Cranial Nerves 11th & 12th Neuroanatomy block-Anatomy-Lecture

Editing file Objectives

At the end of the lecture, students should be able to:

01 List the nuclei related to accessory and hypoglossal nerves in the brain stem.

02 Describe the type and site of each nucleus.

03 Describe site of emergence and course of accessory & hypoglossal nerves.

04 Describe important relations of accessory & hypoglossal nerves in the neck. Color guide

● Only in boys slides in Green 05 List the branches of accessory and hypoglossal nerves. ● Only in girls slides in Purple ● important in Red 06 Describe the main motor effects in case of lesion of accessory & hypoglossal ● Notes in Grey nerves. 11th CN: Accessory Nerve ● Type: Motor. ● Has two parts (roots): cranial & spinal. ● Foramen of exit from skull: Jugular foramen. There’re 4 structures that pass through the jugular foramen : Cranial nerves IX,X,XI and internal jugular vein

1. Cranial Part 2. Spinal Part carries fibres that originate in the caudal arises from motor neurons in ventral horn of part of nucleus ambiguus. the spinal gray matter at levels C1-C5 (spinal nucleus). ❶● Emerges from lateral aspect of the medulla as a linear series of rootlets ❶● The axons leave the cord via series of rootlets, between olive and inferior cerebellar emerge laterally midway between the dorsal ❶ & ventral roots of the spinal nerves. peduncle,caudal to rootlets of the vagus ❷ ❶ nerve. ❸ ❹ ❷● Courses rostrally and enter the cranial cavity ❷ through the foramen magnum, and joins the ● At the side of medulla it joins the spinal Accessory root briefly. nucleus in cranial root briefly. ventral horn of ❹ spinal cord ● It separates once again as the nerve segment ❸● Separates once again as the nerve leaves the ❸ C1-C5 leaves the cranial cavity through the cranial cavity through the Jugular foramen. Jugular foramen. ❹● Supplies the: sternomastoid and trapezius ❹● At the level of jugular foramen these muscles. fibres join the vagus nerve and distribute with it to muscles of the: soft plate, esophagus, pharynx and larynx. 3 11th CN: Accessory Nerve

● The nucleus ambiguus and the spinal nucleus receive bilateral corticonuclear fibers (from both cerebral hemispheres).

Functions of accessory nerve: 1. Movements of the soft palate, larynx, pharynx. 2. Controls the movements of neck.

Injury of spinal root of accessory nerve:

Because of the relatively superficial Difficulty in swallowing and speech position of the nerve in the posterior triangle, it may be damaged by & Inability to turn the head. 01. penetrating trauma as stab wounds.

Causes: Atrophy & weakness Manifestations: Drooping of the of trapezius. shoulder.

It is considered the most commonly iatrogenically injured nerve as during Unilateral paralysis of trapezius: removal of malignant lymph nodes in the 02. is evident by inability to elevate & retract the posterior triangle. shoulder ,difficulty in elevating the arm & Winging of scapula.

4 12th CN: Hypoglossal Nerve

● Type: Motor. ● Origin: Hypoglossal nucleus of the medulla (in the floor of 4th ventricle). ● Foramen of exit from skull: hypoglossal canal.

Hypoglossal nucleus

Course:

❶● The fibers emerge from the anterior surface The hypoglossal nucleus receives: of the medulla oblongata through the sulcus between the pyramid & the olive. ❶ ❶1. corticonuclear fibers from both cerebral ❷● The nerve courses downward with cervical hemispheres EXCEPT the region that neurovascular bundle (internal carotid ❷ artery, internal Jugular vein, vagus nerve). supplies genioglossus muscle (receives Then curves forward behind mandible to contralateral supply only). supply the tongue. ❸ ❷2. Afferent fibers from nucleus solitarius ❸● During its initial course, it carries C1 fibers and trigeminal sensory nucleus. which leave in a branch to take part in the formation of ansa cervicalis (a loop of nerves supplying neck muscles).

5 12th CN: Hypoglossal Nerve

Functions of Hypoglossal nerve: 1. Supplies motor innervation to all of the muscles of the tongue Except the palatoglossus (which is supplied by the vagus nerve). ➔ So, it Controls the movements and shape of the tongue during speech & swallowing. 2. Carries proprioceptive afferents from the tongue muscles.

Manifestations Lesion of the nerve (LMN) :

01. Loss of tongue 03. The tongue movements. paralyses, atrophies, 04. On protrusion, tongue deviates becomes shrunken and to the affected side. furrowed on the affected side 02. Difficulty in 05. If both nerves are damaged, (LMN paralysis). chewing & speech. person can’t protrude tongue.

6 Practice Q1: The Accessory Nerve exit from which foramen in the skull? Q5: The 12th cranial nerve is A. Foramen ovale A. glossopharyngeal nerve B) Foramen Lacerum B. vagus nerve C) Jugular Foramen C. hypoglossal nerve D) Foramen Magnum D. optic nerve Q2: The spinal part of Accessory Nerve supplies which muscles? Q6: Lesions of the 12th cranial nerve wouldn’t affect which muscle ? A. Sternomastoid & Trapezius A.Palatoglossus. B. Serratus anterior & Trapezius B.Styloglossus. C. Sternomastoid and scalene C. Hyoglossus. D. Sternomastoid and omohyoid D. Tongue. Q3: Which of the following nerve commonly injured during removal of malignant lymph Q7: If the tongue is deviated to the left side that means? nodes in the posterior triangle? A.Right hypoglossal nerve injury. A.Cranial root of Accessory Nerve B. Left hypoglossal nerve injury. B.Hypoglossal Nerve C. Both A&B. C. Spinal root of Accessory Nerve D. None of the above. D. Vagus Nerve. Q8 : Type of paralysis combined with 12th cranial nerve lesions is ? Q4: The function of accessory cranial nerve is ? A. LMN paralysis. A.Movements of the tongue B. UMN paralysis. B. Controls the movements of the neck C. Upper motor neuron lesion C. Carries proprioceptive afferents from the tongue muscle . Answers: Q1(C) Q2(A) Q3(C) Q4(B) Q5(c) Q6(A) Q7(B) Q8(A) 7 Members board

Team leaders

● Abdulrahman Shadid ● Ateen Almutairi Girls team : Boys team: ● Ajeed Al Rashoud ● Mohammed Al-huqbani ● Taif Alotaibi ● Salman Alagla ● Noura Al Turki ● Ziyad Al-jofan ● Amirah Al-Zahrani ● Ali Aldawood ● Alhanouf Al-haluli ● Khalid Nagshabandi ● Sara Al-Abdulkarem ● Omar Alammari ● Renad Al Haqbani ● Sameh nuser ● Nouf Al Humaidhi ● Abdullah Basamh ● Jude Al Khalifah ● Alwaleed Alsaleh ● Nouf Al Hussaini ● Mohaned Makkawi ● Rahaf Al Shabri ● Abdullah Alghamdi ● Danah Al Halees ● Rema Al Mutawa ● Amirah Al Dakhilallah ● Maha Al Nahdi Contact us: ● Razan Al zohaifi ● Ghalia Alnufaei Editing file most probably you don't need this