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Hypoglossal nerve

Hypoglossal nucleus & its central connections
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1) Its nucleus receive Corticonuclear fibers from both cerebral hemispheres, but the cells supplying the genioglossus muscle receives corticonuclear fibers only from the opposite cerebral hemisphere
2) It supplies
1. All the intrinsic muscles of the tongue
2. Styloglossus
3. Hyoglossus
4. Genioglossus
5. Doesn’t supply Palatoglossus – Supplied by the vagus
3) Function is to control the movement of the tongue
4) In the upper part, the Hypoglossal nerve is supplied by the C1 fibers
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Examination of the hypoglossal muscle
1) Ask the patient to open the mouth & inspect the tongue
2) Look for evidence of:
1. Atrophy (Increased folds, wasting)
2. Fibrillations
3) Ask the patient to protrude the tongue : Note any deviation or difficulty (Protrude tongue deviates towards the side of weakness)

The summary of cranial nerves

Nerve
Component
Function
Opening in skull
1.Olfactory
Sensory
Smell
Openings of the cribriform plate of the ethmoid
2.Optic
Sensory
Vision
Optic canal
3.Occulomotor

Motor
Raises upper eye lid
Turns eye balls upwards, downwards, medially
Constrict pupils
Accommodate eyes 
Superior orbital fissure
4. Trochlear
Motor
Turn the eye ball downward & lateral
Superior orbital fissure
5. Trigeminal
Ophthalmic division
Sensory
Cornea, skin of forehead, scalp, eyelids, nose mucus membranes of paranasal sinuses & nasal cavity
Superior orbital fissure
Maxillary division
Sensory
Skin of face over maxilla, Teeth of upper jaw, mucus membrane of nose, maxillary sinus & palate
Foramen rotundum
Mandibular division
Motor
Muscles of mastication, Mylohyoid, anterior belly of Digastric, tensor veli palatini, tensor tympani 
Foramen ovale

Sensory
Skin of cheek, skin of mandible & side of head, teeth of lower jaw & TMJ, mucus membrane of mouth & anterior part of the tongue
6. Abducent
Motor
Turns eye balls laterally
Superior orbital fissure
7. Facial
Motor
Muscles of face & scalp, Stapedius, posterior belly of Digastric, Stylohyoid muscles 
Internal acoustic meatus, facial canal, stylomastoid foramen
Sensory
Taste from anterior 2/3 of the tongue, from floor of the mouth & palate
Secretomotor (PS)
Sub mandibular & sub lingual salivary glands, Lacrimal glands
8. Vestibular cochlear
Vestibular
Sensory
From utricle, saccule & semi circular canals – Position & movement of head
Internal acoustic meatus
Cochlear
Sensory
Organ of Corti – Hearing 
9.Glossopharyngeal
Motor
Stylopharyngeus
Jugular foramen


Sensory
General & taste sensation from the posterior 1/3 of the tongue & pharynx, carotid sinus (Baroreceptors) and Carotid sinus (Chemoreceptor)
Secretomotor (PS)
Parotid gland
10. Vagus
Motor
Note
Jugular foramen
Sensory
11.Accessory
Cranial root

Motor
Supply the muscles of Soft palate (Except tensor veli palatini), Pharynx (Except stylopharyngeus), Larynx (Except cricothyroid)
Jugular foramen
Spinal root
Motor
SCM & trapezius
12. Hypoglossal
Motor
Muscles of the tongue except palatoglossus
Hypoglossal canal
Hypoglossal nerve Hypoglossal nerve Reviewed by Radiology Madeeasy on August 05, 2010 Rating: 5
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