Brainstem nuclei and cranial nerves

Question 1

What CN leaves the cribiform plate?

Answer 1

Olfactory (CN1)

Question 2

What CN leaves the optic canal?

Answer 2

Optic nerve (CNII)

Question 3

What CNs leave the superior orbital fissure?

Answer 3

Oculomotor (CNIII), trochlear (CNIV), ophthalmic (CNV1) abducens (CNVI)

Question 4

What CN leaves the foremen rotundum?

Answer 4

Maxillary nerve (CNV2)

Question 5

What CN leaves the foremen ovale?

Answer 5

Mandbular nerve (CNV3)

Question 6

What CNs leave the internal acoustic meatus?

Answer 6

Facial nerve (CNVII), vestibulocochlear (CNVIII)

Question 7

What CNs leave the jugular foramen?

Answer 7

Glossopharyngeal (CNIX), vagus (CNX), accessory (CNXI)

Question 8

What CN leaves the hypoglossal canal?

Answer 8

Hypoglossal nerve (CNXII)

Question 9

What is SSA

Answer 9

Special somatic afferent = special senses related to external environment; sight, balance

Question 10

What is GSA

Answer 10

General somatic afferent = sensation on skin, mucous membrane; pain, touch, proprioception

Question 11

What is SVA

Answer 11

Special visceral afferent = primarily with tasye

Question 12

What is GVA

Answer 12

General visceral afferent = pain in the GIT, heart, lungs, hollow organs

Question 13

What is GSE

Answer 13

General somatic efferent = skeletal muscles that control specific myotomes

Question 14

What is SVE

Answer 14

Special visceral efferent = muscles from brachial/pharyngeal embryo logical origins

Question 15

What is GVE

Answer 15

General visceral efferent = preganglionic fibres of the autonomic nervous system

Question 16

Type, function and foramen/origin of olfactory CNVI

Answer 16

SVA, smell, cribiform plate/forebrain

Question 17

Type, function and foramen/origin of optic CNII

Answer 17

SSA, vision, optic canal/forebrain

Question 18

Type, function and foramen/origin of Oculomotor CNIII

Answer 18

GSE - movement of the eye (all muscles except lateral rectus and superior oblique)
GVE - parasympathetic pupillary constriction and lens accommodation
Superior orbital fissure/midbrain

Question 19

Type, function and foramen/origin of trochlear CNIV

Answer 19

GSE, movement of the eye (just superior oblique), superior orbital fissure/midbrain

Question 20

Type, function and foramen/origin of trigeminal CNV

Answer 20

SVE - chewing via muscles of mastication
GSA - general sensation on anterior 2/3 of the tongue, face, gingiva, teeth, scalp, paranasal sinuses
V1 = superior orbital fissure; V2 = foramen rotundum; V3 = foramen ovale (all pons)

Question 21

Type, function and foramen/origin of abducens CNVI

Answer 21

GSE, movement of the eye (just lateral rectus), superior orbital fissure/pons

Question 22

Type, function and foramen/origin of facial CNVII

Answer 22

GSA - general sensation on area posterior to the ear and external auditory meatus
GVA - visceral sensation on middle ear, nasal cavity and soft palate
SVA - taste on anterior 2/3 of tongue
GVE - parasympathetic lacrimal glands, mucous secretion and salivary glands (submandibular and sublingual)
SVE - muscles of facial expression

Internal acoustic meatus and facial canal/pons

Question 23

Type, function and foramen/origin of vestibulocochlear CNVIII

Answer 23

SSA - hearing and equilibrium/balance, internal acoustic meatus/pons

Question 24

Type, function and foramen/origin of glossopharyngeal CNIX

Answer 24

GSA - general sensation on posterior 1/3 of tongue, soft palate, upper pharynx
GVA - visceral sensation on middle ear, pharynx, tongue, carotid sinus
SVA - taste on posterior 1/3 tongue
GVE - salivation (parotid)
SVE - swallowing
Jugular foramen/medulla oblongata

