POSTERIOR COMPARTMENT OF THIGH OBJECTIVES By the end of this lecture students should know:      

The muscles of posterior compartment of the thigh The arterial supply of posterior compartment of thigh The greater and cruciate anastomosis at the back of thigh The venous drainage of back of thigh The nerve supply of posterior compartment of thigh Clinical conditions effecting the back of thigh

MUSCLES OF POSTERIOR COMPARTMENT

 All the muscles are known as the Hamstrings  ALL arise from the ischial tuberosity  The hamstrings are:   

Biceps femoris (long head) Semimembranosus Semitendinosus

 The hamstring muscles flex the leg upon the thigh  Taking their fixed point from below, these muscles serve to support the pelvis upon the head of the femur  Draw the trunk directly backward, as in raising it from the stooping position or in feats of strength, when the body is thrown backward in the form of an arch. Complete flexion of the hip cannot be effected unless the knee-joint is also flexed, on account of the shortness of the hamstring muscles. NERVE SUPPLY: The muscles of this region are supplied by the fourth and fifth lumbar and the first, second, and third sacral nerves BICEPS FEMORIS(biceps): 

The Biceps femoris (Biceps) is situated on the posterior and lateral aspect of the thigh.

ORIGIN:  

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It has two heads of origin; The long head arises from the lower and inner impression on the back part of the tuberosity of the ischium, by a tendon common to it and the Semitendinosus, and from the lower part of the sacrotuberous ligament; The short head, arises from the lateral lip of the linea aspera, between the Adductor magnus and Vastus lateralis, extending up almost as high as the insertion of the Glutæus maximus; from the lateral prolongation of the linea aspera to within 5 cm. of the lateral condyle; and from the lateral intermuscular septum. The fibers of the long head pass laterally to end in an aponeurosis which covers the posterior surface of the muscle, and receives the fibers of the short head

INSERTION:     

This aponeurosis contracts into a tendon, which is inserted into the lateral side of the head of the fibula, and by a small slip into the lateral condyle of the tibia. At its insertion the tendon divides into two portions, which embrace the fibular collateral ligament of the knee-joint. From the posterior border of the tendon a thin expansion is given off to the fascia of the leg. The tendon of insertion of this muscle forms the lateral hamstring The common peroneal nerve descends along its medial border.

NERVE SUPPLY:  Short head: supplied by the common peroneal nerve  Long head: tibial nerve ACTIONS: When the knee is semiflexed, the Biceps femoris in consequence of its oblique direction rotates the leg slightly outward VARIATIONS:  

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The short head may be absent Additional heads may arise from the ischial tuberosity, the linea aspera, the medial supracondylar ridge of the femur or from various other parts. A slip may pass to the Gastrocnemius. THE SEMITENDINOSUS

The Semitendinosus, (great length of its tendon of insertion), is situated at the posterior and medial aspect of the thigh. ORIGIN:   

Arises from the lower and medial impression on the tuberosity of the ischium, by a tendon common to it and the long head of the Biceps femoris It also arises from an aponeurosis which connects the adjacent surfaces of the two muscles The muscle is fusiform and ends a little below the middle of the thigh in a long round tendon which lies along the medial side of the popliteal fossa

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It then curves around the medial condyle of the tibia and passes over the tibial collateral ligament of the knee-joint, from which it is separated by a bursa

INSERTION: 

It is inserted into the upper part of the medial surface of the body of the tibia, nearly as far forward as its anterior crest.  At its insertion it gives off from its lower border a prolongation to the deep fascia of the leg and lies behind the tendon of the Sartorius, and below that of the Gracilis, to which it is united.  A tendinous intersection is usually observed about the middle of the muscle. NERVE SUPPLY: Tibial nerve ACTIONS: When the knee is semiflexed, the Semitendinosus rotate the leg inward, assisting the Popliteus THE SEMIMEMBRANOSUS The Semimembranosus so called from its membranous tendon of origin situated at the back and medial side of the thigh. ORIGIN:  

It arises by a thick tendon from the upper and outer impression on the tuberosity of the ischium, above and lateral to the Biceps femoris and Semitendinosus. The tendon of origin expands into an aponeurosis, which covers the upper part of the anterior surface of the muscle

INSERTION:  

From this aponeurosis muscular fibers arise, and converge to another aponeurosis which covers the lower part of the posterior surface of the muscle and contracts into the tendon of insertion. It is inserted mainly into the horizontal groove on the posterior medial aspect of the medial condyle of the tibia

FIBROUS EXPANSIONS OF THE TENDON OF INSERTION: 

The tendon of insertion gives off certain fibrous expansions:

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One, passes upward and laterally to be inserted into the back part of the lateral condyle of the femur, forming part of the oblique popliteal ligament of the kneejoint Second is continued downward to the fascia which covers the Popliteus muscle A few fibers join the tibial collateral ligament of the joint and the fascia of the leg. The muscle overlaps the upper part of the popliteal vessels.

NERVE SUPPLY: Tibial nerve ACTIONS: Assist semitendinosus (and popliteus) in internal rotation of leg

VARIATIONS:   

It may be reduced or absent, or double May arise mainly from the sacrotuberous ligament May give off a slip to the femur or Adductor magnus.

