Anatomy K-Coop: 2003 Exam 1 Explained
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Hi first years! Good luck on your first exam, I know you’ll do well. A great group of 2nd
years went over the first exam from last year and explained the answers. Every person
had their own style for answering the questions so the explanations and information may
differ from section to section. Anything in italics is part of the explanation.
Tanya Bailey
bail0238@umn.edu
Writers
Angie Voight
Tate Gisslen
Paul Luikart
Krista Wilhelmson
Zubaid Rafique
questions 1-10 and cutaneous innervation of the hand (a-e)
questions 11-22 and vertebral short answer (a-e)
questions 23-34 and matching #1
questions 35-44 and cross section of thigh (a-e)
questions 45-54 and matching #2
______________________________________________________________________
Examination 1: Extremities & Back
Fall 2003
______________________________________________________________________
MULTIPLE CHOICE and SHORT ANSWER: For the following multiple choice
questions select the single best response for each of the following. Record your
answer on the bubble sheet. There are also diagrams to be labeled. An answer sheet
for the diagrams is found on the last page of the exam. Write your answers on the
answer sheet page, as legibly as possible, and they will be graded by hand. Notice
that the multiple choice questions are vignettes that continue for two or more
questions. A short set of asterisks (****) will separate one vignette from the next. All
multiple choice questions are worth 1 point.
David Harleyson was riding his scooter home from his anatomy lab when he hit a curb in
his parking lot and crashed. Flying from the scooter he landed on his head and shoulder.
Although he had a ‘hurt bad’ feeling, he was able to get to his apartment. After much
pain removing his shirt, he could not see any difference between his injured and his
uninjured shoulders. However, when he pushed down on his acromion, the pain was
intense.
1. What ligament did David most likely stretch or tear in this accident?
A.
the coracoclavicular If this ligament tore, the shoulder would fall away
from the clavicle (Moore & Dalley pg 787).
B.
the acromioclavicular The AC joint is weak and easily injured by a direct
blow (Moore & Dalley 787).
C.
the coracoacromial The coracoacromial arch is so strong that the humeral
body or clavicle would fracture first (Moore & Dalley 790).
D.
the costoclavicular This is located between the first rib and the clavicle,
not near the acromion where the pain is (Moore & Dalley 784).
E.
none of the above
Anatomy K-Coop: 2003 Exam 1 Explained
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The next morning David noticed some numbness on the lateral aspect of his forearm.
Fearing his injury may be worse than he thought, he went to the doctor. The doctor,
suspecting a brachial plexus injury, noticed weakness in David’s ability to flex at the
elbow joint.
2. Given these symptoms, what nerve has definitely been compromised in the accident.
(See Moore & Dalley pages 710-711 for the distribution of each nerve)
A.
the radial nerve
B.
the ulnar nerve
C.
the musculocutaneous nerve It innervates the brachialis, which flexes the
forearm. It becomes cutaneous in the lateral forearm.
D.
the medial pectoral nerve
E.
the median nerve
Never missing an opportunity to teach a student the value of anatomical knowledge as it
relates to physical exam, she quizzes another student who was observing her exam of
David on the cutaneous innervation of the forearm and hand. Supposing you were this
student, name the cord of the brachial plexus which supplies the innervations to the
regions of the forearm and hand labeled in the following figure of the palmar surface
from Netter’s atlas.
Cutaneous Innervation of Hand (Netter
plates 413 and 455)
A. ________lateral_______
B. ________medial_______
C. ________posterior_____
D. ___lateral and medial__
E. ________medial_______
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3. What kind of an injury does the physician suspect has occurred as a result of David’s
fall?
A.
an injury to the ventral rami forming the upper brachial plexus
Injuries to superior parts of the brachial plexus (C5 and C6) usually result
from an excessive increase in the angle between the neck and the shoulder
(Moore & Dalley 716).
B.
an injury to the ventral rami forming the lower brachial plexus
4. Given that the physicians suspicions are correct, and given David’s symptoms of
lateral forearm numbness and weakness in the flexor compartment of the arm, which of
the following muscles do you also suspect will be weakened as a result of the injury?
A.
pectoralis minor Innervated by the medial pectoral nerve.
B.
dorsal interosseous muscles of the hand Innervated by the ulnar nerve
(from C8 and T1)
C.
infraspinatus muscle Innervated by the suprascapular nerve (from C5
and C6)
D.
serratus posterior superior Innervated by the 2nd-5th intercostals nerves
******
A young woman presented to her physician with a mass in the cubital fossa. It had been
getting larger over the last month and the woman became worried when she began to
sense tingling and numbness in her finger tips, especially when she flexed her forearm at
the elbow.
