DENTAL GROSS ANATOMY: Answers to Sample Questions

WEEK 4 -- September 24, 2007

The sympathetic nervous system
- A. is also called the craniosacral nervous system.
- B. has long preganglionic and short postganglionic fibers.
- C. inhibits salivary secretion.
- D. stimulates blood flow to the gastrointestinal tract.
- E. inhibits sweat gland secretion.
Which of the following muscles is NOT supplied by the facial nerve?
- A. buccinator
- B. anterior belly of digastric
- C. stylohyoid
- D. platysma
- E. frontalis
Which of the following foramina is not associated with a branch of the trigeminal nerve?
- A. mandibular foramen
- B. foramen ovale
- C. mental foramen
- D. stylomastoid foramen
- E. foramen rotudum

IDENTIFICATIONS

Zygomatic arch
Mastoid process of the temporal bone
Angle of the mandible

Mental protuberance

CLINICAL CASE
This is a classic presentation of Raynaud's syndrome. The syndrome is defined as an idiopathic (unknown cause) paroxysmal (sudden and recurrent onset) bilateral cyanosis of the digits usually caused by cold or emotion.

Contraction of the smooth muscle in the walls of the small arteries (arterioles) of the fingers would reduce blood flow to the tissue. As oxygen in the blood is utilized the oxygen-carrying protein (hemoglobin) is reduced and gives the skin and mucous membranes a dark bluish or purplish coloration (cyanosis).
Smooth muscle is innervated by the autonomic nervous system.
The specific pathway to the digits of the hand would consist of
- Preganglionic cell bodies in the intermediolateral cell colum of the spinal cord (T2 & T3). These fibers leave the spinal cord via the ventral root, spinal nerve, ventral primary ramus and white ramus to enter the sympathetic trunk.
- The preganglionic fibers ascend in the sympathetic trunk to synapse with cells in the sympathetic chain ganglia (inferior cervical or stellate ganglion).
- Postganglionic fibers leave the sympathetic chain ganglia via the gray rami to join the spinal nerves that form the brachial plexus (C5-T1). These postganglionic fibers would join the median nerve and then pass as motor branches which join the radial and ulnar arteries. These fibers travel along with the arteries to their smaller branches supplying the smooth muscle in the walls of these vessels.