Lower limb and pelvic cavity Flashcards
What makes up the bony pelvis?
The bony pelvis consists of the two hip bones (also known as innominate or pelvic bones), the sacrum and the coccyx.
What are the articulations with the bony pelvis?
Sacroiliac joints (x2) – between the ilium of the hip bones, and the sacrum
Sacrococcygeal symphysis – between the sacrum and the coccyx.
Pubic symphysis – between the pubis bodies of the two hip bones.
What are the roles of the pelvis?
Transfer of weight from the upper axial skeleton to the lower appendicular components of the skeleton, especially during movement.
Provides attachment for a number of muscles and ligaments used in locomotion.
Contains and protects the abdominopelvic and pelvic viscera.
What are the greater and lesser pelvis?
Greater pelvis (false pelvis) – located superiorly, it provides support of the lower abdominal viscera (such as a ileum and sigmoid colon). It has little obstetric relevance. Lesser pelvis (true pelvis) – located inferiorly. Within the lesser pelvis reside the pelvic cavity and pelvic viscera.
What is the pelvic inlet and the pelvic rim?
The junction between the greater and lesser pelvis is known as the pelvic inlet. The outer bony edges of the pelvic inlet are called the pelvic brim.
The pelvic inlet marks the boundary between the greater pelvis and lesser pelvis. Its size is defined by its edge, the pelvic brim.
What are the borders of the pelvic inlet?
Posterior – sacral promontory (the superior portion of the sacrum) and sacral wings (ala).
Lateral – arcuate line on the inner surface of the ilium, and the pectineal line on the superior pubic ramus.
Anterior – pubic symphysis.
What determines the dynamics of the birth canal?
The pelvic inlet determines the size and shape of the birth canal, with the prominent ridges key areas of muscle and ligament attachment.
What is the linea terminalis?
The combined pectineal line, arcuate line and sacral promontory.
What is the Iliopectineal line?
The combined arcuate and pectineal lines. This represents the lateral border of the pelvic inlet.
What are the borders of the pelvic outlet?
Posterior: The tip of the coccyx
Lateral: The ischial tuberosities and the inferior margin of the sacrotuberous ligament
Anterior: The pubic arch (the inferior border of the ischiopubic rami).
What is the sub pubic angle?
The angle beneath the pubic arch is known as the sub-pubic angle and is of a greater size in women.
What are the characteristic features of a female pelvis?
A wider and broader structure yet it is lighter in weight
An oval-shaped inlet compared with the heart-shaped android pelvis.
Less prominent ischial spines, allowing for a greater bispinous diameter
A greater angled sub-pubic arch, more than 80-90 degrees.
A sacrum which is shorter, more curved and with a less pronounced sacral promontory.
How can the female pelvic extend during child birth?
In addition to the bony adaptations, the sacrotuberous and sacrospinous ligaments can stretch under the influence of progesterone and increase the size of the outlet further.
What are the roles of the bladder?
Temporary storage of urine – the bladder is a hollow organ with distensible walls. It has a folded internal lining (known as rugae), which allows it to accommodate up to 300-400ml of urine in healthy adults.
Assists in the expulsion of urine – the musculature of the bladder contracts during micturition, with concomitant relaxation of the sphincters.
What is the appearance of the bladder?
The appearance of the bladder varies depending on the amount of urine stored. When full, it exhibits an oval shape, and when empty it is flattened by the overlying bowel.
What are the external features of the bladder?
Apex – located superiorly, pointing towards the pubic symphysis. It is connected to the umbilicus by the median umbilical ligament (a remnant of the urachus).
Body – main part of the bladder, located between the apex and the fundus
Fundus (or base) – located posteriorly. It is triangular-shaped, with the tip of the triangle pointing backwards.
Neck – formed by the convergence of the fundus and the two inferolateral surfaces. It is continuous with the urethra.
How does urine enter and exit the bladder?
Urine enters the bladder through the left and right ureters, and exits via the urethra.
What is the trigone of the bladder?
A triangular area located within the fundus of the bladder.
In contrast to the rest of the internal bladder, the trigone has smooth walls (this is explained by the different embryological origin: the trigone is developed by the integration of two mesonephric ducts at the base of the bladder).
What is the rugae of the bladder?
When the bladder is empty, the mucosa has numerous folds called rugae. The rugae and transitional epithelium allow the bladder to expand as it fills.
What is the submucosa of the bladder?
The second layer in the walls is the submucosa, which supports the mucous membrane. It is composed of connective tissue with elastic fibers.
What is the detrusor muscle?
