Saturday, January 28, 2012

How to write references in your thesis or paper? (Citing and Referencing)


Citing and referencing






All of our work (as papers or texts) is based on others work, the ones with previous expertise in the field because their work is established and evidence based.
Therefore we have to acknowledge our sources to validate our work and avoid plagiarism (Using ideas, plots, text and other intellectual property developed by someone else while claiming it is your original work). 








we can acknowledge our sources by 2 steps:

1-Citation: mentioning the source in the text (in brief).

2- Referencing: mentioning the source in details in reference list (Bibliography) at end of the text. 


when not to cite?
when the information copied is a common knowledge (not the case in most of our texts).


Sources (Publications)
sources (publications) used as reference may be:
  1. Book
  2. Book chapter
  3. Journal article
  4. Web site
Referencing styles


Many styles can be used for referencing
styles of referencing can be classified into:
  1. Author-date styles: used in medicine and others e.g, Harvard style 
  2. Numbering styles: used in medicine and others e.g, Vancouver style
  3. Footnote styles: used in arts and law

The most used are, the harvard style and  Vancouver style.


Harvard style of referencing
Harvard is an author-date style of referencing widely used in academic publications (thesis and essays).

Harvard style consists of:
  • citations in the text, using author name and year.
  • a reference list at the end of your text (full details).
Citation in In Harvard referencing style
different situations include:

Single author: name (only family name) and year are mentioned
Example:
Prevalence increases with age, and renal cysts can be found in more than 50% of patients older than 50 years (Kissane, 1976 ).

Single author with 2 publications in different years: no problem here
 Example:
Tricyclic antidepressants, such as imipramine and amitriptyline, have been shown to be clinically effective in reducing the level of detrusor overactivity under specific conditions (Wein, 1998).
Consistent with my philosophy and prior attempts to make the understanding, evaluation, and management of voiding dysfunction as logical and simple as possible, a functional and practical approach is favored (Wein, 2002).

Single author with 2 publications in same year: will be named a, b, c, .........
Example:
However, more recent data suggest that this information applies primarily to the more common conventional and chromophilic variants of RCC, whereas most other histologic subtypes of RCC appear to be derived from the more distal elements of the nephron ( Pantuck, 2001a).
RCC is primarily a disease of the elderly patient, with typical presentation in the sixth and seventh decades of life ( Pantuck, 2001b).

2 Authors: both mentioned with and inbetween then the year mentioned as usual.
 Example:
Several radiographic modalities are currently available for detection and evaluation of renal masses, each with relative strengths and weaknesses ( Israel and Bosniak, 2003a ).

N.B. of course the same principles of 2 publications apply to 2, 3 or more authors

3 or more authors: first author mentioned then et al, (means: and others)
Example:
In general, any renal mass that enhances with intravenous administration of contrast material on CT scanning by more than 15 Hounsfield units (HU) should be considered a renal cell carcinoma (RCC) until proved otherwise (Hartman et al, 2004).

N.B. of course the same principles of 2 publications apply to 2, 3 or more authors

2 publications with same piece of information: both mentioned to further establish the data
Example:
Several radiographic modalities are currently available for detection and evaluation of renal masses, each with relative strengths and weaknesses (Davidson et al, 1997 ; Israel and Bosniak, 2003a ; Zagoria, 2000). 
Referencing in Harvard referencing style
Books
Book author(s) or editor(s) family name,   followed by initials  
Title of the work,                    followed by a full stop. (first word of the title begins with a capital letter).  
Edition (if not the first),            followed by a full stop. 
Volume (if multivolume)           followed by a colon

Place of publication,                followed by a colon 
Publisher,                                followed by a semi-colon 

Year of publication,                 followed by a colon.
Pages.   p. (if single) pp. (if range) followed by full stop.    

Simplified format:
AUTHOR(S)/EDITOR(S), (eds). Book title. Edition. Place of publication: Publisher, Pages.



Example:
Feinberg, T.E. and Farah, M.J. (eds) Behavioural neurology and neuropsychology. 2nd ed. New York: McGraw-Hill: 1997. 


