Lower limb anatomy

Bones

The structural framework of the hip region is provided by the pelvis, a structure composed of the pelvic girdle and the coccyx. In turn, the pelvic girdle consists of two hip bones and the sacrum, interconnected at the pubic symphysis and sacroiliac joints.

Each hip bone has three parts (ilium, ischium, pubis) and accepts the head of the femur to form the hip joint. This ball-and-socket joint is responsible for providing the lower extremity with an extensive degree of movement.

If you want to learn more about the hip joint and pelvic girdle, take a look below:

Muscles

Several hip muscles act on the hip joint, causing the thigh, and hence the lower extremity, to move. They are divided into anterior and posterior muscle groups. The latter is further divided into superficial and deep subgroups. The anterior muscle group includes iliacus, psoas major and psoas minor. The posterior superficial muscles are the three gluteal muscles (gluteus maximus, gluteus medius, gluteus minimus), and the tensor fasciae latae. In turn, the posterior deep muscles are the piriformis, obturator internus, obturator externus, superior gemellus, inferior gemellus, and quadratus femoris.

Get a first introduction into these muscles with the following quiz.

The lower limb muscles are a big topic to learn! Feeling a bit overwhelmed? Learn the attachments, innervations and functions of these muscles faster and easier with our lower extremity muscle chart.

Nerves and vessels

Let’s move now to the neurovasculature and see how the structures of the hip are nourished (you can learn more about the neurovasculature of the entire lower limb in this article). The main arteries of this region are the gluteal and femoral arteries, which stem from the iliac arteries. The venous drainage of the entire lower extremity is carried out by superficial and deep venous systems. The main veins draining the hip and pelvis are considered deep and include the external and internal iliac veins, which unite to form the common iliac veins. They have many tributaries, but the most important are the femoral veins, together with the deep veins of the pelvis and thigh. The main nerves supplying the hip region are the cluneal nerves, femoral cutaneous nerves, femoral nerve, obturator nerve, sciatic nerve, and gluteal nerves. All of them, except the cluneal nerves, originate from the lumbar and sacral plexuses.

If you want to find out more about the neurovasculature and take one step closer to mastering the hip and pelvis anatomy, check out the following resources.

Bones and muscles

Now that we’ve learned about the hip and pelvis, we’ll explore the thigh anatomy. The thigh is located between the hip and the knee. It is the strongest and most prominent part of the lower extremity, thus a personal favourite for fitness enthusiasts to showcase. The scaffold of the thigh is provided by the femur, the only bone of this region and the longest bone in the body. It has an upper extremity, a shaft, and a lower extremity, all of which are full of various structural landmarks.

Several muscles attach to, and act on, the femur. They take full advantage of the mobility provided by two joints.

The muscles of the thigh can be divided into three groups: anterior, medial, and posterior. The anterior group occupies the anterior compartment situated at the front of the thigh, and includes the sartorius and quadriceps femoris. The latter is, in fact, one large muscle composed of four smaller ones called rectus femoris, vastus medialis, vastus lateralis, and vastus intermedius. 

The medial group occupies, you guessed it, the medial compartment of the thigh. It includes the pectineus, adductor magnus, adductor minimus, adductor longus, adductor brevis, and gracilis. These muscles are also called the adductors of the thigh.

The posterior muscle group is the smallest group, occupying the posterior compartment of the thigh. It contains the three hamstring muscles called the semimembranosus, semitendinosus, and biceps femoris. 

If you want a summary of the muscles of both regions and a way to actively learn their attachments together with further details, use the following study unit!

Nerves and vessels

The neurovasculature of the thigh is a direct continuation of the one from the hip. The arterial supply comes from the femoral artery and its branches. The main vein draining the thigh, and actually the entire lower limb, is the femoral vein. It is part of the deep venous system, drains into the external iliac vein, and is a direct continuation of the popliteal vein. The femoral vein also receives deoxygenated blood from the circumflex veins, the long saphenous vein, and the deep vein of the thigh. Innervation is provided by two major nerves and their branches: femoral and sciatic nerves. They originate from the lumbar and sacral plexuses, respectively.

Before moving on, review the neurovasculature of the hip and thigh with our quiz!

Bones

The two main bones of the leg are the tibia (‘shin bone’) located medially and the fibula, which is located more laterally. The tibia is the largest of the two, hence it is responsible for weight bearing. Two joints hold the tibia and fibula together (the superior and inferior tibiofibular joints), as well as an anatomical structure called the interosseous membrane.

