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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. Superior Orbital Fissure. Medial Rectus muscle. Midbrain. Superior Rectus muscle.
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PNS:Somatic and Visceral Biol. 211 Anatomy & Physiology 1 Tony Serino, Ph.D. Biology Department Misericordia University
Superior Orbital Fissure Medial Rectus muscle Midbrain Superior Rectus muscle Levator Palpabrae muscle Inferior Oblique muscle Ciliaryganglion Inferior Rectus muscle Parasympathetic Motor fibers Oculomotor N. (III) Pons CN III: Occulomotor Nerve
Cervical Plexus Serves neck and diaphragm
Brachial Plexus Innervates most of the arm and someof the body wall.
Lumbar Plexus Innervate the anterior leg.
Sacral Plexus Innervates the posterior leg
Dermatomes • A dermatome is the area of skin innervated by the cutaneous branches of a single sensory spinal nerve • All spinal nerves except C1 participate in dermatomes
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
Golgi Tendon Reflex • 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
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automatic withdrawal of the threatened body part • The crossed extensor reflex has two parts • The stimulated side is withdrawn • The contralateral side is extended