Bladder Anatomy

Original Editor - Khloud Shreif

Top Contributors - Khloud Shreif and David Olukayode

Description

Detrusor muscle

It is a hollow muscular, elastic, subperitoneal organ, , located at the lesser pelvic cavity, it collects the urine that is filtered through the kidney  through ureters to be evacuated/ voided later on.

It can accommodate about 1000 ml of urine with an average of about 400-600 ml which varies from one to another. The outer layer of the bladder wall is formed of smooth involuntary muscle fibers (detrusor muscles), it contracts at urination to empty the bladder.

Anatomical Surface of The Bladder

When it is filled it is like an oval, formed of four surfaces. The neck is the constricted part, located inferiorly, and leads to the urethra. The apex is anterosuperior and points to the abdominal wall. The base/ fundus is located posteriorly, it is triangular-shaped its tip points backward. The body of the bladder is the main part of the bladder and is located between the apex and fundus.

The trigon is a triangular region at the base of the bladder, lined with smooth muscle, collagen, and elastin to a lesser degree. Located between the internal-urethral meatus and the two ureteral orifices.

Urethral Sphincters

Internal urethral sphincter

It is formed of smooth involuntary muscle fibbers under the control of the autonomic nervous system, it contains alpha-adrenergic receptors its stimulation helps to fill the bladder. In females, it is formed by the bladder neck and the proximal urethra (the urethra in females is about 4 -5 cm while in males it is bout 20cm in length).

External urethral sphincter

It is consisted of skeletal muscle fibers, it is under voluntary control, and contains nicotinic receptors.

Innervation

Nerve

Parasympathetic (s2-s4): responds to stretch receptors of the bladder wall and it is responsible for detrusor contraction to empty the bladder. The pudendal nerve is a somatic parasympathetic that innervates the external urethral sphincter and helps to voluntary control the emptying of the bladder.

Sympathetic (t12-l2): store the urine as it causes relaxation of the detrusor muscle of the bladder.

Artery

Branches from internal iliac artery; superior and inferior vesicle arteries.

Small branches from the obturator and inferior gluteal artery.

Lymphatic Drainage

The neck and fundus of the bladder through internal, sacral, and common iliac lymph nodes.

The superolateral aspect of the bladder is through the external iliac lymph nodes.

Clinical Relevance

Urinary incontinence an involuntary loss of urine it is divided into subtypes; stress incontinence in which patients loss control when there is an increase in intraabdominal pressure, or sudden need to urinate as in urg incontinence and overactive bladder OAB that is associated with increase frequency of urination than normal and may be associated with urgency and named wet OAB.

Atonic bladder(overflow incontinence) there is continuous loss of urine when there is insufficient contraction of detrusor muscle.

Automatic (a spastic bladder) associated with spinal cord injury above the sacral level and associated with frequent urination.

Detrusor sphincter dyssynergia (DSD), there is a spontaneous contraction of both urethral sphincter and detrusor muscle.

Interstitial cystitis or bladder pain syndrome, a chronic bladder health problem cause painful urinary tract symptoms; lower abdominal pain, pelvic pain, sudden need to evacuate, or an increase in urination frequency at night.

Physical Therapy

Pelvic floor physical therapist concerned to deal with different conditions associated with urinary bladder or any pelvic floor disorders. Every condition even every case has its own program. Pelvic rehabilitation program will vary between biofeedback training, electrotherapy modalities, exercise programs and mainly concentrate on pelvic floor muscle, bladder training.