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62 Cards in this Set

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boundaries of perineum
- The perineum is a diamond shaped region located inferior to the pelvic diaphragm (levator ani plus coccygeus)
- Bounded by the pubic symphysis anteriorly, the coccyx posteriorly, and the left and right ischial tuberosities laterally
division of perineum
- A line drawn between the ischial tuberosities divides the perineum into two triangles
o Anal Triangle (posterior to the line)
o Urogenital (UG) Triangle (anterior to the line)
anal triangle
posterior to line between ischila tuberosities; contains ischioanal fossae, anal canal
ischioanal (ischiorectal) fossae
o Fat filled spaces on either side of the anal canal
o Allows for dilation of the anal canal
o The lateral wall of each fossa is formed by obturator internus and the ischial tuberosity
o The medial wall of each fossa is formed by the levator ani and the anal canal
o Each fossa projects anteriorly into the UG triangle, forming an anterior recess
o The fossae communicate with one another posterior to the anal canal
anal canal
posterior to line between ischial tuberosities; begins at anorectal flexure and ends at anus; includes anal columns, anal valves, pectinate line, internal and external anal sphincter
anal columns
vertical folds in the mucosal lining
anal valves
crescent shaped folds that unite the anal columns inferiorly
pectinate line
irregular line at the level of the anal valves
superior to the pectinate line
• Anal canal is derived from the hindgut (endoderm)
• Supplied by superior rectal vessels (origin: inferior mesenteric vessels) (minor supply/drainage via the middle rectal vessels (origin: internal iliac vessels))
• Site of internal hemorrhoids
• Lymph drains to the internal iliac lymph nodes
• Parasympathetic and sympathetic innervation similar to the hindgut; sensitive to stretch but not pain/temp/touch
inferior to the pectinate line
• Anal canal is derived from ectoderm
• Supplied by inferior rectal vessels (origin: internal pudendal vessels from internal iliac)
• Site of external hemorrhoids
• Lymph drains to the superficial inguinal lymph nodes
• Somatic innervation via the inferior rectal nerve (branch of the pudendal nerve); very sensitive to pain/temp/touch
internal anal sphincter
(involuntary)
• Smooth muscle sphincter
• Thickening of the superior 2/3 of the anal canal
• Sympathetic innervation stimulates its contraction (preventing defecation)
• Parasympathetic innervation relaxes the sphincter (allowing defecation to occur)
external anal sphincter
(voluntary)
• Skeletal muscle sphincter surrounding the inferior 2/3 of the anal canal
• Somatic innervation (inferior rectal nerve) stimulates its contraction (‘potty’ training involves learning how to control this sphincter)
urogenital triangle
includes superficial perineal fascia, deep perineal fascia, perineal membrane, perineal body, external genitalia, muscles, glands
superficial perineal fascia
o Superficial fatty layer
• Continuous with Camper fascia of the abdomen
o Deep membranous layer (Colles fascia)
• Continuous with Scarpa fascia of the abdomen
• In males, also continuous with dartos fascia
deep perineal fascia
o Invests the muscles of the perineum
perineal membrane
o Facial layer that divides the UG triangle into a superficial perineal pouch and a deep perineal pouch
o Provides attachment for the erectile tissue and muscles of the UG triangle
o The urethra passes through the perineal membrane as it courses from the pelvic cavity to the perineum
o In female, the vagina also passes through the perineal membrane posterior to the urethral hiatus
superficial perineal pouch
located between the perineal membrane and the membranous layer of the superficial fascia (Colles’ fascia)
deep perineal pouch
located between the perineal membrane and the levator ani
perineal body
o Midline thickening of the posterior border of the perineal membrane
o Muscles of the pelvic floor and the perineum insert into the perineal body, so it is an important in maintaining the integrity of the pelvic floor and perineum
o Weakening of the perineal body can result in vaginal prolapse
female external genitalia
collectively known as vulva or pudendum; mons pubis, labia majora, labia minora, vestibule, clitoris, bulbs of vestibule
episiotomy
