Summary of Brainstem I

Summary of Brainstem I

1. Brainstem

   • Pons
     • Identify by the basillar part
   • Midbrain
     • Starts below the mammillary body
   • Medulla Oblongata

2. Functional Components

   • GSA
     • Carry sensory info from muscles and skin
   • GSE
     • Carry motor info from CNS to skeletal muscles
   • GVA
     • Carry sensory information to the CNS from organs and blood vessels
   • GVE
     • Carry motor information from the CNS to smooth muscle and glands (parasympathetic innervation)
   • SVE
     • Branchial arch striated muscles
   • SVA
     • smell, taste
   • SSA
     • Vision, hearing and balance

3. CN III, IV, VI

   • All innervate extraocular muscles
   • All attach to the eyeball
     • Extraocular muscles
       • Superior rectus
         • Rectus means straight
       • Inferior rectus
       • Medial rectus
       • Laterak rectus
       • Superior Oblique
       • Inferior Oblique

4. CRANIAL NERVES

   • Oculomotor Nerve
     • Oculomotor Nucleus
       • Provides motor innervation to a muscle that lifts the upper eyelid
       • Innervation of 4 extraocular muscles, except superior oblique and lateral rectus
     • Edinger-Wesphal Nuclei
       • Provides parasympathetic innervation to smooth muscles in the eyes
         • There are 2 pairs of them
           • One is responsible for pupillary constriction
           • The other is responsible for accomodation (focusing the lens).
   • Trochlear Nerve
     • innervates the superior oblique muscle only
       • When this muscle contracts your eye moves down and out
   • Abducent Nerve
     • Innervates the lateral rectus only
       • When this muscle contracts it abducts your eyes
   • Trigeminal Nerve
     • provides sensory innervtion to the face, the oral cavity
     • Provides motor innervation to the muscle of mastication
     • Nucleus
       • Mesencephalic
       • Main sensory nucleus and spinal nucleus
       • Motor nucleus
     • Divides into 3 divisions when it leaves the skull
       • Ophthalmic division
         • CNV1
         • Sensation from nose, upper eyelid, cornea of eyes and forehead
       • Maxillary division
         • CNV2
         • Sensation from upper lip, lateral side of the nose, ceek, below the eye, upper teeth and lateral side of the forehad
       • Mandibular diviion
         • CNV3
         • sensory from lower lip, jaw,chin, ear, temple
         • Also provides motor innervation to muscles of mastication
   • Facial Nerve
     • Motor nucleus
       • Innervates muscles of facial expression
     • Upper part of the nucleus of tractus solitarius (NTS)
       • Taste from anterior 2/3 of the tongue
     • Superior salivatory nucleus and lacrimal nucleus
       • Provides plasmatic innervation to 2 salivary glands
         • Submandibular & Sublingual
         • Lacrimal gland
         • Nasal glands
         • Glands in the palate
   • Vestibulocochlear Nerve
     • Consists of 2 nerves
       • Vestibular Nerve
         • Associated with balance
         • Conducts nerve impulses concerning the position and movement of the head
       • Cochlear Nerve
         • Conveys hearing impulses
   • Glossopharyngeal Nerve
     • Nucleus ambiguus
       • Provides motor innervation to pharyngeal muscle, responsible for swallowing
     • Inferior salivatory nucleus
       • Provides parasympathetic innervation to one salivary gland (parotid)
         • Parotid salivary gland is the largest salivary gland in the human body
     • NTS
       • Taste from posterior 1/3 of tongue
         • Will terminate in the upper part of the NTS
       • GVA from carotid sinus and carotid body terminate in NTS as well
         • Carotid sinus are baroreceptors so sense blood pressure
         • Carotid body are chemoreceptors so sense blood composition
     • Spinal nucleus of CN V
       • Convey some common sensation from the head
   • Vagus Nerve
     • Only CN to go below head/neck
       • Vagus means wondering
       • Ends up in abdomen
     • Nucleus ambiguus
       • Innervates muscles of the pharynx (swallowing)
       • Innervates muscles of the larynx (speech)
     • Dorsal nucleus of the vagus
       • Provides parasympathetic innervation to involuntary muscles between the walls of the viscera
         • Slows heart rate
         • Constricts bronchioles
     • NTS
       • Taste from the epiglottis
       • Visceral sensation
     • Spinal nucleus of CN V
       • Common sensation from the head
         • Will terminate in the spinal nucleus of the trigeminal nerve
   • Accessory Nerve
     • Cranial root
       • Arises from the nucleus ambiguus
         • Found in medulla oblongata
       • Innervates muscle of the pharynx, larynx and soft palate
     • Spinal root
       • Arises from spinal nucleus of the accessory nerve
         • Found in the upper cervical cord segments
       • Innervates two muscles: sternocleidornastoid and trapezius muscle
   • Hypoglossal Nerve
     • Hypoglossal nucleus
       • In medulla oblongata
       • Innervates muscles of the tongue