Study sheet: Brain Anatomy and Function

📋 Course Outline

1. Brain Composition and Signaling
2. Major Brain Divisions
3. Cerebral Cortex and Hemispheres
4. Brainstem and Cerebellum
5. Meninges and Cerebrospinal Fluid
6. Lobes and Deep Structures
7. Brain Blood Supply and Ventricles
8. Cranial Nerves

📖 1. Brain Composition and Signaling

🔑 Key Concepts & Definitions

• Central nervous system : Consists of the brain and the spinal cord extending from it.

★ Must-know

📌 Gray matter is primarily composed of neuron cell bodies and processes information, whereas white matter is primarily composed of myelinated axons and transmits information to other parts of the nervous system.

• The brain communicates through chemical and electrical signals carried by billions of neurons, with some messages remaining within the brain and others traveling through the spinal cord and peripheral nerves.

Further detail

• The average adult brain weighs about 3 pounds and is approximately 60% fat.

💡 Memory Hook

Gray matter processes; white matter transmits.

📖 2. Major Brain Divisions

🔑 Key Concepts & Definitions

• Cerebrum : The largest part of the brain and initiates and coordinates movement, regulates temperature, and supports speech, judgment, thinking, reasoning, problem-solving, emotions, learning, and sensory functions.
• Brainstem : Connects the cerebrum with the spinal cord and consists of the midbrain, pons, and medulla.
• Cerebellum : Located at the back of the head below the temporal and occipital lobes and above the brainstem, and coordinates voluntary muscle movements while maintaining posture, balance, and equilibrium.

📝 Essential Points

• The three high-level divisions are:
  • the cerebrum
  • the brainstem
  • the cerebellum

💡 Memory Hook

Cerebrum, brainstem, cerebellum: CBC.

📖 3. Cerebral Cortex and Hemispheres

🔑 Key Concepts & Definitions

• Cerebral cortex : The folded outer gray matter covering of the cerebrum and comprises about half of the brain’s weight.
• Corpus callosum : A large, C-shaped structure of white matter and nerve pathways in the center of the cerebrum that connects the two cerebral hemispheres.

★ Must-know

📌 The right cerebral hemisphere controls the left side of the body, while the left cerebral hemisphere controls the right side.

Further detail

• The cerebral cortex is divided into two hemispheres and covered by ridges called gyri and grooves called sulci.

💡 Memory Hook

A folded gray mantle split into two communicating halves.

📖 4. Brainstem and Cerebellum

🔑 Key Concepts & Definitions

• Medulla : The lowest part of the brainstem, where the brain meets the spinal cord, and regulates heart rhythm, breathing, blood flow, oxygen and carbon dioxide levels, sneezing, vomiting, coughing, and swallowing.
• Pons : The pons connects the midbrain and medulla and is the origin of four cranial nerves involved in functions including tear production, chewing, blinking, vision focusing, balance, hearing, and facial expression.

📝 Essential Points

• The midbrain contains neural nuclei and pathways involved in hearing, movement, responses to environmental changes, and coordination through the substantia nigra and basal ganglia.

• The substantia nigra is rich in dopamine neurons and is affected by Parkinson’s disease.

💡 Memory Hook

Midbrain → pons → medulla.

📖 5. Meninges and Cerebrospinal Fluid

🔑 Key Concepts & Definitions

• Meninges : Three protective layers surrounding the brain and spinal cord: the dura mater, arachnoid mater, and pia mater.
• Cerebrospinal fluid : A watery fluid that cushions the brain and spinal cord, circulates around them, removes waste and impurities, and delivers nutrients.

📝 Essential Points

• The dura mater is the thick, tough outer layer and has periosteal and meningeal layers, with spaces between them allowing passage of vessels supplying the brain.

• The pia mater is a thin membrane that closely follows the brain’s contours and is rich in veins and arteries, while the arachnoid mater contains no nerves or blood vessels.