o During childbirth, the perineal body may be stretched or torn; to avoid a ragged tear, an incision (episiotomy) can be made either through the perineal body, or lateral to it to allow for passage of the baby’s head
mons pubis
- Fat and connective tissue located anterior to the pubic symphysis
- Covered with pubic hair
labia majora
• Fat filled folds containing the round ligament of the uterus
• Covered with pubic hair
• Correspond to the scrotum in males
labia minora
• Thin folds (no fat, no hair) located on either side of the midline
• The labia minora join together superior to the clitoris to form the prepuce
vestibule
• Space between the labia minora
• Contains the openings of the urethra and vagina (hymen is a mucous membrane that spans the vaginal orifice)
erectile tissues
female: clitoris (corpora cavernosa), bulbs of vestibule; male: penis
clitoris
• The root of the clitoris is formed by the crura (proximal ends of the corpora cavernosa)
• The body of the clitoris is formed by the distal ends of the corpora cavernosa
• The clitoris is supported by the suspensory ligament, an extension of the deep fascia that attaches to the pubic symphysis
corposa cavernosa of clitoris
(paired structures)
o Proximal ends attached firmly to the pubic arch, forming the crura (singular: crus) of the clitoris
o Distal ends form the body of the clitoris and its terminal expansion, the glans clitoris
bulbs of vestibule
(paired structures)
• Located on either side of the vaginal opening
• Do not contribute to the clitoris
• Correspond to the bulb of the penis (proximal part of the corpus spongiosum) in males
corpora cavernosa of penis
(paired structures)
o Proximal ends attached firmly to the pubic arch, forming the crura of the penis
o Distal ends form the posterior parts of the body of the penis
corpus spongiosum
(unpaired structure)
o Forms the bulb of the penis
o Distal end forms the anterior part of the body of the penis and its terminal expansion, the glans penis
o Encloses the penile (spongy) urethra
penis
• The root is composed ofthe crura (proximal ends of the corpora cavernosa), and the bulb of the penis (proximal part of the corpus spongiosum)
• The body is composed of the distal ends of the corpora cavernosa posteriorly and the corpus spongiosum anteriorly
• Distally the skin of the penis is loosely attached and forms the prepuce (foreskin) covering the glans
• The penis is supported by the suspensory ligament, an extension of the deep fascia that attaches to the pubic symphysis
muscles of UG triangle
ischiocavernosus, bulbospongiosus, superficial transverse perineal muscles, urogenital diaphragm (deep transverse perineal muscles, external urethral sphincter)
ischiocavernosus
(in superficial perineal pouch)
• Paired muscles covering the crura of the clitoris and penis
• Aid in erection (compress veins of the corpora cavernosa, maintaining blood within these tissues)
bulbospongiosus
(in superficial perineal pouch)
• Paired muscles associated with the bulbs of the vestibule in females and the bulb of the penis in males
• Attached to the perineal body
superficial transverse perineal muscles
(in superficial perineal pouch)
• Paired muscles attached to the ischial tuberosities laterally and the perineal body medially
• Help stabilize the perineal body
urogenital diaphragm
(in deep perineal pouch); include deep transverse perineal muscles and external urethral sphincter
deep transverse perineal muscles
• Paired muscles attached to the ischial tuberosities laterally and the perineal body medially
• Help stabilize the perineal body
external urethral sphincter
• In males, the external urethral sphincter surrounds the membranous urethra
bulbospongiosus (male vs. female)
• In males, the right and left muscles unite in the midline to surround the bulb of the penis; compress the veins in the bulb to aid in erection and expel semen (during ejaculation) or residual urine
• In females, right and left muscles do not unite in the midline
glands of the UG triangle
o Greater vestibular (Bartholin) glands in the female
• Located just posterior to the bulbs of the vestibule
• Ducts open into the vagina and secrete mucus
• Infection and formation of cysts common
o Bulbourethral (Cowper) glands in the male
• Located just lateral to the external urethral sphincter
• Ducts empty into the penile urethra and contribute to the semen
membranous urethra
• Shortest part of the urethra (which has prostatic, membranous, and penile parts)
• Thin walls can be ruptured (e.g., when inserting catheters)
