PNS

PNS:

12 Cranial nerves

CN I, Olfactory nerve

• Function

  • Smell

• Location

  • Originate in superior portion of nasal cavity and terminates in olfactory bulbs

• Pathology

  • Loss of smell

CN II, optic nerve 

• Function

  • Sight 

• Location 

  • Retina, through optic foramina of sphenoid bone, optic chiasm to form optic tracts, thalamus, then to visual cortex

• Pathology

  • Contralateral loss of vision

CN III, oculomotor nerve

• Function 

  • Ciliary muscles: adapt the lens in your eye for focus

  • Pupillary sphincter of iris

• Location 

  • midbrain origin, to motor muscles

• Pathology 

  • Focal issues, inability to move eye to area, light entry

CN IV, Trochlear nerve

• Function

  • Superior oblique muscle: medially rotate the eye (intorsion

• Location 

  • Nucleus near midbrain, near to oculomotor nerves

• Pathology

  • Inability to control cross eyed movement, loss of motor

CN V, Trigeminal Nerve

• Branch 1: Ophthalmic

  • Function: 

    • Sensations from forehead, lacrimal glands, eyelids, ciliary bodies, nose sides​

• Branch 2: Maxillary​

  • Function: 

    • Sensation from eyes to top teeth​

• Branch 3: Mandibular​

  • Function: 

    • Sensations from cheek, lower teeth, mandible, mouth floor​

  • Sensations on tongue: 

    • Touch, temp, pressure, NOT taste​

  • Motor: 

    • Mastication, biting, chewing​

CN VI, Abducens Nerve

• Function: 

  • Lateral rectus muscle, abducts and moves eye laterally

• Location: 

  • Origin in pons

• Pathology: 

  • Restricted lateral eye movement

CN VII, Facial nerve

• Function

  • Motor

    • 5 branches, innervates face, scalp, neck muscles

  • Sensory

    • Taste from the anterior two-thirds of the tongue and proprioceptive signals of face and scalp

• Location 

  • Originates in the pons and ends in the pons gustatory cortex

• Pathology

  • Facial expression issues 

  • Loss to anterior taste

CN VIII, Vestibulocochlear Nerve

• Vestibular 

  • Function: orientation and movement of the head

  • Location: vestibular ganglion

• Cochlear 

  • Function: sense of hearing

  • Location: spiral ganglion

• Pathology:

  • Loss of hearing and equilibrium (balance), potential vertigo

CN IX, Glossopharyngeal nerve

• Function

  • Motor: only innervates the stylopharyngeus muscle

  • Sensory: taste on posterior tongue, BP changes in carotid artery, blood chemistry changes

• Location: 

  • Pharynx and larynx muscle, stimulate saliva glands

• Pathology 

  • loss of swallowing and reduction of saliva production while eating, position capabilities or tongue, loss of BP and B chemistry changes

CN X, vagus nerve

• Function: 

  • PNS (parasympathetic nervous system) activation and pharyngeal principal motor nerve innervation 

  • Aortic bodies and aortic arch

• Location

  • Medulla to target tissue

• Pathology

  • Loss of sensation of ear, taste, buds, neck, throat, larynx, loss of motor function for the heart, GI organs, breathing rate, sweating 

CN XI, accessory nerve

• Function: 

  • Sternocleidomastoid and trapezius muscle function

• Location

  • Cranial: medulla oblongata

  • Spinal: C1-C6, arise from spinal cord

• Pathology

  • Inability to move neck and shoulder 

CN XII, Hypoglossal nerve

• Function: 

  • Extrinsic and intrinsic control muscles of speech and swallowing

• Location: 

  • Medulla to tongue

• Pathology: 

  • Difficulty swallowing and speaking

Somatic and autonomic functions of the PNS

• Somatic 

  • Voluntary control of skeletal muscles

  • Sensory signals from the environment 

    • Sensory receptors → spinal nerves → ascending tracts of spinal cord → processed in cerebral cortex

• Autonomic 

  • Heart rate

  • Respiration

  • Visceral organs

  • Monitors internal conditions

  • Involuntary

Skin sensory receptors

• Convey signals for tactile sensations

• Meissner corpuscles

  • Touch

• Merkel cells

  • Light touch, pressure, vibration

• Pacinian corpuscles

  • Pressure, vibration

• Free nerve endings

  • Pain, temperature, Itch/tickle

Cervical Plexus

• Transverse cervical

• Great auricula

• Lesser occipital

• Supraclavicular

• Phrenic - supplies diaphragm muscle

Brachial Plexus

• Supra/subscapular

• Thoracodorsal

• Axillary

• Medial/Lateral Pectoral

• Musculocutaneous

• Median

• Radial/Ulnar

Lumbosacral Plexus

• Femoral

• Ilioinguinal

• Sciatic – Biggest nerve of plexus 

• Gluteal