CHAPTER 13 PERIPHERAL NERVOUS SYSTEM Functional division of nervous system = afferent info to the CNS ascending spinal cord = efferent info from CNS descending spinal cord somatic skin, muscles visceral organs nerves outside the CNS cranial nerves CNS = brain in to brain out from brain Peripheral nervous system spinal nerves CNS = spinal cord in to spinal cord out from spinal cord # neurons between periphery and CNS: receptor to spinal cord - 1 neuron spinal cord to muscle - 1 neuron ANS CNS to organ 2 neurons special senses varies PNS basic structure ganglia nuclei exteroceptors interoceptors proprioceptors group of cell bodies outside CNS usually group of cell bodies within CNS location of receptors info from environment info from organs, vessels info from joints, muscles mechanoreceptors mechanical force type of stimulus chemoreceptors thermoreceptors photoreceptors chemical or chemical change heat light, color nociceptors pain (chemical?)
free nerve endings pain, temperature, itch Merkel specialized free ending for touch encapsulated nerve endings Meissner, Pacinian, Ruffini touch and pressure Proprioceptors kinesthetic sense muscle spindles Golgi tendon organ joint position structure of receptors neuromuscular junction axon terminal synapse end plate endings unit somatic visceral skeletal muscle smooth, cardiac muscle peripheral nerves to head and neck (CN X - to thorax and abdomen) Cranial nerves cell bodies cell bodies axons pass through skull foramen numbered I - XII nuclei in brain cranial ganglia special sense organs Cranial nerves I Olfactory smell II Optic vision III Oculo eye movement IV Trochlear eye movement V Trigeminal face sensation VI Abducens eye movement VII Facial face movement VIII Vestibulocochlear hearing; equilibrium IX Glossopharyngeal taste,swallow, BP reflex X Vagus parasympathetic effects XI Accessory trapezius, SCM XII Hypoglossal tongue movement Cranial nerve I
CN I Olfactory nerve smell receptors in olfactory epithelium foramen??? synapse in olfactory bulb olfactory tract Cranial nerve II CN II optic nerve vision receptors = retina of the eye optic nerve through optic canal crossover at optic chiasma optic tract to occipital lobe Cranial nerves - eye movement III Oculo 4 extrinsic eye muscles IV Trochlear superior oblique muscle VI Abducens lateral rectus muscle III Oculo pupil constriction (ANS) from midbrain (III and IV) or Pons (VI) through superior orbital fissure Cranial nerves - face CN V Trigeminal to face to masseter, temporalis, pterygoids CN VII Facial to face - taste salivary glands (ANS) lacrimal glands (ANS) CN V - face sensation 3 divisions ophthalmic V 1 maxillary V 2 mandibular V 3 face to Pons V 1 supraorbital foramen ; superior orbital fissure V 2 infraorbital foramen ; foramen rotundum V 3 mental foramen ; foramen ovale CN VII Facial facial muscles 5 branches CN VII - face movement taste - anterior 2/3 of tongue chorda tympani ANS parasympathetic to lacrimal glands and salivary glands (not parotid) foramen internal acoustic meatus stylomastoid foramen
CN VIII Vestibulocochlear cranial nerves - ear Cochlear nerve hearing receptors Cochlea to Medulla ; to auditory cortex?? auditory reflex?? Vestibular nerve balance, equilibrium receptors Vestibule to Medulla ; to cerebellum equilibrium reflex internal acoustic meatus CN IX taste, swallow, saliva, BP taste BP carotid sinus stylopharyngeus ANS Parotid gland jugular foramen Glossopharyngeal = tongue and pharynx CN X Vagus nerve Parasympathetic medulla through jugular foramen ANS parasympathetic to most organs thorax and abdomen some for speech and swallowing pharyngeal and laryngeal muscles - Midbrain Cranial nerve IX cranial nerve X CN XI Accessory to Trapezius muscle SCM jugular foramen cranial nerve lower muscles CN XII Hypoglossal to muscles of tongue glossus and suprahyoid group hypoglossal canal joined spinal roots spinal nerves spinal nerve = joined spinal roots 31 spinal levels, bilateral C1-8; T1-12; L1-5; S1-5; Coc1 spinal nerve - branches
rami : dorsal ramus to posterior trunk ventral ramus to ventral trunk and limbs peripheral nerves named branches of rami back branches of dorsal rami C1 S5 peripheral nerves trunk thorax branches of ventral rami T1 T12 intercostal nerves abdomen branches of ventral rami T6 T12 intercostal nerves a group of spinal nerves - ventral rami nerve plexuses each peripheral nerve has fibers from a few spinal nerves Cervical C1 - C4 to neck Brachial C5 T1 to upper extremity Lumbar L1 L4 to L/S and LE Sacral L4 S4 to LE and perineum C1 C4 ventral rami to skin of neck and occiput to anterior neck muscles cervical plexus lesser occipital n. greater auricular n. transverse cervical n. phrenic nerve C3,4, 5 diaphragm C5 T1 spinal nerves brachial plexus branch into peripheral nerves to UE musculocutaneous n. median n. ulnar n. axillary n. radial n. brachial plexus peripheral nerves
musculocutaneous n. median n. ulnar n. radial n. axillary n. L1 - L4 spinal nerves to : anterior thigh abdominal wall psoas muscle peripheral nerves : lumbar plexus femoral n. ant. thigh muscles anter/medial thigh saphenous n. medial leg obturator n. adductor muscles medial thigh lateral femoral cutaneous n. lateral thigh L4 - S4 spinal nerves = lumbosacral plexus to: posterior thigh lower leg perineum peripheral nerves : sciatic n. posterior thigh entire leg and foot tibial n. common fibular n. posterior leg, plantar area lateral leg, dorsum area sacral plexus superficial fibular n. deep fibular n. gluteal nerves to gluteal muscles area of skin innervated by a spinal nerve C1 is only all dermatomes overlap show embryological development limb buds from lower neck and L/S areas. () dermatomes joints Hilton s law : joints innervated by same nerves that innervate the muscles moving that joint