Posterior Thigh

Vocabulary flashcards covering key terms and definitions related to the posterior thigh, its muscles, innervation, and blood supply from the provided notes.

Semitendinosus - Attachments

Proximal attachment: ischial tuberosity; Distal attachment: superomedial surface of tibia (pes\ anserinus).

Semitendinosus - Innervation

Tibial division of the sciatic nerve (L5–S2).

Semitendinosus - Actions

• Extends the hip (weak)

• Flexes the knee

• With a semi-flexed knee: medially rotates the knee

• With foot on the ground: laterally rotates the hip

Pes anserinus

Goose-foot insertion on the superior medial tibia formed by the sartorius, gracilis, and semitendinosus.

Semimembranosus - Attachments

Proximal attachment: ischial tuberosity; Distal attachment: posterior surface of the medial tibial condyle.

Semimembranosus - Innervation

Tibial division of the sciatic nerve (L5–S2).

Semimembranosus - Actions

• Extends the hip (weak)
• Eccentrically controls forward flexion of the trunk
• Flexes the knee
• With a semi-flexed knee: medially rotates the knee
• With foot on the ground: laterally rotates the hip

Biceps femoris long head - Attachments

Proximal attachment: ischial tuberosity; Distal attachment: lateral side of the fibular head.

Biceps femoris long head - Innervation

Tibial division of the sciatic nerve (L5–S2).

Biceps femoris long head - Actions

• Flexes the knee
• With a semi-flexed knee: laterally rotates the knee
• Extends the hip (weak), better when trunk is bent forward
• Eccentrically controls forward trunk flexion

Biceps femoris short head - Attachments

Proximal attachment: lower \frac{1}{2} of the linea aspera and lateral supracondylar ridge; Distal attachment: lateral side of the fibular head.

Biceps femoris short head - Innervation

Common fibular division of the sciatic nerve (L5–S2).

Biceps femoris short head - Actions

• Flexes the knee
• With a semi-flexed knee: laterally rotates the knee

Sciatic nerve

Major nerve of the posterior thigh. Emerges below the gluteal muscles; travels deep to posterior thigh between the medial and lateral hamstrings; divides into tibial and common fibular divisions about \frac{2}{3} down the thigh.

Tibial division of sciatic nerve

Division of the sciatic nerve that supplies most posterior thigh muscles; L5–S2.

Common fibular (peroneal) division

Division of the sciatic nerve; winds around the head/neck of the fibula; supplies the short head of the biceps femoris; L5–S2.

Adductor magnus (ischiocondylar portion) - Attachments

Proximal: ischial tuberosity; Distal: adductor tubercle.

Adductor magnus (ischiocondylar portion) - Innervation

Tibial division of the sciatic nerve.

Adductor magnus (ischiocondylar portion) - Action

Extends the hip; hamstring-like portion located deep to the semimembranosus.

Adductor magnus (adductor portion)

Innervation: obturator nerve. Action: adducts the thigh.

Adductor hiatus

Opening in the adductor magnus through which the femoral vessels pass to become the popliteal vessels.

Ischial tuberosity

Bony prominence that serves as proximal attachment for semitendinosus, semimembranosus, and the long head of biceps femoris.

Perforating arteries

Branches of the deep femoral artery that perforate the adductor magnus to reach and supply the posterior thigh muscles.

Deep femoral artery

Main deep artery of the thigh; gives off perforating arteries that supply the posterior thigh.

Greater saphenous vein

Medial superficial vein in the leg; lies within superficial fat of the posterior thigh; should not be cut during dissection.

Deep fascia compartments

Dense fascia forming compartments in the thigh and separating muscle groups; important for accessing and separating muscles within compartments.

Posterior thigh blood supply (summary)

No major vessels pass from the gluteal region into the posterior thigh; perforating branches of the deep femoral artery supply it; popliteal vessels emerge through the adductor hiatus.

Innervation pattern of posterior thigh muscles

Most posterior thigh muscles are innervated by the tibial division of the sciatic nerve; the short head of the biceps femoris is innervated by the common fibular division.