PNB 3255: Human Neuroanatomy Lecture Review

Textbooks Required:
- Clinical Neuroanatomy, 28th Edition, by S.G. Waxman
- Draw It to Know It Tutorial: Neuroanatomy, UCONN - Undergraduate Neuroanatomy
- Clinical Neuroanatomy Made Ridiculously Simple, by Goldberg (PDF available in Resources Folder on Husky CT)
Grading Breakdown:
- 10 Homework Quizzes = 20% (200 points)
- 11 Drawing Assignments = 20% (200 points)
- 7 In-Class Quizzes = 10% (100 points)
- 2 Exams = 50% (500 points)
- 1st Exam: March 5 & 6
- 2nd Exam: April 16 & 17

Module Focus: Development of the Nervous System
Key Phases in Neurulation:
- The notochord induces the overlying ectoderm to develop into the neural plate.
- Neural plate folds into the neural tube; neural crests are pinched off.
- Outcomes:
  - The neural tube derives the Central Nervous System (CNS).
  - The neural crests derive the Peripheral Nervous System (PNS) and select other cells (e.g., melanocytes).

Timeline of Development:
- ~Day 17: Formation of the neural plate.
- ~Day 18: Neural groove formation.
- ~Day 21: Neural folds begin to elevate.
- ~Day 23: Closure of the anterior (rostral) neuropore.
- Day 26: Posterior (caudal) neuropore closure.
Neural Tube Closure Defects:
- Incomplete rostral closure results in anencephaly, a severe cerebral disorder involving the absence of major portions of the brain and skull.
- Incomplete caudal closure results in myeloschisis or spina bifida, affecting the spinal cord and vertebral column.

Central Nervous System (CNS)

Components: Brain and Spinal Cord.
Glial Cells:
- Oligodendrocytes: Responsible for myelination in the CNS; one cell can myelinate multiple axon segments.
Tissue Organization:
- Gray Matter: Contains densely packed neuronal cell bodies. In the spinal cord, it is located internally (forming the 'H' shape), including the commissure which connects the two sides.
- White Matter: Composed of myelinated axons. In the spinal cord, it is located on the outside. White matter bundles are referred to as a tract, fasciculus, or lemniscus.
Cell Body Clusters: Known as nuclei.

Peripheral Nervous System (PNS)

Components: Cranial nerves and Spinal nerves.
Glial Cells:
- Schwann Cells: Responsible for myelination in the PNS. Unlike oligodendrocytes, Schwann cells are more permissive and actively support nerve regeneration.
Cell Body Clusters: Known as ganglia.

Autonomic Nervous System (ANS) Innervation

Sympathetic Division: "Fight or flight."
- Sweat Glands Exception: Typically, sympathetic postganglionic neurons release norepinephrine (NE). However, the innervation of sweat glands is an exception where Acetylcholine (ACh) is released at both the preganglionic and postganglionic synapses.
Parasympathetic Division: "Rest and digest."

Dorsal Root: Transmits sensory (afferent) information into the spinal cord from the periphery.
Ventral Root: Carries motor (efferent) commands out of the spinal cord.
Demyelination:
- Multiple Sclerosis (MS): A primary pathology characterized by the destruction of the myelin sheath in the CNS, impairing signal conduction.

Computed Tomography (CT Scan)

Description: Uses X-rays to create cross-sectional images.
Application: The preferred initial study for acute brain trauma and hemorrhage due to its speed.

Magnetic Resonance Imaging (MRI)

Mechanism: Utilizes magnetic fields and radio waves.
Contrast: Image contrast is highly dependent on the time between excitation and sampling (Repetition Time TR and Echo Time TE). Increasing these intervals allows for better differentiation between various soft tissues.

Functional MRI (fMRI)

Application: Measures brain activity by detecting changes in blood flow. Can be used to map specific functional areas, such as the activity of the visual cortex during sensory stimulation.