Week Three Flashcards
Organization of the Cortex
• Cytoarchitectonic Maps of the Cerebral Cortex
• Maps based on the organization, structure, and distribution of cortical cells
• Brodmann’s Atlas (44 areas)
- Most widely used cytoarchitectonic map
- von Economo and Koskinas’ Atlas (107 areas)
o Talairach’s stereotactic atlas based on one brain
- Montreal Neurological Institute (MNI) Mapping Scheme: based on hundreds of brains
Forebrain: Basal Ganglia
Collection of nuclei that includes the:
- Putamen
- Globus Pallidus
- Caudate Nucleus
- Subthalamic Nucleus
- Substantia nigra
• Supports stimulus-response learning
- Functions in sequencing movements
- Modulates muscle force
- Control and regulate activities of the motor and premotor cortical areas so that voluntary
movements can be performed smoothly
The limbic System
A collection of functionally and anatomically interconnected structures in the telencephalon and
diencephalon
Amygdala
- Emotion and species-typical behaviors
Hippocampus and fornix
- Memory and spatial navigation
Mammillary bodies
- Memory consolidation
Septum
- a Emotion and species-typical behavior
• Cingulate Cortex (cingulate gyrus)integral part of the limbic system involved with emotion
formation, learning and memory
Diencephalon: region between the telencephalon and brain stem consisting of the
Thalamus
- Relays all sensory information (except olfactory) to appropriate cortical targets
- Relays information amongst cortical areas
- Relays information between forebrain and brainstem
Hypothalamus
- Interacts with the pituitary gland
- Participates in nearly all aspects of motivated behavior
Epithalamus
- Poorly understood; Biorhythms, hunger, thirst
Thalamus — inner chamber (Lat.) a part of the limbic system
- Great “Relay” nucleus bridging the cortex and spinal cord
- Receives Auditory, Somatosensory and Visual signals
- Controls sleep and Awake
- Connected to the hippocampus
The mesencephalon (midbrain)
- Uppermost portion of the brainstem
- Cerebral peduncles fiver texts connecting the cortex, cerebellum and spinal cord
- Tectum (ceiling) inf. And sup. Colliculi
- Tegmentum (covering or midbrain floor) and surrounds the cerebal aqueduct
Midbrain
Red nucleus
- limb movements
Substania Nigra
- Reward and imitation of movement
Peri-aqueductual
- Species-typical behaviours (eg; sexual behaviour)
Hindbrain
Pons and Medulla
- Serve many functions, including waking, sleeping, and locomotion
The Metencephalon
- Pons (bridge) functionally connects cortex and cerebellum
- Cerebellum: neuronal computer, involved in sensorimotor integration
The Myelencephalon
Medulla oblongata control of Verdi’s and respiratory functions; reflex centres for vomiting, coughing, sneezing, swallowing, etc. Central pattern generators
Connections between central and somatic nervous system:
Cranial nerves
-12 pairs (24 nerves) descending from the olfactory nerve
- sensory functions, motor functions, or both
• I (Olfactory)(S) - Smell
• Il (Optic) (S) - Visual acuity, visual fields and ocular fundi
• Ill (Oculomotor) (M) - Pupillary reactions
•IV (Trochlear) (M)
• V (Trigeminal)(B) - Facial sensation, movements of the jaw, and corneal reflexes
•VI (Abducens)(M) - Extra-ocular movements, including opening of the eyes
• VII (Facial) (B) - Facial movements and gustation
• VIII (Auditory) (S) - Hearing and balance
•IX (Glossophyaryngeal) (B),
•X (Vagus)(B) - Swallowing, elevation of the palate, gag reflex and gustation
•XI (Spinal accessory)(M) - Shrugging the shoulders and turning the head
•XII (Hypoglossal)(M) - Movement and protrusion of tongue
•V.VII.X.XIl - Voice and speech
Memory aids for Cranial Nerves
Cranial Nerve names: On old olympus’ towering top a Finn and German bend some hops
Cranial nerve types (sensory/motor/both): Some say marry money but my brother says big boobs matter more
The spinal cord
•Courses through the vertebral canal, inside the vertebral column, from the foramen magnum to Ly
and or/12.
• Below La fibrous strands (cauda equina) continue to the coccyx through the lumbar cistern.
Each spinal segment has TWO PAIRS of somatic nerves associated with it
• a left sensory nerve entering the left dorsal horn of the spinal cord
• a right sensory nerve entering the right dorsal horn of the spinal cord
• a left motor nerve exiting the left ventral horn of the spinal cord
a right motor nerve exiting the right ventral horn of the spinal cord
Myotome
Each muscle is innervated by the output of 1 or more spinal segments. The muscle and nerve are collectively called the ‘myotome’. Examples of myotomes:
• Cervical 3, 4 & 5: Diaphragm muscles
• Cervical 5: Shoulder movements and elbow flexion
• Cervical 6: Wrist dorsiflexion (often only control of shoulder and arm not wrist)
• Cervical 7: Elbow extension (lack off extension)
• Cervical 8: Finger flexion
• Thoracic 1: Finger extension
Somatic Nervous System
Two “thickenings” in the spinal cord:
• Cervical Enlargement (innervates the upper limbs via the Brachial Plexus)
• Lumbar Enlargement (innervate the lower limbs)
Spinal cord is capable of mediating some movements
Reflexive behaviours
• Specific movements elicited by specific stimuli
• Monosynaptic and bisynaptic reflexes
• Evolved to produce Central Pattern generators
Autonomic Nervous System: Two divisions
Sympathetic Division
- Generally: Arouses the body for action
- “Fight or Flight”
- Spinal nerves in the thoracic and lumbar regions are connected to the sympathetic ganglia
- dilates pupil via pupillary dilator muscle
Parasympathetic Division
- Generally: Calms the body down
- “Rest and Digest”
- Connects with parasympathetic ganglia near target organs
- constricts pupil via pupillary sphincter muscle
Tractography: Mapping Connections Amongst Brain Areas
Neocortical regions are connected by four types of axon projections
- Long connections between one lobe and another
- Relatively short connections between one part of a lobe and another part of same
Interhemispheric connections
• Homotopic points (in typicals)
• Heterotopic point (in AgCC patients)
• Connections through the thalamus
Contralateral White Matter Projections (aka ‘Commissures’)
CNS connects mainly with contralateral body
- Each symmetrical half responds to sensory stimulation from the contralateral body or controls musculature on the contralateral body
Decussations
- Sensory and miter fibres cross the midline at the level of the spinal cord, corpus callosum, anterior and posterior commissures
Brain Commisures (crossing the midline)
- Corpus Callosum
- Anterior Commissure
- Hippocampal Commissure (psalterium)
- Habenular Commissure
- Posterior Commissure
- Supraoptic Commissures
