Neuroanatomy of Cutaneous Nerves and Veins

Questions and Answers

Which nerve supplies the skin on the lateral foot?

Lateral cutaneous nerve of leg

Superficial fibular nerve

Sural nerve (correct)

Saphenous nerve

Which of the following nerves is responsible for innervating the anterior leg?

Sural nerve

Superficial fibular nerve (correct)

Lateral cutaneous nerve of leg

Saphenous nerve

What structure does the great saphenous vein primarily drain?

Lateral side of leg

Dorsum of foot and toes

Medial side of arch (correct)

Anterior leg

What defines the anterior and posterior intermuscular septa in the leg?

They divide the leg into anterior and posterior compartments. Signup and view all the answers

Where does the small saphenous vein drain?

Popliteal vein Signup and view all the answers

What anatomical feature is formed by the thickened areas around the ankle?

Retinacula Signup and view all the answers

How do the muscles in the leg compartments contribute to venous return?

Through muscle contraction creating pressure. Signup and view all the answers

Which muscle is primarily responsible for dorsiflexing the foot and inverting it?

Tibialis anterior Signup and view all the answers

Which joint type is the superior tibiofibular joint classified as?

Synovial joint Signup and view all the answers

What is the main action of the extensor digitorum longus muscle?

Extension of the lateral 4 toes Signup and view all the answers

Which nerve is responsible for innervating the muscle fibers of the fibularis longus?

Superficial fibular nerve Signup and view all the answers

Which muscle originates from the lower 1/3rd of the medial surface of the fibula?

Fibularis (Peroneus) Tertius Signup and view all the answers

What is the role of the interosseous membrane in the intermediate tibiofibular joint?

Attachment for muscles Signup and view all the answers

Which of the following statements is correct regarding the inferior tibiofibular joint?

It is strengthened by the interosseous tibiofibular ligament. Signup and view all the answers

Which muscle acts as a weak dorsiflexor and evertor of the foot?

Fibularis (Peroneus) Tertius Signup and view all the answers

What is the primary action of the fibularis (peroneus) brevis muscle?

Eversion of the foot Signup and view all the answers

Which of the following nerves arises from the bifurcation of the sciatic nerve?

Common fibular nerve Signup and view all the answers

Study Notes

Cutaneous Nerves

Sural Nerve: A branch of the tibial nerve, innervates the posterior leg and lateral foot.
Saphenous Nerve: A branch of the femoral nerve, supplies sensation to the skin on the medial side of the leg and foot.
Superficial Fibular Nerve: A branch of the common fibular nerve, provides cutaneous innervation to the anterior leg and dorsum of the foot.
Lateral Cutaneous Nerve of Leg: A branch of the common fibular nerve, serves the superior lateral part of the leg.

Veins of the Superficial Fascia

Dorsal Venous Arch: Drains blood from the dorsum of the foot and toes.
Great Saphenous Vein: Originates from the medial side of the dorsal venous arch and ascends along the medial leg.
Short/Small Saphenous Vein: Arises from the lateral side of the arch, runs up the posterior calf alongside the sural nerve, pierces the deep fascia at the popliteal fossa, and drains into the popliteal vein.

Deep Fascia of the Leg

Dense and strong, forms a "stocking" around the leg, contributing to vascular function.
Thickened regions around the ankle form five retinacula, providing support and stability.
Intermuscular Septa: Separate compartments in the leg; anterior, lateral, and posterior compartments.
Anterior and posterior intermuscular septa extend from deep fascia to fibula, dividing muscle groups and optimizing functional organization.
Muscle contraction increases pressure within compartments, aiding venous blood return through a muscle pump mechanism.
Each compartment is innervated by different nerves, allowing for targeted motor control.

Superior Tibiofibular Joint

Synovial joint located between the head of the fibula and the inferolateral surface of the lateral tibial condyle.
Allows slight gliding movements.

Intermediate Tibiofibular Joint

Fibrous joint that serves as an attachment point for muscles.

