12 Nerves and Vessels of the Lower Extremity
Learning Objectives:
- Explain the anatomy of the nerves of the lower extremity.
- Identify the muscles and sensory regions innervated by each nerve of the lower extremity.
- Describe the arteries of the lower extremity and identify the regions supplied by each artery.
- Describe the veins of the lower extremity and identify the regions drained by each vein.
Terms to Know
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Nerves of the Lower Extremity
Veins of the Lower Extremity
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Arteries of the Lower Extremity
Other Terms
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Introduction
Today you will learn about the neurovasculature of the lower extremity. You will use videos from the digital atlas, lower extremity dissections, plastinated specimens, and image slideshows to explore the nerves, arteries, and veins of the gluteal region, thigh, leg, and foot. Keep in mind that all structures are not visible using all tools, and that is OK. By the end of the lab today, you should have identified all of the structures on the list using multiple sources. Over the next two labs, you will learn about the muscles, and you will make the connection between these nerves and vessels and the muscles they innervate or supply.
In this lab, we will mention the general area innervated and supplied by these nerves and vessels. In future labs, we will study this more in-depth. You should reference the muscle tables posted on Canvas to see the specific muscles innervated by each nerve. Use the chart to complete the practice activity at the end of this virtual lab guide chapter.
Lab Activities
Activity 1: Posterior Neurovasculature of the Lower Extremity
Like the previous units, you should use nearby structures as a reference when identifying neurovascular structures of the lower extremity. By following a nerve or artery to a specific muscle, you can determine which artery or nerve it is. In addition to the videos posted on Canvas, you can observe these structures using Abrahams’ and Netter’s atlases and sources on the Resources page.
- Gluteal Region: Observe the inferior and superior gluteal nerves and inferior and superior gluteal arteries. The inferior gluteal nerve and artery travel together, while the superior gluteal nerve and artery also travel together. Together these nerves and vessels supply and innervate the muscles of the gluteal region and lateral thigh. The arteries are branches off of the internal iliac arteries.
- The ligaments of the pelvis for the greater sciatic foramen in the region of the greater sciatic notch of the pelvis, and the inferior and superior gluteal arteries and nerves both travel through this foramen. The superior gluteal artery and nerve leave the greater sciatic foramen superior to the piriformis muscle. In comparison, the inferior gluteal artery and nerve exit the greater sciatic foramen inferior to the piriformis muscle.
- Popliteal artery: Observe the diamond-shaped region at the posterior aspect of the knee, bounded superiorly by the hamstring tendons on each side, and inferiorly by the lateral and medial heads of the gastrocnemius. This region is called the popliteal fossa. When the femoral artery travels through the opening in the adductor magnus and emerges into this space, it is now called the popliteal artery. The popliteal vein also travels with the artery in this space and is continuous with the femoral vein. The popliteal artery ends just inferior to the knee joint as it splits to form the anterior tibial and posterior tibial arteries. The posterior tibial artery may appear as a continuation of the popliteal artery with the anterior tibial artery branching off it.
- Sciatic nerve: The sciatic nerve comprises the tibial and common fibular (peroneal) nerves together within a fibrous sheath. (Note that fibular and peroneal are interchangeable. Peroneal is the older term, and it is slowly being replaced with fibular. Either would be acceptable on an exam.) In the gluteal region, the sciatic nerve runs deep to the piriformis and emerges at the inferior border of this muscle before descending in the posterior thigh. The sciatic itself does not innervate any muscles as it passes through the thigh, but its branches innervate hamstring muscles. The tibial division innervates the semimembranosus, semitendinosus, and long head of the biceps femoris, while the common fibular division innervates the short head of the biceps femoris. Notice that it splits into the tibial nerve and common fibular (peroneal) nerve in the popliteal fossa. Though this is the most common location of the split, this can occur anywhere along the sciatic nerve path, even as superior as the gluteal region.
- Neurovasculature of the compartments of the leg and foot: The muscles of the leg are divided into four compartments: anterior, lateral, deep posterior, and superficial posterior. Each compartment is typically innervated by one nerve and receives its blood supply from one artery.
- Superficial and deep posterior compartments: The tibial nerve continues into the leg and travels inferiorly between the superficial and deep posterior compartments, innervating the muscles in both compartments. After wrapping around the medial malleolus, it branches into the lateral and medial plantar nerves, which innervate the muscles of the plantar aspect (bottom) of the foot. The posterior tibial artery also travels with the tibial nerve between the superficial and deep posterior compartments, supplying both compartments. It then runs around the medial malleolus and divides into the medial and lateral plantar arteries that supply the medial and lateral aspects of the foot. The lateral plantar artery gives off the plantar arch, which gives off digital arteries to supply the foot and toes.
Activity 2: Anterior And Lateral Neurovasculature of the Lower Extremity
In addition to the videos posted on Canvas, you can observe these structures using Abrahams’ and Netter’s atlases and sources on the Resources page.
- Femoral Triangle: The femoral triangle is a space created by the sartorius laterally, the adductor longus medially, and the inguinal ligament superiorly. The pectineus muscle forms the floor of this space. The femoral nerve, femoral artery, and femoral vein travel through this space wrapped together in a common sheath of tissue.