N.B. remove (eds) if authors other than editors

Chapter of book
Chapter author(s) or editor(s)  family name,   followed by initials  
Chapter Title                           followed by a full stop. 
In: 
Book author or editor family name,   followed by initials  
Title of the work,                    followed by a full stop. (first word of the title begins with a capital letter).  
Edition (if not the first),            followed by a full stop. 
Volume (if multivolume)           followed by a colon
Place of publication,                followed by a colon 
Publisher,                                followed by a semi-colon 
Year of publication,                 followed by a colon.
Pages.   p. (if single) pp. (if range) followed by full stop.    

Simplified format:
AUTHOR(S). Chapter title. In: AUTHOR(S)/EDITOR(S), ed(s). Book title. Edition.
Place of publication: Publisher, Year, Pages.

Example:
D'Amico AV, et al. Radiation therapy for prostate cancer. In AJ Wein et al., eds., Campbell-Walsh Urology, 9th ed., vol. 3, pp. 3006-3031. Philadelphia: Saunders Elsevier.

Ashken MH. Urinary cecal reservoir.   In: King LR, Stone AR, Webster GD, ed. Bladder Reconstruction and Continent Urinary Diversion,  Chicago: Year Book; 1987:238-251.


Journals
Article author(s) or editor(s) family name,   followed by initials  
Title of article ,                             followed by a full stop. (first word of the title begins with a capital letter).  
Title of journal (abbreviated),        followed by a full stop. (Capitals are used for Main Words) 
Year of publication followed by month/date,      followed by semi-colon 
Volume number, and part number in brackets,   followed by colon 
Pagination i.e. the numbers of the first and last pages on which the article appears




Simplified format:
AUTHOR(S). Title of article. Title of journal, Vol. no. (Part no.), Pages.


N.B. another format:  Vol. no. (Part no./Issue/Month)



Example


Naglie G, Radomski SB, Brymer C, et al: A randomized, double-blind, placebo controlled crossover trial of nimodipine in older persons with detrusor instability and urge incontinence.  J Urol  2002; 167(pt 1):586-590.


Annas, GJ. New drugs for acute respiratory distress syndrome. NEJM. 1997; 337: 435-39. 



N.B.  435-39. means that article occupies from page 435 to 439 in the journal volume.



Web Pages, e­mails and CD­Roms

Document author 
Title of document
[Type of resource] e.g. CD­ROM, e­mail, WWW
Organisation responsible (optional).

Available from: web address
[accessed: date]. 



Simplified format:
AUTHOR(S) (Year) Title of document [Type of resource, e.g. CD­ROM, e­mail, WWW]
Organisation responsible (optional). Available from: web address [Date accessed].




Example
UNIVERSITY OF SHEFFIELD LIBRARY (2001) Citing electronic sources of  information [WWW] University of Sheffield. Available from: http://www.shef.ac.uk/library/libdocs/hsl­dvc1.pdf [Accessed 23/02/07].

N.B.

in citation, 3 or more authors, write first one then et al,
in references, more than 3 authors, write first 3 then et al,



Mixed Example for Harvard style
Text (Citation):
Several radiographic modalities are currently available for detection and evaluation of renal masses, each with relative strengths and weaknesses ( Davidson et al, 1997 ; Israel and Bosniak, 2003a ; Zagoria, 2000). 
In general, any renal mass that enhances with intravenous administration of contrast material on CT scanning by more than 15 Hounsfield units (HU) should be considered a renal cell carcinoma (RCC) until proved otherwise (Hartman et al, 2004).
These isotope studies demonstrate an area of increased density if the mass is a pseudotumor and an area of decreased density if the mass is a cyst or solid tumor ( Israel and Bosniak, 2003b).