Inferior Tibiofibular Joint

Strong interosseous tibiofibular ligament connects the tibia and fibula, located superior to the ankle joint.

Muscles Involved in Dorsiflexion and Toe Extension

Comprised of four muscles responsible for dorsiflexing the ankle and extending the toes:
- Tibialis Anterior
  - Origin: Superior 2/3 of lateral tibia and interosseous membrane.
  - Insertion: Medial cuneiform and base of the 1st metatarsal.
  - Action: Dorsiflexes and inverts the foot.
  - Innervation: Deep fibular nerve.
- Extensor Digitorum Longus
  - Origin: Upper ¾ of medial fibula and adjacent interosseous membrane.
  - Insertion: Splits into 4 slips to lateral 4 toes forming dorsal extensor expansions.
  - Action: Dorsiflexes ankle and extends lateral 4 toes.
  - Innervation: Deep fibular nerve.
- Extensor Hallucis Longus
  - Deep to extensor digitorum longus.
  - Origin: Middle ½ of medial fibula and adjacent interosseous membrane.
  - Insertion: Base of the distal phalanx of the big toe.
  - Action: Dorsiflexes ankle and extends big toe.
  - Innervation: Deep fibular nerve.
- Fibularis (Peroneus) Tertius
  - Origin: Lower 1/3 of medial surface of fibula.
  - Insertion: Shaft of the 5th metatarsal.
  - Action: Weak dorsiflexor and evertor of the foot.
  - Nerve supply: Deep fibular nerve, often absent in 61.4% of the population.

Extensor Digitorum Brevis

Origin: Upper lateral calcaneus, splitting into four muscle bellies.
Insertion: Dorsal extensor expansions of the medial 4 toes, with the most medial sometimes referred to as extensor hallucis brevis.
Action: Extends the medial 4 toes.
Innervation: Deep fibular nerve.

Muscles for Foot Eversion

Comprised of fibularis longus and fibularis brevis, both supplied by the superficial fibular nerve.
- Fibularis (Peroneus) Longus
  - Lies superficial to fibularis brevis.
  - Origin: Upper 2/3 of the lateral shaft of fibula.
  - Insertion: Tendon runs behind lateral malleolus, hooking around cuboid bone, and inserts into medial cuneiform and base of the 1st metatarsal.
  - Action: Everts foot, functions as a weak plantar flexor of the ankle, and maintains foot arches.
  - Innervation: Superficial fibular nerve.
- Fibularis (Peroneus) Brevis
  - Origin: Lower 2/3 of the lateral fibula shaft, located deep to fibularis longus.
  - Insertion: Tendon runs behind lateral malleolus and inserts into the tubercle on the base of the 5th metatarsal.
  - Action: Everts the foot and weakly plantar flexes the ankle.
  - Innervation: Superficial fibular nerve.

Nerve Supply

All muscles are supplied by the sciatic nerve via the tibial or common fibular branches.
Tibial Nerve: Innervates the posterior compartment and muscles of the sole of the foot.
Superficial Fibular Nerve: Innervates the lateral compartment.
Deep Fibular Nerve: Innervates the anterior compartment and extensor digitorum brevis.
Nerve origins: L4, L5, S1, S2 from the bifurcation of the sciatic nerve in the thigh, passing through the popliteal fossa and around the neck of the fibula.

Pathway of Nerves

Superficial fibular nerve arises from the common fibular nerve, supplying fibularis longus and brevis, and skin on the inferior anterior leg and dorsum of the foot.
Deep fibular nerve descends along the anterior interosseous membrane with the anterior tibial artery, supplying anterior muscles and skin between the 1st and 2nd toes.

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Description

This quiz covers the anatomy and functions of various cutaneous nerves, including the sural, saphenous, superficial fibular, and lateral cutaneous nerves of the leg. Additionally, it explores the veins of the superficial fascia, such as the dorsal venous arch and great saphenous vein. Test your knowledge on these essential neurovascular structures!