Presentation on Accessory & hypoglossal nerves created by Navdeep Gaur

1. Белгородский государственный
университет
Cranial Nerves
Prof. Dr. A.V. Tverskoy
Prepared By :
Navdeep Gaur
Group No.091218

2. Cranial Nerves
DEFINITION : THE NERVES THAT
EMERGE DIRECTLY FROM THE BRAIN,
IN CONTRAST TO SPINAL NERVES,
WHICH EMERGE FROM SEGMENTS OF
THE SPINAL CORD.

3. Cranial Nerves
A

4. Cranial Nerves in Humans
There are traditionally twelve pairs of cranial nerves. Only the first and
the second pair emerge from the cerebrum ; the remaining ten pairs
emerge from the brainstem.

5. About Cranial Nerves
The cranial nerves are part of the peripheral nervous system (PNS) with
the exception of cranial nerve II. The optic nerve, along with the retina,
is not a true peripheral nerve but a tract of the diencephalon. Cranial
nerve ganglia originate in the central nervous system(CNS). The
remaining eleven axons extend beyond the brain and are therefore
considered part of the PNS.

6. Cranial nerves in non-human
vertebrates
Human cranial nerves are nerves similar to those found in many
other vertebrates. Cranial nerves XI and XII evolved in other species
to amniotes (non-amphibian tetrapods), thus totaling twelve pairs. In
some primitive cartilaginous fishes, such as the spiny dogfish or mud
shark (Squalus acanthias), there is a terminal nerve numbered zero,
since it exits the brain before the traditionally designated first cranial
nerve.

7. Names of Cranial Nerves
Ⅰ Olfactory nerve
Ⅱ Optic nerve
Ⅲ Oculomotor nerve
Ⅳ Trochlear nerve
Ⅴ Trigeminal nerve
Ⅵ Abducent nerve
Ⅶ Facial nerve
Ⅷ Vestibulocochlear nerve
Ⅸ Glossopharyngeal nerve
Ⅹ Vagus nerve
Ⅺ Accessory nerve
Ⅻ Hypoglos

8. How to memorise cranial
nerves

9. Cranial Nerve 11
Name : Accessory Nerve
Basis of Classification :
Motor Cranial Nerves
Reason for their classification :
Because they contain only efferent
(Motor) fibers.

10. Information about
Accessory
Nerve
Cranial Exit :
Jungular Foramen
Main Action :
Motor to sternocleidomastoid
and
trapezius

11. What is Accessory Nerve?
The accessory nerve is a nerve that controls specific muscles of the
shoulder and neck. As part of it was formerly believed to originate in
the brain, it is considered a cranial nerve. Based on its location relative
to other such nerves, it is designated the eleventh of twelve cranial
nerves, and is thus abbreviated as (CN XI).

12. Accessory nerve
Motor:
Turn head side to side
shrug shoulders with resistance

13. Description of Accessory
Nerve
A

14. Description
Traditional description of the Accessory nerve divide it into 2 parts:
(a) a spinal part
and
(b) a cranial part.
But because the cranial component rapidly joins the vagus
nerve and serves the same function as other vagal nerve
fibers, modern descriptions often consider the cranial
component part of the vagus nerve and not part of the
accessory nerve proper

15. More Description
The spinal accessory nerve provides motor innervation
from the central nervous systemto two muscles of the neck:
the sternocleidomastoid muscle and the trapezius muscle.
The sternocleidomastoid muscle tilts and rotates the head,
while the trapezius muscle has several actions on
the scapula, including shoulder elevation and adduction of
the scapula.
The accessory nerve is derived from the basal plate of
the embryonic spinal segments C1–C6.

16. Origin of Accessory
Nerve
The fibers that form the spinal accessory nerve are formed
by lower motor neurons located in the upper segments of
the spinal cord. This cluster of neurons, called the spinal
accessory nucleus, is located in the lateral horn of the
spinal cord. This is in contrast to most other motor neurons,
whose cell bodies are found in the spinal cord's anterior
horn. The lateral horn of high cervical segments appears to
be continuous with the nucleus ambiguus of the medulla
oblongata, from which the cranial component of the
accessory nerve is derived.

17. Classification
Among investigators there is disagreement regarding the terminology
used to describe the type of information carried by the accessory
nerve. As the trapezius and sternocleidomastoid muscles are derived
from the branchial arches, some investigators believe the spinal
accessory nerve that innervates them must carry branchiomeric
(special visceral efferent, SVE) information. This is in line with the
observation that the spinal accessory nucleus appears to be continuous
with the nucleus ambiguus of the medulla. Others, notably Haines,
consider the spinal accessory nerve to carry general somatic
efferent (GSE) information. Still others believe it is reasonable to
conclude that the spinal accessory nerve contains both SVE and GSE
components.