The contents of the cubital fossa, from medial to lateral, include the Median nerve, the
brachial Artery, the Tendon of biceps brachii, and the Radial nerve. (MATR)
5. Remembering her anatomy, the physician knew exactly which of her fingers would be
tingling and numb. Which ones? (Netter plate 455)
A.
index and middle fingers Innervated by the median nerve, which
supplies cutaneous innervation to the thumb, index finger, middle finger,
and half of the ring finger.
B.
little finger and part of the ring finger Innervated be the ulnar nerve,
which is not in the cubital fossa.
Realizing that the mass would have to be removed, the patient was prepped for surgery.
In planning her approach, the physician used the tendon of the biceps brachii as a
landmark.
6. On which side of the biceps tendon was the nerve located that was being impinged by
the mass.
A.
medial side Medial │MATR │ Lateral
B.
lateral side
In an effort to control the bleeding that might occur when the mass was cut free, the
physician isolated the brachial artery in the cubital fossa.
Anatomy K-Coop: 2003 Exam 1 Explained
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7. On which side of the nerve (being impinged by the mass) was the brachial artery most
likely to be found?
A.
medial side
B.
lateral side Medial │MATR │ Lateral
8. Did the surgeon incise the bicipital aponeurosis to gain access to the mass?
A.
yes The bicipital aponeurosis is a triangular membranous band that runs
from the biceps tendon across the cubital fossa and merges with the
antebrachial fascia covering the flexor muscles in the medial side of the
forearm. (Netter plate 463, Moore and Dalley pg 721)
B.
no
****
A (very naughty) little boy fell while running down the hall with scissors in his hand. The
scissors stabbed him in the lateral side of the thorax, went entirely through the skin and
were prevented from puncturing a lung by hitting a rib. The wound bled rather profusely,
but the wound did not appear to be life threatening. The bleeding was controlled by
pressure on the lateral side of the thorax.
9. What artery was likely responsible for the bleeding?
(See Moore and Dalley 702-703, Netter plates 410, 412, 417).
A.
long thoracic artery
B.
lateral thoracic artery It descends along the lateral border of the
pectoralis minor and onto the thoracic wall.
C.
thoracodorsal artery To latissimus dorsi muscle.
D.
an intercostals artery In the intercostals spaces.
Several days after the accident, you notice a transient protrusion over the scapular region
of the boy’s back whenever he pushes with his arms against something. Remembering
your anatomy, you realize that he has also injured a nerve when he was stabbed by the
scissors.
This injury is to the serratus anterior muscle and is known as a winged scapula (Moore
and Dalley 689).
10. What nerve did he injure? (See Moore and Dalley 691)
A.
thoracodorsal nerve Innervates latissimus dorsi muscle.
B.
lower subscapular nerve Innervates teres major and subscapularis.
C.
long thoracic nerve Innervates serratus anterior (Netter plate 412).
D.
a lateral intercostal nerve Innervates the skin of the thoracic and
abdominal walls (Moore and Dalley 85).
E.
lateral thoracic nerve
Anatomy K-Coop: 2003 Exam 1 Explained
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****
A medical student in her Ob/Gyn roatation is trying to stay quietly in the background
when suddenly several patients on the floor go into labor simultaneously. Needing all the
help she can get, the attending physician hands the student a needle and instructs her to
administer an epidural block to one of the patients. After a few minutes of composed
panic, the student remembers the opening for administering an epidural.
11. This opening would be the…
A.
ventral sacral foramina - exits for ventral rami of sacral spinal cord
located on ventral surface of sacrum
B.
posterior sacral foramina - exits for dorsal rami of sacral spinal cord,
located lateral to median sacral crest
C.
sacral hiatus - Epidural anesthesia is injected through the sacral hiatus,
located between the sacral cornua and inferior to the median sacral crest
(used as landmarks), and filled with fatty connective tissue. Anesthesia
rises through the sacral canal and acts on S2 through Coccyx spinal
nerves of the cauda equina causing sensation loss inferior to the block.
(Netter plate 150, Moore&Dalley p. 444-445, 484)
D.
none of the above are correct
12. As the student inserts the needle, she is careful not to put it in too far so as to avoid…
A.
puncturing the lumbar cistern- The lumbar cistern is the enlargement of
the subarachnoid space within the dural sac, caudal to the medullary
cone, (L2-S2) containing the cauda equina. A needle inserted to far will
puncture the dural sac and cause excessive anesthesia. (Moore&Dalley
482, 484)
B.
damaging the cauda equina- The cauda equina is located within the
lumbar cistern, but not damaged by needle insertion (see lumbar puncture
M&D 482)
C.
injecting an intervertebral disk in this area- Intervertebral disks stop at L5
and are anterior to the spinal cord (not reachable or damageable from the
sacral hiatus).
