Neuroanatomy Chapter 7 Quiz

Importance of Neuroanatomy

• Structure of the nervous system provides insights into brain function.
• Understanding anatomical vocabulary is essential for discussing neuroanatomy.

Anatomical Directions

• Medial: towards the midline; Lateral: away from midline.
• Anterior/Ventral: front; Posterior/Dorsal: back.
• Cranial: towards head; Caudal: towards tail.
• Superior: towards head; Inferior: towards feet.
• Superficial: near the surface; Deep: away from the surface.

Brain Planes

• Frontal/Coronal Plane: separates anterior and posterior portions.
• Sagittal Plane: divides right and left portions; midsagittal refers to equal halves.
• Transverse/Horizontal Plane: separates superior and inferior portions.

Nervous System Organization

• Divisions: Central Nervous System (CNS) and Peripheral Nervous System (PNS).
• CNS components: cerebrum, cerebellum, brainstem, spinal cord.

Meninges

• Three layers from external to internal: Dura mater (strongest), Arachnoid mater (web-like), Pia mater (delicate).
• Functions: Protect CNS, enclose blood vessels, contain cerebrospinal fluid (CSF).

Cerebrospinal Fluid (CSF)

• Provides buoyancy, reduces brain weight by 97%, nourishes the brain, and protects from trauma.
• Formed from blood plasma with lower protein content.
• Maintained by the choroid plexus, which filters CSF at a constant rate.

Clinical Connections

• Meningitis: Inflammation of meninges; can lead to encephalitis.
• Hydrocephalus: Blocked CSF circulation leads to increased pressure; treated with ventricular shunt.

Spinal Cord

• Attached to brainstem; serves as a conduit for information between the brain and body.
• Composed of dorsal roots (sensory) and ventral roots (motor control).

Peripheral Nervous System (PNS)

• Somatic PNS innervates skin, joints, muscles.
• Visceral PNS innervates internal organs and glands.

Gray and White Matter

• Gray matter: Nonmyelinated neurons and cell bodies; White matter: Myelinated axons.
• CNS structure: Central cavity surrounded by gray matter with white matter external.

Ventricles

• Fluid-filled chambers containing CSF, lined by ependymal cells.
• Paired lateral ventricles connect to the third ventricle via the interventricular foramen.
• Third ventricle connects to the fourth through the cerebral aqueduct.

Cerebral Hemispheres

• Comprise superior brain, making up 83% of brain mass.
• Gyri (ridges), sulci (grooves), and fissures (deep grooves) structure the surface.
• Major fissures include longitudinal (separates hemispheres) and transverse (separates cerebrum from cerebellum).

Cerebral Lobes

• Divided into five lobes: Frontal, Parietal, Temporal, Occipital, and Insula.
• Each lobe has distinctive functions and surface markings.

Fiber Tracts in Cerebral Hemispheres

• Three types: Association (within hemisphere), Commissural (between hemispheres), and Projection fibers (to/from lower CNS).
• Internal capsule and corona radiata are notable projection fibers.

Cerebral Cortex

• Executives suite for sensory perception, voluntary motor initiation, communication, memory storage.
• Composed of neuron cell bodies; constitutes 40% of brain mass.
• Functions facilitate higher cognitive processes and awareness.### Functional Areas of the Brain
• Motor Areas: Control voluntary movements, primarily located in the frontal lobe.
• Sensory Areas: Responsible for conscious awareness of sensations; distributed across parietal, temporal, occipital, and insular lobes.
• Association Areas: Integrate diverse information from different areas of the cortex; crucial for higher cognitive functions.

Hemispheres and Lateralization

• Each hemisphere controls functions on the contralateral side of the body.
• Lateralization: Specialization of function can occur predominantly in one hemisphere, especially regarding language and cognitive abilities.
• Conscious behavior involves the entire cortex.

Motor Areas

• Primary Motor Cortex: Located in the precentral gyrus; controls precise and skilled skeletal muscle movements.
• Pyramidal Cells: Large neurons in the primary motor cortex facilitating voluntary movement control; arranged in a somatotopic map.
• Motor Homunculi: Represents the motor innervation of various body regions upside down.

Premotor Cortex

• Acts as a planning and staging area for skilled movements.
• Coordinates learned or patterned motor skills and actions depending on sensory feedback.

Broca's Area & Frontal Eye Field

• Broca’s Area: Primarily in the left hemisphere; controls muscles for speech production and planning speech.
• Frontal Eye Field: Coordinates voluntary eye movements.

Damage and Clinical Connections

• Damage to the primary motor cortex results in paralysis on the opposite side of the body, but muscles can still function without the required voluntary control.
• Other neurons can sometimes compensate for damaged areas with practice.

Sensory Areas

• Include diverse regions responsible for processing different types of sensory information, such as:
  • Primary Somatosensory Cortex: Located in the postcentral gyrus; responsible for general sensory information.
  • Somatosensory Association Cortex: Integrates sensory information for object understanding.
  • Visual Areas: Primary visual cortex in the occipital lobe interprets visual stimuli; visual association area aids in recognizing faces and objects.
  • Auditory Areas: Primary auditory cortex processes sound characteristics; auditory association area stores auditory memories.
  • Olfactory Cortex: Recognizes and processes odors.
  • Gustatory Cortex: Involved in taste perception.
  • Vestibular Cortex: Awareness of balance and position.
  • Visceral Sensory Area: Perception of visceral sensations.

Multimodal Association Areas

• Receive inputs from multiple sensory areas, allowing for integration of sensory experiences, memory storage, and decision-making.
• Prefrontal Cortex: Involved in cognition, intellect, and personality; not fully developed until late 20s.
• Posterior Association Area: Recognizes patterns and spatial orientation; includes Wernicke’s area for language comprehension.
• Limbic System: Influences emotional responses and memory formation.

Clinical Connections and Disorders

• Lesions in the anterior association area may lead to personality disorders and impaired judgment.
• Damage to specific cortical areas can result in neglect of opposite body sides, demonstrating the importance of spatial awareness.

Lateralization of Cortical Function

• Cerebral Dominance: Predominantly left hemisphere dominance for language-related tasks; affects handedness.
• Right hemisphere excels in visual-spatial skills, emotional recognition, and artistic abilities.

Basal Ganglia

• Collections of nuclei in the brain associated with movement regulation, cognition, emotion, and filtering responses.
• Disorders like Parkinson’s and Huntington’s disease are linked to basal ganglia dysfunction.

Thalamus

• Acts as the main relay station for sensory input; influences learning, memory, and sensory processing.

Hypothalamus

• Critical for homeostasis regulation; controls autonomic functions, emotional responses, and physiological drives.

Brain Stem

• Comprises the midbrain, pons, and medulla oblongata; essential for controlling automatic survival behaviors like heartbeat and respiration.

Neuron Distribution

• The brain stem constitutes 11% of brain mass yet contains over 50% of the brain's neurons, illustrating its significance in low-level processing.