Lower Body Muscles Flashcards
Psoas Major
Origin:
T12-L5 vertebral bodies, intervertebral discs, transverse processes of lumbar vertebrae
Insertion:
Lesser trochanter of the femur
Function:
Primary Hip Flexor, lateral flexion of the vertebral column, helps maintain an upright posture
Nerve Supply:
Anterior rami of L1-L3 (usually L2-L4)
Blood Supply:
Branches from the lumbar arteries
Psoas Minor
Origin:
Usually from the sides of the bodies and discs of T12 and L1 vertebrae
Insertion:
Iliopubic eminence (pelvic brim) and inguinal ligament
Function:
Assists in flexion of the lumbar spine
Nerve Supply:
Typically innervated by the anterior rami of L1 spinal nerve (T12-L5)
Blood Supply:
Receives blood supply from nearby lumbar arteries
Iliacus
Origin:
Iliac fossa of the ilium
Insertion:
Lesser trochanter of the femur, merging with the psoas major to form the iliopsoas tendon
Function:
Flexes the hip joint, helps stabilize the pelvis during standing and walking
Nerve Supply:
Femoral nerve (L2-L4)
Blood Supply:
Branches from the iliac arteries
Diaphragm
🦧
Quadratus Lumborum
Origin:
Iliac crest (posterior part) and iliolumbar ligament
Insertion:
Transverse processes of lumbar vertebrae (L1-L4) and the 12th rib
Function:
Bilateral contraction extends the lumbar spine, unilaterally contracts to laterally flex the spine (bends the trunk to the side), and assists in forced respiration
Like a natural weight belt
Nerve Supply:
Anterior rami of lower thoracolumbar nerves (T12-L4) (not too concerned with nerve supply of abdominal muscles - Tim)
Blood Supply:
Supplied by branches of the lumbar arteries
Diaphragmatic Crura
Right Crus:
Attaches to the bodies of the lumbar vertebrae, primarily L1-L3.
Left Crus:
Attaches to the bodies of the lumbar vertebrae, primarily L1-L2, and sometimes L3.
Function: The crura anchors the diaphragm, providing support for its central tendon and aiding in the muscle’s contraction during inhalation.
Nerve Supply:
The diaphragm, including its crura, is primarily innervated by the phrenic nerves (C3-C5)
Blood Supply:
The diaphragm receives its blood supply from various arteries, including the inferior phrenic arteries, which branch from the abdominal aorta, and the musculophrenic artery, a branch of the internal thoracic artery.
Coccygeus
Origin:
The ischial spine
Insertion:
Blends with the fibers of the opposite side at the midline, forming a tendinous raphe along the coccyx.
Function:
forms part of the pelvic diaphragm. It contributes to pelvic floor support and assists in maintaining continence by supporting the pelvic organs (including the rectum and uterus in females). It plays a role in stabilizing the coccyx.
Nerve Supply:
Innervated by branches from the sacral plexus, primarily the fourth and fifth sacral nerves (S4-S5).
Blood Supply:
Receives blood supply from branches of the internal iliac artery
Levator Ani
dont need nerve supply
Origin:
The levator ani muscle has several components:
Puborectalis: Arises from the pubis bone.
Pubococcygeus: Arises from the posterior aspect of the pubis.
Iliococcygeus: Arises from the tendinous arch of the obturator fascia and the ischial spine.
Insertion:
Blends with the fibers of the opposite side at the midline, forming a tendinous raphe along the coccyx, similar to the coccygeus muscle.
Function:
The levator ani muscle forms a major part of the pelvic diaphragm.
It contributes to pelvic floor support and assists in maintaining continence by supporting the pelvic organs, including the rectum and uterus in females.
It plays a role in stabilizing the coccyx.
Blood Supply:
internal iliac artery,
Puborectalis
just know general attachments
Origin:
Arises from the pubic bone (specifically, the pubic crest and the pubic symphysis).
Insertion: Blends with the fibers of the external anal sphincter and the muscularis of the rectum.
Function: The puborectalis muscle is part of the levator ani muscle group and plays a crucial role in maintaining fecal continence by creating a loop or “sling” around the anorectal junction. It prevents involuntary passage of stool by maintaining a kink in the anorectal angle. When it relaxes, this kink straightens, allowing for defecation.
