Transcript Q&A Review Session on Topics Back and Thorax

Review Session
Anatomy
Of Back and Thorax
A 42-year-old woman with metastatic
breast cancer is known to have tumors in
the intervertebral foramina between the
fourth and fifth cervical vertebrae and
between the fourth and fifth thoracic vertebrae. Which of the following spinal nerves
may be damaged?
(A) Fourth cervical and fourth thoracic
nerves
(B) Fifth cervical and fi fth thoracic nerves
(C) Fourth cervical and fi fth thoracic nerves
(D) Fifth cervical and fourth thoracic nerves
(E) Third cervical and fourth thoracic nerves
All cervical spinal nerves exit
through the intervertebral
foramina above the
corresponding vertebrae,
except the eighth cervical
nerves, which run inferior to
the seventh cervical vertebra.
All other spinal nerves exit the
intervertebral foramina below
the corresponding vertebrae.
Therefore, the fi fth cervical
nerve passes between the
fourth and fi fth cervical
vertebrae, and the fourth
thoracic nerve runs between
the fourth and fi fth thoracic
vertebrae.
After a 26-year-old man’s car was broadsided by
a large truck, he is brought to the emergency
department with multiple fractures of the
transverse processes of the cervical and upper
thoracic vertebrae. Which of the following
muscles might be affected?
(A) Trapezius
(B) Levator scapulae
(C) Rhomboid major
(D) Serratus posterior superior
(E) Rectus capitis posterior major
Levator scapulae
Attachment
Transverse processes of the upper 3 or 4 cervical vertebrae
Superior part of the medial border of the scapula
Dorsal Scapular Nerve(C3-4)/Artery
Rhomboids
Rhomboid major
Spinous processes of the T2 to T5 vertebrae
Medial border of the scapula
Rhomboid minor
Nuchal ligaments and spinous processes of C7–T1
Medial border of scapula
Dorsal Scapular Nerve(C5)/Artery
• The levator scapulae arise from the transverse
processes of the upper cervical vertebrae and
inserts on the medial border of the scapula.
The other muscles are attached to the spinous
processes of the vertebrae.
• 7. A 27-year-old mountain climber falls from a steep
rock wall and is brought to the emergency department.
His physical examination and computed tomography
(CT) scan reveal dislocation fracture of the upper
thoracic vertebrae. The fractured body of the T4
vertebra articulates with which of the following parts of
the ribs?
• (A) Head of the third rib
• (B) Neck of the fourth rib
• (C) Tubercle of the fourth rib
• (D) Head of the fifth rib
• (E) Tubercle of the fifth rib
• The body of the T3 vertebra articulates with the
head of the third and fourth ribs.
• The body of vertebra T4 articulates with the heads
of the fourth and fifth ribs.
The neck of a rib does not articulate with any
part of the vertebra.
The transverse process of the vertebra
articulates with the tubercle of the corresponding
rib.
Therefore, the transverse process of vertebra T4
articulates with the tubercle of the fourth rib.
• 8. A young toddler presents to her pediatrician with
rather new onset of bowel and bladder dysfunction
and loss of the lower limb function. Her mother had
not taken enough folic acid (to the point of a
deficiency) during her pregnancy. On examination, the
child has protrusion of the spinal cord and meninges
and is diagnosed with which of the following
conditions?
• (A) Spina bifida occulta
• (B) Meningocele
• (C) Meningomyelocele
• (D) Myeloschisis
• (E) Syringomyelocele
NEURAL TUBE DEFECTS
•
•
•
•
•
•
Failure of a portion of the neural tube to close, or reopening
Neural tube defects account for most CNS malformations
Causes:
Both genetic and environmental
Overall recurrence rate for a neural tube defect in subsequent
pregnancies: 4% - 5%.
Folate deficiency during the initial weeks of gestation (affect cell
division during critical periods)
• Antenatal diagnosis: is based on imaging and the
screening of maternal blood samples for elevation of αfetoprotein.
•
1.
2.
3.
4.
Types:
Encephalocele
Spina bifida
Myelomeningocele
Anencephaly
Encephalocele
• Encephalocele is a
diverticulum of
malformed CNS
tissue extending
through a defect in
the cranium.