- Femoral artery: This artery is an extension of the external iliac artery from the pelvis. It is named the femoral artery after it travels deep to the inguinal ligament to enter the leg. Similar to the arteries of the upper extremity, this is a case of the same vessel (“tube”) having a different name depending on its location. This artery supplies the anterior structures of the thigh. Follow this artery as it descends through the thigh, and notice that it travels through an opening in the adductor magnus muscle towards the posterior aspect of the knee.
- The largest branch of the femoral artery is the deep femoral artery. This artery runs posteriorly and supplies the muscles of the posterior and medial regions of the thigh. Also, observe the medial and lateral circumflex femoral arteries branching from the deep femoral artery and traveling towards the femur.
- Femoral nerve: This nerve branches into many small branches shortly after entering the thigh. These branches innervate muscles of the anterior thigh and some fibers of the pectineus, and you can follow the branches to these muscles.
- Femoral vein: This vein travels with the femoral artery through the thigh. It carries blood from the lower extremity back to the pelvis. The artery has a thicker wall and maintains a round shape, while the vein tends to collapse against the artery.
- Femoral artery: This artery is an extension of the external iliac artery from the pelvis. It is named the femoral artery after it travels deep to the inguinal ligament to enter the leg. Similar to the arteries of the upper extremity, this is a case of the same vessel (“tube”) having a different name depending on its location. This artery supplies the anterior structures of the thigh. Follow this artery as it descends through the thigh, and notice that it travels through an opening in the adductor magnus muscle towards the posterior aspect of the knee.
- Anterior compartment of the leg: Observe the common fibular (peroneal) nerve wrapping around the head of the fibula. It then splits into the superficial fibular (peroneal) and deep fibular (peroneal) nerves. The deep fibular nerve travels through the anterior compartment of the leg and innervates the muscles of this compartment. From the popliteal artery and posterior tibial artery, follow the anterior tibial artery as it travels towards the anterior compartment. You can see this artery traveling with the deep fibular nerve deep to the tibialis anterior. As the anterior tibial artery crosses the talocrural (ankle) joint, it becomes the dorsal pedis (dorsalis pedis) artery, which supplies muscles and nerves on the dorsal aspect of the foot. If a clinician suspects blood flow to the foot may be blocked, which could occur with an injury such as a full knee dislocation or with occlusion due to atherosclerosis, a clinician will check for a pulse at this artery.
- Lateral compartment: The superficial fibular (peroneal) nerve innervates the muscles of the lateral compartment of the leg. This compartment receives its blood supply from the fibular artery. This artery is a branch of the posterior tibial artery shortly after it branches from the popliteal artery in the popliteal fossa.
Activity 3: Medial Neurovasculature of the Lower Extremity
In addition to the videos posted on Canvas, you can observe these structures using Abrahams’ and Netter’s atlases and sources on the Resources page.
- Obturator nerve: Observe the nerve /nerve branches running to adductor longus, adductor brevis, and/or gracilis. These are branches of the obturator nerve, which innervates several of the muscles in the medial aspect of the thigh.
- Obdurator artery: The obturator artery, which branches from the internal iliac artery just inferior to the superior gluteal artery, runs anterolaterally along the ilium. It then runs through the obturator foramen of the pelvis along with the obturator nerve.
- The obturator artery gives off the acetabular branch or the artery to the femoral head. This artery travels through the ligamentum teres and helps to supply the femoral head.
The 3D activity below includes the majority of the arteries in the lower extremity. However, it is not perfect, and we do not ask students to know every artery shown, only those in the terms to know list above.
Activity 4: Veins of the Lower Extremity
In addition to the videos posted on Canvas, you can observe these structures using Abrahams’ and Netter’s atlases and sources on the Resources page.
Observe the two main superficial veins of the leg, the great saphenous vein and the small saphenous vein. The small saphenous vein drains the lateral foot and leg and drains into the popliteal vein. The great saphenous vein drains the rest of the lower limb and drains into the femoral vein near the hip.
The deep veins of the lower extremity travel with the artery of the same name. Notice how the anterior tibial vein travels with the anterior tibial artery, and the posterior tibial vein travels with the posterior tibial artery, for example. Furthermore, the fibular vein travels on the posterolateral aspect of the interosseous membrane with the fibular artery. The fibular vein drains the lateral leg and ankle and drains into the posterior tibial vein. The anterior and posterior tibial veins drain the anterior and posterior compartments of the leg, respectively, and unite to form the popliteal vein.
Moving superiorly, observe the popliteal vein and notice that it ends just superior to the knee. At this point, it becomes the femoral vein. In addition to the great saphenous vein, the deep femoral vein also drains into the proximal portion of the femoral vein. Similar to the femoral artery, the femoral vein becomes the external iliac vein as it passes deep to the inguinal ligament.
Wrap up and clinical connection
You have identified the neurovasculature of the lower extremity in this lab. Using the following slideshow, can you start organizing muscles based on innervation?
The clinical connection for today involves an orthopedic surgeon discussing a traumatic injury, a knee dislocation. The discussion is a good review of the bones and ligaments of the knee. The surgeon also discusses potential neurovascular damage associated with a knee dislocation. The second slide shows a video of a patient with drop foot. Damage to which nerve may cause drop foot?