Perineal body : easy and brief description

Perineal body :

Definition: Perineal body, also known as the central tendon of perineum, is a pyramidal fibromuscular mass situated in the middle of the junction of urogenital triangle and anal triangle.

Relations:

It is lies in the subcutanous tissue.

Posterior to.vestible.

Anteriorly it is bend with perineal membrane .

It is situated at the midpoint of line between  ischial tuberosities.

The location of perineal body is different in males and females.

 In males, it is found between the bulb of the penis and the anus

 while in females, it is found between the vagina and the anus.

It provides attachment to the following muscles:

• External anal sphincter muscle
• Bulbospongiosus muscle
• Superficial transverse perineal muscle
• Levator ani muscle (anterior fibers)
• External urinary sphincter
• Deep transverse perineal muscle
• 
  

Function:

1.   Perineal body is essential for the integrity of the pelvic floor, especially in females. 

2.   Gives attachment of perineal muscles

3.   It gives visceral support especially in female

Clinical anatomy :

Its rupture during vaginal birth leads to widening of the gap between the anterior free borders of levator ani muscle of both sides, thus predisposing the woman to prolapse of the uterus, rectum, or even the urinary bladder.

Sphincter urethrae / external urethral sphincter: easy and brief description

Sphincter urethrae / external urethral sphincter

The female or male external sphincter muscle of urethra (sphincter urethrae): located in the deep perineal pouch, at the bladder's distal inferior end in females, and inferior to the prostate (at the level of the membranous urethra) in males. It is a secondary sphincter to control the flow of urine through the urethra. Unlike the internal sphincter muscle, the external sphincter is made of skeletal muscle, therefore it is under voluntary control of the somatic nervous system

Females do have a more elaborate external sphincter muscle than males as it is made up of three parts: the sphincter urethrae, urethrovaginal muscle, and the compressor urethrae. The urethrovaginal muscle fibers wrap around the vagina and urethra and contraction leads to constriction of both the vagina and the urethra. The origin of the compressor urethrae muscle is the right and left inferior pubic ramus and it wraps anteriorly around the urethra so when it contracts it squeezes the urethra against the vagina. The external urethrae, like in males, wraps solely around the urethra

Function: The external urethral sphincter provides voluntary control of urination.

Prostatic utricle : brief description with clinical anatomy

Urethral crest

Urethral crest

Upon the posterior wall of the prostatic urethra is a narrow longitudinal ridge, the urethral crest (verumontanum), formed by an elevation of the mucous membrane and its subjacent tissue. 

 In females, it is known as the crista urethralis femininae, and is a conspicuous longitudinal fold of mucosa on the posterior wall of the urethra

The urethral crest is an anatomical feature present in the urinary system of both males and females. 

In males, the urethral crest is known as the crista urethralis masculinae, or the crista phallica, and is a longitudinal fold on the posterior wall of the urethr extending from the uvula of the bladder through the prostatic urethra

length: It is from 15 to 17 mm. in length, and about 3 mm. in height, and contains muscular and erectile tissue. 

Function: When distended, it may serve to prevent the passage of the semen backward into the bladder

Prostatic utricle: easy and brief description with clinical anatomy

Prostatic utricle

•      It refers to a tiny diverticulum of the prostatic urethra, lined by epithelium.

•      It The prostatic utricle is a small indentation in the prostatic urethra, at the apex of the urethral crest, on the seminal colliculus (verumontanum), laterally flanked by openings of the ejaculatory ducts.

•       is also called the “Vagina masculina.”

•      It is also known as the vagina masculina or uterus masculinus or (in older literature) vesicula prostatica.

•      It is often described as "blind", meaning that it is a duct that does not lead to any other structures.

•      It can sometimes be enlarged.

•      It is 6 mm long

•      It is  projects upward and backward into the substance of the prostate.

•      It appears as a tiny blind pouch that protrudes into the prostate gland from the wall of the prostatic urethra.

•      The prostatic utricle is important, primarily, because it is the homologue of the uterus and vagina, usually described as derived from the paramesonephric duct,  although this is occasionally disputed. Prostatic utricle is a remnant of Mullerian duct in males

•      In 1905 Robert William Taylor stated the function of the utricle, writing, "In coitus it so contracts that it draws upon the openings of the ejaculatory ducts, and thus renders them so patulous that the semen readily passes through."

Prostatic utricle Disorders

In some cases, this pouch can suffer an inflammation. Cysts may also arise on the spot. These are known as Prostatic utricle cyst (PUC) and are more frequently noticed to develop within the first two decades of life. These tend to vary in size and do not generally extend over the prostate gland. The condition may lead to an accumulation of urine in the cysts and possibly cause post-void dribbling.

Most prostatic utricular cysts are asymptomatic, especially when small. When large, symptoms typically consist of urinary incontinence, recurrent infections, or stone formation. Malignant degeneration has been reported in 3% of prostatic utricles with a peak incidence in the fourth decade of life

Deep fascia in general

Deep fascia in general

Deep fascia

Definition: Deep fascia is a fascia, a layer of dense irregular connective tissue that wraps the neck, the limbs and body wall like a bandage or stocking 

It covers muscles, nerves, bone and blood vessel.

