Peripheral nerves system PNS (ch13) Flashcards
What is the peripheral nervous system?
PNS links CNS to body
and to external environment
– Sensory:
* Somatic
* Visceral
– Motor:
* Somatic
* Visceral (Autonomic)
Name all the Cranial Nerves I - XII?
- CN I – Olfactory n
- CN II – Optic n.
- CN III – Oculomotor n.
- CN IV – Trochlear n.
- CN V – Trigeminal n.
- CN VI – Abducens n.
- CN VII – Facial n.
- CN VIII – Vestibulocochlear n.
- CN IX – Glossopharyngeal n.
- CN X – Vagus n.
- CN XI – Spinal accessory n.
- CN XII – Hypoglossal n.
What is the function of each of the cranial nerves?
- CN I – Olfactory Nerve
Function: Sensory nerve for the sense of smell. - CN II – Optic Nerve
Function: Sensory nerve responsible for vision. - CN III – Oculomotor Nerve
Function: Motor nerve controlling most eye movements and pupil constriction. - CN IV – Trochlear Nerve
Function: Motor nerve controlling the superior oblique eye muscle.
-CN V – Trigeminal Nerve
Function: Mixed nerve with sensory function for the face and motor function for chewing muscles. - CN VI – Abducens Nerve
Function: Motor nerve controlling the lateral rectus eye muscle.
-CN VII – Facial Nerve
Function: Mixed nerve with sensory functions for taste and motor functions for facial expressions, tear and saliva secretion. - CN VIII – Vestibulocochlear Nerve
Function: Sensory nerve for hearing and balance. - CN IX – Glossopharyngeal Nerve
Function: Mixed nerve with sensory functions for taste and touch in the back of the tongue and motor functions for swallowing. - CN X – Vagus Nerve
Function: Mixed nerve involved in various functions, including speech, swallowing, and autonomic control of visceral organs.
-CN XI – Spinal Accessory Nerve
Function: Motor nerve controlling certain neck muscles. - CN XII – Hypoglossal Nerve
Function: Motor nerve controlling the muscles of the tongue.
What is Anosmia?
- An: without somia: smell
- Anosmia refers to the loss or absence of the sense of smell.
What is anopia?
- Definition: Anopia is a medical term referring to the absence or loss of vision in one or both eyes.
1) Ipsilateral Blindness: Total blindness in one eye. Causes: Damage to the optic nerve or retina on one side.
2) Bitemporal Hemianopia: Loss of vision in the outer half of both visual fields.
Cause: Lesions affecting the optic chiasm (optic crossing)
CN IV – Trochlear n
Superior oblique m.
– SO4
* Intorsion (medially)
* Depression (inferiorly)
* Abduction
CN V – Trigeminal n
Principle sensory n. to face
* Three brr.
– Ophthalmic br. (CN V1)
* sensory
– Maxillary br. (CN V2)
* sensory
– Mandibular br. (CN V3)
* sensory & motor
CN VI (Abducens Nerve)
Innervated Muscle: Lateral rectus muscle.
Function: Abducts the eye (moves it laterally).
Mnemonic: “LR6” - Lateral Rectus is innervated by CN VI.
CN VI – Abducen n. palsy
Medial Strabismus: Inward deviation of the affected eye.
Diplopia: Double vision due to misalignment of the eyes.
Note: CN VI controls the lateral rectus muscle, responsible for moving the eye outward. Palsy leads to an imbalance in eye muscle function.
CN VII (Facial Nerve)
Makes Muscles Move:
Helps you make facial expressions.
Takes care of the parotid gland.
Keeps Things Moist:
Manages the saliva and tears.
Taste and Feel:
Deals with taste on the front part of your tongue.
Takes care of feelings on your ear and around it.
CN VIII (Vestibulocochlear Nerve)?
Double Duty Nerve:
Splits into two parts: Cochlear (for hearing) and Vestibular (for balance).
Cochlear Branch:
Responds to sound waves, helping you hear.
Vestibular Branch:
Reacts to body positions, maintaining balance and equilibrium.
CN IX (Glossopharyngeal Nerve)
*Motor Functions:
Controls Stylopharyngeus and Superior Pharyngeal Constrictor muscles.
* Parasympathetic Control:
Influences the Parotid Gland.
* Sensory Domains:
Handles various sensory functions in areas like pharyngotympanic tubes, palatine tonsils, oropharynx, and the posterior 1/3 of the tongue.
* Gustatory Sensation:
Involved in taste perception for the posterior 1/3 of the tongue.
CN X (Vagus Nerve)
- Sensory Neurons: Monitors sensations in the inferior pharynx, larynx, thoracic organs, and visceral organs.
- Somatic Motor Neurons: Controls muscles of the soft palate, pharynx, and intrinsic laryngeal muscles.
- Visceral Motor Neurons: Influences the function of vital organs like the heart, esophagus, stomach, small intestine, large intestine, and gallbladder.
CN XI (Accessory Nerve)
- Cranial Component:
*Travels with CN X (Vagus Nerve).
*Innervates muscles of the larynx involved in speech. - Spinal Component:
*Controls the sternocleidomastoid and trapezius muscles.
Overview of cranial nerves
Only sensory neurons
– Olfactory (I)
– Optic (II)
– Vestibulocochlear (VIII)
* Primarily motor neurons
– Oculomotor (III)
– Trochlear (IV)
– Abducen (VI)
– Accessory (XI)
– Hypoglossal (XII)
* Both sensory & motor
neurons
– Trigeminal (V)
– Facial (VII)
– Glossopharyngeal (IX)
– Vagus (X)