Nerve Supply:
primarily the fourth and fifth sacral nerves (S4-S5).
Blood Supply:
branches of the internal iliac artery.
Pubococcygeus
just know general attachments
Origin:
Arises from the posterior surface of the pubic bone (pubic symphysis) and the anterior fibers of the obturator fascia.
Insertion: Blends with the fibers of the external anal sphincter and attaches to the coccyx.
Function: The pubococcygeus muscle is a vital component of the pelvic floor musculature. It helps support the pelvic organs, including the bladder and rectum, and contributes to urinary and fecal continence. It plays a role in the voluntary control of urination, helps to close off the urethra, and assists in the maintenance of fecal continence. Contraction of this muscle can also play a role in sexual function.
Nerve Supply: Innervated by branches from the sacral plexus, primarily the fourth and fifth sacral nerves (S4-S5).
Blood Supply: Receives blood supply from branches of the internal iliac artery
Iliococcygeus
just know general attachments
Origin:
Arises from the arcus tendineus levator ani, which is a thick, fibrous structure in the pelvis.
Insertion:
Blends with the fibers of the pubococcygeus and coccygeus muscles and attaches to the coccyx.
Function:
The iliococcygeus muscle is part of the levator ani muscle group, which is crucial for maintaining the integrity and support of the pelvic floor. It helps support pelvic organs such as the bladder and rectum. The iliococcygeus, along with other pelvic floor muscles, plays a role in continence, the control of urination and defecation, and sexual function.
Nerve Supply:
Innervated by branches from the sacral plexus, primarily the fourth and fifth sacral nerves (S4-S5).
Blood Supply:
Receives blood supply from branches of the internal iliac artery.
Sartorius (S)
Origin:
Anterior superior iliac spine of the pelvis
Attachment:
Inserts into the proximal part of the tibia, near the pes anserinus,.
Function:
The sartorius muscle is the longest muscle in the body and has several functions, including flexing the hip joint, abducting the thigh and externally rotating the thigh.
It also flexes the knee joint, contributing to sitting cross-legged (hence its name “sartorius,” which means “tailor” in Latin).
Blood Supply:
branches of the femoral artery, including the superficial circumflex iliac artery and the
Nerve Supply:
the femoral nerve (L2-L4),
Rectus Femoris (TF)
Origin:
Anterior inferior iliac spine (AIIS) of the pelvis
Attachment:
Inserts into the patella via the quadriceps tendon and continues as the patellar ligament, which attaches to the tibial tuberosity on the tibia.
Function:
The rectus femoris is one of the four quadriceps muscles and plays a significant role in extending the knee joint.
It also assists in flexing the hip joint
Blood Supply:
branches of the femoral artery,
Nerve Supply:
femoral nerve (L2-L4),
Vastus Lateralis (VL)
Origin:
originates from the greater trochanter of the femur and the linea aspera,
Attachment:
It inserts into the patella via the quadriceps tendon, and from there, the quadriceps tendon continues as the patellar ligament, attaching to the tibial tuberosity on the tibia.
Function:
The vastus lateralis is one of the four quadriceps muscles and plays a major role in extending the knee joint. It is particularly responsible for the terminal portion of the knee extension during activities like walking, running, and jumping.
Blood Supply:
branches of the femoral artery, including the
Nerve Supply:
femoral nerve (L2-L4),
Vastus Medialis (VM)
Origin:
originates from the linea aspera and the intertrochanteric line of the femur.
Attachment:
It inserts into the patella via the quadriceps tendon, which continues as the patellar ligament, attaching to the tibial tuberosity on the tibia.
Function:
The vastus medialis is one of the four quadriceps muscles and plays a significant role in extending the knee joint. It is particularly important for knee stability and proper tracking of the patella within the patellofemoral groove.
Blood Supply:
branches of the femoral artery
Nerve Supply:
femoral nerve (L2-L4),
Vastus Intermedius
Origin:
The vastus intermedius originates from the anterior and lateral surfaces of the femur, specifically from the body of the femur and the proximal two-thirds of the femur’s shaft.
