Anterior and Medial thigh Muscles

ANA 208

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• Thigh is divided into flexor, extensor and adductor compartments.

• Superficial fascia of the abdominal wall fuses to the fascia lata, at the skin crease of the hip joint just below the inguinal ligament.

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Deep fascia of the thigh (fascia lata)• Covers the thigh.• Attached to the inguinal ligament and bony margins

of the pelvis and below to the tibial condyles, head of the fibula and patella.

• Three fascial septa pass from the deep surface to insert onto the linea aspera of the femur and divide the thigh into three compartments.

• Laterally, it is condensed to form the iliotibial tract. - Attached above to the iliac crest and receives the

insertions of tensor fasciae latae and three-quarters of gluteus maximus.

- Inserts into the lateral condyle of the tibia.

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• Saphenous opening is a gap in the deep fascia filled with loose connective tissue at the cribriform fascia.

• The great saphenous vein pierces the cribriform fascia to drain into the femoral vein.

• Superficial branches of the femoral artery and lymphatics are also transmitted through the saphenous opening.

ANTERIOR AND MEDIAL REGIONS OF THIGH• Thigh muscles are organized into three

compartments by intermuscular septa from the inner surface of the fascia lata to the linea aspera of the femur.

• The compartments are anterior or extensor, medial or adductor,and posterior or flexor.

• Anterior group is innervated by the femoral nerve, the medial group by the obturator nerve, and the posterior group by the tibial portion of the sciatic nerve.

• Anterior compartment is the largest overall.5

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Anterior Compartment Muscles• Contains the anterior thigh muscles- the flexors of the hip

and extensors of the knee. • Include the pectineus, iliopsoas, sartorius, and quadriceps

femoris.

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PECTINEUS• Flat quadrangular muscle• Located in the anterior part of the superomedial aspect of

the thigh. • Composed of two layers, superficial and deep innervated

by two different nerves. • Because of the dual nerve supply and the muscle’s actions

(the pectineus adducts and flexes the thigh and assists in medial rotation of the thigh)

• Transitional muscle between the anterior and medial compartments.

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ILIOPSOAS• Chief flexor of the thigh, most powerful of the hip

flexors • Its broad lateral part, the iliacus, and its long medial

part, the psoas major, arise from the iliac fossa and lumbar vertebrae, respectively.

• Attached to the vertebral column, pelvis, and femur. • A postural muscle, active during standing in

maintaining normal lumbar lordosis (and indirectly the compensatory thoracic kyphosis; and resisting hyperextension of the hip joint.

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SARTORIUS (Tailor’s muscle) • Long and ribbon-like. • Passes lateral to medial across the superoanterior part of

the thigh.• Lies superficially in the anterior compartment, within its

own relatively distinct fascial sheath. • Longest muscle in the body• Acts across two joints. • It flexes the hip and knee joint. • It also weakly abducts the thigh and laterally rotates it.

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QUADRICEPS FEMORIS• Four-headed femoral muscle• Forms the bulk of the anterior thigh muscles• Constitutes the largest and one of the most powerful muscles in

the body. • Covers the anterior aspect and sides of the femur • Consists of four parts: (1) rectus femoris, (2) vastus lateralis, (3)

vastus intermedius, and (4) vastus medialis. • A two-joint muscle capable of producing action at both the hip

and knee. • Great extensor of the leg. • Tendons of the four parts unite in the distal portion of the thigh

to form a single, strong, broad quadriceps tendon • Patellar ligament attached to the tibial tuberosity - continuation

of the quadriceps tendon in which the patella is embedded. 11

• Medial and lateral vasti muscles form aponeuroses, the medial and lateral patellar retinacula, which reinforce the joint capsule of the knee joint.

• Patella provides a bony surface which withstands compression placed on the quadriceps tendon during kneeling

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Patella• Sesamoid bone in the quadriceps tendon.• Mobile from side to side. • When quadriceps muscle contracts the patella is drawn

laterally. • Three factors discourage this lateral dislocation; they

are the bony, ligamentous and muscular factors that control the stability of any bone.

- Bony factor consists in the forward prominence of the lateral condyle of the femur

- Ligamentous factor is the tension of the medial patellar retinaculum

- Lowest fibres of vastus medialis hold the patella medially when the quadriceps contracts.

Rectus Femoris• Runs straight down the thigh.• Crosses two joints• Flexes the thigh at the hip joint and extending the

leg at the knee joint.• Only part of the quadriceps that crosses the hip

joint.• Susceptible to injury and avulsion from the anterior

inferior iliac spine during kicking, hence the name “kicking muscle”.

