Medial Side of Thigh

Competencies

  • AN15.1: Describe and demonstrate origin, course, relations,branches (or tributaries), and termination of important nerves and vessels of medial side of thigh.
  • AN15.2: Describe and demonstrate major muscles with their attachment nerve supply and actions.

Introduction

The adductor compartment, also known as the medial compartment of the thigh, contains the muscles responsible primarily for adduction of the thigh. It is well developed in humans because of its important role in maintaining posture and locomotion.

Note: The coracobrachialis muscle represents the me

Boundaries

The adductor compartment is bounded by:

  • Anteriorly: Anterior intermuscular septum
  • Posteriorly: Medial part of the posterior muscular compartment of the thigh (ill-defined)
Contents of adductor compartment

Muscles

Intrinsic muscles

  1. Pectineus
  2. Gracilis
  3. Adductor longus
  4. Adductor brevis
  5. Adductor magnus

Extrinsic muscle

  • Obturator externus (functionally related to the gluteal muscles)

Nerves

  1. Obturator nerve
  2. Accessory obturator nerve (when present)

Arteries

  1. Obturator artery
  2. Medial circumflex femoral artery

Muscles Of Adductor Compartment

The muscles of the adductor compartment are collectively known as the adductor group. They are arranged in three layers from superficial to deep.

Anterior (Superficial) Layer

  1. Pectineus
  2. Gracilis
  3. Adductor longus

Middle Layer

  1. Adductor brevis

Posterior (Deep) Layer

  1. Adductor magnus

Pectineus

The pectineus is a flat, quadrangular muscle located in the upper medial part of the thigh. It forms part of the floor of the femoral triangle and acts as a transitional muscle between the anterior and medial compartments of the thigh.

Origin

The pectineus arises from:

  • Pecten pubis (pectineal line of the pubis)
  • Upper half of the pectineal surface of the pubis
  • Pectineal fascia covering the muscle

Direction of Fibres

The muscle fibres run downward, backward, and laterally towards the femur.

Insertion

The pectineus is inserted into the pectineal line of the femur, extending from the lesser trochanter to the upper part of the linea aspera.

Innervation

The pectineus has a dual nerve supply:

  • Anterior fibres: Femoral nerve
  • Posterior fibres: Anterior division of the obturator nerve
Actions
  • Flexes the thigh at the hip joint
  • Adducts the thigh

Gracilis

The gracilis is the most superficial, long, and slender muscle of the medial compartment of the thigh. It is the only adductor muscle that crosses both the hip and knee joints.

Origin

The gracilis arises from:

  • Medial margin of the lower half of the body of the pubis
  • Ischiopubic ramus

Direction of Fibres

The muscle fibres run vertically downward. The upper part is broad, while the lower part narrows to form a long rounded tendon.

Insertion

The tendon of the gracilis is inserted into the upper part of the medial surface of the tibia, between the tendons of the sartorius and semitendinosus, forming part of the pes anserinus.

Innervation
  • Anterior division of the obturator nerve
Actions
  • Adducts the thigh at the hip joint
  • Flexes the leg at the knee joint
  • Medially rotates the flexed leg

CLINICAL INTEGRATION

The gracilis is commonly used in muscle transplantation and reconstructive surgery because it has a dependable blood supply and causes minimal functional loss after removal. A gracilis flap includes the muscle, its vascular pedicle (branch of the medial circumflex femoral artery), and its motor nerve (anterior division of the obturator nerve). Historically, the gracilis has been called the “custodian of virginity.”

Adductor Longus

The adductor longus is a triangular muscle of the medial compartment of the thigh. It forms the medial part of the floor of the femoral triangle. The adductor longus and pectineus lie in the same coronal plane.

Origin

The adductor longus arises by a rounded tendon from the anterior surface of the body of the pubis, between the pubic crest and the pubic symphysis.

Direction of Fibres

The muscle fibres pass downward, laterally, and slightly backward towards the femur.

Insertion

The muscle is inserted into the middle third of the linea aspera on the posterior surface of the femur, between the attachments of the vastus medialis and the adductor brevis and adductor magnus.

Innervation
  • Anterior division of the obturator nerve
Actions
  • Adducts the thigh
  • Assists in flexion of the thigh

Clinical Anatomy

Rider’s bone is a sesamoid bone that may develop within the tendon of the adductor longus. In some individuals, it represents calcification of the tendon. It has been described in horse riders, where repeated friction and mechanical stress on the tendon may contribute to its formation.

Adductor Brevis

The adductor brevis is a small, triangular muscle of the medial compartment of the thigh. It lies between the adductor longus and adductor magnus. During dissection, the muscle is exposed by cutting the adductor longus near its origin and reflecting it laterally.

Origin

The adductor brevis arises from:

  • Anterior surface of the body of the pubis
  • Outer surface of the inferior ramus of the pubis, between the gracilis and obturator externus

Direction of Fibres

The muscle fibres pass downward, backward, and laterally, expanding towards the femur.

Insertion

The muscle is inserted into the pectineal line and the upper part of the linea aspera of the femur, extending from the lesser trochanter to the proximal linea aspera.