D.
injecting the terminal end of the spinal cord- The terminal end of the
spinal cord is at L1-L2, the medullary cone
E.
damaging the delicate denticulate ligaments- denticulate ligaments
suspends the spinal cord at the most inferior between T12 and L1 nerve
roots, quite far from the entrance of the sacral hiatus.
****
After teaching anatomy all day every day for a couple of weeks, one of your anatomy
instructors began having pain in his hip area. The pain seemed to get more intense during
the day but was better in the morning. One day, while helping students turn a rather large
cadaver, he felt a distinct snap followed by a sharp pain shooting down his leg.
Anatomy K-Coop: 2003 Exam 1 Explained
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13. What most likely caused the ‘snap’?
A.
rupture of a lumbar lamina-bone connecting pedicle to spinous process,
less likely to ‘rupture’.
B.
rupture of a lumbar intervertebral disk- i.e. Herniation of nucleus
pulposus-usually occur due to hyperflexion and in adults where discs are
weakened. Usually posterolateral due to thinner part of annulus fibrosus
causing herniation into cauda equina and explaining pain felt in leg.
(Moore&Dalley 451)
C.
rupture of a lumbar vertebral body- bone of vertebra held apart by discs,
less likely to ‘rupture’
14. What structure was impinged upon to cause his leg pain?
A.
B.
a ventral ramus contributing to the sciatic nerve-ventral rami are
adjacent to the spinal cord due to discs being located ventral to the cord.
a dorsal ramus contributing to the sciatic nerve
Several months later, this anatomy professor decides to undergo a surgical repair of his
lower back. You are observing the orthopedic surgeon doing the procedure. When the
surgeon discovers you have taken anatomy, she begins to quiz you on the vertebral
anatomy in the region.
15. She shows you the following picture and asks you which is a lumbar vertebra? (A, B,
or C)
A-Lumbar vertebra heave a large vertebral body, a thick spinous process, a medially
facing superior articular process, thin transverse process and a vertebral foramen larger
than that of a thoracic vertebra (Netter 147-148)
She also asks you to identify the features of the vertebra labeled ‘B’. (Netter 147)
A. vertebral body
B. pedicle
C. transverse costal facet
D. transverse process
E. spinous process
Anatomy K-Coop: 2003 Exam 1 Explained
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In addition to the injury to lumbar vertebra, this anatomy professor also has a pronounced
stoop and an abnormal increase in the anteroposterior dimension of the thorax.
16. What is this type of shape in the spine called?
A.
scoliosis- abnormal lateral curvature accompanied with rotation of
vertebrae
B.
lordosis- (hollow back, sway back) anterior rotation of pelvis producing
abnormal lumbar curvature; vertebral column curves anteriorly
C.
kyphosis- (humpback, hunchback) characterized by abnormal increase in
thoracic curvature resulting from anterior deterioration of anterior part of
one or more vertebra (Moore&Dalley 434)
D.
pronounced secondary curvature defect- cervical and lumbar curvatures
that begin to appear during the fetal period but are not obvious until
infancy; caused mainly by differences in thickness between anterior and
posterior parts of IV disks
E.
spina bifida- lamina of L5 and/or S1 fail to develop and fuse
*****
A water skier coming toward the dock at the end of a great run decides to come in a little
faster than normal in order to spray his onlookers with his ski. Unfortunately, he
miscalculates his distance from the dock versus the speed of his approach and crashes
into one of the dock support beams. He takes a direct hit on his tibial tuberosity,
displacing his tibia posteriorly relative to the femur. This is a bad injury for sure.
17. Which of his cruciate ligaments was certainly torn in this accident?
A.
anterior cruciate ligament- Slack when knee is flexed and taut when it is
fully extended, preventing posterior displacement of temur on tibia and
hyperflexion.
Anatomy K-Coop: 2003 Exam 1 Explained
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B.
posterior cruciate ligament- tightened during flexion, prevents anterior
displacement of the femur on the tibia and hyperflexion of the knee; often
torn during head-on collisions without seatbelts (Moore&Dalley620-626)
Being the only person on the dock with any anatomical experience, you decide to have a
look at the injury before the EMTs arrive. In addition to the displaced proximal tibia, you
notice that the skier’s leg and foot are turning blue relative to his other leg. You suspect
that an artery has been torn or pinched in the accident.