💡 Memory Hook

Dura → arachnoid → CSF → pia.

📖 6. Lobes and Deep Structures

🔑 Key Concepts & Definitions

• Frontal lobe : Involved in personality, decision-making, movement, smell recognition, and speech through Broca’s area.
• Parietal lobe : Helps identify objects, understand spatial relationships, and interpret pain and touch, and contains Wernicke’s area for understanding spoken language.
• Hypothalamus : Lies above the pituitary gland and regulates body temperature, sleep patterns, hunger, thirst, and aspects of memory and emotion by sending chemical messages to the pituitary gland.
• Hippocampus : A curved, seahorse-shaped structure beneath each temporal lobe that supports memory, learning, navigation, and spatial perception.

★ Must-know

• The occipital lobe is the posterior brain lobe primarily involved in vision.

Further detail

• The temporal lobe is involved in short-term memory, speech, musical rhythm, and some smell recognition.

• The pituitary gland is a pea-sized structure behind the bridge of the nose that governs other glands by regulating hormones from the thyroid, adrenals, ovaries, and testicles.

• The amygdalae regulate emotion and memory and are associated with reward, stress, and the fight-or-flight response to perceived threats.

• The pineal gland responds to light and darkness and secretes melatonin, which regulates circadian rhythms and the sleep-wake cycle.

📖 7. Brain Blood Supply and Ventricles

🔑 Key Concepts & Definitions

• Ventricular cerebrospinal fluid : Manufactured by the ventricles, circulates through the ventricles, spinal cord, and spaces between the meninges to cushion the central nervous system, remove waste, and deliver nutrients.
• Circle of Willis : A loop of blood vessels near the bottom of the brain that connects major arteries, circulates blood between the front and back of the brain, and helps arterial systems communicate.

📝 Essential Points

• The brain contains four ventricles connected by passageways that open into the central spinal canal and the space beneath the arachnoid layer.

• The vertebral and carotid arteries supply blood and oxygen to the brain.

• 🔄 Brain arterial supply follows this pattern:

  1. The vertebral arteries follow the spinal column into the skull.
  2. They join at the brainstem to form the basilar artery.
  3. The basilar artery supplies the rear portions of the brain.
  4. The internal carotid arteries enter the skull and supply the front of the brain.

💡 Memory Hook

Arterial connections maintain circulation from the brain’s front to its back.

📖 8. Cranial Nerves

★ Must-know

• There are 12 cranial nerves; cranial nerves 1 and 2 originate in the cerebrum, while cranial nerves 3 through 12 emerge from the brainstem.

• Cranial nerves 1–4 are:

  • the olfactory nerve for smell
  • the optic nerve for eyesight
  • the oculomotor nerve for pupil response and eye movements
  • the trochlear nerve for eye muscles

• Cranial nerves 5–8 are: the trigeminal nerve for facial sensation and chewing, the abducens nerve for eye muscles, the facial nerve for facial movement and taste, the vestibulocochlear nerve for balance and hearing

Further detail

• Cranial nerves 9–12 are: the glossopharyngeal nerve for taste and throat movement, the vagus nerve for ear and digestive sensation and motor control of the heart, throat, and digestive system, the accessory nerve for head, neck, and shoulder muscles, the hypoglossal nerve for tongue motor activity

💡 Memory Hook

Nerves 1–2 arise from the cerebrum; nerves 3–12 arise from the brainstem.

📊 Synthesis Tables

Brain Regions and Main Functions

Region	Main functions	Key structures or associations
Cerebrum	Movement, cognition, language, emotion, senses	Cerebral cortex and corpus callosum
Brainstem	Connection to spinal cord and vital regulation	Midbrain, pons, medulla
Cerebellum	Voluntary movement, posture, balance, equilibrium	Two hemispheres; posterior location
Lobes	Specialized sensory, language, memory, and executive functions	Frontal, parietal, temporal, occipital