Lower Limb and Thorax Written Examination Part III - September 1, 2000 (56 pts)
Structural Basis of Medical Practice -- Human Gross Anatomy, Radiology,
and Embryology
Note: This is an outline of items to discuss -- NOT the "Answer"
Table of Contents
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Describe the lymphatic drainage
of the breast into the venous system. (6 pts)
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Review the anatomy of the profunda femoris
artery (12 pts)
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Review the anatomy of the right
ventricle including structure, relationships, and innervation. (8 pts)
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Review the course of the left vagus nerve
and its branches in the thorax. (8 pts)
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Review the anatomy of the dorsum of the foot
and include muscles, relationships, vasculature, and innervation.
(12 pts)
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Discuss the anatomy and function of the gluteus
medius and minimus muscles. (8 pts)
1. Describe the lymphatic
drainage of the breast. (6 pts)
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Laterally, lymph drainage from the breast is into groups of axillary nodes.
Most of this drainage is into the pectoral nodes located along pectoral
branches of the thoracoacromial vessels. Pectoral nodes drain into the
apical nodes located near the apex of the axilla. On the left, the
axillary nodes give rise to the subclavian lymphatic trunk. This vessel
commonly drains into the thoracic duct and then the angle of internal jugular.
The right subclavian duct often drains directly into the venous system.
Apical nodes also have drainages into cervical and supraclavicular nodes.
Metastatic disease in these nodes is especially difficult to remove.
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The medial aspect of the breast is drained by intercostal vessels into
parasternal nodes. Parasternal and paratrachial drainages combine
to form the bronchomediastinal lymph trunks. Drainage continues into
the right lymphatic duct on the right and the thoracic duct on the left.
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The breast is also drained by subcutaneous vessels. These vessels
have a wide distribution ranging from the cervical region to the inguinal
region and crossing the midline. If the deeper lymph channels are
blocked, as may be the case with cancer, subcutaneous drainage may greatly
increase and widely disperse cancerous cells.
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axillary notes receive 75% of lymphatic drainage
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pectoral nodes - lateral border of pectoralis major
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apical nodes - beneath the clavicle
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supraclavicular nodes
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cervical nodes
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parasternal nodes
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along the internal thoracic artery
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subcutaneous lymphatics
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distribute to wide area if deep lymphatics are blocked (e.g. cancer)
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left/right differences
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right side into right (subclavian) lymph duct
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left side into thoracic duct and left subclavian v.
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Summary
Laterally, lymph drainage from the breast is into groups of axillary
nodes. Most of this drainage is into the pectoral nodes located along
pectoral branches of the thoracoacromial vessels. Pectoral nodes drain
into the apical nodes located near the apex of the axilla. On the
left, the axillary nodes give rise to the subclavian lymphatic trunk. This
vessel commonly drains into the thoracic duct and then the angle of internal
jugular. The right subclavian duct often drains directly into the
venous system. Apical nodes also have drainages into cervical and
supraclavicular nodes. Metastatic disease in these nodes is especially
difficult to remove.
The medial aspect of the breast is drained by intercostal vessels into
parasternal nodes. Parasternal and paratrachial drainages combine
to form the bronchomediastinal lymph trunks. Drainage continues into
the right lymphatic duct on the right and the thoracic duct on the left.
The breast is also drained by subcutaneous vessels. These vessels
have a wide distribution ranging from the cervical region to the inguinal
region and crossing the midline. If the deeper lymph channels are
blocked, as may be the case with cancer, subcutaneous drainage may greatly
increase and widely disperse cancerous cells.
2. Review the anatomy of the
profunda femoris artery, including its course, key relationships (especially
when the artery and/or its branches leaves one region of the thigh to enter
another), and branches. (12 pts)
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Branch of (common) femoral a. on the posterior lateral side within 2 cm
of the inquinal ligament (base of femoral triangle)
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Inferior course on the anterior surface of iliopsoas, pectineus, adductor
brevis, adductor magnus, and posterior surface of adductor longus
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Within femoral triangle profunda femoral a/v exits posteromedial deep to
super border of adductor longus and inferior to inferior border of pectineus
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Leaves femoral triangle between pectineus and adductor longus
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continues between adductor longus and adductor magnus to supply the adductor
mm
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medial femoral circumflex a. - leaves floor of femoral triangle between
pectineus and iliopsoas
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acetabular branch - anastomosis with posterior branch of obturator and
contributes to artery of ligament of head of femur
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ascending branch - anterior surface of quadratus femoris, contributes to
cruciate anastomosis
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transverse branch - anterior surface of quadratus femoris toward joint
capsule and cruciate anastomosis
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lateral femoral circumflex a.
