Pelvis Anatomy Lab 1 (PDF)

PELVIS By Brooke, Kristin, Salma, Emma, Cheyenne, Myryame ********DISCLAIMER- DR. LUTFI TAUGHT US PELVIS/PERINEUM LAST YEAR SO HIGH YIELD STUFF MAY BE A BIT DIFF...

PELVIS By Brooke, Kristin, Salma, Emma, Cheyenne, Myryame ********DISCLAIMER- DR. LUTFI TAUGHT US PELVIS/PERINEUM LAST YEAR SO HIGH YIELD STUFF MAY BE A BIT DIFFERENT -AS ALWAYS, LISTEN TO WHAT DR. JONES EMPHASIZES OR REPEATS IN CLASS  BONY LANDMARKS -Hip Joint -Acetabulum “socket” for hip joint -Femoral Head “ball” of hip joint -Greater & Lesser Trochanter -Femoral Neck -Femur Bone Bony Landmarks of the PELVIS & SACRUM PUBIS ISCHIUM ILIUM Anterior Sacral Foramen (HY): ventral rami of sacral spinal nerves Posterior Sacral Foramen (HY): dorsal rami of sacral spinal nerves Sacral Hiatus (HY): fat, filum terminale, S5, and coccygeal nerve  Pelvis + Pelvic Girdle Pelvic Girdle -Bear weight & transfer weight from axial → lower appendicular skeleton -provide attachment for muscles of locomotion of lower extremity and provide attachment of muscles and membranes of pelvis floor Pelvis: formed by bilateral hip bones + sacrum + coccyx -Hip bone → formed by fusion of ilium + ischium + pelvis → fuse at the acetabulum FUNCTION OF THE PELVIC GIRDLE -contain and protect pelvic viscera and the inferior abdominal viscera while permitting passage of the terminal perineum -provide support for the abdominopelvic viscera and gravid (pregnant) uterus -provide attachment for the erectile bodies of the external genitalia -provide attachment for the muscles and membranes  PELVIC BRIM (HY!!) PELVIC BRIM: Linea Terminalis, Superior Pelvic Aperture, Pelvic Inlet 1. Sacral promontory 2. Ala of the sacrum 3. Arcuate line 4. Pectineal line Know this image 100% → 5. Pubic crest -Inclination of the pelvic brim: 55 degrees =The pelvis slopes downward and forward. Pelvic INLET vs OUTLET (HY) -the linea terminalis delineates the pelvic inlet and provides the boundary between → The greater pelvis (major, or false), which is the portion between the iliac crests and the pelvic brim, superior to the pelvic inlet, and the lesser pelvis (minor, deep, or true) which lies inferior to the pelvic GREATER vs LESSER Pelvis GREATER vs LESSER Pelvis (HY!!) GREATER “the false pelvis”= part of the pelvis superior to the pelvic inlet bounded by the iliac alae posterolaterally and the anterosuperior aspect of the S1 vertebra posteriorly. Within this area we find the abdominal viscera (e.g., the ileum and sigmoid colon). contents= the internal iliac artery,median sacral artery, and the ovarian artery, femoral nerve LESSER “the true pelvis” = part of the pelvis between the pelvic inlet and pelvic outlet. This area is bounded by the pelvic surfaces of the hip bones, sacrum, and coccyx contents= the pelvic splanchnic nerves FEMALE PELVIS→ PUBERTY CHANGES -LOWER half of the pelvis widens to provide LARGER birth canal -this widens the hips creating an “hourglass” shape of the female form -fat tissue INCREASES in breasts, buttocks, thighs, upper arms, pubis Female Pelvis Shapes (HY!!) Android (HY): “male” pelvis yet occurs in 32.5% of white women; heavy, heart-shaped pelvis; increases incidence of forceps delivery and C-section Gynecoid (HY): female pelvis; MC (42% of F), BEST for child bearing, well rounded Anthropoid: more common in non-white women (40% vs 23%) , oval shape with AP diameter > transverse; anterior narrower than posterior; favors fetal position but adequate for vaginal delivery Platypelloid: rare ( AP diameter; widest of ALL pelvis types Female vs. Male Pelvis *HY - Know this chart!