In order to contract during micturition, the bladder wall contains specialised smooth muscle – known as detrusor muscle. Its fibres are orientated in multiple directions, thus retaining structural integrity when stretched. It receives innervation from both the sympathetic and parasympathetic nervous systems.
What happens when the detrusor muscle becomes hypertrophic?
The fibers of the detrusor muscle often become hypertrophic (presenting as prominent trabeculae) in order to compensate for increased workload of the bladder emptying. This is very common in conditions that obstruct the urine outflow such as benign prostatic hyperplasia.
What are the two sphincters in the urethra?
Internal urethral sphincter:
Male – consists of circular smooth fibres, which are under autonomic control. It is thought to prevent seminal regurgitation during ejaculation.
Females – thought to be a functional sphincter (i.e. no sphincteric muscle present). It is formed by the anatomy of the bladder neck and proximal urethra.
External urethral sphincter – has the same structure in both sexes. It is skeletal muscle, and under voluntary control. However, in males the external sphincteric mechanism is more complex, as it correlates with fibers of the rectourethralis muscle and the levator ani muscle.
What is the arterial supply of the bladder?
Arterial supply is via the superior vesical branch of the internal iliac artery. In males, this is supplemented by the inferior vesical artery, and in females by the vaginal arteries. In both sexes, the obturator and inferior gluteal arteries may also contribute small branches.
What is the venous drainage of the bladder?
Venous drainage is achieved by the vesical venous plexus, which empties into the internal iliac veins. The vesical plexus in males is in continuity at the retropubic space with the prostate venous plexus (plexus of Santorini), which also receives blood from the dorsal vein of the penis.
What is the nervous supply of the bladder?
Sympathetic – hypogastric nerve (T12 – L2). It causes relaxation of the detrusor muscle, promoting urine retention.
Parasympathetic – pelvic nerve (S2-S4). Increased signals from this nerve causes contraction of the detrusor muscle, stimulating micturition.
Somatic – pudendal nerve (S2-4). It innervates the external urethral sphincter, providing voluntary control over micturition.
Sensory (afferent) nerves - found in the bladder wall and signal the need to urinate when the bladder becomes full to the brain.
What is the bladder stretch reflex?
The bladder stretch reflex is a primitive spinal reflex, in which micturition is stimulated in response to stretch of the bladder wall. It is analogous to a muscle spinal reflex, such as the patella reflex.
What happens when toddlers are potty trained?
During toilet training in infants, this spinal reflex is overridden by the higher centres of the brain, to give voluntary control over micturition.
What is the reflex arc of micturition?
Bladder fills with urine, and the bladder walls stretch. Sensory nerves detect stretch and transmit this information to the spinal cord.
Interneurons within the spinal cord relay the signal to the parasympathetic efferents (the pelvic nerve).
The pelvic nerve acts to contract the detrusor muscle, and stimulate micturition.
How can the bladder stretch reflex be damaged?
Spinal injuries (where the descending inhibition cannot reach the bladder), and in neurodegenerative diseases (where the brain is unable to generate inhibition).
What is the Interureteric bar?
A useful landmark during examination of the inside of the bladder using a telescope (cystoscopy), the two ureters can be seen discharging urine at either end of the bar.
What is benign prostatic hypertrophy?
The prostate gland completely encircles the urethra. With progressing age enlargement of the prostatic tissue (hypertrophy) is common and may lead to complete blockage of the urethra and the inability to pass any urine. This requires emergency catheterisation.
Where can prostatic cancer metastase to?
Venous drainage from the prostate passes into a plexus of veins which lie anterior to the sacrum and communicate with veins which run up to the azygos vein in the chest. These veins communicate with veins in the vertebral bodies.
The veins do not have valves so can flow in either direction. During inspiration the negative pressure in the chest sucks blood up the veins but during expiration gravity pulls it back down again. Tumour cells travel up the veins and then pass down into the vertebral bodies where they may attach and cause a metastasis.
What are the effects of a loss of brain control in micturition?
Loss of brain control: bladder fills, spinal cord knows that the bladder is full but this does not reach the brain. Spinal cord asks brain permission to empty, brain does not reply so spinal cord controls a complete normal emptying of the bladder. The patient suddenly and unexpectedly passes urine with no control, there is low pressure in the bladder so no risk of renal failure.
What are the effects of a loss of sensation in micturition?
Loss of sensation: spinal cord and brain cannot know that the bladder is full so do not tell it to empty. Bladder fills up and the patient continually dribbles urine with high pressure in the bladder and kidney which rapidly progresses to kidney damage. Patient has no awareness of the full bladder.
