ANHB3324 Lecture Notes - Lecture 3: Pharyngeal Arch, Glossopharyngeal Nerve, Dorsal Root Ganglion
LECTURE THREE: Overview of Cranial Nerves
Cranial Nerves:
• Emerge from brain and brainstem
• 12 (XII) pairs
• Numbered from rostral (front end) to caudal (tail end)
• I (Olfactory) → first seen rostrally
• XII (Hypoglossal) → last, or caudal end before cervical spinal nerves
• Found on ventral surface of brain
Functions:
• Various functions
• General functions
o Like spinal nerves
o E.g. pain, temperature, touch, proprioception
• Special functions
o Unique to cranial nerves
o E.g. smell, sight, taste, hearing, balance
Spinal Nerves:
• Run down vertebral column
• 40 pairs
• Each nerve matches a vertebra
• Dorsal root → sensory/afferent → dorsal root ganglion next to spinal
cord
• Ventral root → motor/efferent → inside spinal cord
• Dorsal and ventral cords meet (and mix) and then separate again
Spinal Nerve Development:
• From neural tube/crest → forms CNS
• Occurs 4 weeks post-conception
• Cells dorsal (top) to tube → sensory
• Cells ventral (bottom) to tube → motor
Functions of Spinal Nerves:
• Sensory
o Nerve impulses from body → somatic sensory
▪ E.g. skin, muscles, tendons, ligaments
o Nerve impulses from visceral anatomy → visceral sensory
▪ E.g. stomach mucosa, gallbladder
• Motor
o Impulses to skeletal muscles → somatic motor
o Impulses to muscles in the gut/visceral structures/smooth muscle
→ visceral motor
o Fibers travel with autonomic system
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