* (also very relevant for OPP)  Ligaments of the Pelvis Anterior sacroiliac ○ Thin, anterior part of the fibrous capsule of the cavity Posterior/Interosseous sacroiliac ○ Involved in transfer of weight from axial skeleton to two ilia (appendicular skeleton) Relaxin - released by corpus luteum; increases in early pregnancy & inhibits early contractions *During labor and delivery, it helps to relax pelvic bones & ligaments to help with fetal passage!* Ligaments cont… Be able to recognize and label each of the ligaments on this image!  Greater vs. Lesser Sciatic Foramen Greater Sciatic Foramen (A) Lesser Sciatic Foramen (C) Created by the sacrospinous Created by the ligament (B) sacroTUBEROUS ligament (D) Superior - anterior sacroiliac Superior - sacrospinous ligament ligament and ischial spine Posteromedial - sacrotuberous Anterior - ischial spine, lesser ligament sciatic notch and ischial Anterolateral - greater sciatic tuberosity notch of ilium Posterior - sacrotuberous Inferior - sacrospinous ligament ligament and ischial spine Joints of the Pelvis ★ Sacroiliac Joints ○ Unites axial and inferior appendicular skeleton ○ Common source of LOW BACK PAIN ★ Sacrococcygeal Joint ○ Joint of the axial skeleton ○ Secondary cartilaginous with intervertebral disc ○ Fibrocartilage and ligaments join apex of sacrum to base of coccyx ○ Anterior and posterior sacrococcygeal ligaments reinforce the joint Joints cont… ★ Public Symphasis ○ Fibrocartilaginous disc + surrounding ligaments ○ Interpubic disc = wider in women ○ Superior pubic ligament = connects superior aspect of pubic bodies and interpublic disc (extends laterally to tubercles) ○ Rounds off suprapubic angle and forms apex of pubic arch ○ Fibers from rectus abdominis and external oblique strengthen symphysis anteriorly Joints cont… ★ Lumbosacral Joints ○ Symphysis (Fibrocartilaginous) Type: Articulation of L5 to base of sacrum ○ Synovial Type: Articulation of Articular Processes (facet/zygapophyseal) ○ Subtype: Arthrodial/Gliding Joint/Planar Type: Articulation of Articular Processes Movements of the Hip/Joints of Pelvis Movements of the hip (6): Flexion Extension Abduction Adduction External Rotation Internal Rotation Pelvic Tilt Pelvic tilt = positioning of pelvis in relation to Types of pelvic tilt: the body ★ Anterior Muscle imbalance is the most common cause! ★ Posterior Pelvic tilt can cause lack of: ★ Lateral Mobility Stability *Dr. Jones included an image of Postural control pelvic external rotation, but did Motor control not specify this as a type of pelvic tilt  Posterior Pelvic Tilt Anterior Pelvic Tilt Front of pelvis tilts UP and BACK, while the bottom rotates Front of pelvis rotates FORWARD; back of pelvis rotates UP under the body Cause: Tight hip flexors Cause: Tight hamstrings, gluteal muscles, and abdominal ASIS: Anterior and inferior muscles PSIS: Anterior and superior ASIS: Posterior and superior PSIS: Posterior and inferior Lower crossed syndrome - an imbalance in tight (hip flexors) and weak (deep abdominal, pelvic and glute) muscles *Commonly seen in pregnancy Lateral Pelvic Tilt Pelvis shifts side to side - one side will be higher than the other! Cause (FYI): Unilateral lower back hypertonicity which can be caused by several muscle groups (MC Quadratus Lumborum) MUSCLES Brought to you by Moo Deng Psoas Major O = bodies and transverse processes of lumbar vertebrae I = lesser trochanter of femur (with iliacus) via iliopsoas tendon flexes the thigh F = flexes & laterally bends the lumbar vertebral column N = branches of the ventral primary rami of spinal nerves L2- L4 A = subcostal a. and lumbar a. Relationships ○ Genitofemoral nerve pierces the anterior surface of the psoas major m. Can be affected by tuberculosis of the lumbar spine ○ Femoral nerve