Reference list (listed alphabetically)
Davidson AJ, Hayes WS, Hartman DS, et al: Renal oncocytoma and carcinoma: Failure of differentiation with CT imaging.  Radiology  1993; 183:693-696.
Davidson AJ, Choyke PL, Hartman DS, Davis CJ: Renal medullary carcinoma associated with sickle cell trait: Radiologic findings.  Radiology  1995; 195:83-85.
Davidson AJ, Hartman DS, Choyke PL, et al: Radiologic assessment of renal masses: Implications for patient care.  Radiology  1997; 202:297-305.
Hartman CS, Choyke PL, Hartman MS: A practical approach to the cystic renal mass.  Radiographics  2004; 24:S101-S115.
Israel GM, Bosniak MA: Renal imaging for diagnosis and staging of renal cell carcinoma.  Urol Clin North Am  2003a; 30:499-514. 
Israel GM, Bosniak MA: Follow-up CT of moderately complex cystic lesions of the kidney (Bosniak category IIF).  AJR Am J Roentgenol  2003b; 181:627-633.
Zagoria RJ: Imaging of small renal masses: A medical success story.  AJR Am J Roentgenol  2000; 175:945-955.


Vancouver style of referencing
Vancouver is a numbered referencing style commonly used in medicine and science
Vancouver style consists of: 
  • citations in the text, using numbers
  • a numbered reference list at the end of the document
It follows rules established by the International committee of Medical Journal Editors, now maintained by the U.S. National Library of Medicine. It is also knows as Uniform Requirements for Manuscripts submitted to Biomedical Journals.


Citing in vancouver referencing style
it is quiet easy, you just write a number.
Example:
In general, any renal mass that enhances with intravenous administration of contrast material on CT scanning by more than 15 Hounsfield units (HU) should be considered a renal cell carcinoma (RCC) until proved otherwise (4).
These isotope studies demonstrate an area of increased density if the mass is a pseudotumor and an area of decreased density if the mass is a cyst or solid tumor (5).

Referencing in Vancouver referencing style
as in Harvard style



Mixed Example for Vancouver style
Text (Citation):
Several radiographic modalities are currently available for detection and evaluation of renal masses, each with relative strengths and weaknesses (1), (2), (3).
In general, any renal mass that enhances with intravenous administration of contrast material on CT scanning by more than 15 Hounsfield units (HU) should be considered a renal cell carcinoma (RCC) until proved otherwise (4).
These isotope studies demonstrate an area of increased density if the mass is a pseudotumor and an area of decreased density if the mass is a cyst or solid tumor (5).
Reference list: (listed according to time of mentioning reference in text, not alphabetical)
(1) Davidson AJ, Hartman DS, Choyke PL, et al: Radiologic assessment of renal masses: Implications for patient care.  Radiology  1997; 202:297-305.





(2) Israel GM, Bosniak MA: Renal imaging for diagnosis and staging of renal cell carcinoma.  Urol Clin North Am  2003a; 30:499-514. 
(3) Zagoria RJ: Imaging of small renal masses: A medical success story.  AJR Am J Roentgenol  2000; 175:945-955.





(4) Hartman CS, Choyke PL, Hartman MS: A practical approach to the cystic renal mass.  Radiographics  2004; 24:S101-S115.
(5) Israel GM, Bosniak MA: Follow-up CT of moderately complex cystic lesions of the kidney (Bosniak category IIF).  AJR Am J Roentgenol  2003b; 181:627-633.


Commonly used abbreviations:
c. = circa (about, approximately)
ch. = Chapter
ed. = edition
et al.. = and others
fig; figs = figure(s)
ill ills = illustrator(s)
p. = page(s)
p. = single page, e.g. p.134
pp. = page range, e.g. pp. 115-117 or 115-17
para paras = paragraph(s)
pt pts = part(s)
rev = revised
suppl = Supplement







Physiology of Continence



Factors maintaining urinary continence

Urinary continence depends on many physiological factors that are not equally important or necessarily operative at the same time but all act in concert together to preserve the two main functions of the lower urinary tract that maintain continence, storage and emptying. These factors are partially local and partially due to central coordination and include:
1. Functioning bladder (storage and emptying). This depends mainly on bladder compliance, detrusor stability and contractility.
2. Intact urethral sphincters, mucosa and submucosa.
3. Intact pelvic floor muscles (Peri-urethral muscles).
4. Neural control (autonomic and somatic innervations)
                                                    