• It most often occurs
in the occipital region
or in the posterior
fossa
Spina bifida
• A.k.a Spinal dysraphism
- severe malformation
with a flattened,
disorganized segment of
spinal cord, associated
with an overlying
meningeal outpouching
• spina bifida occulta asymptomatic bony
defect
SPINA
BIFIDA
Myelomeningocele
• a.k.a
meningomyelocele extension of CNS tissue
through a defect in the
vertebral column;
• most common
location - lumbosacral
region
Anencephaly
• Malformation of the
anterior end of the neural
tube, with absence of the
brain and calvarium
• Frog-like appearance of
baby
A 34-year-old woman crashes into a tree
during a skiing lesson and is brought to a
hospital with multiple injuries that impinge
the dorsal primary rami of several spinal
nerves. Such lesions could affect which of
the following muscles?
(A) Rhomboid major
(B) Levator scapulae
(C) Serratus posterior superior
(D) Iliocostalis
(E) Latissimus dorsi
• The dorsal primary rami of the spinal
nerves innervate the deep muscles of the
back, including the iliocostalis. The other
muscles are the superficial muscles of the
back, which are innervated by the ventral
primary rami of the spinal nerves.
Peripheral Nervous System: Spinal Nerve
Dorsal root
Dorsal root ganglion
Dorsal ramus
Dorsal rootlets
Ventral root
Ventral ramus
Ventral rootlets
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The deep back muscles are grouped into superficial, intermediate, and deep
layers according to their relationship to the surface.
Superficial Layer of Intrinsic Back Muscles
The splenius muscles are thick and flat and lie
on the lateral and posterior aspects of the
neck, covering the vertical muscles somewhat
like a bandage, which explains their name (L.
splenion = bandage).
Intermediate Layer of Intrinsic Back Muscles
The massive erector spinae is the chief
extensor of the vertebral column and is
divided into three columns: The iliocostalis
forms the lateral column, the longissimus
forms the intermediate column, and the
spinalis forms the medial column.
Each column is divided regionally into three parts according to the superior
attachments (e.g., iliocostalis lumborum, iliocostalis thoracis, and iliocostalis
cervicis).
Deep Layer of Intrinsic Back Muscles
Deep to the erector spinae is an obliquely disposed group of much shorter
muscles called the transversospinal muscle group (transversospinalis), consisting
of the semispinalis, multifidus, and rotatores.
These muscles originate from transverse processes of vertebrae and pass to
spinous processes of more superior vertebrae.
They occupy the
trench •
between
the transverse and
the spinous
processes and are
attached to these
processes, the
laminae between
them, and the
ligaments linking
them together.
Peripheral Nervous System: Somatic NS
Example: Iliocostalis
C5-L3 myotomes
C5-L3 dorsal rami
 Dorsal rami:
● motor and sensory innervation to epaxial muscles and overlying skin
● strictly segmental
 Exception:
 Greater occipital n. (C2 dorsal ramus; pure sensory)
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An elderly man at a nursing home is
known to have degenerative brain disease.
When cerebrospinal fluid (CSF) is withdrawn
by lumbar puncture for further examination,
which of the following structures is most
likely penetrated by the needle?
(A) Pia mater
(B) Filum terminale externum
(C) Posterior longitudinal ligament
(D) Ligamentum flavum
(E) Annulus fibrosus
• The cerebrospinal fluid (CSF) is located in the
subarachnoid space, between the arachnoid layer and
the pia mater. In a lumbar puncture, the needle
penetrates the skin, fascia, ligamentum flavum,
epidural space, dura mater, subdural space, and
arachnoid mater.
• The pia mater forms the internal boundary of the
subarachnoid
• space; thus, it cannot be penetrated by needle.
• The posterior longitudinal ligament lies anterior to the
spinal cord; thus, it is not penetrated by the needle.
• The filum terminale externum is the downward
prolongation of the spinal dura mater from the second
sacral vertebra to the dorsum of the coccyx.
• The annulus fibrosus consists of concentric layers of fi
brous tissue and fi brocartilage surrounding and
retaining the nucleus pulposus of the intervertebral
disk, which lies anterior to the spinal cord.
A middle-aged coal miner injures his back after
an accidental explosion. His magnetic
resonance imaging (MRI) scan reveals that his
spinal cord has shifted to the right because the
lateral extensions of the pia mater were torn.
Function of which of the following structures is
most likely impaired?
(A) Filum terminale internum
(B) Coccygeal ligament
(C) Denticulate ligament
(D) Choroid plexus
(E) Tectorial membrane
• The filum terminale (internum) is an inferior extension
of the pia mater from the tip of the conus medullaris.
