1. A 35-year-old male comes to your office complaining of a painful
tongue sore. He also complains that Over the last 2 weeks he has
had a fever and been experiencing myalgias and arthralgias. He
has no other medical problems. The patient works as a driver for a
local delivery service. He is homosexual and admits to having
unprotected sex with a stranger approximately 1 month ago.
Physical examination reveals a rash over his trunk and cervical
lymphadenopathy. An ulcer is located on the median sulcus of the
tongue 1 cm anterior to the foramen cecum. You decide to draw
blood to test for an HIV viral load and prescribe an oral analgesic
gel to relieve his ulcer related pain. The pain sensation from his
ulcer is most likely carried by which of the following nerves?
A. Chorda tympani
B. Glossopharyngeal nerve
C. Mandibular division of the trigeminal nerve
D. Maxillary division of the trigeminal nerve
E. Vagus nerve
Answer: C
Explanation:
Innervation of the tongue is complex, as there are motor, general
sensory and gustatory (taste) components.
1. Motor innervation of the tongue is provided by the hypoglossal nerve
(CN XII), with the exception of the palatoglossus muscle, which is
innervated by the vagus nerve (CN X).
2. General sensory innervation of the tongue (including touch, pain,
pressure, and temperature sensation) is provided by:
- Anterior 2/3 of the tongue: mandibular branch of trigeminal nerve
(CN V,)
- Posterior 1/3 of the tongue: glossopharyngeal nerve (CN IX)
- Posterior area of the tongue root: vagus nerve (CN X) 3.
3. Gustatory innervation (taste buds) is as follows:
- Anterior 2/3 of the tongue: chorda tympani branch of facial nerve
(CN VII)
, - Posterior 1/3 of the tongue: glossopharyngeal nerve (CN IX)
- Posterior area of the tongue root and taste buds of the larynx and
upper oesophagus: vagus nerve (CN X)
The terminal sulcus delineates the anterior 2/3 of the tongue from the
posterior 1/3.located along the terminal sulcus at the midline. Thus, an
ulcer 1 cm distal to the foramen cecum w ould be located on the anterior
2/3 of the tongue. Pain from this region (as well as sensations of touch,
pressure, and temperature) are transmitted by the mandibular branch of
the trigeminal nerve.
(Choice A): anterior 2/3 of the tongue but not painful stimuli.
(Choice B): The glossopharyngeal nerve transmits taste, pain,
temperature and touch stimuli from the posterior 1/3 of the tongue.
(ChoiceD): The maxillary division of the trigeminal nerve does not
participate in tongue innervation.
(Choice E) The vagus nerve innervates the far posterior area of the
tongue root, transmitting both gustatory and general sensory stimuli.
,2. A 53-year-old man comes to the emergency department because
of severe low back pain. Hisbackpain started 2 weeks ago without a
history of trauma and has been keeping him awake at night. The
pain has acutely worsened over the past 2 days and is not relieved
with over-the-counter pain medications. He takes no other
medication. He has no known drug allergies. He does not use
tobacco, alcohol, or illicit drugs. His vital signs are within normal
limits. Examination shows pain in the low back region with flexing of
the back and raising of the legs. Pinprick in the perianal area does
not cause rapid contraction of the anal sphincter. Which of the
following nerve roots is most likely to be involved in this patient's
condition?
A. T12
B. L2
C. L4
D. L5
E. S1
F. S4
Answer: F
Explanation:
, In an adult, the spinal cord terminates in a tapering fashion at the conus
medullaris at approximately the L2 vertebral level. After this point,
spinal nerves from the conus medullaris exit inferiorly through their
respective intervertebral foramina. This collection of spinal nerves (now
considered peripheral nerves) is referred to as the cauda equina (i.e.,
horse's tail). Conus medullaris syndrome refers to lesions at L2. It has
symptoms of flaccid paralysis of the bladder and rectum, impotence, and
saddle (S3-S5 roots) anaesthesia. There is usually mild weakness of the
leg muscle if the lesion spares both the lumbar cord and the adjacent
spinal and lumbar nerve roots. Common causes include disk herniation,
tumours, and spinal fractures.
In contrast, cauda equina syndrome typically results from a massive
rupture of an intervertebral disk that is capable of causing compression
of two or more of the 18 spinal nerve roots of the cauda equina.