1-   Physiology of the Bladder in relation to continence
The bladder is composed of mucosa, lamina propria, smooth muscle cells, nerve endings, fibroblasts and extracellular matrix. It is this dynamic combination of elements interacting together that makes the bladder is one of the most compliant organs in the body, enabling its volume to expand dramatically without significant increases in pressure until a critical point is reached .
The detrusor (smooth) muscles of bladder consist of sheets containing many small spindle-shaped cells that contain actin (thin filament), myosin (thick filament) and cytoskeletal intermediate filaments that assist in transmission of the force generated during contraction. The actin and myosin filaments are arranged as myofibrils that cross obliquely in a lattice-like arrangement. The contraction of smooth muscle is slow, sustained, and resistant to fatigue maintaining a steady level of contraction and tone.
Tone is important in maintaining the capacity of the bladder and depends on many factors, some intrinsic and some extrinsic. Extrinsic factors include activity in the autonomic nerves and circulating hormones; Intrinsic factors include the response to stretch, local metabolites, locally secreted agents such as nitric oxide, and temperature .
2-   Physiology of the urethra in relation to continence
The urethra is composed of mucosa, submucosa, smooth and striated muscles.
The urethral mucosa and submucosa function as a filler substance to effectively close the urethral lumen after narrowing of lumen by urethral sphincter .
Impaired arterial blood supply to the urethra decreases the intraluminal urethral pressure due to decreased vascular filling and hypoxic effect on the urethral smooth muscle .
The proximal urethral sphincter has inner longitudinal and outer circular smooth muscle layers. Contraction of the inner longitudinal smooth muscle plays a role in resting continence, stabilizing the urethra and allowing force generated by the circular muscle elements to occlude the lumen .
The distal urethral sphincter consists of an inner longitudinal thin smooth muscle layer and an outer circular striated muscle composed predominately of slow-twitch fibers (type I) which are responsible for continence at rest. Despite the horseshoe configuration of the DUS (see the anatomy), the urethral pressure recording at the external sphincter during bladder filling increases uniformly along the entire circumference like an iris. Hypogastric nerve stimulation augments this pressure, suggesting a role for adrenergic receptors and sympathetic nerves in the function of the external urethral sphincter .

3-   Physiology of the Striated Muscles of the Pelvic Floor (Peri-urethral muscles)
The peri-urethral striated muscles of the pelvic floor contain predominatly fast-twitch fibres (type IIa) and few slow-twitch fibers. They are adapted for the rapid recruitment of motor units required during increases in abdominal pressure (active continence).
It has been speculated that the successful treatment of stress incontinence by pelvic floor muscle training (PFMT) or electro-stimulation (ES) is caused by the conversion of fast-twitch fibers to slow-twitch fibers that maintain continence at rest .
Types of Striated Muscle Fibers
The Striated muscle fibers are classified into: slow-twitch fibers and fast-twitch fibers.
The slow-twitch fibers (type I): found in greater percentage in muscles that require sustained tension, such as the DUS and to a lesser degree in the pelvic floor muscles.
These muscle fibers are recruited slowly, fatigue slowly and can perform high rates of oxidative metabolism because they possess less of the myosin ATPase activity and contain an increased expression of a slow iso-form of the Ca2+-ATPase.
The fast-twitch fibers (type II): are found mainly in pelvic floor muscles that maintain continence in stress conditions when intra-abdominal pressure is abruptly increased by adding to sphincter tone rapidly (Such conditions as cough, abdominal straining or voluntary interruption of the urinary stream). Fast-twitch fibers can be recruited rapidly, tend to fatigue rapidly and perform predominantly anaerobic metabolism. Fast-twitch fibers are rich in myosin ATPase that catalyzes the actin-myosin interaction and  fast iso-form of the Ca2+-ATPase. Fast-twitch fibres can be classified into fatigue-resistant (type IIa) as pelvic levator and fatiguable (type IIb) which is not related to continence .
  

Micturition Cycle (Fig. 1)
The micturition cycle is divided into two relatively discrete phases: Bladder filling phase and Bladder emptying phase.







Figure (1):  Mechanism of storage and voiding phase reflexes.
A, Storage reflexes. distention of bladder produces low-level bladder afferent firing which stimulates the sympathetic outflow to bladder outlet (base and urethra) and pudendal outflow to  external urethral sphincter. These responses occur by spinal reflex pathways and represent “guarding reflexes,” which promote continence. Sympathetic firing also inhibits detrusor muscle.
B, Voiding reflexes. At initiation of micturition, intense vesical afferent activity activates PMC, which inhibits spinal guarding reflexes and stimulates parasympathetic outflow to bladder and internal sphincter smooth muscle. Maintenance of voiding reflex is through ascending afferent input from the spinal cord, which may pass through the periaqueductal gray matter (PAG) before reaching the PMC .