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runs laterally across anterior surface of iliopsoas
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ascending branch - deep to sartorious between rectus femoris and tensor
fascia lata toward cruciate anastomosis
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transverse branch - leaves laterally deep to sartorius and then run between
rectus femoris and vastus intermedius and contributes to cruciate anastomosis
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descending branch - descends posterior to rectus femoris and on anterior
surface of vasti and then enters mm and contributes to genicular anastomosis
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first perforating a. - perforates the most superior aspect of adductor
magnus and/or adductor brevis and then ascends toward cruciate anastomosis
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perforating aa. - perforates the tendonus insertions of adductor magnus
and adductor brevis medial to shaft of femur
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arise from profunda femoris a. on anterior surface of adductor magnus
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supplies much of the posterior compartment including the hamstrings and
the sciatic nerve
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1st perforating contributes to cruciate anastomosis and gluteal region
3. Review the anatomy
of the right ventricle including structure, relationships, and innervation.
(8 pts)
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General comments: The right ventricle is "C" shaped relative to the
more circular left venticle. Wall thickness is about 1/3 that of
the left ventricle. This reflects differences in the distribution
of the pulmorary artery (lungs) and the aorta (entire body). The
ventrical is lined by endocardium.
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Tricuspid valve (right atrioventricular valve)
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3 cusps - anterior, posterior, and septal, prevent retrograde flow from
ventricle to atrium
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chordae tendinae - cord like structures attaching the cusps to the papillary
mm,
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papilary mm. - anterior, posterior, and septal, each papillary mm stabilizes
more than one cusp
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prevent eversion of valve cusps
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Trabeculae carnea - muscular ridges of the right ventricle
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septomarginal trabeculae - arising from the interventricular septum and
extending to anterior papillary m., carries purkinje fibers
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Interventricular septum and conduction - separates the right and left ventricles
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membranous portion - superior near pulmonary trunk
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AV node - AV bundle - right and left crus (Purkinje fibers) distribute
to ventricles
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right crus forms moderator band within septomarginal trabeculae
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Conus arteriosus (infundibulum) - smooth "neck of funnel" leading toward
the pulmonary valve
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Pulmonary valve - 3 cusps, lunules, nodules
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prevent retrograde flow from the pulmonary trunk into the right ventrical
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Vascularization
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Right coronary a., marginal a, anterior and posterior interventricular
aa,
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small cardiac v., anterior cardiac vv.
4. Review the course of the left vagus
nerve and its branches in the thorax. (8 pts)
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The left vagus nerve enters the superior aperture of the thoracic cavity
running along the lateral side of the left common carotid artery.
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Within the superior mediastinum the nerve crosses lateral to the arch of
the aorta near the level of the ligamentum arteriosum.
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The left recurrent laryngeal nerve branches at this level and circles the
aorta immediately posterior to the ligamentum arteriosum. It then ascends
along a groove between the trachea and the esophagus (tracheoesophageal
groove).
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Cardiac branches leave the vagus to contribute to the superficial and deep
cardiac plexuses and to the pulmonary plexuses.
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Inferior to the arch of the aorta, the left vagus courses inferiorly and
posteriorly and passes posterior to the root of the lung.
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Upon reaching the esophagus the vagus nerve ramifies and contributes to
the esophageal plexus of nerve fibers.
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Near the diaphragm the majority of fibers from the left vagus nerve converge
to form the anterior vagal trunk. This trunk passes through the esophageal
hiatus to enter the abdomen.
5. Review the anatomy of the dorsum
of the foot and include muscles, relationships, vasculature, and innervation.
