PNS: Somatic and Visceral Biol. 211 Anatomy & Physiology 1 Tony Serino, Ph.D. Biology Department Misericordia University
(Visceral)
Cranial Nerves
CN I: Olfactory Nerve
CN II: Optic Nerve
CN III: Occulomotor Nerve Superior Orbital Fissure Midbrain Pons Oculomotor N. (III) Ciliary ganglion Inferior Rectus muscle Inferior Oblique muscle Superior Rectus muscle Medial Rectus muscle Levator Palpabrae muscle Parasympathetic Motor fibers
CN IV: Trochlear Nerve
CN V: Trigeminal Nerve
CN VI: Abducens Nerve
CN VII: Facial Nerve
CN VIII: Vestibulocochlear Nerve
CN IX: Glossopharyngeal Nerve
CN X: Vagus Nerve
CN XI: Accessory Nerve
CN XII: Hypoglossal Nerve
Spinal Nerves and Plexuses
Spinal Nerve Anatomy
Cervical Plexus Serves neck and diaphragm
Brachial Plexus and pectoral nerves
Brachial Plexus Innervates most of the arm and some of the body wall.
Lumbar Plexus Innervate the anterior leg.
Sacral Plexus Innervates the posterior leg
A dermatome is the area of skin innervated by the cutaneous branches of a single sensory spinal nerve All spinal nerves except C 1 participate in dermatomes Dermatomes
Reflex Arc
Stretch Reflex
Stretching the muscle activates the muscle spindle Excited motor neurons of the spindle cause the stretched muscle to contract Afferent impulses from the spindle result in inhibition of the antagonist Example: patellar reflex –Tapping the patellar tendon stretches the quadriceps and starts the reflex action –The quadriceps contract and the antagonistic hamstrings relax
The opposite of the stretch reflex Contracting the muscle activates the Golgi tendon organs Afferent Golgi tendon neurons are stimulated, neurons inhibit the contracting muscle, and the antagonistic muscle is activated As a result, the contracting muscle relaxes and the antagonist contracts Golgi Tendon Reflex
Flexor and Crossed Extensor Reflexes The flexor reflex is initiated by a painful stimulus (actual or perceived) that causes automatic withdrawal of the threatened body part The crossed extensor reflex has two parts –The stimulated side is withdrawn –The contralateral side is extended
Neurotransmission Scenario
ANS Divsions
Parasympathetic (Craniosacral)
Sympathetic (Thoracolumbar)
Sympathetic Ganglia
Levels of Control in ANS