Trunk Wall and Inguinal Region Flashcards
The mammary gland overlies what two muscles
pectoralis major and serratus anterior
The nipple lies where
at about the 4th intercostal space
the nipple is _____ and the ____ ____ opens onto it
fissured; lactiferous duct
What allows the nipple to become erect?
circularly arranged smooth muscle
What is the pigmented area around the nipple
areola
The areola exhibits ____ and what is there purpose
small bumps or sebaceous glands; secrete oil during pregnancy to lubricate and protect while lactating
How does the appearance of the areola differ in women who have not had children vs women who have
before children it is a pinkish color, after having children it changes permanently to brown (allows the baby to see it better for breast feeding)
Does the mammary gland have capsule?
No
The mammary gland is a modified what
sweat gland
Location of the mammary gland
lies in the superficial fascia, its deep aspect separated from the underlying
musculature by deep fascia (epimysium)
What is the retromammary space?
thin area between the gland and deep fascia that contains no fat; allows free movement of the gland over the muscle
How is the mammary gland attached?
firmly attached to the overlying skin by suspensory ligaments
that extend down to the posterior mammary fascia
What happens to the lactiferous ducts during puberty?
they branch and fat is deposited around
The mammary gland is predominantly what
fat, which gives the breasts their shape
During pregnancy, the ____ ____ within the fat increase in size
secretory lobules
What are secretory lobules composed of?
milk-secreting cells arranged into groups or alveoli at the ends of the lactiferous ducts
What are alveoli of the lactiferous ducts?
groups of milk secreting cells
What is the lactiferous sinus?
a swelling just before the ducts open onto the surface of the nipple where milk is stored
When do woman start secreting milk?
after child birth
When can secrete ____ which is what?
colostrum, a creamy pre-milk fluid, may be expressed during the last trimester of pregnancy
Mammary glands innervation
lateral and cutaneous branches of intercostal nerves 2 through 6; they receive sensory and sympathetic innervation
Arterial supply of the mammary glands
- perforating br. of the internal thoracic a.
- lateral thoracic a. from the axillary a.
- lateral and anterior br. of the intercostal aa.
Venous drainage of the mammary glands
similar to arterial supply, but axillary drainage is the most important
What is the axillary tail of the mammary gland
a tail of fatty tissue that extends back into the axilla region
Why is lymphatic drainage important?
due to the frequency of carcinoma of the breast
About __% of lumphatic drainage flows via the ___ ___ to the ___ ___
75%; axillary tail; axillary nodes
The remaining __% pass toward the ___ ___ or to the ___ ___
25%; parasternal nodes; opposite breast
Where are carcinomas most frequent in the breast?
supero-lateral quadrant (upper outer quadrant)
Why are carcinomas frequent in the supero-lateral quadrant?
since 75% of lymph passes through this region
Characteristics of carcinoma in the breast
- less mobile as the breast is anchored to the deep fascia
- dimpled, orange peel appearance due to the suspensory ligaments
What are the accessory muscles of respiration
pectoralis major and minor, external oblique, and serratus anterior
How do these muscles aide in respiration?
by fixing the pectoral girdles (scapula and clavicle) so
these muscles then act on the rib cage
Muscles of the thorax proper
- serratus posterior supeior
- serratus posterior inferior
- levator costarum
- intercostals
- external
- internal
- innermost
- transversus thoracis
- subcostals
Muscles of the back of the thorax proper
serratus posterior superior and inferior, and levator costarum
Serratus posterior superior attachment
from the vertebrae to the ribs R2-R4/5
Serratus posterior superior action
elevates the upper 4 ribs to increase thoracic diameter
Serratus posterior inferior attachment
inferior 3 or 4 ribs near the angle and is direct supero-laterally
Action of serratus posterior inferior
will pull (depress) the ribs preventing the diaphragm from pulling them up
Muscles of the thoracic wall
intercostal muscles, are organized in to 3 layers
First layer of intercostal muscles
external intercostals
External intercostals attachment
extend from the posterior aspect around to the costochondral junction where they become a membrane
Membrane by the external intercostals meeting the costchondral junction
anterior intercostal membrane
how are the fibers of the external intercostals directed?
inferomedially (like putting your hands into your pockets).