18. Which artery is likely to be directly injured?
A.
the femoral artery-main artery of the anterior thigh, enters adductor
hiatus
B.
the popliteal artery-emerges from adductor hiatus in popliteal fossa,
posterior to knee. (Netter 498-500)
C.
the posterior tibial artery- continuation of popliteal artery, deep to soleus
muscle, inferior of knee joint
D.
the peroneal artery- branch of posterior tibial inferior of knee
19. Why is it that an injury like this can cause a complete lack of blood flow to the leg?
A.
there is no arterial anastomosis around the knee joint- for knee
anastamosis see Netter 494
B.
the anastomotic network around the knee joint cannot accommodate
an acute occlusion of the primary artery across the knee- Popliteal
artery is main blood supply for ant. tibial, post. tibial, and peroneal
arteries (Netter 494)
C.
all of the anastomotic arteries around the knee were probably also
blocked in this injury- unlikely, too many to be blocked, several go around
the joint
****
A very accomplished snow skier is cruising down the slopes when she loses control on a
turn. The skier goes airborne off of the turn and hits a tree, with her knee fully flexed,
directly on the distal end of the femur. An X-ray at the hospital confirms your suspicion
that the femoral neck has been broken. The physician in charge is worried about loss of
blood supply to the skier’s hip, since the supply is easily compromised in such an injury.
20. What vessel is the primary source of blood to the head and neck of the femur?
A.
the obturator artery- supplies head of femur through ligament of head of
femur
B.
the medial circumflex artery- See Tony Weinhaus’ notes “between
iliopsoas tendon and pectineus muscle before going posterior to femur,
supplies blood to head and neck of femur” (Netter 486, 494)
C.
the lateral circumflex artery- anterior to femur, some blood to neck
D.
the inferior gluteal artery- supplies muscles of gluteal region
E.
the internal pudendal artery- goes to perineum with pudendal nerve
Anatomy K-Coop: 2003 Exam 1 Explained
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One artery gives rise to a branch that supplies only the head of the femur. If this artery is
injured, the head of the femur may die for a lack of blood supply (aseptic vascular
necrosis).
21. Which artery supplies a branch only to the head of the femur?
A.
the obturator artery- See Tony Weinhaus’ notes “branch of obturator
passes through the ligament of the head of the femur to supply the head of
the femur” (Netter 486)
B.
the medial circumflex artery- see explanations for Q 20
C.
the lateral circumflex artery- see explanations for Q 20
D.
the inferior gluteal artery- see explanations for Q 20
E.
the internal pudendal artery- see explanations for Q 20
Although accidents like the one described above do happen, fractures and dislocations of
the hip are relatively uncommon. This is because the hip joint is very stable and there are
many muscles that pass from the pelvis to the femur that stabilize the joint. Many of these
muscles are lateral rotators of the hip that attach to the greater trochanter.
22. Which of the following muscles attaches to the greater trochanter of the femur but
does not laterally rotate the hip?
A.
gluteus maximus- inserts 1/3 gluteal tuberosity of posterior femur and 2/3
iliotibial tract
B.
gluteus medius- inserts on greater trochanter, abduct thigh and stablize
pelvis (Netter 472-473)
C.
obturator internus- inserts on greater trochanter, laterally rotates thigh
D.
obturator externus- inserts on trochanteric fossa, laterally rotates thigh
E.
piriformis- inserts on greater trochanter, laterally rotates thigh
A third year medical student in her surgery rotation is shadowing a vascular surgeon. One
afternoon the surgeon is called for a consult on a patient who has just undergone an
angioplasty via the femoral artery (PTCA). The patient’s hemoglobin level is dropping
and the interventional cardiologist who did the procedure is suspicious of a femoral artery
bleed. The vascular surgeon concurs and they decide to do a femoral cut-down to expose
the vessel, find the source of the bleeding and close it. The surgeon feels for the femoral
pulse and cuts down over the vessel. The surgeon is acutely aware that the femoral nerve
must not be damaged and asks the third year student if she remembers where the nerve is
located.
23. On which side of the femoral artery is the femoral nerve located?
A.
medial
B.
lateral- For the femoral sheath from lateral to medial think NAVL (nerve,
artery, vein, lymph)
24. Is the femoral nerve found within the femoral sheath?
A.
yes
B.
no- For the femoral sheath the nerve is not in it, the rest of NAVL are.
Anatomy K-Coop: 2003 Exam 1 Explained
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Having cut into the femoral sheath and isolated the femoral artery, the surgeon quickly
finds and repairs the bleed. She notices that the femoral artery was bleeding adjacent to
what looked like the medial circumflex artery. This is unusual since the medial
circumflex is usually a branch of the deep femoral. However, the surgeon was convince
that this branch was the medial circumflex because of the course of this artery.
25. The medial circumflex artery passes…
A.
between the pectineus and adductor longus muscles
B.
between the pectineus and the iliopsoas muscles- This is a landmark to
know, see Netter plate 470 for more info.
C.
between the adductor longus and brevis muscles
D.
superficial to pectineus and adductor longus
As the surgeon was observing the medial circumflex artery, she noticed what appeared to
be a protrusion of small bowel (intestine). She knew immediately that the patient had a
femoral hernia.
