Lumbar Plexus and Nerve Anatomy

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Questions and Answers

Which spinal nerves contribute to the lumbar plexus?

L2 - L4 and T10

L1 - L5 and T12

L1 - L4 and T12 (correct)

L1 - L3 and T11

What is the primary motor innervation provided by the iliohypogastric nerve?

Transversus abdominis muscle (correct)

Serratus anterior muscle

Rectus abdominis muscle

Psoas major muscle

What type of sensory information does the lateral cutaneous branch of the iliohypogastric nerve provide?

Skin of the medial leg

Skin of the forearm

Skin of the posterolateral gluteal region (correct)

Skin of the anterior thigh

Which condition is least likely to cause damage to the iliohypogastric nerve?

Rapid weight loss Signup and view all the answers

The ilioinguinal nerve primarily innervates which muscle?

Internal oblique muscle Signup and view all the answers

Which of the following is a common clinical sign of iliohypogastric nerve damage?

Burning pain in the suprapubic region Signup and view all the answers

What is the function of the anterior cutaneous branch of the iliohypogastric nerve?

Provides sensory innervation to the suprapubic region Signup and view all the answers

The lumbar plexus is primarily responsible for innervating which part of the body?

Lower extremities Signup and view all the answers

What skin area does the saphenous nerve provide sensory innervation to?

Medial leg and foot Signup and view all the answers

Which muscle is NOT innervated by the obturator nerve?

Gluteus medius Signup and view all the answers

Which function is NOT associated with the motor actions of the obturator nerve?

Extending the knee Signup and view all the answers

Which specific branch is responsible for the sensory innervation of the skin over the proximal part of the medial thigh?

Obturator nerve Signup and view all the answers

What is the primary cutaneous supply of the perforating cutaneous nerve?

Inferior medial part of the buttock Signup and view all the answers

Which statement about the sacral plexus is true?

It provides innervation to the gluteal muscles. Signup and view all the answers

Which nerve supplies the hip joint in addition to the quadratus femoris and inferior gemellus muscles?

Nerve to quadratus femoris Signup and view all the answers

Which nerve innervates the tensor fasciae latae muscle?

Superior gluteal nerve Signup and view all the answers

Which of the following muscles is not innervated by the tibial nerve?

Biceps femoris (short head) Signup and view all the answers

Which nerve exits the pelvic cavity through the greater sciatic foramen and is responsible for motor function to the external anal sphincter?

Pudendal nerve Signup and view all the answers

What is the primary role of the obturator nerve in the thigh?

Motor innervation to hip adductors Signup and view all the answers

The posterior femoral cutaneous nerve is responsible for sensory innervation of which body part?

Posterior surface of the thigh and leg Signup and view all the answers

Which statement accurately describes the inferior gluteal nerve?

It innervates the gluteus maximus muscle. Signup and view all the answers

What is the function of the tibial nerve's sensory rami?

Innervate the knee joint Signup and view all the answers

Which of these muscles does the pudendal nerve not innervate?

Quadratus femoris Signup and view all the answers

Which nerve branches into the tibial nerve and the common fibular nerve?

Sciatic nerve Signup and view all the answers

What sensory areas are innervated by the ilioinguinal nerve?

Skin over the pubis and superior antero-medial thigh Signup and view all the answers

What is a common consequence of ilioinguinal nerve damage?

Chronic pain in the groin region Signup and view all the answers

Which muscles are supplied by the ilioinguinal nerve?

Transversus abdominis and internal oblique Signup and view all the answers

The genitofemoral nerve divides into which branches?

Femoral and genital branches Signup and view all the answers

What areas does the femoral branch of the genitofemoral nerve innervate?

Skin of the anterior, upper, and medial thigh Signup and view all the answers

What function does the genital branch of the genitofemoral nerve serve?

Innervates the cremaster muscle in males Signup and view all the answers

Which nerve innervates the skin of the anterior and posterior lateral thigh to the knee?

Lateral femoral cutaneous nerve Signup and view all the answers

How does the femoral nerve reach the thigh?

Emerging below the inguinal ligament Signup and view all the answers

What is the primary function of the gastrocnemius muscle?

Flexion of the knee and plantarflexion of the ankle Signup and view all the answers

Which nerve contributes to sensory innervation of the posterolateral leg and lateral side of the foot?

Sural nerve Signup and view all the answers

The deep fibular nerve is responsible for the motor function of which group of muscles?

