Lumbar plexus Flashcards
where is the lumbar plexus located
located in the lumbar region, within the substance of the psoas major muscle and anterior to the transverse processes of the lumbar vertebrae.
how is the plexus formed
by the anterior rami (divisions) of the lumbar spinal nerves L1, L2, L3 and L4.
which other nerve contributes to the lumbar plexus
T12
spinal nerves
The spinal nerves L1 – L4 form the basis of the lumbar plexus.
At each vertebral level, paired spinal nerves leave the spinal cord via the intervertebral foramina of the vertebral column.
Each nerve then divides into anterior and posterior nerve fibres.
branches
The anterior rami of the L1-L4 spinal roots divide into several cords. These cords then combine together to form the six major peripheral nerves of the lumbar plexus. These nerves then descend down the posterior abdominal wall to reach the lower limb, where they innervate their target structures.
name the six major peripheral nerves of the lumbar plexus in order
- illiohypogastric nerve
- illioinguinal
- genitofemroal
- lateral cutaenous
- femroal
- obturator
acronynm for the lumbar plexus
Imogen gets leftovers on fridays
The iliohypogastric nerve is the
first major branch of the lumbar plexus. Does not supply any structures in the lower limb so it is beyond the scope of this unit.
Illiohypogastric roots
L1 with contributions from T12
how to rememebr ilihypogastric comes before illioinguinal
H comes be fore I in the alphabet
Ilioinguinal Nerve
The ilioinguinal nerve follows the same anatomical course as the larger iliohypogastric 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.
roots of the illioinguinal nerve
L1
motor function of the illioinguinal nerve
Innervates the internal oblique and transversus abdominis.
sensory function of the illioinguinal nerve
Innervates the skin 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.
genitofemoral nerve
After leaving the psoas major muscle, the genitofemoral nerve quickly divides into a genital branch, and a femoral branch.
roots fo the genitofemoral nerve
L1, L2
motor function of the genitofemoral nerve
The genital branch innervates the cremasteric muscle.
Sensory Functions of the genitofemoral nerve
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.
Lateral Cutaneous Nerve of the Thigh
This nerve has a purely sensory function. It enters the thigh at the lateral aspect of the inguinal ligament, where it provides cutaneous innervation to the skin there.
roots of the Lateral Cutaneous Nerve of the Thigh
L2, L3
motor function of Lateral Cutaneous Nerve of the Thigh
none
sensory function of Lateral Cutaneous Nerve of the Thigh
Innervates the anterior and lateral thigh down to the level of the knee.
roots of the obturator nerve
L2, L3, L4
motor function fo the obturator nerve
Innervates the muscles: obturator externus, pectineus, adductor longus, adductor brevis, adductor magnus, gracilis.