26. Through what space does a femoral hernia pass into the femoral triangle?
A.
medial to the femoral sheath
B.
through the femoral canal
C.
through the inguinal canal
Femoral hernia, so C is wrong, between the other two, this is just a fact to know. The
occur through the femoral ring and into the the femoral canal. Femoral hernias happen
most often in the ladies.
****
Knowing that you are taking the Gross Anatomy course, your neighbor runs to your yard
from across the street to ask you an anatomy question. She said that while giving golf
lessons to her son, he accidentally struck her in the leg with a 7-iron. She then points to a
bruise located two inches inferior to the head of her fibula on the lateral side of her leg.
27. When the 7-iron hit her leg, which cutaneous nerve transmitted the pain of the
impact?
A.
tibial nerve
B.
posterior cutaneous nerve of the thigh
C.
deep peroneal nerve
D.
superficial peroneal nerve
E.
lateral sural nerve-Check out plate 520 and 522 for a picture of the
cutaneous nerve supply of the legs.
She knows that she cannot seem to extend her foot at the ankle. Upon performing a pinprick test, you find out that she has no sensitivity between her first two toes.
Anatomy K-Coop: 2003 Exam 1 Explained
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28. Which nerve are you certain that she has injured?
A.
tibial nerve
B.
common peroneal nerve
C.
deep peroneal nerve - The pin prick test in that place shows that it is the
deep peroneal nerve (plate 524).
D.
superficial peroneal nerve
E.
sural nerve
Upon determining that in addition to her other symptoms, she also has no sensitivity over
most of the rest of the dorsum of her foot.
29. Which nerve would you tell her that she has damaged?
A.
tibial nerve
B.
saphenous nerve
C.
deep peroneal nerve
D.
superficial peroneal nerve - Again, look at plate 524 to see the cutaneous
innervation of the dorsal foot.
E.
sural nerve
30. Innvervation to which of the following muscles to you suspect is also affected?
A.
dorsal interosseous muscle
B.
lumbricals
C.
plantaris
D.
short head of biceps femoris
E.
none of the above
Ok, A is wrong because that is innervated by the lateral plantar branch off the tibial
nerve, B is wrong because that innervation is from the medial and lateral plantar
branches of the tibial nerve. C is from the tibial nerve. D is from the peroneal nerve, but
you need to remember where the neighbor was hit was below this muscle. Since none of
these are right E is correct.
****
Driving home from the Minnesota State Fair, a couple of fair-goers were in a one-car
accident. The driver of the car was struck violently with the steering wheel just at the
level of the superior pubic ramus. The attending physician tells you that this person has
received a crushing injury to the femoral nerve just after it emerged from the pelvis. What
do you expect the functional deficits to be in an injury of this sort?
31. Do you expect the patient to be able to extend at the knee joint?
A.
yes
B.
no - Femoral nerve does knee extension
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32. Do you expect the patient to be able to flex at the hip joint?
A.
yes- That no good rascal the iliopsoas flexes the hip joint via lumbar
nerves.
B.
no
33. Do you expect the adductor compartment to be significantly affected?
A.
yes
B.
no - That is innervated by the obturator nerve so wouldn’t be affected
34. What area of sensory innervation do you expect will be completely normal?
A.
skin over the anterior thigh
B.
skin over the lateral leg -This skin is innervated by the peroneal nerves
branches. Since this isn’t part of the femoral nerve and comes out of the
greater sciatic foramen it isn’t affected.
C.
skin over the medial leg
MATCHING (#1).
There are certain bony structures and location sin the body that serve as insertion points
for multiple muscles. This tends to make these structures clinically, as well as
anatomically, important. For the following structures, list the muscles that are attached in
the spaces provided. In some cases there are actually more muscles attached than there
are spaces. Just give three for credit. RECORD YOUR ANSWERS IN THE SPACE
PROVIDED ON THE LEFT AND THIS SECTION WILL BE GRADED BY HAND.
This question is worth a total of 4 points (you must have three correct muscles for each to
get credit).
coracoid process of scapula:
coracobrachialis
biceps brachii short head
pectoralis major
See Netter plate 409.
greater tubercle of humerus:
supraspinatus
infraspinatus
teres minor
See Netter plate 404
pes anserinus on medial aspect of tibia:
Sartorius,
gracilis
semitendonosus
See Netter plate 472.
This is a common question.
Anatomy K-Coop: 2003 Exam 1 Explained
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calcaneus bone of the foot:
soleus
gastrocnemius
plantaris
flexor digitorum brevis
abductor digiti minimi
abductor hallucis
quadratus plantae
See Netter plate 497, 515, and 516
The passenger in the car has just finished his last Pronto Pup and was holding the stick in
his hand. At impact, the stick was thrust into his upper anterior thigh. The cross section of
the injury is shown in the next figure. The stick punctured the deep femoral artery,
accounting for the profuse bleeding in the area and continued into his medial thigh. Name
the three muscles (labeled a, b, and c) that were pierced by the Pronto Pup stick.