4-    The Neural Control of Micturition & Continence (Fig. 2)
The apparently simple lower urinary tract function comprising the storage and periodic elimination of urine is under a complex regulatory control of neural system that involves: central and peripheral neural control.

Figure (2): Neural control of the lower urinary tract. Showing the somatic, sympathetic and parasympathetic peripheral nerves; the pontine micturition centre, the periaqueductal gray and the suprapontine areas involved in control of storage and voiding of urine. There are extensive interactions at all levels (not shown) (Chapple et al., 2009).

A)     Central (Spinal and Sura-spinal) Control of Micturition (Fig. 3)
The spinal center of micturition is located in the lumbo-sacral spinal cord and responsible of voiding reflexes. It is controlled by higher supraspinal micturition centers.
The supra-spinal centers controlling micturition include the pontine micturition center (PMC) (Fig. 3), the periaqueductal grey (PAG) and supra-pontine centers which include the frontal cortex, the hypothalamus, the para-central lobule, the limbic system and the cingulate gyrus .


Figure (3): Pontine micturition center (Horizontal section showing significantly increased blood flow with PET in the dorsal pons during micturition). L, left side; R, right side of the brain .



Role of spinal center in control of micturition
The spinal micturition center controls a number of involuntary reflexes. With bladder filling, the sympathetic activity is increased, the parasympathetic activity is inhibited and the pudendal (somatic) neurons are activated (guarding reflex). Micturition reflex is also a spinal reflex which is controlled by higher supra-spinal centers .
Role of supra-spinal centers in control of micturition
The brain supra-spinal centers allow for the perception of bladder fullness, determine the “social correctness” of the micturition act and coordinate the activities of the striated and smooth muscles involved in the micturition reflex to maintain a reciprocal relationship between the bladder and the urethral outlet .
The PAG is an integrative brain center that receives sensory stimuli of bladder fullness via the spinal cord then sends it to the PMC.
The PMC is essential in co-ordinating the micturition process and is itself under the control of the suprapontine area .

B)   Peripheral Control of Micturition (Fig. 4)
The bladder is supplied by three sets of nerve fibres: the pelvic nerve, the pudendal nerve and the hypogastric nerve.


Figure (4): The sympathetic, parasympathetic, and somatic innervation of the urogenital tract of the male.
Sympathetic preganglionic pathways emerge from lumbar cord to symp. chain ganglia (SCG) then through inferior splanchnic nerves (ISN) to infer. mesenteric ganglia (IMG). Pre- and post-ganglionic sympathetic axons travel in hypogastric nerve (HGN) to pelvic plexus and urogenital organs.
Parasympathetic preganglionic axons originate in the sacral cord & pass in pelvic nerve to ganglion cells in pelvic plexus and to distal ganglia in organs.
Sacral somatic pathways are contained in pudendal nerve, which innervates penis and ischiocavernosus (IC), bulbocavernosus (BC), and distal urethral sphincter (DUS) muscles. The pudendal and pelvic nerves also receive postganglionic axons from the caudal sympathetic chain ganglia. These three sets of nerves contain afferent axons from lumbosacral dorsal root ganglia. (PG: prostate gland; U: ureter; VD: vas deferens).
1- The pelvic nerves (S2–S4)–(Parasympathetic):
The principal nerve supply of the bladder is by way of the pelvic nerves, which connect with the spinal cord through the sacral plexus, mainly connecting with cord segments S-2 and S-3. The pelvic nerves contains both sensory and motor nerve fibers. The sensory fibers detect the degree of stretch in the bladder wall and posterior urethra and responsible for initiating the reflexes that cause bladder emptying. The motor nerves are parasympathetic fibers that innervate the detrusor muscle . 
2- The pudendal nerve (Somatic):
Motor innervation to skeletal muscle fibers of the distal urethral sphincter is transmitted through the pudendal nerve.
3- The hypogastric nerves (T11–L2)-(Sympathetic):
Sympathetic innervation emerges from the sympathetic chain through the hypogastric nerves, connecting mainly with the L-2 segment of the spinal cord. These sympathetic fibers stimulate mainly the blood vessels and have little to do with bladder contraction .