Question 25

Type, function and foramen/origin of vagus CNX

Answer 25

GSA - general sensation in area posterior to ear, external acoustic meatus and posterior part of the meninges GVA - visceral sensation in thoracic and abdominal viscera SVA - taste on epiglottis GVE - parasympathetic peristalsis SVE - phonation - muscles of larynx and pharynx Jugular foramen/medulla oblongata

Question 26

Type, function and foramen/origin of accessory CNXI

Answer 26

SVE - phonation (laryngeal muscles), head and shoulder movements (SCM and trapezius) Foramen magnum/medulla oblongata

Question 27

Type, function and foramen/origin of hypoglossal CNXII

Answer 27

GSE - tongue movement (muscles of the tongue), hypoglossal canal/medulla oblongata

Question 28

What happens if there is a lesion in the olfactory nerve

Answer 28

Patient cannot smell

Question 29

What happens if there is a lesion in the optic nerve?

Answer 29

Patients vision is affected. Specific symptoms occur depending on where the lesion occurs. Lesion 2 occur due to an enlarged pituitary gland and affect the optic chiasm. Lesion 1 causes monocular blindness, lesion 2 causes tunnel vision, lesion 3 causes homonymous hemianopia.

Question 30

What happens if there is a lesion in the Oculomotor nerve?

Answer 30

Leads to ptosis (drooped eyelid) and the eye pointing down and outwards. Pupil will also dilate in the same eye.

Question 31

What happens if there is a lesion in the trochlear nerve

Answer 31

Superior oblique affected. Causes eye to point upward and outward causing double vision due to a paralysed superior oblique muscle. Affected eye will be unable to point down and towards the nose.

Question 32

What happens if there is a lesion in the abducens nerve?

Answer 32

Paralysis of the lateral rectus causing the eye to point inwards leading to double vision (diplopia). The affected eye will be unable to point outward.

Question 33

What happens if there is a lesion in the trigeminal nerve?

Answer 33

If lesion in the motor aspect, patient will not be able to chew food. If lesion in sensory aspect then the patient will not feel anything in their face. Specific lesions will cause specific areas of the face symptoms.

Question 34

What happens if there is a lesion in the facial nerve?

Answer 34

Five branches: temporal, zygomatic, buccal, marginal mandibular, cervical. All have contralateral innervation except the temporal which received bilateral innervation. If lesion in the facial motor nucleus then the muscles of facial expression will be affected, however the forehead will be unaffected due to the temporal branch. If sensory aspect is affected then the patient will be unable to taste anything on the anterior 2/3 of the tongue.

Question 35

What happens if there is a lesion in the vestibulocochlear nerve?

Answer 35

Loss of hearing and diminished ability to maintain balance. Other symptoms may include vertigo and dizziness.

Question 36

What happens if there is a lesion in the glossopharyngeal nerve?

Answer 36

Death. Sensory info that will be lost includes the baroreceptor reflex, taste in the posterior 1/3 of the tongue and visceral sensation to the pharynx. Afferent innervation that will be affected includes the inability to elevate the pharynx to swallow and inability to secrete saliva from the parotid gland.

Question 37

What happens if there is a lesion in the vagus nerve?

Answer 37

Inability to raise the soft palate (making breathing and swallowing difficult), loss of the gag reflex, loss of sensation from the pharynx, oesophagus and trachea. Can lead to irregular heartbeat due to a lack of info being sent to the SAN and cardiac ventricular muscles.

Question 38

What happens if there is a lesion in the accessory nerve?

Answer 38

Inability to talk and make coherent sounds as well as the inability to use the SCM and trapezius muscles. Patient will not be able to turn their head and these muscles will be paralysed.

Question 39

What happens if there is a lesion in the hypoglossal nerve?

Answer 39

Tongue to point towards the side of the lesion due to a paralysis of the tongue muscles of the contralateral side.