Attachment:
It inserts into the patella via the quadriceps tendon, which extends as the patellar ligament and attaches to the tibial tuberosity on the tibia.
Function:
The vastus intermedius is one of the four quadriceps muscles and primarily functions to extend the knee joint. It is involved in activities like standing, walking, running, and jumping.
Blood Supply:
branches of the femoral artery, including the deep artery of the thigh.
Nerve Supply:
femoral nerve (L2-L4)
Pectineus
Origin:
originates from the pectineal line of the pubis, which is a ridge on the superior ramus of the pubic bone.
Attachment:
It inserts into the pectineal line of the femur and the linea aspera, which is a ridge on the posterior aspect of the femur.
Function:
The Pectineus muscle is involved in both hip flexion and hip adduction. It also assists in medial rotation of the thigh.
Blood Supply:
branches of the obturator artery, a branch of the internal iliac artery.
Nerve Supply:
the obturator nerve L2-L4.
Piriformis
Origin:
Arises from the anterior surface of the sacrum.
Attachment:
Inserts into the greater trochanter of femur.
Function:
Primarily functions as an external rotator of the hip joint, rotating the thigh away from the body. It also helps abduct the thigh and assists in stabilizing the hip joint.
Blood Supply:
Supplied by branches of the superior and inferior gluteal arteries.
Nerve Supply:
Innervated by the sacral plexus, specifically spinal nerves S1 and S2.
Gluteus Maximus
more concerned with function
Origin:
Posterior part of the ilium, sacrum, and coccyx.
Attachment:
Gluteal tuberosity of the femur and the iliotibial band (IT band).
Function:
The largest and most superficial gluteal muscle, it’s the major extensor of the hip joint. It’s responsible for actions like standing up from a seated position, walking, and running.
Blood Supply:
Supplied by branches of the superior and inferior gluteal arteries.
Nerve Supply:
Innervated by the inferior gluteal nerve.
Gluteus Medius
Origin:
External surface of the ilium, between the anterior and posterior gluteal lines.
Attachment:
Greater trochanter of the femur.
Function:
It abducts and medially rotates the hip, playing a key role in maintaining hip stability, especially during activities like walking and standing on one leg.
Blood Supply:
Supplied by branches of the superior gluteal artery.
Nerve Supply:
Innervated by the superior gluteal nerve.
Gluteus Minimus
Origin:
External surface of the ilium, between the anterior and inferior gluteal lines.
Attachment:
Greater trochanter of the femur.
Function:
Similar to the gluteus medius, it abducts and medially rotates the hip and is important for hip joint stability during walking and other movements.
Blood Supply:
branches of the superior gluteal artery.
Nerve Supply:
Innervated by the superior gluteal nerve.
Gemellus Superior
Origin:
Ischial spine.
Attachment:
Joins with the tendon of obturator internus to insert into the greater trochanter of the femur.
Function:
Acts as an external rotator of the hip joint and assists in hip joint stability.
Blood Supply:
branches of the internal iliac artery.
Nerve Supply:
Innervated by the nerve to obturator internus, a branch of the sacral plexus.
Gemellus Inferior
Origin:
Ischial tuberosity.
Attachment:
Joins with the tendon of obturator internus to insert into the greater trochanter of femur.
Function:
Acts as an external rotator of the hip joint and contributes to hip joint stability.
Blood Supply:
branches of the internal iliac artery.
Nerve Supply:
Innervated by the nerve to obturator internus, a branch of the sacral plexus.
Obturator Internus
Origin:
Internal obturator membrane and surrounding bone of the obturator foramen.
Attachment:
Greater trochanter of the femur.
Function:
Acts as an external rotator of the hip joint and helps stabilize the head of the femur in the hip socket.
Blood Supply:
branches of the internal iliac artery.
Nerve Supply:
Innervated by the nerve to obturator internus, which is a branch of the sacral plexus.
Obturator Externus
Origin:
External surface of the obturator membrane.
Attachment:
Inserts into the trochanteric fossa of the femur.
Function:
Acts as an external rotator of the hip joint, helping to rotate the thigh away from the body’s midline. It also plays a role in hip joint stability and in maintaining the head of the femur in the hip socket.
