Muscle Anatomy: Psoas and Iliacus Overview

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary action of the psoas major muscle?

Abduction of the thigh

Flexion and medial rotation of the thigh (correct)

Extension of the thigh

Lateral rotation of the thigh

Which statement about the psoas minor is correct?

It originates from the sides of the 12th thoracic vertebra. (correct)

It primarily assists in the extension of the lumbar spine.

It has a strong contribution to the flexion of the hip.

It is always present in humans.

From where does the psoas major muscle originate?

Pelvic bones

Coccyx and sacrum

Lower ribs

Thoracic to 5th lumbar vertebrae (correct)

Which muscle is associated with the iliopubic eminence?

Psoas minor Signup and view all the answers

What is the nerve supply for the psoas major muscle?

Branches of the lumbar plexus (L2-4) Signup and view all the answers

What is the primary action of the Iliacus muscle?

Flexion and medial rotation of the thigh Signup and view all the answers

Which nerve supplies the Quadratus Lumborum muscle?

Lumbar plexus Signup and view all the answers

Where does the Iliacus muscle primarily originate?

Upper 2/3 of the iliac fossa of the hip bone Signup and view all the answers

Which statement accurately describes the Quadratus Lumborum muscle's role during respiration?

It fixes or depresses the 12th rib during respiration Signup and view all the answers

What contributes to the formation of the lumbar plexus?

Anterior rami of the upper 4 lumbar nerves and T12 nerve Signup and view all the answers

What spinal segments primarily contribute to the formation of the lumbar plexus?

L1 to L4, with some contribution from L5 Signup and view all the answers

Which nerve is responsible for innervating the anterior thigh muscle?

Femoral nerve Signup and view all the answers

Which of the following nerves does NOT arise from the lumbar plexus?

Inferior gluteal nerve Signup and view all the answers

What is the function of the obturator nerve?

Provides sensation to the medial thigh and supplies adductor muscles Signup and view all the answers

Which of the following nerves is formed from roots L2 and L3 and innervates the lateral aspect of the thigh?

Lateral cutaneous nerve of the thigh Signup and view all the answers

Which structure does the lumbar plexus primarily lie within?

Psoas major muscle Signup and view all the answers

Which nerves supply the external genitals?

Genitofemoral and iliohypogastric nerves Signup and view all the answers

What is the contribution of the lumbosacral trunk to the lumbar plexus?

It connects the lumbar plexus with the sacral plexus. Signup and view all the answers

Study Notes

Psoas Major

Originates from the thoracic and lumbar vertebrae, extending from the transverse processes, vertebral bodies, and intervertebral discs
Inserts into the lesser trochanter of the femur.
Supplied by the lumbar plexus (L2-4)
Primarily responsible for flexing and medially rotating the thigh, and flexing the trunk when the thigh is fixed.

Psoas Minor

May be absent in up to 40% of individuals.
Long and slender, originates from the 12th thoracic and 1st lumbar vertebrae as well as the disc between them.
Inserts into the iliopectineal eminence of the hip bone.
Supplied by a branch from the 1st lumbar nerve.
Acts as a weak flexor of the lumbar vertebral column.

Iliacus

Located in the false pelvis, separate from the psoas muscles.
Originates from the upper 2/3 of the iliac fossa, the inner lip of the iliac crest, and the iliolumbar ligament.
Inserts into the lesser trochanter of the femur, joining the tendon of the psoas major to form the iliopsoas muscle.
Supplied by the femoral nerve within the abdomen.
Responsible for flexing and medially rotating the thigh, as well as assisting in flexing the trunk when the thigh is fixed.

Quadratus Lumborum

Flat, quadrilateral-shaped muscle located alongside the vertebral column and lateral to the psoas major.
Originates from the iliolumbar ligament, the adjoining part of the iliac crest, and the tips of the transverse processes of the lower lumbar vertebrae.
Inserts into the lower border of the 12th rib and the transverse processes of the upper four lumbar vertebrae.
Supplied by the lumbar plexus (T12 and L1, 2, 3, 4).
Primarily responsible for fixing or depressing the 12th rib during respiration and laterally flexing the vertebral column towards the same side.

Lumbar Plexus

Formed by the anterior rami of the upper four lumbar nerves as well as a contribution from the T12 (subcostal) nerve.
Lies within the psoas major muscle and interacts with the sympathetic plexus.
The lumbar plexus provides innervation to the lower abdominal wall, external genitalia, hip, thigh, and the medial part of the leg.

Nerves of Lumbar Plexus

Subcostal (T12)
Iliohypogastric (L1)
Ilioinguinal (L1)
Genitofemoral (L1, L2)
Lateral cutaneous nerve of the thigh (L2,3)
Femoral nerve (L2,3,4)
Obturator nerve (L2,3,4)
Accessory obturator nerve (L3,4)
Lumbosacral trunk (L4,5)

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz explores the anatomy and functions of key hip flexor muscles, including the Psoas Major, Psoas Minor, and Iliacus. Discover their origins, insertions, nerve supplies, and roles in movement. Perfect for students studying human anatomy and physiology.