What are the effects of a loss of the spinal motor control in micturition?
Loss of the spinal cord motor control: patient knows that the bladder is full but cannot empty it. High pressure in the bladder and renal failure.
What is a rectal prostate examination?
Prostatic disease is very common and palpation (feeling) the prostate is useful. As the prostate lies immediately anterior to the rectum examination through the anal canal is possible.
What are the major features of the uterus?
The pear-shaped uterus is a hollow muscular organ about 8cm long.
It communicates laterally with the uterine tubes and inferiorly with the vagina. For description, the uterus is divided into the fundus (above the uterine tubes), the body and the cervix.
What is the angle of the uterus?
The body of the uterus is typically bent forwards: ante-flexed and lies on the superior surface of the bladder. The junction between the body and the cervix may be tilted forwards (ante-verted) or backwards (retro-verted).
What is the internal and external os?
The cervix has a narrow lumen, the cervical canal which communicates with the uterine cavity via the internal os and with the vagina via the external os.
What are layers of the uterus?
Peritoneum – a double layered membrane, continuous with the abdominal peritoneum.
Myometrium – thick smooth muscle layer. Cells of this layer undergo hypertrophy and hyperplasia during pregnancy in preparation to expel the fetus at birth.
Endometrium – inner mucous membrane lining the uterus. It can be further subdivided into 2 parts:
- Deep stratum basalis: Changes little throughout the menstrual cycle and is not shed at menstruation.
- Superficial stratum functionalis: Proliferates in response to oestrogens, and becomes secretory in response to progesterone. It is shed during menstruation and regenerates from cells in the stratum basalis layer.
What are the vaginal fornices?
The lower part of the cervix lies inside the vagina creating spaces, the vaginal fornices around the edge of the cervix.
How is cervix held in place?
The position of the cervix is stabilised by tone of the levator ani muscle and by condensations of pelvic fascia, the cardinal ligaments. The cardinal ligaments run from the lateral wall of the cervix to the lateral pelvic sidewall at the base of the broad ligament.
What are the ligaments in the female reproductive system?
Broad Ligament: double layer of peritoneum attaching the sides of the uterus to the pelvis. It acts as a mesentery for the uterus and contributes to maintaining it in position.
Round Ligament: A remnant of the gubernaculum extending from the uterine horns to the labia majora via the inguinal canal. It functions to maintain the anteverted position of the uterus.
Ovarian Ligament: Joins the ovaries to the uterus.
Cardinal Ligament: Located at the base of the broad ligament, the cardinal ligament extends from the cervix to the lateral pelvic walls. It contains the uterine artery and vein in addition to providing support to the uterus.
Uterosacral Ligament: Extends from the cervix to the sacrum. It provides support to the uterus.
What is the arterial supply and venous drainage of the uterus?
The blood supply to the uterus is via the uterine artery. Venous drainage is via a plexus in the broad ligament that drains into the uterine veins.
What is the lymphatic drainage of the uterus?
Lymphatic drainage of the uterus is via the iliac, sacral, aortic and inguinal lymph nodes.
What is the nervous supply of the uterus?
Sympathetic nerve fibres of the uterus arise from the uterovaginal plexus. This largely comprises the anterior and intermediate parts of the inferior hypogastric plexus.
Parasympathetic fibres of the uterus are derived from the pelvic splanchnic nerves (S2-S4).
The cervix is largely innervated by the inferior nerve fibres of the uterovaginal plexus.
The afferent fibres mostly ascend through the inferior hypogastric plexus to enter the spinal cord via T10-T12 and L1 nerve fibres.
What are the uterine tubes?
The paired uterine tubes (or fallopian tubes, oviducts, salpinx) are about 10cm long and are found running in the upper border of the broad ligament. Near the uterus the tubes have a narrow isthmus.
What is the role of the uterine tubes?
The main function of the uterine tubes is to assist in the transfer and transport of the ovum from the ovary, to the uterus.
What is the structure of the uterine tubes?
Laterally the tubes have a dilated ampulla, leading into a funnel-shaped infundibulum. The free edge of the funnel is broken up into finger-like projections, the fimbriae, which are draped over the ovary. In this region the uterine tubes open into the peritoneal cavity at the ostium.
What is the lymphatic drainage of the uterine tubes?
Lymphatic drainage is via the iliac, sacral and aortic lymph nodes.
What is the innervation of the uterine tubes?
The uterine tubes receive both sympathetic and parasympathetic innervation via nerve fibres from the ovarian and uterine (pelvic) plexuses. Sensory afferent fibres run from T11- L1.
