09 15 2014 Brainstem Flashcards
function of brainstem
- conduit function
- cranial nerve function
- integrative function
Sensory CNs
1,2,8
Motor CNs
3,4,6,9,11
Mixed CNs
5,7,9,10
Mnemonics
- Some
- Say
- Money
- Matters
- But
- My
- Brother
- Says
- Big
- Brains
- Matter
- most
Motor Somatic Efferent nuclei
relates to the framework of the body (skeletal muscles that originates from embryonic somites– extra ocular and tongue muscles)
Motor Visceral General nuclei (efferent)
Relates to efferent fibers that activate the viscera or organs
-preganglionic parasympathetic for cranial, thoracic, and abdominal smooth muscle (viscera)
Motor visceral special nuclei (efferent)
activates striated muscle
- muscle from embryonic branchial arches
- facial expression, jaw muscles, laryngeal and pharyngeal muscles, sternocleidomastoid.
Sensory Somatic afferent nuclei
caries information about the changes in environment from the framework of the body
Sensory General Somatic Afferent nuclei
refers to the impulse that begin at or near the body surface
-pain, temperature, touch, pressure
Sensory Special Somatic Afferent
highly specialized sensory system–
- vision (light)
- hearing (sound)
- Taste
Sensory General Visceral Afferent
receptors from in/around mucus membrane or in organ walls impulses about physical distention or chemical composition of substances or organic wall.
Sensory Special Visceral Afferent
refers to specialized chemical stimuli
-smell and tase
Hypoglossal nerve
(general)
(what in intervates is on another card)
motor– General somatic efferent GSE (ONLY)
- LMN exits between olive and pyramid (medulla) LMN is ipsilateral
- hypoglossal triangle – floor of fourth ventricle
- Controls movement of tongue and maintains muscle tone
-UMN (corticobulbar tract) is mostly contralateral
What muscles does the hypoglossal nerve innervate?
innervates all intrinsic muscles and all but one of the extrinsic tongue muscles
-does not innervate palatoglossus muscle (CN X)
CN XII (Cn # 12) nucleus is innervated by:
- -Corticobulbar pathway (is mainly crossed for XII)
- voluntary movement - Reticular neurons for automatic movements
- control of stereotyped movements while eating and swallowing.
Upper motor lesion in Hypoglossal cranial nerve?
- Tongue deviates to the side opposite of the damage
- if lesion on the left, the right side of the tongue is weak. Tongue is pushed to right side because of weakened muscles
lower motor lesion in Hypoglossal cranial nerve?
- tongue deviates to the same side of damage
- Damage is on the left (right corticobulbar tract has already crossed and is now on the left). The tongue deviates to the left because left muscles are weak.)
- Muscle atrophy in tongue
What happens when you have a bilateral lesion of CN 12?
- disability in speaking
- severe swallowing difficulty of food
Common causes of CN 12 lesions
- motor neuron disease
- demyelination
- bleeding
- tumors of medulla and base of skull
(LMN disease)
Spinal Accessory nerve - composition
MOTOR ONLY! composed of fibers from medial motor nuclei in ventral horn of caudal medulla and the accessory nucleus (close to pyramidal decussation).
LMN in medulla and cervical cord (C1-C5)
Spinal Accessory nerve : branchial motor part
Ipsilateral innervation of sternomastoid and trapezius muscle.
(spinal part)
Spinal Accessory nerve: Visceral motor part
Joins CN X to control larynx
accessory part
Lesion of Spinal Accessory nerve
Head turns to side opposite of lesion.
Explanation:
Sternomastoid m. turns head to opposite side. So a lesion would cause the more powerful side to take over, so therefore, the head will face the side that has been lesioned
- ipsilateral shoulder drop
- weakened voice or hoarseness
Vagus Nerve General
BOTH Motor and Sensory
Forms Vagal triangle (floor of 4th ventricle)
Vagus Nerve (efferents vs. afferents)
2 Efferents: (MOTOR)
- General Viseral Efferent (GVE)
Preganglionic parasympathetic
heart, lungs, GI (to splenic flexure)- neurotransmitter ACh
- Special Visceral Efferent (SVE)
-Pharyngeal and laryngeal muscles (swallowing and vocalization)
3 Afferents: (SENSORY)
- General Somatic Afferent
- pharynx, meninges, small region of external ear.
- Special Visceral Afferent
- taste from epiglottis and pharynx
- Genreal Visceral Afferent
- chemoreceptors, baroreceptors of aortic arch
Where are the Vagus Cranial nerve GVE fibers located?
GVE- general visceral efferent
-preganglionic parasympathetic
heart lungs and GI
- Dorsal motor nucleus of X
Where are the SVE fibers of CN # 10 located?
Special Visceral Efferents:
-pharyngeal and upper esophageal muscles
(Swallowing and gag reflex)
-Larynx muscles (vocalization)
Nucleus Ambiguus