However, it can also occur due to any trauma or space-occupying lesion
of the lower vertebral column. The cauda equina nerve roots provide the
sensory and motor innervation of most of the lower extremities, the
pelvic floor, and the sphincters.
tongue sore. He also complains that Over the last 2 weeks he has
had a fever and been experiencing myalgias and arthralgias. He
has no other medical problems. The patient works as a driver for a
local delivery service. He is homosexual and admits to having
unprotected sex with a stranger approximately 1 month ago.
Physical examination reveals a rash over his trunk and cervical
lymphadenopathy. An ulcer is located on the median sulcus of the
tongue 1 cm anterior to the foramen cecum. You decide to draw
blood to test for an HIV viral load and prescribe an oral analgesic
gel to relieve his ulcer related pain. The pain sensation from his
ulcer is most likely carried by which of the following nerves?
A. Chorda tympani
B. Glossopharyngeal nerve
C. Mandibular division of the trigeminal nerve
D. Maxillary division of the trigeminal nerve
E. Vagus nerve
Answer: C
Explanation:
Innervation of the tongue is complex, as there are motor, general
sensory and gustatory (taste) components.
1. Motor innervation of the tongue is provided by the hypoglossal nerve
(CN XII), with the exception of the palatoglossus muscle, which is
innervated by the vagus nerve (CN X).
2. General sensory innervation of the tongue (including touch, pain,
pressure, and temperature sensation) is provided by:
- Anterior 2/3 of the tongue: mandibular branch of trigeminal nerve
(CN V,)
- Posterior 1/3 of the tongue: glossopharyngeal nerve (CN IX)
- Posterior area of the tongue root: vagus nerve (CN X) 3.
3. Gustatory innervation (taste buds) is as follows:
- Anterior 2/3 of the tongue: chorda tympani branch of facial nerve
(CN VII)
, - Posterior 1/3 of the tongue: glossopharyngeal nerve (CN IX)
- Posterior area of the tongue root and taste buds of the larynx and
upper oesophagus: vagus nerve (CN X)
The terminal sulcus delineates the anterior 2/3 of the tongue from the
posterior 1/3.located along the terminal sulcus at the midline. Thus, an
ulcer 1 cm distal to the foramen cecum w ould be located on the anterior
2/3 of the tongue. Pain from this region (as well as sensations of touch,
pressure, and temperature) are transmitted by the mandibular branch of
the trigeminal nerve.
(Choice A): anterior 2/3 of the tongue but not painful stimuli.
(Choice B): The glossopharyngeal nerve transmits taste, pain,
temperature and touch stimuli from the posterior 1/3 of the tongue.
(ChoiceD): The maxillary division of the trigeminal nerve does not
participate in tongue innervation.
(Choice E) The vagus nerve innervates the far posterior area of the
tongue root, transmitting both gustatory and general sensory stimuli.
,2. A 53-year-old man comes to the emergency department because
of severe low back pain. Hisbackpain started 2 weeks ago without a
history of trauma and has been keeping him awake at night. The
pain has acutely worsened over the past 2 days and is not relieved
with over-the-counter pain medications. He takes no other
medication. He has no known drug allergies. He does not use
tobacco, alcohol, or illicit drugs. His vital signs are within normal
limits. Examination shows pain in the low back region with flexing of
the back and raising of the legs. Pinprick in the perianal area does
not cause rapid contraction of the anal sphincter. Which of the
following nerve roots is most likely to be involved in this patient's
condition?
A. T12
B. L2
C. L4
D. L5
E. S1
F. S4
Answer: F
Explanation:
, In an adult, the spinal cord terminates in a tapering fashion at the conus
medullaris at approximately the L2 vertebral level. After this point,
spinal nerves from the conus medullaris exit inferiorly through their
respective intervertebral foramina. This collection of spinal nerves (now
considered peripheral nerves) is referred to as the cauda equina (i.e.,
horse's tail). Conus medullaris syndrome refers to lesions at L2. It has
symptoms of flaccid paralysis of the bladder and rectum, impotence, and
saddle (S3-S5 roots) anaesthesia. There is usually mild weakness of the
leg muscle if the lesion spares both the lumbar cord and the adjacent
spinal and lumbar nerve roots. Common causes include disk herniation,
tumours, and spinal fractures.
In contrast, cauda equina syndrome typically results from a massive
rupture of an intervertebral disk that is capable of causing compression
of two or more of the 18 spinal nerve roots of the cauda equina.
However, it can also occur due to any trauma or space-occupying lesion
of the lower vertebral column. The cauda equina nerve roots provide the
sensory and motor innervation of most of the lower extremities, the
pelvic floor, and the sphincters.