Anatomical components of continence mechanism in males


Anatomical components of continence mechanism in males
Effective urethral closure and continence at rest and during periods of increased intra-abdominal pressure depends on several anatomical factors including: well-vascularized urethral mucosa and submucosa, properly functioning striated and smooth urethral sphincter, pelvic floor muscles and fasciae .
The male urethra
The male urethra is 18-20 cm long and extends from the bladder neck to the external meatus at the end of the penis. It may be considered in two parts (Fig. 1):

Figure (1): Anatomy of male urethra.
The anterior urethra
It is about 16 cm long and surrounded by the corpus spongiosum. It is subdivided into:
The bulbar urethra which is more proximal, surrounded by the Bulbospongiosus muscles and lie entirely within the perineum.
The pendulous urethra which is distal and continues to the tip of the penis .
The posterior urethra
It is about 4 cm long and lies in the pelvis proximal to the corpus spongiosum. The posterior urethra is divided into:
The pre-prostatic part of the urethra is about 1 cm long, extends from the base of the bladder to the prostate and surrounded by the proximal (internal) urethral sphincter.


The prostatic part is the widest and passes through the prostate.
The membranous (sphincteric) part is the shortest and narrowest part. In the deep perineal pouch, it is surrounded by distal (external) urethral sphincter. The membranous urethra is called “sphincteric urethra” as it comprises both striated and smooth muscle components that provide continence at this level .
The urethral mucosa and submucosa
The male urethral mucous membrane is continuous with the transitional epithelium of the bladder. The submucous tissue consists of a vascular layer containing longitudinally arranged collagen fibers and elastin fibers surrounded by a layer of circular smooth muscle .
The male urethral sphincter complex (Fig. 2)
The male urethral sphincter complex is composed of: proximal (smooth) sphincter, distal sphincter (mainly striated) and pelvic floor (Peri-urethral) muscles .


Figure (2): Male urethral sphincter complex. PUS (lissosphincter) extends from the bladder neck through the prostatic urethra above the verumontanum. DUS (rhabdosphincter) extends from the prostatic urethra below the veru-montanum through the membranous urethra surrounded by Peri-urethral skeletal muscle (Pelvic floor) .
The Proximal (internal) (lisso-) urethral sphincter (PUS)
The proximal urethral sphincter consists of a relatively thick inner longitudinal layer, a thinner outer circular layer of smooth muscles and a lamina propria layer that is less developed than detrusor. PUS extends in the form of a cylinder completely surrounding the urethra from the bladder neck to the perineal membrane with its main part at the bladder neck and becomes thinner in its further course in the urethra. The proximal sphincter is innervated by adrenergic autonomic fibers .
The Distal (external) (rhabdo-) urethral sphincter (DUS)
It is 1.5 to 2.4 cm in length and surrounds the membranous “sphincteric” urethra which extends from the apex of the prostate to the corpus spongiosum of the penis .
The smooth muscle fibers of DUS are continuous with the PUS and lie internal to the striated muscle. The striated muscle fibers lie externally and extend from the base of the bladder and the anterior aspect of the prostate to the full length of the membranous urethra. The striated muscle form a horseshoe or omega configuration around the membranous urethra being deficient posteriorly and bulky anteriorly . The peri-urethral striated muscles of the pelvic floor lie external to the striated urethral muscle fibers .
The innervation of DUS is complex with both autonomic unmyelinated and somatic myelinated nerves (pudendal nerve and pelvic nerve). The autonomic nerves enter at the 5 and 7 O’clock positions, while the somatic nerves enter the striated fibers of the prostatic capsule at the 9 and 3 O’clock positions. Damage to these nerves lead to loss of sphincteric mechanism .
Role of urethral in continence mechanism
The urethral smooth and striated muscles in addition to pelvic floor play the main role in the anatomical support of continence .
The striated muscle fibers of distal urinary sphincter is responsible for resting continence because it contains predominantly type I slow-twitch fibers (see physiology) .
Prostatectomy, either radical or transurethral, results in a destruction of the proximal smooth muscle sphincteric mechanism. Continence in post-prostatectomy patients continues to be maintained through the action of the distal urethral sphincter
The urethral mucosa and submucosa also play a role in continence. The flow of blood into the large submucosal venules can be controlled assisting in forming a water-tight closure of the mucosal surfaces. So, the urethral mucosa and submucosa function as a filler substance to effectively close the urethral lumen after the urinary sphincters narrow the urethral space .
Role of the prostate in continence
In terms of urinary continence the prostate gland plays an important role. Its enlargement due to benign cause or prostatic cancer causes voiding difficulties and surgical excision of the prostate can be complicated by urinary incontinence .
The pelvic floor (Fig 3)
The pelvic floor lies at the bottom of the abdomino-pelvic cavity and forms a support for the abdominal and pelvic viscera and plays important role in continence. The pelvic floor has three layers of support: the endopelvic fascia, the levator ani muscles and the perineal membrane .
1-    The endopelvic fascia
The endopelvic fascia (outer stratum of the pelvic fascia) is a viscero-fascial layer that lies immediately beneath the peritoneum and connects the viscera to the pelvic sidewalls. It presents an extension of the transversalis fascia which drapes on the pelvic floor. It can be considered the first layer of the pelvic floor .
The endopelvic fascia becomes condensed to form the urethropelvic and puboprostatic ligaments. The Urethropelvic ligaments are an anterior medial condensation of the endopelvic fascia, which combines with fibers from the pubococcygeus muscle to span the area from the anterior aspect of the tendinous arc to the bladder neck and proximal urethra. The puboprostatic ligament attaches the inferior surface of the pubic symphysis to the junction of the prostate and the external sphincter.