Blood Supply:
Supplied by branches of the obturator artery.
Nerve Supply:
Innervated by the obturator nerve, which arises from the lumbar plexus (specifically, spinal cord segments L2-L4).
Quadratus Femoris
Origin:
Ischial tuberosity (part of the pelvic bone).
Attachment:
Quadrate tubercle on the intertrochanteric crest of the femur.
Function:
Acts as a hip adductor and lateral rotator of the thigh.
Blood Supply:
Supplied by branches of femoral artery.
Nerve Supply:
Innervated by the nerve to quadratus femoris, a branch of the sacral plexus.
Adductor Longus
Origin:
Pubic bone.
Attachment:
Linea aspera of the femur.
Function:
Primarily an adductor of the hip
Blood Supply:
Supplied by branches of the obturator artery.
Nerve Supply:
Innervated by the obturator nerve.
Adductor Brevis
Origin:
Pubic bone.
Attachment:
Linea aspera of the femur.
Function:
It is also an adductor of the hip,
Blood Supply:
Supplied by branches of the obturator artery.
Nerve Supply:
Innervated by the obturator nerve.
Adductor Magnus
Origin:
Pubic bone, ischial tuberosity, and the linea aspera of the femur.
Attachment:
Linea aspera & adductor tubercle of femur.
Function: It is a powerful hip adductor, but it also contributes to thigh extension and thigh flexion.
Blood Supply:
Supplied by branches of the obturator artery and the femoral artery.
Nerve Supply:
Innervated by the obturator and sciatic nerves.
Gracilis
Origin:
Pubic bone.
Attachment:
Pes anserinus on the tibia.
Function:
It functions as a hip adductor and helps flex the knee joint.
Blood Supply:
Supplied by branches of the obturator artery.
Nerve Supply:
Innervated by the obturator nerve.
Sartorius
Origin:
Anterior superior iliac spine (ASIS).
Attachment:
Pes anserinus on the tibia.
Function:
It is the longest muscle in the body and acts as a flexor and lateral rotator of the hip, as well as a knee flexor.
Blood Supply:
Supplied by branches of the femoral artery.
Nerve Supply:
Innervated by the femoral nerve
Tensor Fasciae Latae
Origin:
Anterior part of the iliac crest and the anterior superior iliac spine (ASIS).
Attachment:
Iliotibial tract (IT band).
Function:
It helps stabilize the pelvis and thigh, and it can also assist in hip flexion and abduction.
Blood Supply:
Branches of the superior gluteal artery.
Nerve Supply:
Innervated by the superior gluteal nerve.
anterior rami of L4-S1
Biceps Femoris
Origin:
Long Head:
Originates from the ischial tuberosity
Short Head:
Originates from the posterior aspect of the femur.
Attachment:
Both heads of the biceps femoris insert into the head of the fibula and the lateral aspect of the tibia.
Function:
primarily responsible for hip extension and knee flexion ). It also plays a role in the lateral rotation of the hip.
Blood Supply:
Supplied by branches of the profunda femoris artery (deep artery of the thigh).
Nerve Supply:
Innervated by the sciatic nerve, specifically its tibial division (L5-S2)
Semitendinosus
Origin:
Originates from the ischial tuberosity (same as the long head of the biceps femoris).
Attachment:
Inserts into the medial aspect of upper tibia.
Function:
The semitendinosus, like the other hamstring muscles, is primarily responsible for hip extension and knee flexion. It also plays a role in medial rotation of the hip.
Blood Supply:
Supplied by branches of the profunda femoris artery.
Nerve Supply:
Innervated by the sciatic nerve, specifically its tibial division (L5-S2)
Semimembranosus
Origin:
Also originates from the ischial tuberosity.
Attachment:
Inserts into the posterior aspect of the medial tibia.
Function:
The semimembranosus is primarily responsible for hip extension and knee flexion. It also plays a role in medial rotation of the hip.
Blood Supply:
Supplied by branches of the profunda femoris artery.
Nerve Supply:
Innervated by the sciatic nerve, specifically its tibial division (L5-S2)
