THIGH MUSCLES, FEMORAL TRIANGLE AND SUBSARTORIAL CANAL
Muscles of the thigh
The thigh is composed of numerous muscles that are responsible for various movements and functions. Here is a list of the major muscles of the thigh:
- Quadriceps Femoris Group:
- Rectus Femoris: Located in the front of the thigh, it extends the knee and flexes the hip.
- Vastus Lateralis: Located on the outer side of the thigh, it extends the knee.
- Vastus Medialis: Located on the inner side of the thigh, it extends the knee.
- Vastus Intermedius: Located deep to the rectus femoris, it extends the knee.
- Hamstring Group:
- Biceps Femoris: Located on the back of the thigh, it flexes the knee and extends the hip.
- Semitendinosus: Located on the back and medial side of the thigh, it flexes the knee and extends the hip.
- Semimembranosus: Located on the back and medial side of the thigh, it flexes the knee and extends the hip.
- Adductor Group:
- Adductor Longus: Located on the medial side of the thigh, it adducts the thigh.
- Adductor Magnus: Located on the medial side of the thigh, it adducts the thigh.
- Adductor Brevis: Located on the medial side of the thigh, it adducts the thigh.
- Gracilis: Located on the medial side of the thigh, it adducts the thigh.
- Sartorius: Located on the anterior and lateral side of the thigh, it flexes the hip and knee and rotates the thigh outward.
- Tensor Fasciae Latae: Located on the lateral side of the thigh, it flexes and abducts the hip.
- Iliopsoas Group:
- Psoas Major: Located on the front of the lumbar spine, it flexes the hip.
- Iliacus: Located in the iliac fossa of the pelvis, it flexes the hip.
- Gluteus Maximus: Located on the buttocks, it extends and externally rotates the hip.
- Gluteus Medius: Located on the lateral side of the hip, it abducts and internally rotates the hip.
These are some of the major muscles of the thigh, and there are other smaller muscles and deeper muscles as well that contribute to the complex movements and stability of the thigh.
Attachments and innervations of the thigh muscles
The thigh muscles are a group of powerful muscles located in the upper leg region. They are responsible for various movements of the hip and knee joints and play a crucial role in walking, running, and other lower limb activities. The thigh muscles can be divided into three main compartments: anterior (front), medial (inner), and posterior (back) compartments.
- Anterior Compartment:
- Quadriceps Femoris: The quadriceps femoris is a group of four muscles that include the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. These muscles collectively form the bulk of the anterior thigh and are primarily responsible for extending the knee joint. The quadriceps femoris is innervated by the femoral nerve.
- Medial Compartment:
- Adductor Longus: The adductor longus muscle is located on the inner side of the thigh. It helps in adducting the thigh (bringing it closer to the midline) and assists in flexion and medial rotation of the hip joint. The adductor longus is innervated by the obturator nerve.
- Adductor Brevis: The adductor brevis is another muscle in the medial compartment of the thigh. It performs similar functions to the adductor longus, assisting in thigh adduction, flexion, and medial rotation. The adductor brevis is also innervated by the obturator nerve.
- Adductor Magnus: The adductor magnus is the largest muscle in the medial compartment of the thigh. It has two parts: the adductor portion and the hamstring portion. The adductor portion assists in adduction and medial rotation of the hip, while the hamstring portion contributes to hip extension. The adductor magnus is innervated by the obturator and sciatic nerves.
- Posterior Compartment:
- Hamstrings: The hamstrings are a group of three muscles that include the biceps femoris, semitendinosus, and semimembranosus. They are located at the back of the thigh. The hamstrings are responsible for flexing the knee joint and extending the hip joint. They are innervated by the sciatic nerve.
- Gluteus Maximus: Although the gluteus maximus primarily belongs to the buttock region, its lower fibers extend into the posterior thigh. It acts to extend and laterally rotate the hip joint. The gluteus maximus is innervated by the inferior gluteal nerve.
Each of these thigh muscles receives its blood supply from various arteries and is innervated by specific nerves. The attachments of these muscles include various bony landmarks in the hip, pelvis, and thigh region, enabling them to produce the desired movements and stabilize the lower limb during locomotion.
Femoral triangle
The femoral triangle is an anatomical region located in the upper thigh, specifically in the inguinal (groin) area. It is formed by the borders of three muscles: the inguinal ligament, the sartorius muscle, and the adductor longus muscle. The femoral triangle is so named because it resembles a triangular shape when these structures are outlined.