emerges lateral to the psoas major m. ○ Obturator nerve is medial to the psoas major m. Psoas Minor F = flexes & laterally bends the lumbar vertebral column N = branches of the ventral primary ramus of spinal nerves L1-L2 A = lumbar a. Adductor Brevis + Adductor Longus F = adducts, flexes, and medially rotates the femur N = anterior division of the obturator nerve A = obturator a. and deep femoral a. Gracilis F = adducts the thigh, flexes and medially rotates the thigh, flexes the leg N = anterior division of the obturator nerve A = obturator a. Remember = the pes anserinus is the common insertion of the gracilis, sartorius, and semitendinosus muscles Gluteus Maximus F = extends the thigh; laterally rotates the femur N = inferior gluteal nerve A = superior and inferior gluteal a. Site of IM injection Gluteus Medius/Minimus F = abducts the femur; medially rotates the thigh ○ The angle at which the gluteus medius/minimus tendon approaches the greater trochanter of the femur is anterior to the axis of rotation of the thigh, resulting in medial rotation N = superior gluteal nerve A = superior gluteal a. Gemellus Inferior/Superior F = laterally rotates the femur N = nerve to the quadratus femoris m. A = inferior gluteal a. The superior and inferior gemellus muscles insert on the obturator internus tendon Quadratus Lumborum F = laterally bends the trunk, fixes the 12th rib N = subcostal nerve and ventral primary rami of spinal nerves L1- L4 A = subcostal a. and lumbar a. The lateral arcuate ligament of the diaphragm crosses the anterior surface of the quadratus lumborum Pelvic Diaphragm or Pelvic Floor Muscles Ischiococcygeus (Coccygeus) ○ N = Anterior rami of S4 and S5 Levator Ani = Iliococcygeus, Pubococcygeus, Puborectalis ○ N = Anterior ramus of S4 and branches of the pudendal nerve (roots S2, S3 and S4) F = Forms the pelvic diaphragm that supports pelvic viscera and resists increases in intra-abdominal pressure; flexes coccyx Ischiococcygeus (Coccygeus) O = Ischial spine I = Vertebrae S4-Cx2 The smallest and most posterior pelvic floor component (levator ani muscles are situated anteriorly) Levator Ani Broad sheet of muscle of three separate paired muscles ○ Pubococcygeus, puborectalis and iliococcygeus Pelvic attachments: ○ Anterior = pubic bodies of the pelvic bones ○ Laterally = thickened fascia of the obturator internus muscle, known as the tendinous arch ○ Posteriorly = ischial spines of the pelvic bones Iliococcygeus Thin muscle fibers O = Tendinous Arch (obturator internus fascia) and ischial spines I = Coccyx F = elevates the pelvic floor ○ The actual “levator” of the levator ani = the “muscle lifter” N = branches of the ventral primary rami of spinal nerves S3- S4 A = inferior gluteal a. Pubococcygeus O = Tendinous arch and body of pubic bone I = Coccyx and anococcygeal ligament The largest → the main constituent of the levator ani Main target for Kegels (exercise to strengthen your pelvic floor) Puborectalis Thick muscle O = Body of pubic bone I = Midline and rectum F = maintain fecal continence (this muscle relaxes during defecation) Most medial and massive Some fibers pass posterior to the vagina (pubovaginalis), and posterior to the prostate (puboprostaticus) Forms a U-shaped rectal sling ○ Its tonic contraction bends the canal anteriorly, creating the anorectal angle (90 degrees) at the anorectal junction (where the rectum meets the anus) Pelvic Wall Muscles Lateral Wall = Obturator Internus ○ Leaves the pelvis by passing through the lesser sciatic foramen ○ N = Nerve to obturator internus (L5, S1, S2) ○ A = obturator a. Posterosuperior Wall = Piriformis ○ Leaves the pelvis by passing through the greater sciatic