nerves of the perineum
pudendal nerve (S2-S4); branches into inferior rectal nerves, perineal nerves, dorsal nerve of penis or clitoris
pudendal nerve
(S2-S4)
o Leaves the pelvic cavity through the greater sciatic foramen, inferior to piriformis, courses around the ischial spine, and enters the perineum through the lesser sciatic foramen
o After passing through the lesser sciatic foramen, the pudendal nerve enters the pudendal (Alcock) canal on the lateral wall of the ischioanal fossa
pudendal nerve block
can be performed to anesthetize the perineum; the needle is directed towards the ischial spine
inferior rectal nerves
• branch of pudendal nerve
• Course medially across the ischioanal fossa
• Innervate the external anal sphincter and the skin of the anal triangle
perineal nerves
Innervate the muscles and skin of the UG triangle
dorsal nerve of penis or clitoris
Innervates skin of the penis/clitoris, particularly the glans
internal pudendal artery
o Primary source of blood to the perineum
o Branch of the internal iliac artery
o Accompanies the pudendal nerve (leaves the pelvis through the greater sciatic foramen, inferior to piriformis, courses around the ischial spine, passes through the lesser sciatic foramen and enters the pudendal canal)
branches of pudendal artery
• Inferior rectal artery
• Perineal arteries
• Dorsal artery of the penis or clitoris
• Deep artery of the penis or clitoris
veins of perineum
accompany the arteries and share the same names
o Exceptions: superficial and deep dorsal veins of the penis
lymphatic drainage of perineum
o Deep perineal tissues > lymphatic vessels accompany the internal pudendal vessels and drain into internal iliac nodes
o Superficial perineal tissues > lymphatic vessels drain to the superficial inguinal nodes
o Remember: lymph from the testes drains to the lumbar nodes (alongside the abdominal aorta)
divisions of the lower extremity
- The lower extremity includes the gluteal region and all structures inferior to it
- Divisions of the lower extremity:
o Gluteal region
o Thigh (hip to knee)
o Popliteal fossa (posterior aspect of knee)
o Leg (knee to ankle)
o Foot (dorsal and plantar aspects)
bones of the lower extremity
- Bones of the lower extremity: hip bones (see Pelvis I notes), femur, patella, tibia (medial bone of leg), fibula (lateral bone of leg), 7 tarsals (calcaneus, talus, navicular, cuboid, medial, intermediate, and lateral cuneiforms), 5 metatarsals (proximal part is the base, distal part is the head), 14 phalanges (proximal, middle, distal; the hallux (big toe) has a proximal and distal phalanx only)
femur
o Head
o Neck
o Shaft (body) with linea aspera (on posterior surface)
o Medial and lateral femoral condyles (distal)
tibia
o Medial and lateral tibial condyles (proximal)
o Shaft (body)
o Medial malleolus is the distal protuberance on medial side of the ankle
fibula
o Head (proximal protuberance)
o Shaft (body)
o Lateral malleolus is the distal protuberance on lateral side of the ankle
hip joint
o Acetabulum of the hip bone articulates with the femoral head
o Ball and socket synovial joint
o Flexion reduces the angle between the thigh and trunk anteriorly
o Extension increases the angle between the thigh and trunk anteriorly
o Abduction draws the thigh away from the midline of the body
o Adduction draws the thigh towards the midline of the body
o Medial rotation femur rotates medially along its long axis
o Lateral rotation femur rotates laterally along it long axis
knee joint
o Femoral condyles articulate with the tibial condyles
o Hinge synovial joint
o Flexion brings the leg closer to the posterior aspect of the thigh
o Extension draws the leg away from the posterior aspect of the thigh
ankle (talocrural) joint
o Talus articulates with distal tibia and lateral malleolus of the fibula
o Hinge synovial joint
o Dorsiflexion brings the foot closer to the anterior aspect of the leg (directs toes superiorly)
o Plantarflexion draws the foot away from the anterior aspect of the leg (directs toes inferiorly)
subtalar joint
o Synovial joint between the talus and the calcaneus
o Eversion causes the sole to face laterally
o Inversion causes the sole to face medially
metatarsophalangeal (MTP) joints
o Synovial joints between the metatarsals and the proximal phalanges
o Flexion of toes (towards the ground)
o Extension of toes (away from the ground)
o Abduction (movement away from the second digit)
o Adduction (movement towards the second digit)