Cranial Nerves

Question 1

Spinal root of accessory nerve arises from

Answer 1

C1-C6 segments (upper 5-6)

Question 2

Course of spinal root of accessory Nerve

Answer 2

1. Ascends and enters the cranial cavity through foramen magnum
2. It then curves laterally to leave skull throuh Jugular foramen
3. It descends between IJV & ICA (deep to styloid proccess)
4. It then passes backwards, crossing IJV
5. it pierces sternomastoid muscle, to enter posterior triangle of the neck
6. It crosses the posterior triangle within the deep fascia of the roof of the triangle
7. It leaves the triangle deep to trapezius muscle 5cm above clavicle

Question 3

Spinal root of accessory Nerve supplies

Answer 3

2 Muscles:
* Sternomastoid
* Trapezius

Question 4

Cranial root of accessory Nerve arises from

Answer 4

Medulla oblongata, (lower part) of Nucleus ambiguus

Question 5

course of Cranial root of accessory Nerve

Answer 5

Exits skull through jugular foramen and joins Vagus N

Question 6

(through Vagus Nerve) Cranial root of accessory Nerve supplies

Answer 6

• Muscles of larynx
• Muscles of Pharynx (except stylopharyngeus)
• Muscles of soft palate (except tensor palati)

Question 7

Injury to spinal root of accessory nerve may lead to

Answer 7

• Weakness & atrophy to trapezius & sternomastoid
• Impaired rotatory movement of neck and face to opposite side

Question 8

Motor part of pharyngeal plexus arises from

Answer 8

Pharyngeal branch of Vagus N (10th CN)

Question 9

Sensory part of pharyngeal plexus arises from

Answer 9

Pharyngeal branch of glossopharyngeal N (9th CN)

Question 10

Sympathetic Part of Pharyngeal plexus arises from

Answer 10

Pharyngeal branch of superior cervical sympathetic ganglion

Question 11

Branches of Pharyngeal plexus

Answer 11

• Motor to all muscles of pharynx (except stylopharyngeus which is supplied by glossopharyngeal N)
• Motor to all Muscles of the soft palate (except tensor palati which is supplied by Nerve to medial pterygoid)
• Sensory to mucosa of Oropharynx

Question 12

Hypoglossal Nerve arises from

Answer 12

Hypoglossal Nucleus (Motor)

Question 13

Course of Hypoglossal Nerve

Answer 13

1. Exits the skull through hypoglossal foramen
2. descends deep to posterior belly of digastric to enter** carotid triangle** , where it lies between IJV & ICA
3. It then curves forwards crossing 3 arteries: ICA, ECA & Loop of lingual A
4. It enters digastric triangle to lay on **lateral surface of hyoglossus **
5. It divides into many branches on the surface of **genioglossus muscle **

Question 14

Hypoglossal nerve is joined just below the skull by a branch from

Answer 14

C1

Question 15

Hypoglossal N (without C1) gives

Answer 15

All extrensic and intrensic muscles of the tongue, except palatoglossus (which is supplied by pharyngeal Plexus by Cranial root of Accessory N through vagus N)

Question 16

Branches of C1 through hypoglossal N

Answer 16

• Menegial branch
• Descendens Hypoglossi (to ansa cervicalis)
• Branch to thyrohyoid
• Branch to geniohyoid

Question 17

Injury to hypoglossal N is characterised by

Answer 17

1. Hemiatrophy of affected side of tongue
2. On protrusion of the tongue, deviation of tongue to affected side

Question 18

Superior root of Ansa cervicalis

Answer 18

branch from C1 through hypoglossal N known as descendens Hypoglossi

Question 19

Inferior root of ansa cervicalis

Answer 19

Descendens Cervicalis:
from C2 & C3

Question 20

Branches of Ansa cervicalis

Answer 20

to 3 infrahyoid muscles
1. Sternohyoid
2. Sternothyroid
3. Inferior belly of omohyoid