foramen ○ N = Anterior/Ventral rami of S1 and S2 Both laterally rotate and abduct the thigh; assist in holding the head of the femur in acetabulum Both have distal attachments at the greater trochanter of the femur Piriformis The piriformis creates two recesses ○ Suprapiriform recess = superior gluteal neurovascular bundle ○ Infrapiriform recess = inferior gluteal neurovascular bundle, sciatic nerve, pudendal neurovascular bundle Sciatica: inflammation or spasm of the the piriformis muscle leading to sciatic nerve entrapment between the piriformis and obturator internus ○ Spinal stenosis or sacroiliac joint (hip) dysfunction may cause sciatica in older adults Levels of Support Level I ○ Uterosacral and cardinal ligaments ○ Support uterus and vaginal apex Level II ○ Lateral attachments of endopelvic fascia and vagina to arcus tendineus fascia pelvis ○ Support bladder, vagina, and rectum Level III ○ Perineal membrane and perineal body ○ Support Ureterovesical Junction (UVJ) and perineum  Pelvic Vasculature, Lymphatics & Nerve Supply  Arterial Supply Abdominal aorta → Common Iliac arteries → External Iliac a. supplies LE → Inferior epigastric a. → Deep circumflex iliac a. → Internal Iliac a. supplies pelvic organs, gluteal muscles & peritoneum  Internal Iliac Artery Branches “I Love Going Places In My Very Own Different Underwear” Posterior Trunk Anterior Trunk ○ Internal Pudendal Artery ○ Inferior Vesical Artery ○ Iliolumbar Artery ○ Obturator Artery Inferior Rectal Artery ○ Lateral Sacral Artery ○ Deferential Artery Scrotal/Labial Artery ○ Superior Gluteal ○ Vas Deferens Artery (M), Perineal Artery Artery Uterine Artery (F) Deep and Dorsal Arteries of the Penis ○ Umbilical Artery and Clitoris Superior Vesical ○ Inferior Gluteal Artery Artery ○ Middle Rectal Middle Vesical Artery (Hemorrhoidal) ○ Vaginal Artery (F), Vesicular Artery (M) (superior and inferior)  Ligation of the Internal Iliac Artery Ligation of the Internal Iliac Artery does NOT stop blood flow (but it reduces blood pressure, allowing hemostasis) because of three arterial anastomoses: ○ Lumbar (Aorta) to Iliolumbar (Internal Iliac A, Posterior Division) ○ Median Sacral (Aorta) to Lateral Sacral (Internal Iliac A, Posterior Division) ○ Superior Rectal (IMA) to Middle Rectal (Internal Iliac A, Anterior Division) Blood flow is maintained to the pelvis, gluteal region, and genital organs  Blood Supply to the Ovaries Ovaries - Arterial Supply ○ Ovarian Artery (direct branch from abdominal aorta) - Venous Drainage ○ Left ovarian vein → left renal vein ○ Right ovarian vein → IVC  Venous Return to the Pelvis Internal Iliac V. + External Iliac V. → Common Iliac V. → IVC Collateral Drainage: Vertebral Venous (Batson’s) Plexus → Superior Sagittal Sinus  Lymphatic Drainage Lymphatic Drainage of the Pelvis 3 Main groups of LNs related External and internal inguinal to the pelvis: lymph nodes - Superficial/Deep Inguinal Internal (pelvic) lymph nodes LN External and Internal iliac lymph - Common Internal/ nodes External Iliac LNs Sacral Lymph Nodes - Para-aortic/Lumbar LNs Common Iliac Lymph Nodes LN are arranged around main blood vessels Superficial Inguinal In superior fascia Horizontal Group: below & parallel to inguinal ligament - Medial Part: anterior abdominal wall, perineum, urethra, external genitalia (EXCEPT TESTES), lower ½ of anal canal - Lateral Part: iliac crest (gluteal region) Vertical Group: along great saphenous veins, drains LE Deep Inguinal In deep fascia of the thigh, medial to femoral vein Drains glans penis, clitoris, superficial LNs Both drain into External Iliac LNs  Common Iliac External and internal LN External Iliac With femoral vein Internal