What are the external intercostal fibers continuous with?
the fibers of the external oblique mm. of the anterior abdominal wall
Second layer of the muscles of the thoracic wall
internal intercostals
Internal intercostals attachment
extend from the sternum around to the angle of the ribs where they
become a membrane
The internal intercostals become what membrane
internal intercostal membrane
How are the fibers of the internal intercostals directed?
run at right angles to those in the external layer - inferoposterior in direction
What are the internal intercostal fibers continues with?
internal oblique mm. of the anterior abdominal wall
Third layer of muscles of the thoracic wall
composed of 3 muscles linked in a membrane
- transversus thoracis
- innermost intercostals
- subcostals
Transversus thoracis attachment
attach to the back of the sternum and xiphoid process
-continuous with the transversus adbominis mm. of the anterior abdominal wall
Innermost intercostals attachment
found along the mid-axillary line; similar indirection to the internal intercostals and may be considered a subset of them, separated by the intercostal neurovascular bundle
Subcostals attachment
found posteriorly near the angle of the ribs; characteristically
cross one rib before reattaching
Function of the third layer of muscles of the thoracic wall
elevate the ribs, expanding the thoracic diameter and keeping the
intercostal spaces rigid to prevent the lungs pushing the muscle outward
Innervation of the muscles of the intercostal spaces
innervated segment-ally by the anterior rami of the spinal nerves which from T1-T12 are referred to as inter- costal nerves
The intercostal nerves give rise to which nerves?
lateral and anterior cutaneous br. that supply the over-lying skin in a band-like
(dermatome) fashion
The dorsal aspect of the muscles of the intercostal spaces are innervated by
segmentally by the posterior rami of the spinal nerves
Where do the muscles of the intercostal spaces receive their arterial supply?
branches of the anterior and posterior inter-costal arteries that arise from the internal thoracic and aorta respectively
These arteries give rise to what vessels?
posterior, lateral and anterior (perforating) cutaneous br. that supply the overlying skin in a band-like fashion.
anterior and posterior intercostal arteries anastomose within the ___ ___
intercostal space
Venous drainage of the intercostal spaces through ___ ___ that drain either to ___ ___ ___ or the ___/___ system of the thorax
intercostal veins; internal thoracic veins (anteriorly); azygous/hemiazygous (posteriorly)
Muscles of the anterolateral abdominal wall
external oblique, internal oblique, transversus abdominis
External oblique location and attachment
has fibers that extend inferoanteriorly/medially, in a similar fashion to those of the external intercostal
- takes origin from the 8 lower ribs
- free posterior border that does not fuse with the lumbar fascia
How is the inguinal ligament formed?
the extensive anterior aponeurosis doubles back on itself between the anterior superior iliac spine and the pubic tubercle to form it
What is the deficiency in the lower medial aspect of the aponeurosis?
superficial ring of the inguinal canal
Internal oblique location and attachment
it is the middle layer, fibers extend supero-anteriorly similar to those of
the internal intercostal
What does the internal oblique fuse with?
lumbar fascia posteriorly
Where does the internal oblique exhibit a deficiency
in its aponeurosis in the region of the inguinal canal
Transversus abdominus location
innermost layer and it has the smallest extent
What does the transversus abdominis fuse with
fuses posteriorly with the lumbar fascia and its aponeurosis also
extends anteriorly to the mid-line to participate in the composition of the sheath of the rectus abdominis with the two overlying oblique mm
Where does the transversus abdominis exhibit a deficiency
exhibits a large deficiency in the region of the inguinal canal
Function of the anterolateral abdominal wall muscles
- provide support and protection for the trunk and abdominal viscera
- increase intra-abdominal pressure required for defaction, micturation, and childbirth
external and internal obliques rotate and flex the trunk
What is the rectus abdominis?
- a 4th muscle in the anterolateral abdominal wall muscles
- it is enclosed in a sheath formed by the aponeuroses of the other 3 sheet-like muscles
What forms the arcuate line?
at the midpoint of the rectus abdominis between the umbilicus and the pubic crest, the posterior aspect of the rectus sheath becomes deficient leaving only fascia transversalis between the posterior aspect of the rectus and the peritoneum; this forms it
What are the tendinous intersections of the rectus abdominis?
- attach to the posterior aspect of the anterior sheath
- function in flexing the trunk as well as assisting in compression of the abdominal viscera
-form the “6-pack” appearance
What are the 4 muscles of the anterolateral abdominal wall innervated by?
segmentally by the anterior (ventral) rami of the spinal (thoracoabdominal) nerves
What action results in lateral trunk flexion?
ipsilateral contraction of both external and internal oblique muscle
groups
-a bending towards the contracted side
What results in the action torso twisting?
