Cranial XI-XII Color Code Important (Accessory & Hypoglossal Nerves) Doctors Notes Notes/Extra explanation Please view our Editing File before studying this lecture to check for any changes. Objectives At the end of the lecture, the students should be able to: ✓ List the nuclei related to accessory and hypoglossal nerves in the brain stem. ✓ Describe the type and site of each nucleus. ✓ Describe site of emergence and course of accessory and hypoglossal nerves. ✓ Describe important relations of accessory and hypoglossal nerves in the . ✓ List the branches of accessory and hypoglossal nerves. ✓ Describe the main motor effects in case of lesion of accessory and hypoglossal nerves. Extra Slide: Mnemonics And Pictures To Help

Memorise The 07:32

Big Brains Matter More Accessory (XI) 11th Cranial o Type: Motor o Has two parts (roots)*: • Cranial part • Spinal part Extra carries fibres that arises from motor originate in the neurones in ventral caudal part of horn of the spinal gray . matter at levels C1-C5 (spinal nucleus) o Foramen of exit from skull: .

* يختلف هذا العصب بأنه الوحيد بين الباقين إلي يأخذ من جزئيين Accessory (XI) 11th Cranial Nerve Cranial Part o Emerges from lateral aspect of the medulla as a linear series of rootlets caudal to rootlets of the . o At the side of medulla it joins the spinal root briefly. o It separates once again as the nerve leaves the cranial cavity through the Jugular foramen. o At the level of jugular foramen these fibres join the vagus nerve and distribute with it to muscles of the soft plate, esophagus, pharynx and larynx.

Extra Accessory (XI) 11th Cranial Nerve Spinal Part o The axons leave the cord via series of rootlets, emerge laterally midway between the dorsal and ventral roots of the spinal nerves. o Courses rostrally and enter the cranial cavity* through the , and joins the cranial root briefly o Separates once again as the nerve leaves the cranial cavity through the Jugular foramen.Then descend to the posterior triangle of neck o Supplies the sternomastoid and muscles

*It is the only nerve that enters the cranial cavity, all others exit.

Extra Accessory (XI) 11th Cranial Nerve o The nucleus ambiguus and the spinal nucleus receive bilateral corticonuclear or corticospinal fibers (from both cerebral hemispheres). o Function: • Movements of the soft palate, larynx, pharynx (cranial part). • Controls the movements of neck (spinal part) “via the sternomastoid and trapezius muscles)”. Accessory (XI) 11th Cranial Nerve Injury of Spinal Root o Causes: • Because of the relatively superficial position of the nerve in the posterior triangle, it may be damaged by penetrating trauma as stab wounds. • It is considered the most commonly iatrgenically* injured nerve as during removal of malignant lymph nodes in the posterior triangle.

* induced inadvertently by a physician or surgeon or by medical treatment or diagnostic procedures Accessory (XI) 11th Cranial Nerve Injury of Spinal Root o Manifestations: • It produces atrophy and weakness of trapezius. • Unilateral paralysis of trapezius is evident by (1) inability to elevate & (2) retract the shoulder, (3) difficulty in elevating the arm & (4) Winging of . • Dropping of the shoulder is an obvious sign of injury of the nerve. • If the cranial root is also injured: the lesion also causes difficulty in and speech, and • Inability to turn the head. Hypoglossal (XII) 12th Cranial Nerve

o Type: Motor o Origin: of the medulla (in the floor of 4th ventricle)* o The fibers emerge from the anterior surface of the through the sulcus between the pyramid and the olive. o Foramen of exit from skull:

* The most medial nucleus Pyramid

Olive Extra Hypoglossal (XII) 12th Cranial Nerve o The hypoglossal nucleus receives corticonuclear fibers from both (bilateral) cerebral hemispheres

EXCEPT the region that supplies * muscle (receives contralateral supply only) unilateral o Also receives afferent fibers from nucleus solitarius and trigeminal sensory nucleus.

* The only muscle that take fibers from one side, which is the opposite side

Extra Hypoglossal (XII) 12th Cranial Nerve Course o The nerve courses downward with cervical neuro-vascular bundle (, , vagus nerve) o Then curves forward behind mandible to supply the . o During its initial course, it carries C1 fibers* which leave in a branch to take part in the formation of (a loop of nerves supplying neck muscles) * الـ يعتبر زي التاكسي لـ c1 فايبرز بس ترتبط معاه ويوصلها وبعدين يتركها وتنفصل عنه وترتبط مع فايبرز أخرى عشان يك ّونوا)Ansa cervicalis( C1 fibers Hypoglossal (XII) 12th Cranial Nerve Function

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 and swallowing 2. Carries proprioceptive afferents from the Extra tongue muscles. Hypoglossal (XII) 12th Cranial Nerve Lesion

Manifestations of Lesion of the nerve (LMN) : o Loss of tongue movements o Difficulty in chewing and speech o The tongue paralyses, atrophies, becomes shrunken and furrowed on the affected side (LMN paralysis) o On protrusion, tongue deviates to the affected side. “normally it’s in the middle” o If both nerves are damaged, person can’t protrude tongue. *مثال في الصورة؛ اللسان منحرف إلى الجهة اليسار، معناتو إلي أتأثر هو left hypoglossal nerve Lesion left CN 12، ولو النيرف في الجهتين أتاثر الشخص ما يقدر يمد لسانه لبرا Nerve Type Origin Foramen of Function Injury Exit

Trapezius atrophy & Nucleus Movement of the soft Cranial Part weakness Ambigius palate, larynx & Pharynx Trapezius paralysis

XI Spinal Jugular Shoulder dropping motor accessory foramen C1-C5 Speech & Spinal Part (Spinal Movement of the neck swallowing difficulty nucleus) Inability to turn head loss of tongue Motor to all tongue movement muscles except Speech &chewing Anterior surface of palatoglossus difficulty XII Medulla Hypoglossal hypoglossal motor (hypoglossal nucleus) canal Speech & swallowing Tongue paralysis

Carries afferents from Tongue deviation on tongue muscles protrusion to affected side 1. The exit from which foramen in the skull ? MCQs 5. The hypoglossal nucleus of the medulla locate in which A- Foramen ovale ventricle? B- Foramen Lacerum A- The 2nd Ventricle C- Jugular Foramen B- The 3rd Ventricle D- Foramen Magnum C- The top of 4th Ventricle Answer: C D- The floor of 4th Ventricle Answer: D 2. The spinal part of Accessory Nerve supplies which muscles ? A- The sternomastoid and Trapezius 6. The Hypoglossal Nerve supplies motor innervation of all the B- The serratus anterior and Trapezius muscle of the tongue except ? C- The sternomastoid and scalene A- superior longitudinal D- The sternomastoid and omohyoid B- The palatoglossus Answer: A C- Cranial root of Accessory Nerve 3. Which of the following nerve commonly injured during removal D- of malignant lymph nodes in the posterior tringle ? Answer: B A- Vagus Nerve B- Hypoglossal Nerve SAQ C- Cranial root of Accessory Nerve D- Spinal root of Accessory Nerve A 12 year boy came to the ER with difficulty in chewing and Answer: D speech .

4. Hypoglossal Nerve is a ? 1\ Which Nerve is most likely affected ? A- Motor type The hypoglossal nerve B- Sensory Type 2\ The tongue shrunken and furrowed in which side ? C- Both The affected side Answer: A Leaders: Members: Nawaf AlKhudairy Ameera Niazi Jawaher Abanumy Do'aa abdulfattah Nada Aldakheel Shatha Alghaihb

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