A. __Sartorius____________
B ___Pectineus___________
C. __Adductor Brevis______
OK, kids, go to Netter plate 487 and memorize it. Memorize the cross-sections for the
arm as well. First get an understanding of the compartments of the legs (ie hamstrings
on the back) and then go from there. For these questions, first determine if you are
looking at the arm of the leg (I know this sounds basic, but people panic). Then
determine if you’re proximal or distal. A good knowledge of where muscles attach and
insert will also help you here.
Anatomy K-Coop: 2003 Exam 1 Explained
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MATCHING (#2). In anatomy, we often identify one structure in light of another
structure that is usually found close to it, or in some constant relationship to it.. So,
for each of the following structures, select the letter of the structure from the list in
the right hand column that is BEST associated with, is represented by, or serves as a
definitive landmark for, the structure listed or described in the left hand column.
Use an answer only once. RECORD YOUR ANSWERS IN THE SPACE
PROVIDED ON THE LEFT AND THIS SECTION WILL BE GRADED BY
HAND. This question is worth a total of 5 points.
__L____ pudendal nerve
__D___ ulnar nerve
__H___ piriformis muscle
__K___ musculocutaneous nerve
__G___ axillary nerve
__F___ deltoid branch of
thoracoacromial artery
__A___ scaphoid bone
__B___ deep branch of radial nerve
__C___ medial pectoral nerve
__I___ radial nerve
A.
B.
C.
D.
E.
F.
G.
H.
I.
J.
K.
L.
anatomical snuff box
supinator muscle
pectoralis minor
medial humeral epicondyle
lateral humeral epicondyle
cephalic vein
quadrangular space
gluteal arteries
triangular interval
pronator muscle
coracobrachialis muscle
sacrospinus ligament
.
=============================================================
EMBRYOLOGY
=============================================================
For the following multiple choice Embryology questions, select the single best
response for each of the following. Record your answer on the bubble sheet.
35. Cells that give rise to the gametes originate within:
A.
the primary ectoderm (epiblast) - Remember, cells of the epiblast
undergo gastrulation to form the 3 primary germ layers. Key fact:
Everything that becomes a baby comes from the epiblast.
B.
the primary endoderm (hypoblast)
C.
the extraembryonic mesoderm
D.
Heuser’s membrane
E.
none of the above
36. When does a primary oocyte complete its first meiotic division?
A.
at ovulation
B.
after the ovulatory surge of FSH and LH- OK… so know this: Oogonia
(46, 2N) enter meiosis I and replicate to form primary oocytes (remember
that there’s two stages of meiosis). A woman has all her primary oocytes
by her 5th month of development. The oocytes finish meiosis I at the
ovulatory surge of hormones to become secondary oocytes. Ovulation
occurs when the secondary oocytes’ chromosomes align at metaphase of
meiosis II. Meiosis II is not finished until fertilization.
Anatomy K-Coop: 2003 Exam 1 Explained
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C.
D.
E.
at fertilization
at 5 months of fetal life
before birth
37. Which of the following is true regarding gametogenesis?
A.
male gametogenesis is discontinuous and results in 4 equal gametes
B.
the male gamete is fully mature after the process of spermiation
C.
the secondary oocyte arrests at the second meiotic metaphase - See the
explanation for 36. With boys, at puberty, dormant primordial germ cells
differentiate into type A spermatogonia which then undergo mitosis (not
meiosis) to form more type As and also type B spermatogonia. Type B
undergo meiosis to form a continuous supply of sperm. Meiosis never
stops, it is ongoing, unlike in the female cycle. A is wrong because male
gametogenesis is continuous. B is wrong because the sperm needs to
undergo capacitation as well. D is wrong because the primary oocyte
does not have a polar body, the secondary oocyte does.
D.
prior to puberty the primary oocyte and the first polar body are dormant at
the first meiotic prophase
E.
none of the above
38. Heuser’s membrane is formed from the:
A.
epiblast
B.
hypoblast - OK, so I couldn’t find Heuser’s membrane in any of my
USMLE review books, so how important can it be… Remember that
epiblast = baby and Heuser’s membrane is not part of the baby.