The boundaries of the femoral triangle are as follows:
- Superior boundary: Formed by the inguinal ligament, a fibrous band that stretches from the anterior superior iliac spine (ASIS) of the hip bone to the pubic tubercle.
- Medial boundary: Formed by the adductor longus muscle, one of the muscles of the inner thigh. This muscle runs from the pubic bone to the middle of the femur (thigh bone).
- Lateral boundary: Formed by the sartorius muscle, the longest muscle in the body, which extends diagonally across the thigh from the anterior superior iliac spine to the medial side of the knee.
Within the femoral triangle, several important structures pass or are located:
- Femoral artery: The main artery that supplies blood to the lower limb. It passes through the femoral triangle, just below the inguinal ligament.
- Femoral vein: This vein runs parallel to the femoral artery and carries deoxygenated blood back from the lower limb.
- Femoral nerve: The femoral nerve provides sensory and motor innervation to the muscles and skin of the anterior thigh.
- Deep inguinal lymph nodes: These lymph nodes are located within the femoral triangle and receive lymphatic drainage from the lower limb.
The femoral triangle serves as an important landmark for various medical procedures, such as vascular access, nerve blocks, and surgical interventions in the groin region.
Subsartorial canal
The subsartorial canal, also known as the adductor canal, is a narrow passageway located in the thigh region of the human body. It is situated in the anterior (front) compartment of the thigh, just below the inguinal ligament, which is the band of connective tissue stretching from the anterior superior iliac spine (ASIS) to the pubic tubercle.
Anatomically, the subsartorial canal extends from the apex of the femoral triangle, where the femoral artery passes beneath the sartorius muscle, to the adductor hiatus. The adductor hiatus is an opening within the distal portion of the adductor magnus muscle, where the canal transitions into the popliteal fossa at the back of the knee.
The subsartorial canal is traversed by several structures, including the femoral artery, femoral vein, saphenous nerve, and nerve to vastus medialis (a branch of the femoral nerve). These structures are contained within a fibrous sheath called the adductor canal, which provides a protective covering and helps maintain their position within the canal.
The primary function of the subsartorial canal is to serve as a conduit for the neurovascular structures passing through it. The femoral artery is a major blood vessel that supplies the thigh, and it travels through the canal, giving off various branches that provide oxygenated blood to the surrounding muscles and tissues. The femoral vein runs alongside the artery, facilitating the return of deoxygenated blood back to the heart. The saphenous nerve, a sensory nerve, also passes through the canal, providing innervation to the skin on the medial side of the leg and foot.
The subsartorial canal has clinical significance in the context of surgical procedures, particularly in knee surgery. Nerve blocks or anesthetic injections can be administered within the canal to provide pain relief during and after surgery. Additionally, understanding the anatomy of the subsartorial canal is essential for avoiding injury to the neurovascular structures during surgical interventions in the thigh region.
Thigh Muscles Classification
The muscles of the thigh can be classified according to their actions into the following categories:
- Flexors of the hip: a. Iliopsoas: This muscle group consists of the psoas major and iliacus muscles. They flex the hip joint, bringing the thigh towards the abdomen. b. Rectus femoris: This muscle is one of the quadriceps muscles and functions to flex the hip as well as extend the knee.
- Extensors of the hip: a. Gluteus maximus: This is the largest muscle in the body and extends the hip joint, moving the thigh backward. b. Hamstrings: The hamstrings consist of three muscles: biceps femoris, semitendinosus, and semimembranosus. They extend the hip joint and also flex the knee joint.
- Adductors of the thigh: a. Adductor magnus: This muscle performs both hip adduction and hip extension. b. Adductor longus: It primarily functions to adduct the thigh, bringing it towards the midline of the body. c. Adductor brevis: Similar to the adductor longus, it contributes to adduction of the thigh. d. Gracilis: This muscle lies on the inner side of the thigh and assists in hip adduction.
- Abductors of the thigh: a. Gluteus medius: It is located on the lateral side of the hip and performs hip abduction. b. Gluteus minimus: It works together with the gluteus medius to abduct the thigh.
- Medial rotators of the thigh: a. Tensor fasciae latae: This muscle is located on the lateral side of the hip and assists in both hip flexion and medial rotation.
- Lateral rotators of the thigh: a. Piriformis: It is a deep muscle that performs lateral rotation of the thigh. b. Obturator externus: This muscle is located on the medial side of the hip and contributes to lateral rotation.
It’s important to note that many muscles in the thigh can have multiple actions, and their roles may vary depending on the position of the hip and knee joints.
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