2-    The levator ani muscles (Fig 3)
The levator ani muscle is the second layer of pelvic floor and considered the true muscular floor of the pelvis that provides the main support for the pelvic organs. The layer formed by the muscle and its fascial layers (superior and inferior) is referred to as the “Pelvic diaphragm.
The levator ani can be divided into three parts: the pubococcygeus, iliococcygeus and ischiococcygeus muscles but the boundaries between each part cannot be easily distinguished and they perform many similar physiological functions .



Figure (3): Pelvic diaphragm muscles and pelvic walls .

a- The Pubococcygeus muscle
Pubococcygeus forms a U-shaped thick band being deficient at the ventral aspect of the urethra. It arises from the back of the body of the pubis on either side of the midline and passes back almost horizontally surronding the urethra and rectum.
Pubococcygeus is often subdivided into two parts:
The pubourethralis (Puboprostaticus) is the most medial fibers of pubococcygeus that runs directly lateral to the urethra and its sphincter and inferio-lateral to the prostate.
The puborectalis is a thick muscular sling that wraps around the anorectal junction and behind the rectum .
b- The iliococcygeal muscle
It is attached to the inner surface of the ischial spine. The most posterior fibers are attached to the tip of the sacrum and coccyx but most join with fibers from the opposite side to form a raphe which provides a strong attachment for the pelvic floor posteriorly.
c- The ischiococcygeal muscle (also called coccygeus)
It is the most posterosuperior portion of levator ani and arises as a triangular musculo-tendinous sheet with its apex attached to the tip of the ischial spine and base attached to the lateral margins of the coccyx .
3-    The perineal membrane (urogenital diaphragm)
This is the third layer of pelvic floor and it provides some weak support for urethra .
Role of the pelvic floor in continence mechanism
The levator ani muscle plays an important role in urinary continence and support of the striated DUS but the exact anatomical relationship between this muscle and external urethral sphincter remains incompletely understood .
The levator ani muscle fibers are responsible for the voluntary active continence during stress conditions such as cough, abdominal straining or interruption of the urinary stream by contracting forcefully and rapidly but for a short time because it contains predominately fast-twitch type IIa fibres .
          The pelvic fasciae also play a role in continence and pelvic viscera support. The puboprostatic ligaments, in conjunction with the pubourethralis muscle prevent the rotational decent of the proximal urethra .

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