- Contralateral (opposite side) contraction of the external oblique group on one side and the internal oblique group on the opposite side
- the rectus abdominis acts as a fixed post to aide in this movement
How are the internal oblique and contralateral external oblique connected?
across the midline by their aponeuroses and as such constitute a two-
bellied (digastric) muscle
What happens if the muscles below the arcuate line contract?
only result will be compression of the abdominal contents
What does not exist below the arcuate line?
posterior leaf of the rectus abdominis since it is not required for compression of abdominal contents
What happens in quiet inspiration?
- diaphragm contracts, moving inferiorly, thereby increasing the vertical diameter of the thoracic cavity
- muscles of the anterior abdominal wall relax
- intercostal muscles contract to elevate the ribs and increase thoracic cavity in 2 diameters (transverse and anteroposterior)
What happens in forced inspiration?
Heavy breathing resulting in maximum increase in thoracic capacity. Every muscle available to elevate rib cage is activated including the scalenus anterior, scalenus medius, and sternocleidomastoid
What happens during respiratory distress?
-scapula is fixed by the rhomboids, trapezius and levator scapulae so
that the serratus anterior and pectoralis minor can also assist in elevating the rib cage to increase thoracic capacity
-Fixing the upper limbs by bracing the arms against the back of a
chair will also allow the sternal origin of the pectoralis major to assist during respiratory distress
What happens in quiet expiration?
- largely passive process
- you have elastic recoil of the lungs
- relaxation of the intercostal muscles and diaphragm
- increased tone of anterior abdominal wall forcing the diaphragm superiorly
- serratus posterior inferior my pull the ribs inferiorly as well
What happens in forced expiration?
-active and is brought about by contraction of the anterior abdominal wall
increasing abdominal pressure and forcing the diaphragm up into the thoracic cavity
-quadratus lumborum can also be used to pull down the 12th rib
What is the inguinal ligmament?
a thickening of the lower border of the aponeurosis of the external oblique m.
Attachment of the inguinal ligament
Superolaterally to the anterior superior iliac spine of the hip bone, and inferomedially to the pubic tubercle
How is the inguinal ligament connected to the pubis?
connected to the pectineal line of the superior ramus of the pubis by the lacunar ligament
What does the testis pass through during its descent into the scrotum?
the lower part of the anterior abdominal wall
The testis passing into the scrotum in the way that it does can cause what?
herniae
How is the superficial ring formed?
- fibers of the external oblique aponeurosis split to leave a triangular gap
- intercrural fibers make this space look more ring shaped
Borders of the superficial ring
- lateral crus: passes to the pubic tubercle
- medial crus: passed to the pubic symphysis
- base: pubic crest
What passes through the superficial ring in both male and female?
- male: spermatic cord
- female: round ligament
What is the inguinal canal?
A compressed vertical slit lying above and parallel to the inguinal ligament
extending medially about 4 cm. from the deep to the superficial inguinal rings
Borders of the inguinal canal
anterior: the aponeurosis of the ext. oblique as well as some medial fibers of
the internal oblique muscle
roof: fibers of the internal oblique and transversus mm. arching over the canal passing towards their medial insertion into the conjoint tendon
posterior: same muscles that formed the roof as well as the trans-versalis fascia located behind them
floor: laterally by the curved edge of the inguinal ligament and medially by the lacunar ligament
The fibers that enter and leave the inguinal canal at the deep inguinal ring pass through the what?
trans-versalis fascia
Deep inguinal ring location
lies at about the mid region of the inguinal ligament
What four things pass through the deep inguinal ring
- inferior epigastric a.
- ductus deferens
- testicular a.
- genital branch of the genito-femoral a.
How does the inferior epigastric a. pass through the deep inguinal ring
passes on its medial aspect on its way to pass beneath the arcuate ligament and into the rectus sheath
How does the ductus deferens pass through the deep inguinal ring?
leaves the ring and crosses the inferior epigastric vessels before descending into the pelvis
How does the testicular a. pass through the deep inguinal ring
leaves the surface of the psoas major to enter the ring laterally and is accompanied by the testicular vv
How does the genitofemoral n. pass through the deep inguinal ring?
enters the ring to lie on the dorsal aspect of the spermatic cord
what structures form the spermatic cord
ductus deferens, genital branch of genitofemoral n, pampiniform plexxus of v., testicular a.
