The adductors serve to bring a body part closer to the body (adduction= to lead, lat. adducere= to lead, to pull). Adductors belong to the group of skeletal muscles.
Their antagonists are the abductors, which pull a body part away from the trunk. The adductors of the thigh are divided into three layers. The superficial, middle and deep adductor group.
All adductors are innervated by the obturator nerve, with the exception of the pectine and adductor magnus muscles, which additionally receive fibers from the femoral and sciatic nerves. In addition to the adductors of the thigh, there is also an adductor on the foot and on the hand. The superficial adductor group on the thigh consists of
- The muscle pectineus originates at the pecten ossis pubis (bony protrusion of the pubic bone) and attaches to the linea pectinea of the thigh bone (femur).
It is used for adduction of the thigh. It can also rotate and bend the thigh externally. – The adductor longus muscle originates from the upper part of the pubic bone (ramus superior des Os pubis) and extends to the middle part of the linea aspera of the femur.
This lies in the middle of the back of the thigh bone. This muscle is also used for adduction and also bends the thigh in the hip joint. – The gracilis muscle originates in the lower part of the pubic bone (ramus inferior des Os pubis) and at the symphysis.
It extends to the tibia and begins there below the head of the tibia together with the sartorius and semitendinosus muscles. Since the gracilis muscle extends over both the hip and knee joint, it is the only two-jointed muscle in the entire adductor group. In the hip joint it causes both flexion and adduction, in the knee joint it is involved in internal rotation and flexion.
Only the adductor brevis muscle belongs to the middle adductor group. Like the gracilis muscle, it originates from the lower part of the pubic bone (ramus inferior des Os pubis) and is attached to the middle part of the linea aspera of the femur (labium mediale of the linea aspera of the femur). This also serves for adduction and contributes a small part to flexion and external rotation in the hip joint.
The deep adductor group consists of the large (magnus) and small (minimus) adductor muscle:
- The adductor magnus muscle originates from the ischial tuberosity (tuber ischiadicum) and the smaller part of the ischium (ramus ossis ischii). It starts at the middle part of the linea aspera at the back of the thigh bone (labrum mediale of the linea aspera of the femur). Another large part of this muscle is attached to the epicondylus medialis of the thigh.
This is considered the strongest adductor of the entire adductor group. It also stretches the thigh in the hip joint. In addition, the muscle fibres close to the hip joint (proximal) can rotate the thigh outwards, while the muscle fibres distant from the hip (distal) rotate the thigh inwards.
- The muscle adductor minimus is considered a split of the large adductor muscle. It therefore has the same origin and attachment as the adductor magnus muscle. Its function consists in the adduction and external rotation of the thigh in the hip joint.
The muscle adductor hallucis consists of two muscle heads which have a different origin. The transverse caput originates at the joint capsule of the 3rd – 5th metatarsophalangeal joint, the oblique caput originates at the cuboid bone (Os cuboideum), the outer sphenoid bone (Os cuneiform lateral) and the 2nd – 4th metatarsal bone. The common base is found at the base of the big toe.
The big toe is thus adducted, i.e. brought up to the second toe. The innervation of this muscle takes place through the lateral plantar nerve. The adductor pollicis muscle is similar in structure to the adductor of the foot.
This muscle also consists of two muscle heads. The caput obliquum originates at the head bone (Os capitatum), the caput transversum originates at the 3rd metacarpal bone (Os metacarpale III). Both heads start at the medial side of the sesamoid bone.
Through this the muscle leads to adduction of the thumb. It is also essential for the opposition movement in the thumb saddle joint. Here the thumb is moved to the palm of the hand.