** Heuser’s membrane = exocoelemic membrane and is derived from
hypoblast which was initially formed from the inner cell mass or
“embryoblast”
C.
epiblast and hypoblast
D.
embryoblast
E.
cytotrophoblast
39. A complete hydatidiform mole:
A.
causes Prader-Villi carcinoma
B.
has a triploid karyotype
C.
produces high levels of Human Chorionic Gonadotropin (hCG) - In a
hydatitiform mole, something happens to the blastocyst and the embryo
dies, but the trophoblast proliferates like mad. The clinical signs include
preeclampsia in the first trimester, elevated HCG, and an enlarged uterus
with bleeding. A is wrong because this disorder doesn’t exist. PraderVilli is a genetic abnormality. B and D are simply incorrect for this
disorder.
D.
suggests that the paternal complement is responsible for the
early development of the embryo
E.
all of the above
Anatomy K-Coop: 2003 Exam 1 Explained
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40. Human Chorionic Gonadotropin (hCG):
A.
is produced by the cytotrophoblast
B.
enters the maternal blood circulation - This is true… hCG is the basis of
pregnancy testing (using blood). A is wrong because it is produced by the
syncytiotrophoblast. C is wrong because it stimulates the production of
progesterone. D is wrong for the same reason A is wrong.
C.
stimulates the production of estrogen
D.
is produced by the developing gonads
E.
A, B, and C
41. Metabolites and gasses travel from the mother to the developing embryo through the
layers of the uteroplacental circulatory system in this order:
A.
synctiotrophoblast, trophoblastic lacuna, cytotrophoblast, extraembryonic
mesoderm, chorionic blood vessels
B.
trophoblastic lacuna, cytotrophoblast, syncytiotrophoblast, extraembryonic
mesoderm, chorionic blood vessels
C.
chorionic blood vessels, extraembryonic mesoderm, syncytiotrophoblast,
cytotrophoblast, trophoblastic lacuna
D.
trophoblastic lacuna, syncytiotrophoblast, cytotrophoblast,
extraembryonic mesoderm, chorionic blood vessels - This question will
be on the test. Memorize the answer… I have no good suggestions.
E.
chorionic blood vessels, extraembryonic mesoderm, trophoblastic lacuna,
synctiotrophoblast, cytotrophoblast
42. The chorionic membrane consists of:
A.
epiblast, cytotrophoblast, and syncytiotrophoblast
B.
hypoblast, cytotrophoblast, and syncytiotrophoblast
C.
extraembryonic mesoderm, cytotrophoblast, and syncytiotrophoblast
- The chorionic membrane is part of what becomes the placenta. A is wrong
because the epiblast becomes the baby. B is wrong because the Hypoblast
becomes the yolk sac, not the placenta. D is wrong because the Heuser’s
membrane comes from the hypoblast which will develop into the yolk sac
D.
Heuser’s membrane, extraembryonic mesoderm, and cytotrophoblast
43. The process of gastrulation causes:
A.
the formation f the primary ectoderm (epiblast)
B.
the formation of the extraembryonic mesoderm
C.
the formation of the definitive endoderm - Gastrulation is the process
through which the epiblast differentiates into the 3 germ layers. A is
wrong because it is the epiblast itself that is undergoing gastrulation. B is
wrong because gastrulation forms the layers that will become the baby,
not extraembryonic layers.
D.
B and C
E.
A, B, and C
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44. The layers of the trilamina germ disc are formed from the:
A.
epiblast - Again, if you know anything, know this: the epiblast undergoes
gastrulation to form the three primary germ layers. Epiblast = baby. Enough
said
B.
hypoblast
C.
epiblast and hypoblast
D.
embryoblast and hypoblast
E.
cytotrophoblast
45. Which statement best describes the development of the neural tube?
A. it develops directly from the primitive streak.
B. it develops directly from the notochord.
C. it develops from the ectoderm immediately dorsal to the notochord.
D. it develops from the ectoderm immediately dorsal to the primitive streak.
E. none of the above.
A. incorrect; the primitive streak forms at the beginning of gastrulation during which the
three germ layers – ectoderm, mesoderm and endoderm – form, and then it disappears.
Neurolation occurs after gastrulation; this is when the neural tube forms. So the neural
tube cannot directly form from the primitive streak. B. incorrect; the notochord induces
the formation of the neural tube. The neural tube forms from the invagination of the
ectoderm. C. correct; the notochord induces the ectoderm right above it to invaginate
and form the neural tube. D. incorrect; the primitive streak regresses caudally by the end
of gastrulation, and by day 26 it completely disappears.
46. Which of the following statements regarding neural crest cells are correct?
A. cranial neural crest cells can give rise to cartilage and bone, but spinal (trunk)
neural crest cells do not.