• The denticulate ligament is a lateral extension of the
pia mater
• The coccygeal ligament, which is also called the fi
lum terminale externum or the filum of the dura,
extends from the tip of the dural sac to the coccyx.
• The vascular choroid plexuses produce the
cerebrospinal fluid (CSF) in the ventricles of the
brain.
• The tectorial membrane is an upward extension of
the posterior longitudinal ligaments from the body of
the axis to the basilar part of the occipital bone.
After an automobile accident, a back
muscle that forms the boundaries of the triangle of auscultation and the lumbar triangle receives no blood. Which of the following
muscles might be ischemic?
(A) Levator scapulae
(B) Rhomboid minor
(C) Latissimus dorsi
(D) Trapezius
(E) Splenius capitis
• The levator scapulae, rhomboid minor, and
splenius capitis muscles do not form
boundaries of these two triangles.
• The latissimus dorsi forms boundaries of the
auscultation and lumbar triangles and receives
blood from the thoracodorsal artery.
• The trapezius muscle forms a boundary of the
auscultation triangle but not the lumbar triangle.
• The levator scapulae, rhomboid minor, and
trapezius muscles receive blood from the
transverse cervical artery. The splenius capitis
muscle receives blood from the occipital and
transverse cervical arteries.
A 38-year-old woman with a long history
of shoulder pain is admitted to a hospital for
surgery. Which of the following muscles
becomes ischemic soon after ligation of the
superficial or ascending branch of the transverse
cervical artery?
(A) Latissimus dorsi
(B) Multifi dus
(C) Trapezius
(D) Rhomboid major
(E) Longissimus capitis
• The rhomboid major
- deep or
descending branch
of the transverse
cervical artery.
• The multifidus and
longissimus capitis
- segmental
arteries.
• The trapezius superficial branch of
the transverse
cervical artery.
• The latissimus dorsi
- thoracodorsal
artery.
A 35-year-old soldier suffers a gunshot wound on
the lower part of his back and is unable to move
his legs. A neurologic examination and
magnetic resonance imaging (MRI) scan reveal
injury of the cauda equina. Which of the
following is most likely damaged?
(A) Dorsal primary rami
(B) Ventral primary rami
(C) Dorsal roots of the thoracic spinal
nerves
(D) Ventral roots of the sacral spinal nerves
(E) Lumbar spinal nerves
• The cauda equina is the collection of dorsal and ventral
roots of the lower lumbar and sacral spinal nerves below
the spinal cord. Dorsal and ventral primary rami and dorsal
roots of the thoracic spinal nerves and lumbar spinal
nerves do not participate in the formation of the cauda
equina.
• Choose the appropriate lettered structure
in this magnetic resonance imaging (MRI)
scan of the back
• When the internal
vertebral venous
plexus is ruptured,
venous blood may
spread into which
tissue and space?
• Epidural fat is shown in the magnetic
resonance imaging (MRI) scan.
• In addition, the internal vertebral venous
plexus lies in the epidural space; thus,
venous blood from the plexus may spread
into epidural fat.
• Dorsal and
ventral roots
of the lower
lumbar and
sacral nerves
are lacerated.
Which
structure is
most likely
damaged?
• The cauda equina is formed by a great
lash of the dorsal and ventral roots of the
lumbar and sacral nerves.
• The spinal
cord is
crushed at
the level of
the upper
part of the
first lumbar
vertebra.
Which
structure is
most likely
damaged?
• The conus medullaris is a conical end of the
spinal cord and terminates at the level of the L2
vertebra or the intervertebral disk between L1
and L2 vertebrae.
• A spinal cord injury at the level of the upper part
of the first lumbar vertebra damages the conus
medullaris.
• Which
structure may
herniate
through the
annulus
fibrosus,
thereby
impinging on
the roots of
the spinal
nerve?
• The intervertebral disk lies between the bodies
of two vertebrae and consists of a central
mucoid substance, the nucleus pulposus, and a
surrounding fibrous tissue and fibrocartilage,
the annulus fibrosus.
• The nucleus pulposus may herniate through the
annulus fibrosus, thereby impinging on the
roots of the spinal nerves.
• Cerebrospinal
fl uid (CSF) is
produced by
vascular
choroid
plexuses in
the ventricles
of the brain
and
accumulated
in which
space?
• The cerebrospinal fluid (CSF) is found in the
lumbar cistern, which is a subarachnoid space
in the lumbar area. CSF is produced by
vascular choroid plexuses in the ventricles of
the brain, circulated in the subarachnoid
space, and filtered into the venous system
through the arachnoid villi and arachnoid
granulations.