Iliac (Rectal) Perineum & majority of gluteal region All three drain into Para-aortic LNs & run along their respective arteries Lymph Node Drains Lumbar (Para-Aortic) Along the aorta & IVC Receive lymph from: Kidneys/suprarenal glands, ovaries/testes, uterine tubes, fundus of uterus, abdominal wall Inferior Mesenteric Superior rectum and sigmoid/descending colon Sacral Between pelvic organs & Internal Iliac LNs Pararectal Near Internal Iliac Lymph Vessels  Nerve Supply of the Pelvis = Lumbosacral Plexus Lumbar Plexus: - Anterior + Posterior Divisions of Lumbar Nerves L1, L2, L3, L4 - In 50% of people T12 nerve root contributes to lumbar plexus - Contributes to the iliohypogastric nerve - Nerves exit through intervertebral foramina → anterior & posterior branches - Posterior Branches → paravertebral muscles & skin of lumbar region - Anterior Branches → single nerves to supply pelvis  Pelvis L56-57 By Myryame Desrosiers & Cheyenne Lilienthal Pathways of Major Nerves in The Pelvis Region Structures passing through the Greater Sciatic Foramen: ○ Piriformis muscle: Above piriformis muscle: Superior gluteal nerves and vessels Below Piriformis muscle Inferior Gluteal nerves and vessels Sciatic nerve Posterior femoral cutaneous nerve Nerve to quadratus femoris muscle Nerve to obturator internus muscle* Pudendal nerve* Structures passing through the Lesser Sciatic Foramen: ○ Nerve to obturator internus muscle* ○ Pudendal nerve* Travels through the greater sciatic foramen inferior to the piriformis muscle, but then loops back around to enter the perineum through the lesser sciatic foramen, entering the pudendal canal. Pudendal Canal The pudendal canal: ○ also called Alcock's canal is an anatomical structure in the pelvis through which the internal pudendal artery, internal pudendal veins, and the pudendal nerve pass. Structure: ○ The pudendal canal is formed by the obturator internus fascia Anesthesia For Childbirth Spinal = L3 - L4 subarachnoid space ○ Everything from the waist down is anesthetized, including the lower extremities Pudendal = S2 - S4 dermatomes (sensory block) ○ lower ¼ of the vagina, and most of the perineum are anesthetized Cervix, uterus, and upper vagina are not affected. Pt is able to feel uterine contractions ○ Pudental block: episiotomy ○ Palpate ischial spine to localize nerve region! Epidural = S2-S4 nerve roots ○ Popular (for good reasons!!) Administer in advance. ○ It affects pain fibers from the uterus and upper vagina, and the afferent fibers from the pudendal. SO, birth canal + most of the perineum + pelvic floor are anesthetized. The lower extremities are spared. Caudal Anesthesia Caudal —> Tail Can be useful in the pediatric population for sub-umbilical procedures ○ inguinal hernia repair ○ urological interventions ○ anal atresia repair, and lower extremity procedures. Caudal epidural injections can also help in the management of chronic low back pain unresponsive to conservative medical management Caudal Epidural: palpation of sacral hiatus THE PERINEUM AND EXTERNAL GENITALIA The perineum (pelvic outlet): ○ area below the pelvic diaphragm, covering the pelvic outlet. In the anatomical position, it is a narrow space between the thighs. When the thighs are abducted, the perineum forms a diamond shape between the ischial tuberosities, stretching from the pubis to the coccyx. The pelvic outlet is closed by the pelvic diaphragm, covered by the perineum, and reinforced by the urogenital diaphragm. ○ Simply: the skin region between your genitals and your anus Anatomical Borders: ○ Anterior - pubic symphysis ○ Posterior - tip of the coccyx ○ Laterally - inferior pubic rami and inferior ischial rami, and the