INTRODUCTION-FUNCTIONAL COMPONENTS-HYPOGLOSSAL NUCLEUS-INTRANEURAL COURSE-BRANCHES AND DISTRIBUTION-CLINICAL ANATOMY- It is very useful UG & PG Medical and dental & Nursing students. It also helps physiotherapist and paramedical students.

1. HYPOGLOSSAL NERVE
By
DR.M.MD.MUSTAFA SHARIFF
SENIOR LECTURER
SRMDCH-21

2. HYPOGLOSSAL NERVE
INTRODUCTION :
• It is twelveth cranial nerve.
• It arises from antrolateral sulcus of medulla oblongata.
• The nerve leaves the skull through hypoglossal canal.
• It supplies the muscles of the tongue.

4. FUNCTIONAL COMPONENTS:
GENERAL SOMATIC EFFERENT COLUMN:
• The fibers arise from the hypoglossal nucleus which lies
in the medulla.
• In the floor of the fourth ventricle deep to the
hypoglossal triangle.

5. GENERAL SOMATIC AFFERENT COLUMN:
 Spinal nucleus of cranial nerve 5th.
 where proprioceptive fibers from tongue end

6. HYPOGLOSSAL NUCLEUS
 It is 2cm long
 It lies in the floor of fourth ventricle beneath
the hypoglossal triangle.
 It is divided into two parts for individual
muscles innervated.

8. HYPOGLOSSAL NUCLEUS
• Connection of the nucleus with opposite pyramidal
tract forms supranuclear pathway of the nerve.
It is also connection to
 Cerebellum
 Reticular formation of medulla
 Sensory nuclei of 5th nerve
 Nucleus of tractus solitarius

9. INTRANEURAL COURSE
Fibers pass forwards
Lateral:
 Medial longitudinal bundle
 Medial lemniscus
 Pyramidal tract
Medial:
 Reticular formation
 Olivary nucleus

10. EXTRACRANIAL COURSE
• The nerve first lies
deep to internal
jugular vein and
descends between
internal jugular vein
and internal carotid
artery.

11. It is present to deep to the
 Parotid gland
 The styloid process
 The posterior belly
of the digastric and
 Stylohyoid muscle

12.  At the lower border of posterior belly of the digastric it
curves forwards and crosses internal and external
carotid artery and anterior to loop of lingual artery.
 The nerve then continues forwards on the hyoglossus.
 And Genioglossus muscles, deep to submandibular
gland and mylohyoid muscle and enters the substance
of the tongue to supply its muscles.

14. BRANCHES AND DISTRIBUTION
Muscular branches :
• It supply Intrinsic and Extrinsic muscles of the tongue .
• Except palatoglossus which is supplied by cranial root of
accessory nerve
• Other branches containing C1 nerve through 12th nerve.
• Meningeal branch
• Ansa cervicalis
• Branches to thyrohyoid and geniohyoid.

16. CLINICAL ANATOMY
o Hypoglossal nerve is tested clinically by asking the
patient to protrude his tongue.
o Lesion of the hypoglossal nerve produce paralysis of the
tongue to the side of lesion.
o If the lesion is infra nuclear there is gradual atrophy on
the side of lesion.

17. SUPRANUCLEAR LESIONS CAUSES:
 Paralysis without wasting.
 The tongue moves sluggish
and resulting in defective
speech.
 On protrusion , the tongue
deviates to opposite side.

18. REFERENCES
 EXAM-ORINTED ANATOMY SHOUKAT N.KAZI
 HEAD & NECK AK DATTA 5TH EDITION
 GRAYS ANATOMY STUDENTS EDITION
 CLINCAL ANATOMY SNELL 8TH EDITION
 CLINICAL ANATOMY MOORE 5TH EDITION
 HEAD & NECK BD CHAURASIA’S 4TH EDITION
 HEAD & NECK DR. AS.MONI