Main structures that leave the inguinal canal
-ductus deferens
-testicular a. & v.
-genital br. of genito-
femoral n.
Other structures that leave the inguinal canal?
- a. of ductus deferens
- cremasteric a.
- autonomic nn.
sheath layers encasing the contents of the inguinal canal
- internal spermatic fascia: deep, dervied from transversalis
- cremasteric fascia (continuation of cremaster muscle), dervied from aponeurosis of the internal oblique
- external spermatic fascia, aponeurosis of the external oblique
What comprises the spermatic cord?
structures of the inguinal canal and their associated wrappings, not fully formed until it passes through the superficial inguinal ring
-the cord then passes over the pubic tubercle and enters the scrotum, descending vertically to the testis
in the female the round ligament comes through the inguinal canal but terminates where
fatty tissue of the labia majora
What is the cremaster muscle and its location
incomplete muscle layer (discrete muscle bundles) derived from the internal oblique m. that spirals around the spermatic cord
The bundles of the cremator muscle are linked by what?
cremasteric fascia
Cremaster muscle innervation
genital br. of the genitofemoral nerve
Action of the cremaster muscle
On contraction it can raise the testis toward the superficial inguinal ring
What is the cremasteric reflex?
stroking the inside of the thigh will cause the testis to raise in the scrotum
What causes the cremasteric reflex?
the result of the other branch of the genitofemoral n. - the femoral branch
What is the pampiniform plexus of veins
In the region between the superficial inguinal ring and the testis, the testicular vv. form a plexus around the cord
What is the Ilioinguinal nerve
- from the lumbar plexus
- pierces the internal oblique m. to join the spermatic cord as it passes through the superficial inguinal ring
Distribution of the ilioinguinal n.
It is distributed to the skin of the external genitalia and the adjacent region of
the thigh
Where do the testis develop
on the posterior abdominal wall, behind the peritoneum, leaves abdominal cavity through the inguinal canal
What is the gubernaculum testis?
fibrous band that connects the testis to the scrotum during fetal life. guides the migration of testis by extending from the lower pole, developing scrotal swellings
what descends behind the testis into the scrotum?
-processus vaginalis
-When the testis reaches the scrotum, it invaginates the sac from behind, becoming partially ensheathed by a parietal and visceral layer of
peritoneum
what is the tunica vaginalis
the left over portion of the communication between the sac and peritoneal cavity. it encases the testis and is serous (slippery)
Failure of the developmental process to follow the normal pattern leads to:
- undescended testis
- failure of the peritoneal communication between the scrotum and peritoneal cavity to obliterate forming congenital hernias
What is an inguinal herniae
Passage of a peritoneal sac with or without abdominal contents through a congenital or acquired weakness in the abdominal wall
What are the two most common sites of an inguinal herniae
- in the inguinal region
- in the femoral canal
Two types of inguinal herniae
- congenital
- acquired
How is a congenital herniae formed?
- complete failure of the processus vaginalis to close and results in a peritoneal sac in continuity with the abdominal cavity
- does not become obvious until a portion of the small intestine is forced through it
Congenital herniaes are often called what and why?
indirect herniaes because they do not pass directly through the abdominal wall
Who are congenital herniaes most common in?
boys and young men
What is an acquired hernia?
the hernia sac entering the inguinal canal through a weakness in its posterior wall
An acquired hernia is also called what and why?
direct herniae because site of weakness is in the posterior wall, and the superficial inguinal ring are superimposed anterior/posterior
What artery can tell you the difference between a direct hernia and an indirect hernia? How?
- inferior epigastric artery
- if the pulse is found lateral to the path of the herniae it is direct, if felt medial to the herniae it is indirect
Where are inguinal hernias found in relation to the inguinal ligament?
above the inguinal ligament - in contrast to femoral herniae which penetrate the femoral canal below the inguinal ligament
Boundaries of the inguinal triangle
- lateral: (deep) inferior epigastric a.
- medial: lateral border of the rectus abdominis
- inferior: inguinal ligament
Deep inguinal ring location
located just lateral to the inferior epigastric a., where it branches off the external iliac a.
Where does the spermatic cord pass?
passes superior to the inguinal ligament
A ______ inguinal hernia passes medial to the inf. epigastric a. (pulse).
direct
An _____ inguinal hernia will pass lateral to the artery
indirect