A 43-year-old female patient has been
lying down on the hospital bed for more
than 4 months. Her normal, quiet expiration
is achieved by contraction of which of the
following structures?
(A) Elastic tissue in the lungs and thoracic wall
(B) Serratus posterior superior muscles
(C) Pectoralis minor muscles
(D) Serratus anterior muscles
(E) Diaphragm
• Inspiration:
Forced: the diaphragm; external, internal
(interchondral part), and innermost intercostal;
sternocleidomastoid; levator costarum; serratus
anterior; scalenus; pectoralis major and minor;
and serratus posterior superior muscles.
Quiet: results from contraction of the diaphragm
• Expiration
Forced: muscles of the anterior abdominal wall,
internal intercostal (costal part) muscles, and
serratus posterior inferior muscles.
Quiet: elastic recoil of the lungs
A 17-year-old boy was involved in a gang fight, and a
stab wound severed the white rami communicantes at
the level of his sixth thoracic vertebra. This injury
would result in degeneration of nerve cell bodies in
which of the following structures?
(A) Dorsal root ganglion and anterior horn
of the spinal cord
(B) Sympathetic chain ganglion and dorsal
root ganglion
(C) Sympathetic chain ganglion and posterior horn of the spinal cord
(D) Dorsal root ganglion and lateral horn of
the spinal cord
(E) Anterior and lateral horns of the spinal cord
Peripheral Nervous System: Visceral Sensation
Dorsal horn of spinal cord
cell
bodies
(synapse on fiber tracts to the
brain)
DRG
from body wall in spinal nerves
gray ramus
communicans
from body cavities in splanchnic nn.
white ramus communicans
Sympathetic paravertebral ganglion: bypass, no synapse!
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Rami Communicantes
White Rami Communicantes
• ■ Contain preganglionic sympathetic GVE
(myelinated) fibers with cell bodies located in the
lateral horn (intermediolateral cell column) of the
spinal cord and GVA fibers with cell bodies located
in the dorsal root ganglia
• ■ connected to spinal nerves only between T1 and L2
Gray Rami Communicantes
• ■ Contain postganglionic sympathetic GVE
(unmyelinated) fibers that supply the blood vessels,
sweat glands, and arrector pili muscles of hair follicles.
• ■ Are connected to every spinal nerve and contain
fibers with cell bodies located in the sympathetic
trunk.
• The white rami communicantes contain
preganglionic sympathetic GVE fibers and GVA
fibers whose cell bodies are located in the
lateral horn of the spinal cord and the dorsal
root ganglia.
• The sympathetic chain ganglion contains cell
bodies of the postganglionic sympathetic nerve
fibers.
• The anterior horn of the spinal cord contains
cell bodies of the GSE fi bers.
• The dorsal root ganglion contains cell bodies of
GSA and GVA fibers.
A 27-year-old cardiac patient with an irregular heartbeat
visits her doctor’s office for examination. Where
should the physician place the stethoscope to listen to
the sound of the mitral valve?
(A) Over the medial end of the second left intercostal
space
(B) Over the medial end of the second right intercostal
space
(C) In the left fourth intercostal space at the
midclavicular line
(D) In the left fifth intercostal space at the midclavicular
line
(E) Over the right half of the lower end of the body of
the sternum
• Mitral valve - the left fifth
intercostal space at the
midclavicular line.
• Pulmonary valve the
medial end of the
second left intercostal
space,
• Aortic valve is most
audible over the medial
end of the second right
intercostal space
• Tricuspid valve is most
audible over the right
half of the lower end of
the body of the sternum.
A 37-year-old patient with palpitation was
examined by her physician, and one of the
diagnostic records included a posterior–anterior
chest radiograph. Which of the following
comprises the largest portion of the
sternocostal surface of the heart seen on the
radiograph?
(A) Left atrium
(B) Right atrium
(C) Left ventricle
(D) Right ventricle
(E) Base of the heart
•The right ventricle forms a large part of the sternocostal surface of the heart.
•The left atrium occupies almost the entire posterior surface of the right
atrium.
•The right atrium occupies the right aspect of the heart. The left ventricle lies
at the back of the heart and bulges roundly to the left.
•The base of the heart is formed by the atria, which lie mainly behind the
ventricles.
The bronchogram of a 45-year-old female smoker
shows the presence of a tumor in the eparterial
bronchus. Which airway is most likely blocked?