sacrotuberous ligament ○ Roof - pelvic floor ○ Base - skin and fascia Surface Borders: ○ Anterior - mons pubis in females, base of the penis in males ○ Laterally - medial surfaces of the thighs ○ Posterior - superior end of the intergluteal cleft THE PERINEUM AND EXTERNAL GENITALIA The perineum is divided into two triangles by the transverse diameter, a line connecting the ischial tuberosities: ○ Anal Triangle: Contents: Dense fat + pudendal nerve/internal pudendal vessels + inferior rectal vessels and nerve Principal structures: anal canal + the anus guarded by the external anal sphincter. ○ Urogenital Triangle: triangular area that shares the levator ani muscle ramus of S4 and branches of the pudendal nerve (roots S2, S3 and S4) Principle structures: external genitalia with their associated erectile tissues and musculature, as well as the gonads in the male. The ischio-anal fossa ○ Wedge-shaped space located on either side of the anal canal. It is filled with fat and loose connective tissue, allowing for the expansion of the anal canal during defecation. Laterally: The ischium and obturator internus muscle. Medially: The external anal sphincter and levator ani muscle. Posteriorly: The sacrotuberous ligament and gluteus maximus. Anteriorly: The pubic bones. THE PERINEUM AND EXTERNAL GENITALIA The Perineal Body: ○ midpoint of the imaginary transverse line joining the ischial tuberosities —> perineal body (central tendon). ○ This is a fibromuscular mass located in the median plane between the anal canal and thevaginal orifice in the female, and the bulb ofthe urethra in the male. ○ Provides support to the pelvic diaphragm ○ If it is damaged during natural childbirth, it could compromise the integrity of the pelvic diaphragm. To avoid that —> Perfom an episiotomy, a procedure whereby an incision lateral to the perineal body is made to increase the diameter of the vaginal canal during delivery to allow easier exit of the fetal head A cut through the perineal body, immediately posterior would cut through the external anal sphincter What nerve block could help with this procedure? Structures attached to the perineal body: ○ Superficial and deep transversus perineal muscles ○ Bulbospongiosus muscle (originates from the perineal body) ○ Levator ani muscle ○ Sphincter ani muscle ○ Superficial and deep perineal fascia ○ NOTE: The ischiocavernosus muscle does not attach to the perineal body!!  Anal Triangle Boundaries: ○ Transverse diameter of pelvic outlet, and lines b/w coccyx & ischial tuberosities ○ Floor = levator ani (superiorly) ○ Walls: Anterolaterally = obturator internus Posteriorly = sacrotuberous ligament & gluteus maximus muscle Contents: ○ Anal canal & anus ○ Ischiorectal fossa: ▪ Fat ▪ Inferior rectal vessels/nerves ▪ Posterior femoral cutaneous nerve (labia majora/scrotal sac) ▪ Sphincter ani muscle ▪ **Pudendal (Alcock’s Canal) = b/w fascia on lateral wall of ischiorectal fossa: ∙ Pudendal nerve ∙ Internal pudendal vessels ∙ Internal pudendal vessels (arteries/vessels)  Female Urogenital Triangle Boundaries: ○ Transverse diameter of pelvic outlet, and lines b/w coccyx & ischial tuberosities Contents: ○ External genitalia mons pubis labia majora labia minora ○ Perineal muscles Superficial and deep transverse perineal muscles ○ Erectile tissues clitoris  Female External Genitalia Mons pubis = rounded fatty eminence anterior to pubic symphysis (covered w/coarse hair) Labia minora = thin delicate folds, hairless skin, located b/w the labia majora o Labia majora = 2 symmetrical folds that protect the great vestibular glands o United via anterior & posterior labial commissure o Note: fourchette = membrane found in children