INTRODUCTION
COMPONENTS
COURSE OF CRANIAL ROOT
COURSE OF SPINAL ROOT
DISTRIBUTION OF SPINAL ACCESSORY NERVE
CLINICAL FINDI...
• The Accessory nerve [XI] carries GSE ( General Somatic
Efferent) fibers.
• Innervates the STERNOCLEIDOMASTIOD and TRAPEZ...
COMPONENTS:
I- Cranial Root. (Nucleus Ambiguous)
II- Spinal Root. ( Spinal Nucleus of Ant. Grey
columns b/w C1 - C5)
CRANIAL ROOT:
• Arises from the lower part of Nucleus
Ambiguous.
• Accessory to the Vagus nerve [X].
• Distributed through...
Course of Cranial Root:
• Rootlets arising from Caudal part of the Medulla Oblongata on the
Anterolateral surface, just in...
Course of the Spinal Root:
• Fibers arising from the motor cells in the lateral part of the Anterior
column of grey substa...
• Crosses the Int. Jugular Vein laterally in 66%, and passes behind in
33.3% of cases.
• Disappear either into or beneath ...
Distribution:
→ Motor Innervation to;
• Sternocleidomastoid muscle.
• Trapezius muscle.
CLINICAL FINDINGS:
• Paralysis of Sternocleidomastoid and Trapezius muscle.
• Drooping of the Shoulder.
• Inability to tur...
Xi  cranial nerve
Xi  cranial nerve
Xi  cranial nerve
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Xi cranial nerve

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Xi cranial nerve

  1. 1. INTRODUCTION COMPONENTS COURSE OF CRANIAL ROOT COURSE OF SPINAL ROOT DISTRIBUTION OF SPINAL ACCESSORY NERVE CLINICAL FINDINGS LESIONS XI- CRANIAL NERVE (ACCESSORY)
  2. 2. • The Accessory nerve [XI] carries GSE ( General Somatic Efferent) fibers. • Innervates the STERNOCLEIDOMASTIOD and TRAPEZIUS muscles. • Unique cranial nerve - - - roots arise from motor neurons of the UPPER FIVE SEGMENTS [C1-C5] OF THE CERVICAL SPINAL CORD.
  3. 3. COMPONENTS: I- Cranial Root. (Nucleus Ambiguous) II- Spinal Root. ( Spinal Nucleus of Ant. Grey columns b/w C1 - C5)
  4. 4. CRANIAL ROOT: • Arises from the lower part of Nucleus Ambiguous. • Accessory to the Vagus nerve [X]. • Distributed through the Branches of Vagus nerve.
  5. 5. Course of Cranial Root: • Rootlets arising from Caudal part of the Medulla Oblongata on the Anterolateral surface, just inferior to the rootlets arising to form Vagus Nerve. • Leaving the Medulla, Cranial roots course with the “spinal” root of Accessory nerve into the Jugular foramen, and again separates outside the foramen. • Join the Vagus nerve [Inf. Ganglion] after exiting the Jugular foramen, supplying the pharyngeal musculature supplied by Vagus Nerve.
  6. 6. Course of the Spinal Root: • Fibers arising from the motor cells in the lateral part of the Anterior column of grey substance of the medulla spinalis as low as fifth cranial nerve[C1-C5]. • Joining together as they ascend. • Enters the Cranial Cavity through Foramen Magnum. • Continues through the Posterior Cranial Fossa, laterally towards Jugular foramen Extra-cranially: • Exits through Jugular foramen. • Descends in the neck, Medial to the Int. Jugular Vein. • B/w the Angle of Mandible and Mastoid process. • Lies under the Stylohyoid and Post. Belly of Digastric muscle.
  7. 7. • Crosses the Int. Jugular Vein laterally in 66%, and passes behind in 33.3% of cases. • Disappear either into or beneath the Ant. Border of Sternocleidomastoid muscle. [NO BRANCHES IN ANT. TRIANGLE OF THE NECK] • Continues its descend & Enters the Post. Triangle of the Neck. • Still moving obliquely and downward, within the Investing layer of the Cervical fascia. • Reaches the Ant. Border of Trapezius muscle, terminates by innervating the muscle.
  8. 8. Distribution: → Motor Innervation to; • Sternocleidomastoid muscle. • Trapezius muscle.
  9. 9. CLINICAL FINDINGS: • Paralysis of Sternocleidomastoid and Trapezius muscle. • Drooping of the Shoulder. • Inability to turn chin to opposite side. • Inability to draw head forward. • Irritation of the nerve during biopsy of enlarged caseous lymph nodes, may produce TORTICOLLIS or WRY NECK. LESIONs: • Penetrating injury to the Posterior Triangle of the Neck. • Superficial location of the nerve in Post. Triangle of the neck makes it susceptible to injury.
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