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Vastus Muscles • Names of the three large vastus muscles indicate

their position around the femoral shaft- Vastus lateralis, the largest component of the

quadriceps, lies on the lateral side of the thigh.- Vastus medialis covers the medial side of the thigh.- Vastus intermedius lies deep to the rectus femoris,

between the vastus medialis and vastus lateralis.• Articularis genu (articular muscle of the knee) is a

derivative of the vastus intermedius,- Pulls the synovial membrane and preventing folds

of the membrane from being compressed within the knee joint.

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Medial Thigh Muscles• Comprise the adductor group, consisting of the

adductor longus, adductor brevis, adductor magnus, gracilis, obturator externus.

• They attach proximally to the external surface of the bony pelvis (pubic bone, ischiopubic ramus, and ischial tuberosity), and obturator membrane, and distally to the linea aspera of the femur

• Adductor muscles, except the “hamstring part” of the adductor magnus and part of the pectineus are supplied by the obturator nerve (L2–L4).

• The hamstring part of the adductor magnus is supplied by the tibial part of the sciatic nerve (L4)20

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ADDUCTOR LONGUS• Large, long, triangular, fan-shaped muscle• Anteriorly placed of the adductor group. • Arises from the anterior aspect of the body of the pubis,

just inferior to the pubic tubercle (apex of triangle), and expands to attach to the linea aspera of the femur (base of triangle).ADDUCTOR BREVIS

• Short adductor• Deep to the pectineus and adductor longus• It arises from the body and inferior ramus of the pubis. • As the obturator nerve emerges from the obturator canal, it

splits into an anterior and a posterior division. The two divisions pass anterior and posterior to the adductor brevis.

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ADDUCTOR MAGNUS• Largest, most powerful, and most posterior muscle

in the adductor group. • A composite, triangular muscle with a thick, medial

margin that has an adductor part and a hamstring part.

• The two parts differ in their attachments, nerve supply, and main actions

• The adductor part fans out for distal attachment along the entire length of the linea aspera of the femur.

• The hamstring part has a tendinous distal attachment to the adductor tubercle.

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GRACILIS (slender)• Long, strap-like muscle• Most medial muscle of the thigh• Most superficial of the adductor group and the weakest

member• It is the only one of the group to cross the knee joint as

well as the hip joint. • The three muscles are innervated by three different

nerves. • They have a common tendinous insertion, the pes

anserinus, into the superior part of the medial surface of the tibia.

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OBTURATOR EXTERNUS• A flat, fan-shaped muscle that is deeply placed in

the superomedial part of the thigh.

• It extends from the external surface of the obturator membrane and surrounding bone of the pelvis to the posterior aspect of the greater trochanter.

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ADDUCTOR HIATUS• An opening or aperture between the aponeurotic

distal attachment of the adductor part of the adductor magnus and the tendinous distal attachment of the hamstring part.

• Transmits the femoral artery and vein from the adductor canal in the thigh to the popliteal fossa posterior to the knee.

• Located just lateral and superior to the adductor tubercle of the femur.

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SEMITENDINOSUS• Half tendinous • Fusiform belly that is usually interrupted by a

tendinous intersection• Long, cord-like tendon that begins approximately

two thirds of the thigh.• Distally, tendon attaches to the medial surface of

the superior part of the tibia as part of the pes anserinus with the tendinous insertions of the sartorius and gracilis.

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SEMIMEMBRANOSUS• Broad muscle• Flattened membranous form attaches to the ischial

tuberosity.• Tendon forms around the middle of the thigh and descends

to the posterior part of the medial condyle of the tibia.• Tendon divides distally into three parts: - a direct attachment to the posterior aspect of the medial

tibial condyle- a part that blends with the popliteal fascia- a reflected part that reinforces the intercondylar part of the

joint capsule of the knee as the oblique popliteal ligament.

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BICEPS FEMORIS• Fusiform• Two heads: a long head and a short head.• In the inferior part of the thigh, the long head is joined

by the short head, common tendon of these heads attaches to the head of the fibula

• Long head crosses and provides protection for the sciatic nerve after it descends from the gluteal region into the posterior aspect of the thigh.

• Short head arises from the lateral lip of the inferior third of the linea aspera and supracondylar ridge of the femur.

• Hamstrings have a common nerve supply from the tibial division of the sciatic nerve, the short head of the biceps is innervated by the fibular division.

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