Innervation

  • Anterior or posterior division of the obturator nerve
Action
  • Adducts the thigh

Adductor Magnus

The adductor magnus is the largest muscle of the medial compartment of the thigh. It lies posterior to the pectineus, adductor longus, and adductor brevis muscles. It is a composite (hybrid) muscle because it has two parts with different nerve supplies.

Parts and Origin

Adductor Part

Origin: Outer surface of the ischiopubic ramus

Hamstring Part

Origin: Inferolateral part of the ischial tuberosity

Direction of Fibres

  • Fibres arising from the pubic ramus run almost horizontally.
  • Fibres arising from the ischiopubic ramus pass downward, backward, and laterally.
  • Fibres arising from the ischial tuberosity descend almost vertically.
Insertion

Adductor part

  • Medial margin of the gluteal tuberosity
  • Linea aspera
  • Medial supracondylar ridge of the femur

Hamstring part

  • Adductor tubercle on the medial condyle of the femur
Innervation
  • Adductor part: Posterior division of the obturator nerve
  • Hamstring part: Tibial division of the sciatic nerve
Actions

Adductor part

  • Adducts the thigh
  • Assists in medial rotation of the thigh

Hamstring part

  • Extends the thigh at the hip joint

Clinical Anatomy

The pectineus and adductor magnus are hybrid muscles because they receive dual nerve supply. The adductor hiatus is a large opening between the adductor magnus and the femur that transmits the femoral artery and vein from the adductor canal to the popliteal fossa. Four smaller openings above it allow the perforating branches of the profunda femoris artery, the main arterial supply of the adductor compartment, to pass through.

The adductor minimus is a small upper part of the adductor magnus arising from the pubic ramus and inserting on the gluteal tuberosity.

Clinically, the adductor muscles are tested by asking the patient, lying supine with the knee extended, to adduct the thigh against resistance.

The obturator nerve is the main nerve of the medial (adductor) compartment of the thigh. It is a branch of the lumbar plexus and supplies most of the adductor muscles, as well as the hip and knee joints.

Obturator Nerve

Formation

The obturator nerve is formed from the anterior (ventral) divisions of the ventral rami of the L2, L3, and L4 spinal nerves.

Root Value

  • L2, L3, L4
Course
In the Pelvis
  • The obturator nerve emerges from the medial border of the psoas major muscle.
  • It descends along the lateral wall of the pelvis, passing behind the common iliac vessels.
  • It leaves the pelvis through the obturator canal.
In the Thigh
  • As it passes through the obturator canal, the nerve divides into anterior and posterior divisions.

Anterior division

  • Passes in front of the obturator externus muscle.
  • Descends behind the pectineus and adductor longus, and in front of the adductor magnus.

Posterior division

  • Pierces the obturator externus muscle.
  • Descends behind the adductor brevis and in front of the adductor magnus.
Branches (distribution)
Anterior Division

Supplies:

  • Adductor longus
  • Gracilis
  • Pectineus (occasionally)
  • Adductor brevis (in some individuals)
  • Hip joint
  • Branch to the subsartorial plexus supplying the femoral artery
Posterior Division

Supplies:

  • Obturator externus
  • Adductor magnus (adductor part)
  • Adductor brevis (when not supplied by the anterior division)
  • Genicular branch to the knee joint, popliteal vessels, cruciate ligaments, and joint capsule

CLINICAL INTEGRATION

The gracilis is commonly used in muscle transplantation and reconstructive surgery because it has a dependable blood supply and causes minimal functional loss afSurgical Division of the Obturator Nerve : In patients with spastic paraplegia causing severe adductor muscle spasm, obturator neurectomy may be performed to reduce muscle spasticity and improve limb positioning.

Referred Pain: Because the obturator nerve supplies both the hip and knee joints, disorders of the hip joint may produce referred pain in the medial aspect of the knee, even when the knee itself is normal.

Accessory Obturator Nerve

The accessory obturator nerve is an inconstant branch of the lumbar plexus and is present in approximately 30% of individuals.

Formation

The accessory obturator nerve arises from the anterior divisions of the ventral rami of the L3 and L4 spinal nerves.

Root Value
  • L3, L4
Course

The nerve emerges from the medial border of the psoas major on the posterior abdominal wall. It descends across the superior ramus of the pubis to enter the thigh.

Branches and Distribution

The accessory obturator nerve supplies:

  • Pectineus muscle
  • Hip joint
  • A communicating branch to the anterior division of the obturator nerve

Obturator Artery

The obturator artery is a branch of the anterior division of the internal iliac artery. Along with the profunda femoris artery, it contributes to the arterial supply of the adductor compartment of the thigh.

Beginning

The obturator artery arises from the anterior division of the internal iliac artery.

Course

The artery descends through the pelvis alongside the obturator nerve and enters the thigh via the obturator canal. After entering the thigh, it divides into anterior and posterior branches.

Branches and Distribution
Anterior branch
  • Runs on the outer surface of the obturator membrane
  • Supplies the adjacent muscles
  • Anastomoses with the medial circumflex femoral artery
Posterior branch
  • Supplies the muscles attached to the ischial tuberosity
  • Gives an acetabular branch, which passes through the acetabular notch to supply the fat pad of the acetabulum and the head of the femur.

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