Muscles

The leg is divided into three compartments: anterior, posterior, and lateral. The anterior muscle group includes: tibialis anterior, extensor hallucis longus, extensor digitorum longus, and fibularis/peroneus tertius. 

The posterior compartment consists of seven muscles in total, divided into superficial and deep groups. The superficial muscles are the gastrocnemius, soleus (together forming the triceps surae), and plantaris; while the deep layer consists of the popliteus, tibialis posterior, flexor digitorum longus, and flexor hallucis longus.

The lateral compartment of the leg is the smallest one, containing only two muscles: fibularis/peroneal longus and brevis. 

If you want to learn further details about these muscles and master the leg anatomy, take a look below!

Nerves and vessels

The main arteries supplying the leg with oxygenated blood are the anterior and posterior tibial arteries together with their branches. The posterior tibial artery gives off a crucial branch called the fibular/peroneal artery which mainly supplies the muscles of the leg. The tibial arteries originate from the popliteal artery. When it comes to important veins of the leg; the small/short, and the great/long, saphenous veins provide the superficial drainage. The former opens into the femoral vein, while the latter into the popliteal vein. The deep veins of the leg are named fibular and tibial, with the tibial also finishing in the popliteal vein.

In terms of innervation, the leg receives it via the common fibular/peroneal, tibial, and saphenous nerves. The first two are branches of the sciatic nerve while the latter stems from the femoral nerve. These three nerves divide further to supply the various structures of the leg.

Bones

You’ve seen that a bone called the talus is involved in the ankle joint. However, this is only one out of many foot bones. These include the 7 tarsals; calcaneus, talus, navicular, cuboid, and cuneiform (three in total) bones, as well as the metatarsals, and phalanges. They are held together by several ligaments, the most well known being the collateral and long plantar ligaments of the foot.

Learning so many bones takes time, so firstly begin with their names. However, your anatomy exams will expect you to know the foot in detail and this is where the following resources come into play.

Muscles

Several muscles attach to the previously named foot bones. They are divided into four groups: central, lateral, medial, and dorsal. The first three groups are collectively called the plantar muscles of the foot because they are located on the plantar aspect.

The central group of muscles is located within the central compartment of the foot. They are arranged into several layers. These muscles are called; flexor digitorum brevis, quadratus plantae, lumbricals, plantar interossei, and dorsal interossei. 

Moving more laterally, but still on the plantar side of the foot, we meet the muscles of the lateral compartment: abductor digiti minimi, flexor digiti minimi brevis, and opponens digiti minimi.

The medial group of muscles are also three in number and they are called abductor hallucis, adductor hallucis, and flexor hallucis brevis. Note that adductor hallucis is anatomically located in the central compartment of foot, but it is functionally classified as a medial plantar muscle due to its actions on the great toe (hallux).

Now let’s go to the dorsum, or top, of the foot. There are only two dorsal muscles here: extensor digitorum brevis and extensor hallucis brevis. 

Although the vast majority of resources separate the foot muscles by compartments, they can also be separated according to their locations. The muscles originating further up from the leg are called the ‘extrinsic’ muscles of the foot, while those attaching strictly below the ankle are called the ‘intrinsic’ muscles.

If you want to learn all the muscles of the lower limb, take a look at the following video!

Nerves and vessels

The arterial supply of the foot is provided by the dorsal artery of the foot and its branches on the dorsal side. In turn, the deep plantar arch and its branches are responsible for the vascularisation of the plantar side. In terms of venous drainage, the superficial veins of the foot consist of the superficial dorsal and plantar venous networks. The deep veins include the deep plantar arch and the dorsal venous arch. These superficial and deep systems collect blood from the marginal, digital, and metatarsal veins of the foot. The superficial veins drain into the dorsal venous arch. In turn, the venous arches drain into the saphenous veins of the leg. Regarding innervation, the main nerves responsible for supplying the foot are the medial and plantar nerves, together with the digital nerves.

If you want to learn more about the neurovasculature of the foot as well as its origins, take a look at the following study unit!

In order to properly round up the study process of the lower extremity anatomy, we have designed a quiz that specially aims at the bones, joints, muscles, nerves and vessels of this region. Take this quiz and reinforce your knowledge about the lower limb anatomy!