18. Function
The Accessory Nerve functions as to control
the sternocleidomastoid and trapezius muscles. The thoracic branches
of the spinal accessory nerve are matched to vagal innervation in early
embyrologic development of the mammalian heart.

19. Clinical Relevance
Injury :
Accessory nerve disorder :
Injury to the
spinal accessory nerve can cause an accessory nerve
disorder or spinal accessory nerve palsy, which results in
diminished or absent function of thesternocleidomastoid
muscle and upper portion of the trapezius muscle.

20. Accessory Nerve Disorder
Presentation :
Patients with spinal accessory nerve palsy often
exhibit signs of lower motor neuron disease such as
diminished muscle mass,fasciculations, and
partial paralysis of the sternocleidomastoid and trapezius
muscles. Interruption of the nerve supply to the
sternocleidomastoid muscle results in an asymmetric
neckline, while weakness of the trapezius muscle can
produce a drooping shoulder, winged scapula, and a
weakness of forward elevation of the shoulder.

21. Medical procedures are the most common cause of injury
to the spinal accessory nerve.In particular, radical neck
dissection and cervical lymph node biopsy are among the
most common surgical procedures that result in spinal
accessory nerve damage.London notes that a failure to
rapidly identify spinal accessory nerve damage may
exacerbate the problem, as early intervention leads to
improved outcomes.

22. Treatment
There are several options of treatment
when iatrogenic (i.e., caused by the surgeon) spinal
accessory nerve damage is noted during surgery. For
example, during a functional neck dissection that injures
the spinal accessory nerve, injury prompts the surgeon to
cautiously preserve branches of C2, C3, and C4 spinal
nerves that provide supplemental innervation to the
trapezius muscle.Alternatively, or in addition to
intraoperative procedures, postoperative procedures can
also help in recovering the function of a damaged spinal
accessory nerve. For example, the Eden-Lange procedure,
in which remaining functional shoulder muscles are
surgically repositioned, may be useful for treating trapezius
muscle palsy.

24. Hypoglossal Nerve :
is the twelfth cranial nerve (XII),
Leading to muscles of the tongue.
It is called hypoglossal nerve because it is below
the tongue.
It controls tongue movements of speech, food
manipulation, and swallowing.

25. Cranial Nerve XII
Name :
Hypoglossal Nerve.

26. Trajectory
The nerve arises from the hypoglossal nucleus and emerges from the medulla
oblongatain the preolivary sulcus separating the olive and the pyramid. It then
passes through thehypoglossal canal. On emerging from the hypoglossal canal, it
gives off a small meningeal branch and picks up a branch from
the anterior ramus of C1. It spirals behind the vagus nerve and passes between
the internal carotid artery and internal jugular veinlying on the carotid sheath.
After passing deep to the posterior belly of the digastric muscle, it passes to the
submandibular region, passes lateral to the Hyoglossus muscle, and inferior to
the lingual nerve to reach and efferently innervate the tongue.
It supplies motor fibres to all of the muscles of the tongue, except
the palatoglossus muscle, which is innervated by the vagus nerve (cranial nerve X)
or, according to some classifications, by fibres from the glossopharyngeal
nerve (cranial nerve IX) that "hitchhike" within the vagus.
The hypoglossal nerve is derived from the basal plate of the embryonic medulla
oblongata.

27. Hypoglossal nerve
Motor:
Turn head side to side
Shrug shoulders with resistance

28. Function:
Tongue movements of speech, food manipulation, and
swallowing

29. Clinical test:
Tongue function

30. Effects of damage:
Difficulty in speech and swallowing; atrophy of
tongue; inability to stick out (protrude) tongue

32. Uses in nerve repair
Facial nerve paralysis is a difficult situation to fix, but new cranial nerve
substitution techniques allow for some usage to be restored, to include
hypoglossal-facial anastomosis.
This procedure is considered the standard for reanimating the face when
the proximal end of the facial nerve is not available, but the peripheral
system is still viable. There are two options:
Hypoglossal nerve completely transected and connected to facial nerve.
Hypoglossal nerve partially transected and connected to facial nerve. This
may be accomplished with interposition cable grafts or jump grafts. An
advantage of partial transection is minimizing tongue weakness and
purported decrease in synkinesis. There are disadvantages though since
there are then fewer nerve cells to drive the movement of features in the
face.

33. Thanks
For
Attention