The Muscular System Pelvic Girdle and Lower Limb
Nerve Plexuses Cervical phrenic nerve. Lumbar primary nerves that arise off
of, femoral and obturator nerves. Sacral sciatic nerve, gluteal nerves, and
Common fibular and tibial nerves.
Common means more branches. (Common fibular branches into two nerves)
The Illiopsoas Group
Psoas major and minor: don’t differ in function or innervation. Arise of transverse
processes of lumbar vertebrae.
Illiacus: originates off of iliac crest, psoas muscles come together with illiacus to
form illiopsoas muscle. Illiopsoas inserts onto lesser trochanter of femur. Major
hip flexor. Initial pull upwards from a sit up is entirely the illiopsoas muscle.
Two additional hip flexors, with additional functions that are grouped into
o Sartorius originates from Anterior superior iliac spine, crosses the leg.
Inserts on ‘Gooses foot’ medial tibia.
o Rectus femoris straight, attaches proximally on anterior inferior iliac
spine. Inserts distally onto patella. One of the four quadriceps muscle.
Common innervation is the femoral nerve.
The Gluteal Group
Maximus large and superficial. Posterior Iliac crest all the way down the sacrum,
right to where the sacrum meets the coccyx. Inserts on gluteal tuberosity (top of
linea aspera). Gluteus maximus is the main hip extensor. Lateral rotation is also a
main action. Pulling from posterior aspect of femur.
Medius & Minimus similar function and attachments. Medius is more
superficial. The minimus is smaller and underneath the medius. Originate off of
Ilium and insert onto greater trochanter of femur. Their action is abduction.
Medial rotation of hip joint.
Superior (medius and minimus) and inferior (maximus) gluteal nerves.
Tensor Fascia Latae like a stocking around the thigh. Large, bulky muscles in
the leg, fascia that sits around these muscles and bundles them, enhances the
strength. Positioned right beneath anterior superior iliac spine. Around the thigh,
concentrates interiorly called the IT tract. It inserts onto fibula as well as lateral
tibia. Constant overusage of these muscles leads to stretching, which means
constant pulling of fascia latae. To compensate, the IT tract tightens.
Shares innervation by superior gluteal nerve.
Lateral Rotators Piriformis identify sciatic nerve. Always pops out underneath piriformis.
Originates off of sacrum.
Superior Gemellus twin muscle. Sitting on top of sciatic nerve. The two gemella
are separated by obturator internus. Originates off of Ischial spine.
Obturator internus obtruatur means obstructed. The obturator foramen is
obstructed by the internus muscle.
Inferior Gemellus twin muscle. Originate off of ischial tuberosity.
Quadratus Femoris muscle that’s square. Inserts onto femur. Originate ischial
All of these insert onto the greater trochanter of the femur. In addition to lateral rotation,
these muscles assist the gluteus medius and minimus in hip abduction.
Each nerve innervates the muscle with the corresponding name, as well as the muscle
above it. (Quadratus femoris innervates Q.f. as well as inferior Gemellus, etc.)
Obturator externus different innervation, different function. Can see it popping
through the obtu internus and the inferior gemellus. Obturatur foramen is facing
outwards; on the inside of the pelvis is the origin of the obturator internus. On the
outside, is the origin of the obturator externus. Because it’s on a different side, the
obturator externus is part of the Medial Thigh compartment. Causes medial
rotation of the hip joint.
Medial Thigh Muscles
o Involved in hip flexion, adduction, and medial rotation.
o Common innervation through the obturator nerve (runs through obturator
foramen). Some of these muscles are innervated by the femoral nerve
assists some of the muscles.
Gracilis borders medial thigh muscles from poste