Human Neuroanatomy and Nerve Histology Essentials

Nerve Histology

• Epineurium: Protects the entire nerve
• Perineurium
• Fascicle
• Axon: Conducts impulses
• Node of Ranvier: Speeds conduction

Spinal Cord Anatomy

Meninges and Spaces

• Epidural space
• Dura mater: Protects the spinal cord
• Subdural space
• Arachnoid mater: Protective membrane
• Subarachnoid space: Contains Cerebrospinal Fluid (CSF)
• Pia mater: Covers the spinal cord

Roots and Nerves

• Posterior root (dorsal root): Sensory input
• Spinal ganglion (dorsal root ganglion)
• Anterior root (ventral root): Motor output
• Spinal nerve: Mixed nerve
• Posterior ramus: Back muscles and skin
• Anterior ramus: Limbs and anterior trunk

Spinal Cord Structures

• Central canal: Contains CSF
• White matter: Conducting tracts
  • Posterior white column
  • Lateral white column
  • Anterior white column
• Gray matter
  • Posterior horn: Sensory
  • Lateral horn: Visceral motor
  • Anterior horn: Somatic motor
• Ependymal cells: Line the central canal

Neuron Cell Body Locations

• Somatic motor neuron soma: Located in the anterior horn
• Visceral motor neuron soma: Located in the lateral horn
• Somatic sensory neuron soma: Located in the dorsal root ganglion
• Visceral sensory neuron soma: Located in the dorsal root ganglion

Brain Anatomy and Function

Dural Sinuses

Dural sinuses drain venous blood. Key structures include:

• Superior sagittal sinus
• Confluence of sinuses
• Transverse sinus
• Sigmoid sinus

Lobes and Cortex

• Frontal lobe: Thinking, planning, and movement
• Parietal lobe: Somatic sensory
• Temporal lobe: Hearing
• Occipital lobe: Vision
• Insula: Taste
• Precentral gyrus: Motor cortex
• Postcentral gyrus: Somatosensory cortex
• Superior temporal gyrus: Hearing
• Corpus callosum: Connects left and right sides
• Hippocampus: Memory

Anatomical Landmarks to Identify

• Longitudinal fissure
• Lateral sulcus
• Central sulcus
• Fornix
• Septum pellucidum
• Intermediate mass

Cerebrospinal Fluid (CSF)

• Choroid plexus: Produces CSF
• Ventricles: Circulate CSF

CSF Flow Path:
Lateral Ventricles → Interventricular foramen → Third Ventricle → Aqueduct → Fourth Ventricle → Subarachnoid space → Superior sagittal sinus

Cerebellum and Diencephalon

• Cerebellum: Balance and coordination
• Thalamus: Relay station
• Hypothalamus: Homeostasis
• Pituitary gland: Controls the endocrine system
• Pineal gland: Produces melatonin
• Mammillary body: Memory

Brainstem

• Superior colliculus: Visual reflexes
• Inferior colliculus: Auditory reflexes
• Pons: Relay and breathing
• Medulla oblongata: Heart rate and breathing

Additional Brainstem Structures

• Arbor vitae
• Cerebral peduncles

Cranial Nerves

• CN I Olfactory: Nasal cavity
• CN II Optic: Retina
• CN III Oculomotor: Most eye muscles
• CN IV Trochlear: Superior oblique muscle
• CN V Trigeminal: Face
• CN VI Abducens: Lateral rectus muscle
• CN VII Facial: Muscles of facial expression
• CN VIII Vestibulocochlear: Cochlea and vestibular apparatus
• CN IX Glossopharyngeal: Tongue and pharynx
• CN X Vagus: Heart, lungs, and digestive organs
• CN XI Accessory: Sternocleidomastoid and trapezius
• CN XII Hypoglossal: Tongue muscles

Cranial Nerve Structures

• Olfactory bulb: Receives smell information
• Olfactory tract: Carries smell information
• Optic tract: Carries visual information
• Optic chiasm