9. Lumbosacral plexus and kidneys Flashcards
network of nerve fibres that supplies the skin and muscles of the pelvis and lower limb. It is located on the surface of the posterior pelvic wall, anterior to the piriformis muscle.
sacral plexus
the sacral pelxus is formed by
anterior rami (divisions) of the sacral spinal nerves S1, S2, S3 and S4.
It also receives contributions from the lumbar spinal nerves L4 and L5.
peripheral nerves of sacral plexus
5 major
Some Irish Sailor Pesters Polly’.
- Superior Gluteal Nerve 2. Inferior Gluteal Nerve
- Sciatic Nerve
- Posterior Femoral Cutaneous
- Pudendal Nerve
other branches
Nerve to piriformis
Nerve to obturator internus
Nerve to quadratus femoris
2 main destinations the nerves of sacral plexus
- Leave the pelvis via the greater sciatic foramen -> gluteal region
- Remain in the pelvis
this nerve leaves the pelvis via the greater sciatic foramen, entering the gluteal region superiorly to the piriformis muscle. It is accompanied by the superior gluteal artery and vein for much of its course.
superior gluteal nerve
roots of superior gluteal nerve
L4,L5, S1
Roots of inferior gluteal nerve
L5,S1,S2
Roots of sciatic nerve
L4,L5,S1,S2,S3
roots of posterior femoral cutaneous
S1,S2,S3
roots of pundendal nerve
S2,S3,S4
fx of superior gluteal nerve
Motor Functions: Innervates the gluteus minimus, gluteus medius and tensor fascia lata.
Sensory Functions: None.
fx of inferior gluteal nerve
Motor Functions: Innervates gluteus maximus.
Sensory Functions: None.
roots of sciatic nerv
L4, L5, S1, S2, S3
motor fx of sciatic nerve
Tibial portion – Innervates the muscles in the posterior compartment of the thigh (apart from the short head of the biceps femoris), and the hamstring component of adductor magnus. Innervates all the muscles in the posterior compartment of the leg and sole of the foot.
Common fibular portion – Short head of biceps femoris, all muscles in the anterior and lateral compartments of the leg and extensor digitorum brevis.
sensory fx of sciatic nerve
Tibial portion: supplies the skin of the posterolateral leg, lateral foot and the sole of the foot.
Common fibular portion: supplies the skin of the lateral leg and the dorsum of the foot.
leaves the pelvis via the greater sciatic foramen, entering the gluteal region inferiorly to the piriformis muscle. It descends deep to the gluteus maximus and runs down the back of the thigh to the knee.
Posterior Femoral Cutaneous
fx of Posterior Femoral Cutaneous
Motor Functions: None
Sensory Functions: Innervates the skin on the posterior surface of the thigh and leg. Also innervates the skin of the perineum.
This nerve leaves the pelvis via the greater sciatic foramen, then re-enters via the lesser sciatic foramen. It moves anterosuperiorly along the lateral wall of the ischiorectal fossa, and terminates by dividing into several branches.
Pudendal Nerve
fx of pudendal nerve
Motor Functions: Innervates the skeletal muscles in the perineum, the external urethral sphincter, the external anal sphincter, levator ani.
Sensory Functions: Innervates the penis and the clitoris and most of the skin of the perineum.
intramuscular injection into the gluteal region must be given in the
upper lateral quadrant to avoid sciatic nerve (which passess through the lower media quadrant )
refers to compression of the sciatic nerve by the piriformis muscle.
Piriformis syndrome/ deep gluteal syndrome
Clinical features include radicular pain, numbness, muscle weakness and buttock tenderness. The pain can occasionally be exacerbated by internal rotation of the lower limb at the hip.
Piriformis syndrome
Lab findings of piriformis syndrome
X-ray and MRI imaging is usually unremarkable but can exclude other pathology such as spinal compression of the sciatic nerve.
The treatment of piriformis syndrome can be divided into non-operative and operative:
Non-operative – analgesia, physiotherapy and corticosteroid injections
Operative – piriformis muscle release
bilateral bean-shaped organs, reddish-brown in colour and located in the posterior abdomen.
