Brain Anatomy and Functions Quiz

Brain Anatomy and Nervous Tissue

• External Brain Lobes and Functions:
  • Frontal Lobe: Voluntary motor functions, motivation, planning, mood, emotion, social judgment, and aggression.
  • Parietal Lobe: Primary site for receiving and interpreting general sensory signals.
  • Occipital Lobe: Principal visual center of the brain.
  • Temporal Lobe: Hearing, smell, learning, and some aspects of vision and emotion.
  • Insula: Integrates and processes sensory, motor, and autonomic feedback from different parts of the body. Made visible only by retracting or cutting away overlying cerebrum.
  • Gyri: Thick folds.
  • Sulci: Shallow grooves; deeper indentions between the gyri folds.
• Cerebellum:
  • Occupies the posterior cranial fossa, inferior to the cerebrum.
  • A narrow bridge (vermis) connects the left and right hemispheres.
  • Grooves called sulci or fissures (though PowerPoint calls them sulci, the notes say the indentations are called fissures).
  • Folds called folia.
  • Contains Purkinje cells, which help regulate and coordinate motor movements.
• Internal Gross Anatomy:
  • Thalamus: Located deep in the brain, centrally, two ovoid/ball-shaped masses. Key role in motor control.
  • Hypothalamus: Forms the floor and part of the walls of the 3rd ventricle (where CSF circulates). A major control center for the endocrine and autonomic nervous systems. Involved in homeostasis regulation, hormone secretion, autonomic effects, thermoregulation, food and water intake, sleep and circadian rhythms, memory, and emotional behavior.
  • Corpus Callosum: A bundle of nerve fibers connecting the left and right hemispheres, critical for their communication.

Brainstem Components

• Midbrain
• Pons
• Medulla Oblongata

Meninges

• Located in relation to the brain and skull.
• From most superficial to deep:
  • Epidural space
  • Dura mater
  • Subdural space
  • Arachnoid mater
  • Subarachnoid space
  • Pia mater

Axon Conduction Factors

• Speed depends on axon diameter and the presence/absence of myelin.

Nervous System Divisions

• Central Nervous System (CNS): Brain and spinal cord, processes info and issues commands.
• Peripheral Nervous System (PNS):
  • • Sensory (afferent) Division: Somatic sensory receptors in skin, muscles, bones, and joints to the CNS. Visceral sensory receptors from viscera of thoracic and abdominal cavity.
  • Motor (efferent) Division: Somatic nervous system for voluntary skeletal muscle actions, and the Autonomic nervous system for involuntary actions (Sympathetic or Parasympathetic).

Sensory vs Motor Neurons

• Sensory neurons have long dendrites and short axons, transmitting signals from receptors to the CNS.
• Motor neurons have short dendrites and long axons, transmitting signals from the CNS to effectors (muscles or glands).

Glial Cell Functions

• Protect and assist neurons.
  • Astrocytes: Most abundant, form a supportive framework, help maintain the blood-brain barrier, and respond to injury to help protect and begin the healing process in the CNS. They increase in number where neurons are damaged.
  • Microglia: Defensive immune cells for the CNS.
  • Ependymal Cells: in the CNS, they line cavities and produce cerebrospinal fluid.
  • Oligodendrocytes: in the CNS, they myelinate axons.
  • Schwann Cells: in the PNS, they myelinate axons.
  • Satellite Cells: in the PNS, they surround the neurosomas (cell bodies) and regulate the chemical environment of the neuron.

Neuron Microanatomy

• Soma: Cell body.
• Dendrites: Branching processes that receive signals.
• Axons: Single long processes that transmit signals.
• Axon Hillock: The region where axons originate.
• Node of Ranvier: Gaps in myelin.
• Myelin Sheath: Insulating layer around some axons.
• Axoplasm: Cytoplasm of an axon
• Axolemma: The membrane of an axon

Myelin Cells (CNS vs PNS):

• CNS: Oligodendrocytes
• PNS: Schwann Cells.

Diencephalon Components

• Thalamus
• Subthalamus
• Metathalamus
• Hypothalamus
• Epithalamus (including the pineal gland)

Blood-Brain Barrier

• A protective barrier in brain capillaries.
• Consists of tight junctions between endothelial cells that form capillary walls, and helps regulate what can enter the brain.
• Selective permeability. Excludes most molecules, lets in lipid-soluble molecules for example.

Spinal Cord and Reflexes

• Inborn (intrinsic) Reflexes: rapid, predictable, involuntary motor responses built into our neural anatomy.
• Learned (acquired) Reflexes: responses learned through practice and repetition.

Spinal Cord Anatomical Structures

• Gray Matter: Contains cell bodies and unmyelinated fibers.
• White Matter: Contains myelinated fibers.
• Dorsal Root Ganglion: Contains sensory neuron cell bodies.
• Dorsal/Ventral Horns: Areas of gray matter
• Ventral Root: Contains motor nerve fibers exiting the spinal cord.
• Spinal Nerve: Formed by union of dorsal and ventral roots.

Nerve Plexuses

• Regions where spinal nerves branch. 
• Cervical Plexus: Supplies nerves to the head, neck.
• Brachial Plexus: Supplies nerves to shoulder, arms, and hands.
• Lumbar Plexus: Supplies nerves to abdomen, thighs, and legs.
• Sacral Plexus: Supplies nerves to buttocks, genitals, and lower legs.
• Coccygeal Plexus: Supplies nerves to the coccyx.

Cranial Nerves

• Olfactory (I): Smell
• Optic (II): Vision.
• Oculomotor (III): Eye movement.
• Trochlear (IV): Eye movement.
• Trigeminal (V): Facial sensation, chewing
• Abducens (VI): Eye movement.
• Facial (VII): Facial expressions, taste.
• Vestibulocochlear (VIII): Balance, hearing
• Glossopharyngeal (IX): Swallowing, taste
• Vagus (X): Sensory and motor to many internal organs
• Accessory (XI): Head movement
• Hypoglossal (XII): Tongue movement

Otitis Media

• Inflammation in the middle ear. - Common result of a sore throat, common in children.

Otitis Externa

• Inflammation of the external ear canal (often called "swimmer's ear").

Cochlear Branch

• Part of cranial nerve VIII.
• Involved in hearing.

Eye Anatomy

• Extrinsic Eye Muscles: Control eye movement.
  • Lateral Rectus
  • Medial Rectus
  • Superior Rectus
  • Inferior Rectus
  • Inferior Oblique
  • Superior Oblique
• Retina Cells and Function:
  • Photoreceptors: Rod cells for dim light, Cone cells for color vision.
  • Bipolar Cells
  • Ganglion Cells.
  • Pigmented Cells(at the outer layer).

Shingles

• Reactivation of a latent varicella-zoster virus (chickenpox virus).
• Travels by fast axonal transport along sensory nerve fibers to the skin.

Earwax

• Cerumen, produced by ceruminous glands in the external auditory canal.

Color Blindness

• A lack of one or more cone cells.