L2 Brain Anatomy

Draw out the anatomical organization of the nervous system.

A ______ section is cut in the vertical plane, from the crown of the head down, yielding a frontal view of the brains internal structures

Coronal

A ______ section, is usually viewed looking down on the brain from above.

Horizontal

A ______ section is cut lengthways from front to back and viewed from the side

Sagittal

What are the divisions of the brain during development?

• The developing brain first divides into the forebrain, midbrain, and hindbrain.

• Forebrain → telencephalon + diencephalon

• Midbrain → mesencephalon

• Hindbrain → metencephalon + myelencephalon

What major brain structures develop from each brain division?

• Telencephalon → cerebral cortex, basal ganglia, limbic system

• Diencephalon → thalamus + hypothalamus

• Mesencephalon → tectum + tegmentum

• Metencephalon → cerebellum + pons

• Myelencephalon → medulla oblongata

What is Brodmann known for?

• Dividing the cortical areas of the brain (known as Broanmann’s Areas)

• These divisions are correlated with their brain functions

What is the telencephalon and what are its main structures/functions?

• Neocortex → perceptions, thoughts & planning

• Allocortex → emotions & personal memory

• Basal ganglia → reward, movement & routines

What are the basal ganglia and their two pathways?

• Basal ganglia are involved in reward, movement & routines.

• Direct pathway → excitatory (promotes activity/movement).

• Indirect pathway → inhibitory (reduces activity/movement).

What are the main structures of the diencephalon and their functions?

• Epithalamus → seasonal rhythms (pineal gland)

• Thalamus → cortical relay system

• Hypothalamus → maintains body homeostasis through regulatory behaviours

What is the function of the thalamus?

• Acts as a cortical relay system.

• Filters and integrates information entering and leaving the cerebral cortex.

• Contains many nuclei (nut).

What is the function of the hypothalamus?

• Maintains body homeostasis through regulatory behaviours.

• Contains many nuclei that control the pituitary gland.

• Helps regulate basic body functions through its influence on hormones.

What does the hypothalamus regulate?

• Drinking & eating

• Body temperature & sleep

• Salt regulation

• parental behaviour

What is the mesencephalon and its main divisions?

• Mesencephalon = midbrain

• Divided into tectum (“roof”) and tegmentum (“floor”)

• Tectum → sensory; Tegmentum → motor

What is the function of the tectum?

• The tectum is mainly sensory.

• Superior colliculi → visual control

• Inferior colliculi → auditory control

What is the tegmentum?

• The tegmentum is mainly involved in motor functions.

• ex.) species -typical behaviours, such as mating & fighting

• Contains structures including the substantia nigra, red nucleus, reticular formation, Ventral Tegmental area , and periaqueductal gray.

What is the metencephalon?

• A subdivision of the hindbrain.

• Contains the pons and cerebellum.

What is the pons and what does it do?

• Pons = “bridge” → connects upper and lower parts of the brain.

• Major relay between the cerebellum and neocortex.

• Helps control unconscious behaviours like breathing, swallowing, bladder control, balance & posture.

What is the cerebellum and what does it do?

• Cerebellum = “little brain”

• Involved in sensory processing and motor behaviour/skills

• Important for motor learning

What is the myelencephalon and what does it do?

• Myelencephalon → medulla oblongata

• Controls unconscious behaviours

• Regulates breathing, heart rate, blood pressure, sneezing & coughing

What is the reticular formation and what does it do?

• Also called the reticular activating system (RAS).

• Responsible for arousal/alertness and helps regulate wakefulness.

• Sends signals upward to areas including the cerebral cortex.

What is the substantia nigra and what is it associated with?

• Substantia nigra cells produce dopamine and are involved in movement.

• In Parkinson’s disease, these cells/pigmentation are lost.

• This causes hypokinesia → reduced movement, including bradykinesia, akinesia & rigidity.

What movement problems are associated with Parkinson’s disease?

• Bradykinesia → slow movement

• Akinesia → difficulty starting voluntary movement

• Rigidity → increased muscle tone