B. cardiac neural crest cells give rise to the truncoconal septum of the heart.
C. in humans, cranial neural crest cells begin to migrate prior to neural tube closure.
D. all of the above.
A)correct: cranial neural crest gives rise to i)dermal bones of skull ii)truncoconal septum
iii)pharyngeal arch cartilages iv)odontoblasts v)some cranial nerve ganglia, while spinal
neural crest produces i)preaortic ganglia, ii)adrenal medulla and iii)dorsal root ganglia
and chain ganglia. Together (spinal and cranial) they also produce glial cells, schwann
cells, enteric ganglia and melanocytes. B) correct; critical components of the
truncoconal septum are derived from the cardiac neural crest cells. Both the quail-chick
chimera and the cell tracing experiments support this. C. correct; the cephalic neural
crest cells associated with the developing brain begin to detach and migrate before
closure of the cranial neuropore (opening of the neural tube), even while the neural folds
are still widely open. In the spinal cord portion of the neural tube, the neural crest cells
detach as the lateral lips of the tube fuse. Some neural crest cells at the caudal end of the
neural tube are produced even after the caudal neuropore closes on day 26. Thus,
detachment and migration of the neural crest cells occur in a craniocaudal wave, from
Anatomy K-Coop: 2003 Exam 1 Explained
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the mesencephalon to the caudal end of the spinal neural tube. (pg89 Human
Embryology, 3rd Ed.)
47. The muscles of the limbs are derived from:
A. neural crest mesenchyme
B. splanchnopleuric mesoderm
C. intermediate plate mesoderm
D. paraxial mesoderm
E. somatopleuric mesoderm
A. incorrect; see question 46 for what neural crest cells do. B. incorrect;
splanchnopleuric mesoderm (from lateral plate meso) forms the mesothelial covering of
visceral organs C)incorrect; intermediate plate mesoderm forms urinary and genital
systems. D) correct; paraxial mesoderm forms the axial skeleton, voluntary musculature,
etc. E)incorrect.
48. During weeks 6 to 8, the lower limb will rotate
A. laterally 180 degrees
B. medially 90 degrees
C. medially 180 degrees
D. laterally 90 degrees
The upper limbs rotate laterally 90 degrees, whereas the lower limbs rotate medially 90
degrees; they both rotate 90 degrees.
49. Which of the answers below correctly describe the number of cervical sclerotomes,
vertebrae, and spinal nerves, respectively?
A. 8, 8, and 8
B. 8, 7, and 8
C. 7, 7, and 7
D. 8, 8, and 7
E. 7, 8, and 7
Memorize this. See fig 4-3, pg 83 in Human Embryology, 3rd Edition, for how it works
out.
50. The dorsal muscle mass (derived from the myotome) in the lower limb forms what
type of muscles?
A. extensors and abductors
B. extensors and supinators
C. flexors and pronators
D. flexors and adductors
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First, dorsal mass gives rise to extensors while ventral mass gives rise to flexors in both
upper and lower limbs. Second, remember your legs turned 90 degrees medially during
weeks 6 through 8. So before it turned, your toes were pointing in opposite directions
(rotate 90 degrees laterally to get to the position) and your heels were together. Now
your quads (extensors) and abductors are somewhat backwards (pointing lateral and
posterior) – aligned with the dorsal muscle mass!
51. Sclerotomes give rise to the
A. vertebral arches
B. vertebral bodies
C. costal processes
D. A and B only
E. A, B, and C
Sclerotomes give rise to vertebral arches, vertebral bodies, base of the skull, costal
processes and ultimately ribs (in thoracic region).
52. The femur bone develops from which of the following?
A. somite mesoderm
B. somatopleuric mesoderm
C. intermediate mesoderm
D. splanchnopleuric mesoderm
E. sclerotome mesoderm
A) incorrect; forms limb musculature. B)correct; gives rise to bones, tendons, ligaments
and vasculature of limbs. C)incorrect; forms urinary system. D)incorrect; forms
mesothelial covering of the visceral organs. E) I don’t know what this is…I don’t think it
exists.
53. The carpal bones
A. ossify before birth via endochondral ossification
B. ossify before birth via mainly membranous ossification
C. ossify after birth via mainly membranous ossification
D. ossify after birth via endochondral ossification
All bones of both the upper and lower limbs undergo endochondral ossification. Smaller
carpel and tarsal bones ossify after birth. Intramembranous ossification occurs in the
frontal and parietal bones of the cranium. The clavicle, however, undergoes both
membranous and endochondral ossification.
54. Thalidomide
A. disrupts limb development between 20 and 25 weeks.
B. disrupts cell adhesion and angiogenesis in the developing limb.
C. disrupts apoptosis in the necrotic zones of the developing limb.
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D. A and B
E. A and C
Thalidomide exerts its effects only when taken during the sensitive period of limb
morphogenesis, between about 4 and 8 weeks. It is thought to desrupt cell adhesion in the
limb by downregulating cell surface adhesion receptors (integrins and selectin) or by
inhibiting angiogenesis.