Week 10: Lecture 2 - Lumbar Plexus Flashcards
(47 cards)
What is the lumbar plexus and where is it located?
A network of nerve fibres that supplies the skin
and musculature of the lower limb.
Located in the lumbar region, within the psoas major muscle and anterior to the transverse processes of the lumbar vertebrae
Formed by the anterior rami (divisions) of the lumbar spinal nerves L1, L2, L3 and L4.
It also receives contributions from thoracic spinal nerve 12.
Lumbar plexus and what are it’s branches
- Iliohypogastric nerve
- Ilioinguinal nerve
- Genitofemoral nerve
- Lateral cutaneous of the thigh
- Obturator nerve
- Femoral nerve
Which spinal nerves contribute to the lumbar plexus?
Ventral rami of L1–L4, with contributions from T12.
What mnemonic helps remember the branches of the lumbar plexus?
“I (twice) Got Lost On Freeway” – Iliohypogastric, Ilioinguinal, Genitofemoral, Lateral cutaneous nerve of the thigh, Obturator, Femoral
How are the major peripheral nerves of the lumbar plexus formed and where do they travel?
The ventral rami of L1–L4 divide into several cords, which then combine to form the six major peripheral nerves of the lumbar plexus. These nerves descend along the posterior abdominal wall to reach the lower limb.
What is the origin (root) of the Iliohypogastric nerve
L1 with contributions from T12
What is the insertion of the Iliohypogastric nerve
Runs to the iliac crest, across the quadratus lumborum muscle of the posterior abdominal wall
Then perforates the transversus abdominis, and divides into its terminal branches.
What are the motor and sensory functions of the Iliohypogastric nerve
Motor Functions: Innervates the internal
oblique and transversus abdominis
Sensory Functions: Innervates the
posterolateral gluteal skin and suprapubic region
Iliohypogastric nerve
Is the First major branch of the lumbar plexus
Ilioinguinal Nerve
Follows the same anatomical course as the larger iliohypogastric nerve
What is the origin (root) of the Ilioinguinal Nerve
Roots is L1
What are the motor and sensory functions of the ilioinguinal nerve
Motor Functions: Innervates the internal oblique and transversus abdominis
Sensory Functions:
Innervates the on the superior antero-medial thigh
In males, it also supplies the skin over the root of the penis and anterior scrotum.
In females, it supplies the skin over mons pubis and labia majora.
What is the insertion of the Ilioinguinal nerve
After innervating the muscles of the anterior abdominal wall, it passes through the superficial inguinal ring to innervate the skin of the genitalia and middle thigh.
What are the roots of the genitofemoral nerve?
L1 - L2
Into what branches does the genitofemoral nerve divide, after leaving the psoas major muscle, the genitofemoral nerve
genital branch, and a femoral
branch.
What are the motor and sensory function of the Genitofemerol nerve
Motor Functions: The genital branch
innervates the cremasteric muscle
Sensory Functions:
The genital branch innervates the skin of the anterior scrotum (in males) or
the skin over mons pubis and labia majora (in females).
The femoral branch innervates the skin on the upper anterior thigh.
What is the motor function of the genital branch?
Innervates the cremasteric muscle in males.
What are the roots of the lateral cutaneous nerve of the thigh?
roots L2, L3
Does the lateral cutaneous nerve of the thigh have motor function?
No, it is purely sensory.
What are the sensory functions?
Innervates the anterior and lateral thigh down to the level of the knee.
The lateral cutaneous nevre of the the thigh enters ??
the thigh at the lateral
aspect of the inguinal ligament,
where it provides cutaneous
innervation to the skin there.
What are the roots of the obturator nerve?
roots L2, L3, L4
Through what structure does the obturator nerve enter the medial thigh?
The obturator canal.
The obturator nevre divides into 2 branches
Anterior (anterior to the adductor brevis) branch
Posterior (posterior to the adductor brevis)