Kidneys
main fx of kidneys
filter and excrete waste products from the blood. They are also responsible for water and electrolyte balance in the body.
level of kidneys
T12-L3
right kidney is slightly lower due to the presence of the liver
Kidney is covered
deep to superficial
renal capsule
perirenal fat
fenal fascia / Gerota’s fascia
Pararenal fat
the renal parenchyma are divided into
cortex
medulla
The cortex extends into the medulla, dividing it into triangular shapes – these are known as
renal pyramids
The apex of a renal pyramid is called a
renal papilla
Each renal papilla is associated with a structure known as the____, which collects urine from the pyramids
minor calyx
encloses the kidneys and the suprarenal glands.
renal fascia
Several minor calices merge to form a
major calyx
Urine passes through the major calices into the
renal pelvis
The medial margin of each kidney is marked by a deep fissure, known as the
renal hilum
The kidneys are supplied with blood via the
renal arteries
this renal artery is longer, and crosses the vena cava posteriorly.
Due to the anatomical position of the abdominal aorta (slightly to the left of the midline), the right renal artery is longer
carry 75% of blood supply to the kidney
anterior division of the renal artery
25% of the blood supply to the kidney
posterior division of the renal artery
avascular plane of the kidney
aka
line of brodel
is an imaginary line along the lateral and slightly posterior border of the kidney, which delineates the segments of the kidney supplied by the anterior and posterior divisions.
avascular plane of the kidney (line of Brodel)
It is an important access route for both open and endoscopic surgical access of the kidney, as it minimises the risk of damage to major arterial branches.
avascular plane of the kidney (line of Brodel)
Each segmental artery divides to form
interlobar arteries
urine flow from renal papilla to bladder
renal papilla -> minor calyx -> major calyx ->major calyx -> renal pelvis -> ureter -> bladder
This acts as a gateway to the kidney – normally the renal vessels and ureter enter/exit the kidney via this structure.
renal hilum
segmental artery to efferent arterioles
segmental artery -> interlobar arteries -> arcuate arteris -> interlobular arteries -> afferent arterioles (cortex) - form glomerulus -> efferent arterioles
a At 90 degrees to the arcuate arteries, these arteries arise
interlobular arteries
supplies the nephron tubules with oxygen and nutrients.
peritubular network
peritubular network is formed by
efferent arterioles in the outer 2/3 of the renal cortex
The inner third of the cortex and the medulla are supplied by
long, straight arteries called vasa recta.
accessory arteries of the kidneys are common in ___ % of patients
25%
If a supernumerary artery does not enter the kidney through the hilum, it is called
aberrant
venous drainage of the kidneys
left and right renal veins.
left and right renal veins drain into
IVC
this renal vein is longer
As the vena cava lies slightly to the right, the left renal vein is longer
this renal artery lies posterior to the inferior vena cava.
right renal artery
Lymph from the kidney drains into the
lateral aortic (or para-aortic) lymph nodes
In utero, the kidneys develop in the pelvic region and ascend to the lumbar retroperitoneal area. Occasionally, one of the kidneys can fail to ascend and remains in the pelvis – usually at the level of the
common iliac artery
failure of kidneys to ascend in utero
pelvic kidney
is where the two developing kidneys fuse into a single horseshoe-shaped structure.
horseshoe kidney (also known as a cake kidney or fused kidney)
This occurs if the kidneys become too close together during their ascent and rotation from the pelvis to the abdomen – they become fused at their lower poles (the isthmus) and consequently become ‘stuck’ underneath this artery
inferior mesenteric artery
Horseshoe kidney presentation
asymptomatic, although it can be prone to obstruction
most common tumor of the kidneys
renal cell carcinoma
kidneys is closely in contact with this muscle
psoas major
3 structures that enter/ leave at renal hilum
- renal vein - anterior
- renal artery
- renal pelvis - posterior
T/F
fibrous capsule of the kidneys is a true capsule
true
Gerota’s fascia is continuous laterally with
fascia tranversalis
how many renal pyramids
12 pyramids
nerve supply of kidneys
renal sympathetic plexus
T10-12
renal transplantation
usual site
iliac fossa on the posterior abdominal wall
for renal transplantation, renal artery is anastomosed to
internal iliac artery
for renal transplantation, renal vein is anastomosed to
external iliac vein
rare vein compression disorder. It occurs when arteries, most often the abdomen’s aorta and superior mesenteric artery, squeeze the left renal (kidney) vein.
nutcracker syndrome
if left renal vein is compressed by SMA as the vein crosses anterior to the aorta
this results
renal and adrenal hypertension on the Left
in males: varicocele on the left
