Anatomy of the Sacral Plexus

Questions and Answers

What is the sacral plexus formed by?

Inferior gluteal nerve, posterior cutaneous nerve of the thigh, and sciatic nerve

Lumbosacral plexus and gluteal region

Superior gluteal nerve, inferior gluteal nerve, and posterior cutaneous nerve of the thigh (correct)

Sciatic nerve, tibial nerve, and common peroneal nerve

What is the sciatic nerve?

A branch of the common peroneal nerve

A branch of the tibial nerve

A terminal branch of the sacral plexus (correct)

A terminal branch of the lumbar plexus

What is the largest nerve in the body composed of?

Lumbosacral plexus and gluteal region bound together with fascia

Superior gluteal nerve and inferior gluteal nerve bound together with fascia

Posterior cutaneous nerve of the thigh and sciatic nerve bound together with fascia

Tibial nerve and common peroneal nerve bound together with fascia (correct)

Where does the abdominal aorta divide into?

Right and left common iliac arteries Signup and view all the answers

What becomes the femoral artery as it passes behind the inguinal ligament?

External iliac artery Signup and view all the answers

What does the popliteal artery divide into?

Anterior and posterior tibial arteries Signup and view all the answers

What supplies the medial side of the big toe?

Medial plantar artery Signup and view all the answers

What forms the plantar arch?

Lateral plantar artery Signup and view all the answers

Which nerve supplies the nail beds and tips of the toes?

Medial plantar nerve Signup and view all the answers

What is similar to the median nerve?

Medial plantar nerve Signup and view all the answers

What is the purpose of the arches in the foot?

To distribute body weight evenly over the foot Signup and view all the answers

What percentage of body weight is normally carried by the heel?

60% Signup and view all the answers

What type of bone is the femur?

Long bone Signup and view all the answers

What is the function of the patella?

To contain the patellar ligament Signup and view all the answers

What is the name of the bone that connects the sacrum to the femur?

Sacroiliac joint Signup and view all the answers

What is the name of the bone that forms the ankle joint?

Talus Signup and view all the answers

What is the name of the bony prominence on the medial side of the ankle?

Medial malleolus Signup and view all the answers

What is the name of the bone that forms the heel of the foot?

Calcaneus Signup and view all the answers

What is the insertion of the Gracilis muscle?

Upper part of shaft of tibia on medial surface Signup and view all the answers

What type of joint is the knee joint?

Modified hinge joint Signup and view all the answers

Which muscles are responsible for flexion of the knee joint?

Biceps femoris, semitendinosus, and semimembranosus Signup and view all the answers

What is the patella involved in?

A gliding joint between the patella and the patellar surface of the femur Signup and view all the answers

Which muscle is responsible for extension of the knee joint?

Quadriceps femoris Signup and view all the answers

What is the adductor hiatus?

A passage for the femoral artery and vein Signup and view all the answers

What are the actions of the Gracilis muscle?

Adducts thigh at hip joint; flexes leg at knee joint Signup and view all the answers

What is the complexity of the knee joint?

It is the most complicated joint in the body Signup and view all the answers

Study Notes

Sacral Plexus

Formed by superior gluteal nerve, sciatic nerve, inferior gluteal nerve, posterior cutaneous nerve of the thigh, and common peroneal nerve.

Sciatic Nerve

A terminal branch of the sacral plexus.
Emerges from the pelvis through the lower part of the greater sciatic foramen below the piriformis muscle.
The largest nerve in the body, consisting of the tibial and common peroneal nerves bound together with fascia.
Commonly terminates in the middle of the thigh by dividing into tibial nerve (medial popliteal nerve) and common peroneal nerve (lateral popliteal nerve, also called common fibular nerve).

Lumbosacral Plexus

No additional information.

Blood Supply of the Lower Limbs

The abdominal aorta divides into right and left common iliac arteries at the level of L4.
Each common iliac artery divides into external and internal iliac arteries.
The external iliac artery becomes the femoral artery as it passes behind the inguinal ligament.
The internal iliac artery shares in the blood supply of the lower limb through its branches, such as the superior and inferior gluteal arteries and obturator artery.
The femoral artery begins at the mid-inguinal point and ends at the opening in the adductor magnus, where it becomes the popliteal artery.
The popliteal artery ends at the lower border of the popliteus muscle by dividing into anterior and posterior tibial arteries.
The anterior tibial artery supplies the anterior compartment of the leg and terminates in front of the ankle joint by becoming the dorsalis pedis artery.
The posterior tibial artery supplies the posterior and lateral compartments of the leg and ends deep to the flexor retinaculum by dividing into medial and lateral plantar arteries.

Arteries of the Sole of the Foot

Medial plantar artery supplies the medial side of the big toe.
Lateral plantar artery forms the plantar arch.
Dorsalis pedis artery is the dorsal artery of the foot, which joins the lateral plantar artery on entering the sole between the two heads of the first dorsal interosseous muscle.

Nerves of the Sole of the Foot

Medial plantar nerve supplies the nail beds and the tips of the toes, similar to the median nerve.
Lateral plantar nerve supplies the lateral side of the foot.

Thigh Muscles

Gracilis muscle:
- Insertion: Upper part of shaft of tibia on medial surface (SGS area).
- Actions: Adducts thigh at hip joint, flexes leg at knee joint.

Posterior Fascial Compartment of the Thigh

No additional information.

Knee Joint

A modified hinge joint consisting of two condylar joints between the medial and lateral condyles of the femur and the condyles of the tibia, and a gliding joint between the patella and the patellar surface of the femur.
Movements: flexion, extension, produced by the biceps femoris, semitendinosus, semimembranosus, gracilis, sartorius, and quadriceps femoris muscles.

Bones of the Lower Limb

Femur (thigh bone):
- Upper end: head, neck, greater trochanter, and lesser trochanter.
- Shaft or body.
- Lower end: medial condyle, lateral condyle, and lateral epicondyle.
Patella (kneecap): a triangular sesamoid bone contained within the patellar ligament.
Tibia (shin bone):
- Upper end: medial condyle, lateral condyle, and tuberosity.
- Shaft or body.
- Lower end: medial malleolus and lateral malleolus.
Fibula (outer lower leg bone):
- Upper end: head, neck, and lateral malleolus.
- Shaft or body.
- Lower end: lateral malleolus.
Foot bones:
- Talus, calcaneus, cuboid, navicular, medial cuneiform, intermediate cuneiform, lateral cuneiform, and five metatarsal bones.
- Phalanges (toe bones): proximal, middle, and distal phalanges.

Arches of the Foot

The bones of the foot are arranged in two arches that are held in position by ligaments and tendons.
The arches provide an ideal distribution of body weight over the soft and hard tissues of the foot.
Normally, the ball of the foot carries about 40% of the weight, and the heel carries about 60%.

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Description

This quiz covers the formation and components of the sacral plexus, including the superior gluteal nerve, sciatic nerve, and more. Test your knowledge of the gluteal region and lumbosacral plexus.