Important features of deep fascia:

·         It is devoid of fat

·         It is inelastic and tough

·         It has nerve supply and very sensitive structure.

·         It is a golden rule that when fascia approaches bone it becomes attached to it , blending with the covering periosteum

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Distribution of deep fascia

Very well developed: 

1.       iliotibial tract of fascia lata

2.       palmar and planter aponeurosis

3.       flexor and extensor retinaculum

Well developed:

• In the limbs,  it forms tough &  tight sleeves
•  In the neck, it forms a collar.

So thin usually considered as absent:

·         Over the rectus sheath of abdomen

·         Over the trunk  except thoracolumbar fascia at the back of thorax & abdomen

Absent

·         Face except  parotid fascia

·         Ischioanal fascia

Why thickness of deep fascia is different in different parts of body?

Why deep fascia is very well developed is particular location of body: 

1.      iliotibial tract of fascia lata : abduct and stabilized and steady the hip and knee joints during walking and running by putting tension on iliotibial tract

1.      palmar and planter aponeurosis : Deep fascia of particular location is not only thick and also send fibrous strands to skin, so hand and feet is fixed and not wobbly  e.g. palmar and plantar aponeuroses which afford protection to the underlying-structures and help to firm grip.

2.      flexor and extensor retinaculum : prevents spring out of tendon during their movement

Why deep fascia is Well developed in particular location of body :  

In the limbs, 

• it forms tough &  tight sleeves : the tight stocking around muscles not only contours the extremity but also plays an important role in the return of blood to the heart against the gravity 

In the neck,

•  investing layer of deep fascia  forms a collar.
• Prevertebral fascia forms vertebral compartment and help for positioning head
• Pretracheal fascia forms visceral compartment (it surrounds trachea, larynx , esophagus ,the glands of neck : thyroid , parathyroid , thymus )
• Carotid sheath forms vascular compartment
• The primary functions of deep fascia of neck is prevent spread of infection from one compartment to another compartment

Why deep fascia is so thin usually considered as absent in some location of body :

·         Over the rectus sheath of abdomen: deep fascia is thin where considerable expansion is needed

·         Abdomen enlarges in obesity ,  pregnancy , ascitis .

·         Over the trunk  except thoracolumbar fascia at the back of thorax & abdomen

Why deep fascia is absent in some location of the body

·         Face except  parotid fascia : facial muscles are inserted into skin of the face so deep fascia is absent in face

·         Ischioanal fascia : only the lateral wall of the ischioanal fossa is lined by fascia of obturator internus

Modification of deep fascia:

2.      Each muscle is covered by deep fascia known as epimysium which sends in the septa to enclose each muscle fasciculus known as perimysium. From the perimysium septa pass to enclose each Muscle fiber. These fine septa are the endomysium. This connective tissue layer support the muscle and convey nerve , blood vessels and lymphatics.

3.      Deep fascia covers each nerve as epineurium, each nerve fascicle as perineurium and individual nerve fibered as endoneurium. These connective tissue coverings support the nerve fibers and carry capillaries and lymphatics.

4.      From deep fascia , the intermuscular septa is arises which  separating functionally different group of muscles into separate compartments.

5.      It also forms septa between various muscles. These septa are specially well developed in the calf muscles of lower limb. The contraction of calf muscles in the tight sleeve of deep fascia helps in pushing the venous blood and lymph towards the ‘heart. Thus the deep fascia helps in venous and lymphatic return from the lower limb.

6.      The deep fascia is dense around the artery and rather loose around the vein to give an allowance for the vein to distend.
deep fascia forms sheaths around large arteries, e.g. carotid sheath, axillary sheath

7.      Deep fascia is modified to form the capsule, synovial membrane and bursae in relation to the joints.

8.      Deep fascis forms tendon sheaths wherever tendons cross over a joint. This mechanism prevents wear and tear of the tendon.

9.       In the region of palm and sole it is modified  to form aponeuroses. in the forearm and leg, the deep fascia is modified to form the interosseous membrane, which keeps:

• The two bones at optimum distance.
• Increases surface area for attachment of muscles.
• Transmits weight from one bone to other

Functions of Deep Fascia:

1. Deep fascia keeps the underlying structures in position an preserves the characteristic surface contour of the limbs and neck.
2. It provides extra surface for muscular attachment
3. It helps in venous and lymphatic return.
4. It assists muscles in their action by the degree of tension and pressure it exerts upon their surfaces.
5. The retinacula act as pulleys and serve to prevent the loss of power. In such situations the friction is minimized by the synovial sheaths of tendons.

Clinical importance of deep fascia:

It is used as material for surgical repair. Example: fascia lata of thigh use to repair a hernial defect or defect in the dura mater