(12 pts)
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superficial fascia - contains superficial vv and nn
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great saphenous v., short saphenous v., and dorsal venus arch
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dorsal lateral cutaneous n. of the foot (continuous with sural n.) - supplies
dorsal lateral foot
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superficial peroneal n. - supplies cutaneous sensation to dorsum of foot
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deep peroneal n. - enters superfical region at web between first and second
toes
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deep fascia - specialized thickenings
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inferior extensor retinaculum
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prevents "bowstringing" of peroneus tertius, extensor digitorum longus,
extensor hallucis longus, tibialis anterior
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inferior peroneal retinaculum
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supports peroneus longus and brevis tendons
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extensor hood (expansion)
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central cord (base middle phalanges) and lateral cords (base of distal
phalanges)
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site of attachment for plantar and dorsal interossei, lumbricals, long
and short extensor tendons
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intrinsic muscles - extend the mp and ip joints
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extensor hallucis brevis and extensor digitorum brevis
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origin from anterolateral calcaneus and deep surface of inferior extensor
retinaculum
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tendons approach long tendons from the lateral side
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dorsal interosseous mm
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bipennate taking two heads of origin from adjacent metatarsals
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adduction, flex mp, extend ip
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extrinsic muscles
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peroneus tertius - eversion
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extensor hallucis longus, extensor digitorum longus - extension at ankle,
mp, and ip joints
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tibialis anterior - ankle extension and inversion
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peroneus longus and brevis - eversion
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dorsalis pedis a. - enters dorsum between tibialis anterior and extensor
hallucis longus, deep to inferior extensor retinaculum
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lateral tarsal a. - deep to intrinsic musculature
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medial tarsal a. - deep to tendons of extensor hallucis longus and tibialis
anterior
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arcuate a. - branches near base of first metatarsal, courses lateral deep
to intrinsic and extrinsic tendons
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helps supply dorsal metatarsal aa and dorsal digital aa
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dorsal metatarsal aa. - run along dorsal (posterior) surface of dorsal
interosseous mm.
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enters plantar side by passing between heads of first dorsal interosseous
to become deep plantar arch
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deep peroneal n. - runs along lateral side of dorsalis pedis
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lateral branches to intrinsic mm
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cutaneous branch to web between 1st and 2nd toes
6. Discuss the anatomy and
function of the gluteus medius and minimus muscles, and include a review
of the vascular supply, relationships, and innervation. In addition,
explain the ramifications of a loss of these muscles with respect to walking.
(8 pts)
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Origins and Insertions - fan shaped
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gluteus medius - ala of ilium between anterior and posterior gluteal lines,
superior greater trochanter
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gluteus minimus - ala of ilium between anterior and inferior gluteal lines,
superior greater trochanter anterior to gluteus medius
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Actions
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primary - abduction of the femur (abduction of pelvic girdle for reversal
of origin/insertion during walking)
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secondary - anterior fibers provide medial rotation
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Neurovascular relations - neural supply by superior gluteal nerve
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superior gluteal n.a. leaves pelvis to enter gluteal region through the
greater sciatic foramen
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enters gluteal region superior to piriformis
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courses laterally between gluteus medius (anterior to) and minimus (posterior
to) to reach tensor fascia lata
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posterior branch of superior gluteal a. enters gluteus maximus without
superior gluteal n.
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Abductors of the hip - provide stabilization of the pelvic girdle
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gluteus minimus - ileum to superior greater trochater (deepest of gluteal
mm)
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gluteus medius - ileum to superior greater trochanter - posterior to gluteus
minimus, deep to gluteus maximus
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tensor fascia lata - anterior superior iliac spine to iliotibial tract
(lateral side of superior fibular and surrounding area)
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Disruption of gate. Paralysis of gluteus medius and minimus
causes dropping of the pelvic girdle opposite to the side of injury.
Normally, during walking, gluteus minimus and gluteus medius pull downward
on the pelvic girdle opposite to the limb in swing phase. This action
stabilizes the pelvic girdle. The gluteus minimus and medius mm are
viewed as arising from the femur (greater trochanter) and inserting upon
the ilium. This demonstrates a reversal of origin and insertion.
When gluteus medius and minimus are paralyzed the pelvis drops to the side
of swing phase. In order to restore the line of gravity, the patient
leans to the side of the injury. The resulting gate is known as Trendelenberg's
gate (gluteal waddle).
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The Structural Basis of Medical Practice
The Pennsylvania State University
©2000
College of Medicine
Email: lae2@psu.edu