Anterior compartment of the leg Signup and view all the answers

What muscles are primarily involved in the plantarflexion of the ankle?

Soleus and gastrocnemius Signup and view all the answers

Which two nerves combine to form the sural nerve?

Medial sural cutaneous and lateral sural cutaneous nerves Signup and view all the answers

What is the function of the tibialis posterior muscle?

Inversion of the foot and plantarflexion of the ankle Signup and view all the answers

Which of the following best describes the function of the superficial fibular nerve?

Motor function to the lateral compartment muscles and sensory function for the dorsum of the foot Signup and view all the answers

Study Notes

Lumbar Plexus

Formed by spinal nerves L1-L4, and contributions from the anterior ramus of T12.

Iliohypogastric Nerve (T12 - L1)

Innervates quadratus lumborum muscle and transversus abdominis muscle.
Has anterior and lateral cutaneous branches.
Damage can be caused by surgical trauma, specifically open appendix procedures, hysterectomies, and sport injuries.
Pregnancy can also cause damage due to abdominal expansion.
Clinical signs include burning pain in the suprapubic and inguinal regions.

Ilioinguinal Nerve (L1)

Situated posterior to the psoas major.
Passes through the internal oblique muscle, and exits the inguinal canal via the superficial inguinal ring.
Innervates the transversus abdominis and internal oblique muscles.
Damage risk is associated with inguinal hernia repairs and pregnancy.
Clinical manifestations involve chronic groin pain lasting more than three months following inguinal hernia repair surgery.

Genitofemoral Nerve (L1-L2)

After exiting the psoas major, it divides into femoral and genital branches.
The femoral branch supplies sensory innervation to the anterior, upper, and medial thigh regions.
The genital branch innervates the anterior scrotal skin in males and the mons pubis and labia majora in females.
The genital branch also supplies motor innervation to the cremaster muscle in males.

Lateral Femoral Cutaneous Nerve (L2-L3)

Originates from the lateral border of the psoas major.
Passes under the inguinal ligament and in front of the sartorius muscle.
Provides sensory innervation to the parietal peritoneum of the iliac fossa.
It's responsible for sensation of the anterior and posterior lateral thigh to the knee.

Femoral Nerve (L2-L4)

Emerges from the lower lateral border of the psoas major and passes under the inguinal ligament.
A mixed nerve providing motor and sensory innervation to the thigh and leg.
Provides innervation to the anterior compartment of the thigh, specifically flexors of the hip, and the extensors of the knee (quadriceps femoris).

Obturator Nerve (L2-L4)

The obturator nerve passes through the obturator canal within the medial thigh.
It provides motor supply to the hip adductors.
The nerve supplies sensory innervation to the skin covering the proximal part of the medial thigh and articulating branches (proximal).

Sacral Plexus

Located on the posterior pelvic wall and formed by the ventral rami of L4-L5 and S1-S4.

Sciatic Nerve (L4 to S3)

Exits via the greater sciatic foramen; located deep to the gluteus maximus.
Branches into the tibial and common fibular nerves.
The sciatic nerve provides motor and sensory function to the thigh and leg.

Tibial Nerve

Branches to muscles in posterior compartment of leg (deep & superficial).
Superficial branches supply plantaris, soleus, and gastrocnemius muscles.
Deep branches supply popliteus, flexor hallucis longus, flexor digitorum longus, and tibialis posterior muscles.

Common Fibular Nerve

Provides motor supply to the lateral compartment of the leg.
It controls the muscles responsible for everting the foot, including fibularis (peroneus) longus and brevis.
Provides sensory innervation to the lateral lower leg and foot.

Superficial Fibular (Peroneal) Nerve

It supplies the lateral compartment muscles of the leg (evertors).
It provides sensation to the distal anterior surface of the leg and dorsum (top) of the foot.

Deep Fibular (Peroneal) Nerve

Innervates muscles in the anterior compartment of the leg, including tibialis anterior, extensor digitorum longus, and extensor hallucis longus.
It also provides sensation to the triangular region between the first and second toes.

Sural Nerve (S1-S2)

Originates from the medial and lateral sural cutaneous nerves.
Has branches supplying lat. dorsal cutaneous nerves of the foot, and lateral calcaneal branches.

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Description

Explore the critical anatomy of the lumbar plexus, focusing on the iliohypogastric, ilioinguinal, and genitofemoral nerves. This quiz covers their innervation, clinical significance, and potential injuries. Perfect for students of anatomy and neurophysiology.