephalon
- Mesencephalon
- Metencephalon
- Myelencephalon
Forebrain =>
Before birth, the 3 initial swellings become 5 structures
Divisions of the brain
- Telencephalon
- Diencephalon
Midbrain
Before birth, the 3 initial swellings become 5 structures
Divisions of the brain
- Mesencephalon
Hindbrain
Before birth, the 3 initial swellings become 5 structures
Divisions of the brain
- Metencephalon
- Myelencephalon: composed largely of tracts (bundle of axons) carrying signals between the rest of the brain and the body; HAS LOTS OF MYELIN
Metencephalon - made up of what 2 brain structures?
- Pons: houses many fibre tracts and part of reticular formation
- Cerebellum:
- 50% of all neurons in the brain!
- Massively connected to cortex – multiple cerebro- cerebellar systems
- Involved in movement and timing
Mesencephalon (midbrain) - composed of:
the tectum (“roof”), which contains nuclei that receive and relay:
* visual information (superior colliculi)
* auditory information (inferior colliculi)
the tegmentum (“floor”), which contains nuclei related to:
* motor function (substantia nigra and red nucleus)
* pain (periaqueductal grey)
Reticular formation
- midbrain, pons, medulla
- Reticulum means “little net”
- In the myel-, met- and mesencephalon (midbrain + hindbrain)
- Many nuclei that play roles in arousal, attention, cardiac and respiratory reflexes, and other jobs
Disorders/injuries to the mid- and hindbrain
- Dejerine syndrome
- Chiari malformation
- Pontine tegmental cap dysplasia
Dejerine syndrome (bilateral medial medullary stroke)
Disorders/injuries to the mid- and hindbrain
- Respiratory failure
- Paralysis of all four limbs
- Tongue dysfunction
Chiari malformation
Disorders/injuries to the mid- and hindbrain
Compression and distortion of cerebellum due to skull shape
Symptoms
* Headache
* Neck pain
* Coordination issues
* Swallowing issues
Pontine Tegmental Cap Dysplasia
Disorders/injuries to the mid- and hindbrain
A rare genetic disorder of pons and cerebellum formation due to a developmental error in axon growth and guidance
Systems affected:
* Hearing
* Gaze
* Swallowing
* Facial movements
* Abnormal gaze
Diencephalon - composed of…
- thalamus
- hypothalamus
Diencephalon - Thalamus
- 2-lobed structure
- Many different types of nuclei – some process and relay info between receptors and cortex
- Nuclei may be specific to one sense or non-specific and involved in multimodal integration
- Thalamus & cortex are closely connected
Thalamo-cortical loops and consciousness
Diencephalon
- Thalamus and cortex are closely connected - important in how we see the world as a unified place
- General anesthetics tend to act upon the nonspecific nuclei of the thalamus (as well as other structures)
- Abnormal synchronization in the thalamo-cortical network can cause absence (“ab-sonce”) seizures
The hypothalamus
Diencephalon
- Plays an important role in behaviours such as feeding, sex, sleeping, temperature, emotion, and movement
- Acts upon the body’s endocrine (hormone) system via the pituitary gland
Telencephalon - how big is it?
the largest divsion of the brain
Telencephalon involves which
- Basal ganglia
- Limbic system
- Cerebral cortex
Basal Ganglia
Telencephalon
- “Lower knots”
- Collection of nuclei highly connected to cortex, thalamus, and midbrain
- Involved in movement and learning
Limbic system - made up of what 2 structures (amongst other structures):
Telencephalon
- Includes (among other structures):
- Hippocampus (“seahorse”) – plays a role in spatial memory
- Amygdala (“almond”) – plays a role in emotion
Cerebral cortex - Sulci and Gyrus
Telencephalon
Sulci deep enough to indent the ventricles are also called fissures
- Sulcus: bottom of wrinkle
- Gyrus: top of wrinkle
Cerebral cortex - 90% of the human cerebral cortex is…
isocortex (sometimes called neocortex) = 6-layered
Cerebral cortex - 10% of the human cerebral cortex is…
- …allocortex = <6 layers
- Hippocampus, olfactory (piriform) cortex
What happens if cells don’t migrate normally during development?
Cerebral cortex
- Can lead to condition called lissencephaly
The cerebral hemispheres are connected by only a few tracts called the ________.
The largest is the _______.
Cerebral commissures, corpus callosum
4 cortical lobes
- Frontal lobe
- Temporal lobe
- Occipital lobe
- Parietal lobe
Where does cerebral spinal fluid (CSF) remain?
Ventricles
What are the 3 roles of CSF?
- Buoyancy: the brain is suspended in fluid, reducing its effective weight; does not interfere with blood supply or put pressure on lower structures
- Protection: reduces injury upon head impact; if brain does hit skull: hemorrhaging, brain damage, death…
- Chemical stability: CSF flow rinses waste through the blood-brain barrier; maintains appropriate levels of hormones, pH
Do we only use 10% of our brains?
NO! All action/cognition requires many structures of the brain, each tending to small roles