(A) Left superior bronchus
(B) Left inferior bronchus
(C) Right superior bronchus
(D) Right middle bronchus
(E) Right inferior bronchus
The eparterial bronchus is the right superior lobar
(secondary) bronchus;
all of the other bronchi are hyparterial bronchi.
A 44-year-old man with a stab wound was
brought to the emergency department, and a
physician found that the patient was suffering
from a laceration of his right phrenic nerve.
Which of the following conditions has likely
occurred?
(A) Injury to only GSE fibers
(B) Difficulty in expiration
(C) Loss of sensation in the fibrous pericardium
and mediastinal pleura
(D) Normal function of the diaphragm
(E) Loss of sensation in the costal part of the
diaphragm
Superior Mediastinum: Phrenic nerve
 R. phrenic n. in superior
mediastinum…
● lies lateral to R. vagus n.
● descends along right side of R.
brachiocephalic v. and SVC
● is anterior to root of right lung
 L. phrenic n. in superior
mediastinum…
 lies lateral and superficial to L.
vagus n.
 descends along left side of aortic
arch
 superficial to L. superior
intercostal v.
 is anterior to root of left lung
 R. + L. phrenic nn….
▪ originate from C3-C5 spinal
cord segments
▪ carry…
somatic motor fibers (to
diaphragm)
post-ganglionic
sympathetic fibers
 sensory fibers
• The phrenic nerve supplies the pericardium and
mediastinal and diaphragmatic (central part)
pleura and the diaphragm, an important muscle
of inspiration.
• It contains general somatic efferent (GSE),
general somatic afferent (GSA), and GVE (postganglionic sympathetic) fibers.
• The costal part of the diaphragm receives GSA
fibers from the intercostal nerves.
A 75-year-old patient has been suffering
from lung cancer located near the cardiac
notch, a deep indentation on the lung. Which of
the following lobes is most likely to be excised?
(A) Superior lobe of the right lung
(B) Middle lobe of the right lung
(C) Inferior lobe of the right lung
(D) Superior lobe of the left lung
(E) Inferior lobe of the left lung
Left Lung
Superior lobe
 Smaller than right lung
 Oblique fissure…
 separates superior and inferior lobes
Oblique fissure
 Superior lobe:
 largest surface touches upper part of a-l
thoracic wall
 apex projects into cervical root
 Inferior lobe:
● costal surface touches posterior and inferior
thoracic walls
 Heart projects into medial surface
 Lingula = tongue-like extension of superior lobe on
anterior surface
Inferior lobe
Lingula
65
• The cardiac notch is a deep indentation of
the anterior border of the superior lobe of
the left lung. Therefore, the right lung is
not involved.
A thoracentesis is performed to aspirate
an abnormal accumulation of fluid in a
37-year-old patient with pleural effusion. A
needle should be inserted at the midaxillary
line between which of the following two ribs
so as to avoid puncturing the lung?
(A) Ribs 1 and 3
(B) Ribs 3 and 5
(C) Ribs 5 and 7
(D) Ribs 7 and 9
(E) Ribs 9 and 11
Pleural Cavities
Parietal pleura
Pleural cavity
Visceral pleura
 On either side of mediastinum
Rib 1
 Surround the lungs
 Borders and extensions:
● superior: extend above rib 1 into root of neck
● inferior: extend to a level just above costal
margin
● medial: mediastinum
Right lung
Mediastinum
Left lung
69
• A thoracentesis is performed for aspiration of
fluid in the pleural cavity at or posterior to the
midaxillary line one or two intercostal spaces
below the fl uid level but not below the ninth
intercostal space and, therefore, between ribs 7
and 9.
A 75-year-old woman was admitted to a
local hospital, and bronchograms and radiographs revealed a lung carcinoma in her left lung.
Which of the following structures or characteristics does the cancerous lung contain?
• (A) Horizontal fissure
• (B) Groove for superior vena cava (SVC)
• (C) Middle lobe
• (D) Lingula
• (E) Larger capacity than the right
Right Lung
Left Lung
Superior lobe
Superior lobe
Oblique fissure
Oblique fissure
Horizontal fissure
Inferior lobe
Middle lobe
Inferior lobe
72
Lingula
72
The lingula is the tongue-shaped portion of
the upper lobe of the left lung. The right
lung has a groove for the horizontal fi
ssure, superior vena cava (SVC), and
middle lobe and has a larger capacity than
the left lung.