12/03/2021 [back muscles, micturition, UTIs, CRMO, rheumatic fever]] Flashcards
Associated movements of the superficial, intermediate and deep muscles
Superficial - shoulder movements
Intermediate - thoracic cage movements
Deep - vertebral column movements
Where do all the superficial back muscles originate and attach onto?
originate - vertebral column
attach - bones of the shoulder [clavicle, scapula, humerus]
Muscles in the superficial back [from most superficial to deep]
Trapezius, latissimus dorsi, levator scapulae, rhomboids
Actions of the trapezius
The upper fibres of the trapezius elevates the scapula and rotates it during abduction of the arm. The middle fibres retract the scapula and the lower fibres pull the scapula inferiorly
What is the most common cause of accessory nerve damage?
The most common cause of accessory nerve damage is iatrogenic (i.e. due to a medical procedure). In particular, operations such as cervical lymph node biopsy or cannulation of the internal jugular vein can cause trauma to the nerve
How is accessory nerve damage tested for?
To test the accessory nerve, trapezius function can be assessed. This can be done by asking the patient to shrug his/her shoulders. Other clinical features of accessory nerve damage include muscle wasting, partial paralysis of the sternocleidomastoid, and an asymmetrical neckline
Actions of latissimus dorsi
Extends, adducts, medially rotates the upper limb
Action of the levator scapulae
Elevates the scapula
Action of the rhomboids
Rhomboid major - retracts and rotates the scapula
Rhomboid minor - retracts and rotates the scapula
What is in the intermediate group of muscles in the back?
Serratus posterior superior
Serratus posterior inferior
Actions of the intermediate muscles of the back
Serratus posterior superior - elevates ribs 2-5
Serratus posterior inferior - depresses ribs 9-12
Which group of muscles are known as the intrinsic muscles of the back and why?
The deep muscles develop embryologically in the back, and are thus described as intrinsic muscles. The superficial and intermediate muscles do not develop in the back, and are classified as extrinsic muscles.
Superficial deep muscles of the back
Spinotransversales
- splenius capitis
- splenius cervicis
Action of the spinotransversalis
Rotates head to the same side
Intermediate deep muscles of the back
Erector spinae
- iliocostalis
- longissimus
- spinalis
Where do all the intermediate deep muscles attach?
Lumbar and lower thoracic vertebae
Sacrum
Posterior aspect of the iliac crest
Sacroiliac and supraspinous ligaments
Action of the intermediate deep muscles
Acts unilaterally to laterally flex the vertebral column. Acts bilaterally to extend the vertebral column and head
Major muscles in the deep deep back [there are other minor deep intrinsic muscles]
Semispinalis, multifidus and rotatores
[mainly stabilise vertebral column]
Area of the brain involved in the storage of urine
Pontine continence centre [L-region of the pons]
Signal sent from the brain to stimulate micturition
Pons -> sympathetic nuclei [spinal cord] -> detrusor muscle and IUS
How do impulses travel from the spinal cord to the bladder?
Via the hypogastric nerve [nerve roots T10-12]
What does the hypogastric nerve stimulate?
Relaxation of the detrusor muscle in the bladder wall – via stimulation of β3-adrenoreceptors in the fundus and the body of the bladder.
Contraction of the IUS – via stimulation of α1-adrenoreceptors at the bladder neck
What type of innervation is the storage phase?
Sympathetic
What type of control is the EUS under?
Voluntary somatic control
Where do impulses travel to the EUS from?
The pudendal nerve [S2-4] to nicototinic [cholinergic] receptors on the striated muscle, resulting in contraction of the sphincter
Type of innervation is the pudendal nerve?
Somatic voluntary control
What can spinal cord lesion above T12 cause?
reflex bladder
Explain a reflex bladder
In an upper motor neurone lesion, sympathetic input to the bladder is lost, leading to an inability for the detrusor muscle to relax, or the IUS to contract.
Afferent signals via the sensory pelvic nerve are also unable to reach the brain, and so the EUS remains constantly relaxed. The result is decreased bladder capacity and detrusor overactivity. The parasympathetic system initiates detrusor wall contraction in response to bladder wall stretch, resulting in the bladder automatically emptying as it fills. This is known as a reflex bladder.
Causes of a reflex bladder
Trauma and MS
What can lesion in the pontine continence centre [PCC] cause?
Lesions in the pons can lead to a complete loss of voiding control and the inability to store urine. In damage to the PCC, sympathetic input to the bladder is lost. This results in the same symptoms as a reflex bladder, although the damage is in a different location
Causes of PCC incontinence
Typical causes of such brain lesions are strokes, brain tumours and the degeneration of dopaminergic neurones in Parkinson’s disease
Pharmacological Tx of urinary incontinence secondary to neurological insults
- Anticholinergics(e.g. Oxybutynin, Tolterodine) which reduce parasympathetic input to the bladder
- β3-adrenoceptor agonists(e.g. Mirabegron) bind to β3-receptors on the detrusor muscle and stimulate relaxation of the muscle. Therefore, these drugs can be used to increase the bladders capacity to store urine in the treatment of urge urinary incontinence
SE of anticholinergics
More likely to result in anticholinergic side effects such as a dry mouth or constipation, so are used less frequently. Oxybutynin particularly should be avoided in elderly frail patients due to an increased falls risk
other types of Tx for urinary incontinence
Other possible therapies include the injection of botulin toxin A, sacral nerve stimulation, and surgical procedures such as Augmentation enterocystoplasty or urinary diversion.
What is the stress-relaxation phenomenon?
Most of the time, the bladder (detrusor muscle) is used to store urine. As it fills, the rugae distend and a constant pressure in the bladder (intra-vesicular pressure) is maintained.