Cranial-cerebral nerves and their functions

Nerve Nuclei location Functions
I pair, olfactory nerve Skull Participates in olfaction (smelling)
II pair, optic Skull Participates in vision
III pair, oculo-motor nerve Midbrain Rises superior eyelid, turns eyeball up, down, inside and outside
IV pair, trochlear Midbrain Innervates muscles turning eyeball below and outside
V pair, trigeminal nerve Pons Sensory part innervates skin of face, frontal-parietal head parts, haired part, eyeball, nasal and oral mucosa, anterior 2/3 of tongue, facial skull bones periosteum, dura mater of anterior and middle cranial fossae, proprioreceptors of masseter muscle ocular and mimic muscles. Motor fibers innervate masseter, temporal, medial and lateral pterygoideal, mandibular-hyoideal muscle as well as muscle rising tympanal membrane
VI pair, abducent (abducens) nerve Midbrain Innervates eye muscles abducting eyeball outside
VII pair, facial Pons Innervates mimic and other muscles of face and head, platysmal and stylo-hyoideal muscles; sensory part provides innervation of 2/3 of tongue (for sweat, salty and bitter tastes)
VIII pair, vestibular-cochlear nerve Medulla oblongata 2 parts: vestibular (provides static reflexes and gravitation overcoming id est regulates body orientation in space) and acoustic (comes to quadrigemina inferior collins in lateral lemnisc and thus provides orienting reflex to sound stimuli)
IX pair, glosso-pharyngeal Medulla oblongata Motor part innervates stylo-pharyngeal muscle rising pharynx; sensory part – posterior 1/3 of tongue (bitter taste), soft palate, pharynx, fauces, epiglottis anterior surface, acoustic tube and tympanal cavity; vegetative parasympathetic nuclei innervate parotid salivary gland (much liquid saliva releasing)
X pair, vagus Medulla oblongata Motor fibers innervate soft palate, pharynx, larynx, epiglottis, oesophagus superior part, vocal cords, smooth muscles in stomach, small intestine and large intestine superior part; sensory part innervates inner organs; provides voice and swallowing
XI pair, accessory Medulla oblongata Innervates sterno-cleido-mastoideal muscle (provides head turning in opposite side) and trapezial muscle (together with the first muscle, participates in respiration enforcement)
XII pair, hypoglossal Medulla oblongata Motor part provides tongue turnings

Materials for auditory self-work.

4.1.List of study practical tasks necessary to perform at the practical class.


Materials and methods: scale, rotating arm-chair, stall.


Investigation object: guinea pigs, the investigated person.


Task 1. To investigate nerves: oculo-motorius (III), trochlear (IV) and abducens (VI).

While examination of eyeballs the investigator should pay the attention to the:

· pupils’ width;

· orbital fissures width,

· pupil shape,

· eyeballs localization in orbit (falling back, protrusion),

· strabismus (cross-eyedness or squint-eyedness).

Pupillar reactions – the investigated person eye should be closed by scale or hand. After this it’s necessary to determine change of another pupil size. To ask to perform eyes movement on the right and on the left.

At III-rd or IV-th pairs (cranial-cerebral nerves) injury orbital fissure can be narrowed or closed – ptosis. At III-rd pair injury one can see pupil deformation, disturbance convergent eyes movement disturbance.


Task 2. Stato-kinetic human reflexes.

The investigated person must sit in rotatory arm-chair, turn his head forward and close his eyes. In such a position horizontal semicurcular channnels are investigated. Then it’s necessary to carry out arm-chair rotation on the right or on the left with the velocity of 5 times in 10 sec (1 turn in 2 sec). Then to stop arm-chair quickly, to ask the investigated person to open his eyes and to observe eyelids movements, how long do they continue. It’s also possible to carry out rotation with head turned on 90° on right or left shoulder or tossed (throwed) back on 60° behind (vertical channels are investigated). To describe investigated reactions, to call receptive fields of investigated reflexes and to indicate closure level of them in CNS.

To take another investigated person, to sit into arm-chair. To propose to turn his head on 30° forward, to perform rotation as in previous investigation, to stop arm-chair and to propose to investigated person to go after rotation directly on straight line forward. To observe movements character.

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