Neuro:nuclei and fiber types of CN's

Question 1

nuclear groups

Answer 1

motor (efferent) nuclei are located medially

sensory (afferent) nuclei ..laterally

Question 2

motor ( efferent nuclei)

Answer 2

contain multipolar neurons, their axons leave the brain and terminates on the target (muscle/gland)

SM (GSE)-CN 3,4,6,12
BM (SVM/SVE)= CN 5,7,9,10,11
GVM (GVE)= CN 3, 7,9, 10

***innervation of viscera = 2 steps

Question 3

innervation of viscera

MOTOR

Answer 3

2 steps

1. the CN nuclei have preggl. parasympathetic neurons- their axons leave the brain and ends in an autonomic (in case of cranial nerves: parasympathetic ggl.); there is synapses with a multipolar neuron located in the ggl.
2. an axon of this (post ggl neuron) will reach the target cell
   preggl. —> autonomic CN (parasympathetic ggl—>synapse in multipolar neuron

**EXCEPTION: adrenal medulla: it receives direct preggl. fibres from the SC ( why???? BECAUSE THE ADRENAL MEDULLLA CAN BE CLASSIFIED AS MODIFIED SYMPATHETIC GANGLION)

Question 4

sensory (afferent) nuclei:

Answer 4

also contain multipolar nuclei* but they receive inputs ( afferent fibers) from sensory nerves which synapse on the neurons

**EXCEPTION: MESENCEPHALIC TRIGEMINAL NUCLEUS- WHICH HAS PSEUDOUNIPOLAR NEURONS (A GGL. WHICH WAS PUT INTO THE BRAINSTEM). THEIR PERIPHERAL PROCESSES ARRIVE FROM THE MUSCLE SPINDLES OF TH MUSCLES OF MASTICATION, THE CENTRAL PROCESSES TERMINATE IN THE MOTOR TRIGEMINAL NUCLEUS- PLEASE ALSO SEE MASSESTER REFLEX ( STRETCH/PROPRIOCEPTIVE REFLEX)

Question 5

GVS (GVA

Answer 5

GENERAL VISCEROSENSORY- RELAY NEURONS LYING LATERAL TO THE VISCERAL MOTOR. THEY RECEIVE AFFERENT FIBER INPUT FROM INTERCEPTORS/CHEMO AND BARORECEPTORS ( CAROTID SINUS, CAROTID BODY ABDOMINAL AND THORACIC VISCERA)

Question 6

SVS

Answer 6

or SVA
for taste ( an organ of special senses). also relay neutrons- they receive afferent inputs from the taste fibres coming from taste buds ( i.e. from the tongue)

Question 7

GSS

Answer 7

GSA relay neurons-receive afferent fibres from the somatic(body receptors)

mechano-
noci-
thermo- (from skin, muscles and joints of head)

3 types of sensory subtypes exist:

1. epicritic: fine, discriminative touch, pressure and vibration
2. protopathic: vitally nb info ( pain, rough ( non discriminative, crude touch and temperature
3. proprioceptive: the position of the muscles, joints and information from the body of the subject proper= self)

afferent inputs from muscle spindles, tendons and organs

Question 8

SSS

Answer 8

SSA

relay neutrons from the most lateral column of the brainstem. they receive afferent fibres carrying vestibular and auditory signals ( from the ear). they belong to organs of special senses ( hearing and balance).

Question 9

CN III

Answer 9

superior rectus muscle
inferior rectus muscle
medial rectus muscle
inferior oblique
levator palpebrae
superioris m.

**SM by oculomotor nucleus

Question 10

CN IV

Answer 10

superior oblique muscle

*SM by trochlear nucleus