The tendons of insertion of the two preceding muscles form the medial hamstrings. ADDUCTOR MAGNUS (HAMSTRING PART) ORIGIN: ischial tuberosity INSERTION: adductor tubercle of femur NERVE SUPPLY: tibial nerve ACTIONS: extends thigh

ARTERIES OF THE POSTERIOR COMPARTMENT OF THIGH The arteries of the posterior compartment of the thigh arise from two major arteries:  

inferior gluteal (upper posterior compartment) perforating branches of the profunda femoris

THE PROFUNDA FEMORIS ARTERY (A. PROFUNDA FEMORIS; DEEP FEMORAL ARTERY)

A branch of the femoral artery arising, from 2 to 5 cm below the inguinal ligament. COURSE: Lateral to the femoral artery and the femoral vein

behind femoral artery

medial side of the femur downward behind the Adductor longus ends at the lower third of the thigh in a small terminal branch, the fourth perforating artery, which pierces the Adductor magnus, and is distributed on the back of the thigh to the hamstrings.

RELATIONS: Posteriorly:  Iliacus  Pectineus  Adductor brevis  Adductor magnus. Anteriorly:  Separated from the femoral artery by the femoral and profunda veins above  The Adductor longus below. Laterally:  The origin of the Vastus medialis  The femur. SURGICALLY IMPORTANT PECULARITIES:    

It can arise(more often) from 2.25 to 5 cm. below the inguinal ligament; In a few cases the distance can be less than 2.25 cm.; Occasionally the distance between the origin of the vessel and the inguinal ligament exceeds 5 cm More rarely, opposite the ligament; and very rarely above the inguinal ligament, from the external iliac.

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BRANCHES:  Medial circumflex femoral artery  Lateral circumflex femoral artery

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Four perforating arteries Highest genicular artery

IMPORTANT ANASTOMOSIS: The trochanteric and the Cruciate anastomosis provide important connection between the internal iliac and femoral arteries TROCHANTERIC ANASTOMOSIS: Provides main supply to the head of femur via:  Superior gluteal artery  Inferior gluteal artery  Medial circumflex femoral artery  Lateral circumflex femoral artery

CRUCIATE ANASTOMOSIS:  Inferior gluteal artery  Medial circumflex femoral artery  Lateral circumflex femoral artery  Fourth perforating artery(Branch of profunda femoris artery)

NERVES OF BACK OF THIGH 

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The Lateral Femoral Cutaneous Nerve (n. cutaneus femoralis lateralis; external cutaneous nerve) arises from the dorsal divisions of L2 and L3. It emerges from the lateral border of the Psoas major about its middle, passes under the inguinal ligament into the thigh, where it divides into two branches, and anterior and a posterior The anterior branch is distributed to the skin of the anterior and lateral parts of the thigh, as far as the knee. The posterior branch pierces the fascia lata, innervates the lateral and posterior surfaces of the thigh, supplying the skin from the level of the greater trochanter to the middle of the thigh. The Posterior Femoral Cutaneous Nerve (n. cutaneus femoralis posterior; small sciatic nerve) is distributed to the skin of the perineum and posterior surface of the thigh and leg.

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It arises partly from the dorsal divisions of the first and second, and from the ventral divisions of the second and third sacral nerves Issues from the pelvis through the greater sciatic foramen below the Piriformis. It then descends beneath the Glutæus maximus with the inferior gluteal artery, and runs down the back of the thigh beneath the fascia lata, and over the long head of the Biceps femoris to the back of the knee Its branches are all cutaneous Distributed to the gluteal region, the perineum, and the back of the thigh and leg. The branches to the back of the thigh and leg consist of numerous filaments derived from both sides of the nerve, and distributed to the skin covering the back and medial side of the thigh, the popliteal fossa, and the upper part of the back of the leg

PATELLAR PLEXUS:    

Anterior branch of the lateral cutaneous nerve of thigh Intermediate cutaneous nerve of thigh Medial cutaneous nerve of thigh Infrapatellar branch of the saphenous nerve

SCIATIC NERVE (L4, L5, S1, S2, S3):   

The Sciatic (n. ischiadicus; great sciatic nerve) supplies nearly the whole of the skin of the leg, the muscles of the back of the thigh, the leg and the foot. It is the largest nerve in the body, measuring 2 cm. in breadth, and is the continuation of the flattened band of the sacral plexus. It passes out of the pelvis through the greater sciatic foramen, below the Piriformis muscle

COURSE:  It descends between the greater trochanter of the femur and the tuberosity of the ischium, and along the back of the thigh to about its lower third, where it divides into two large branches, the tibial and common peroneal nerves.

SURGICALLY IMPORTANT PECULARITIES:  

The division of sciatic nerve into Tibial and Common Peroneal nerve may take place at any point between the sacral plexus and the lower third of the thigh. When it occurs at the plexus, the common peroneal nerve usually pierces the Piriformis

RELATIONS: Upper part ANTERIORLY:  The posterior surface of the ischium  The nerve to the Quadratus femoris  The Obturator internus  The superior and inferior Gemelli  The Quadratus femoris POSTERIORLY:  The posterior femoral cutaneous nerve and the inferior gluteal artery  The Gluteus maximus Lower part: ANTERIORLY:  The Adductor magnus POSTERIORLY:  The long head of the Biceps femoris.

BRANCHES:  

The articular branches supply the hip joint Muscular branches:

1. COMMON PERONEAL NERVE:  At the back of thigh supplies the short head of biceps femoris

2. THE TIBIAL NERVE  larger  Arises from the anterior branches of L4, L5 and S1, S2, S3.

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It descends along the back of the thigh and through the middle of the popliteal fossa, to the lower part of the Popliteus muscle, where it passes with the popliteal artery beneath the arch of the Soleus. Tibial nerve supplies: o Biceps femoris (long head) o Semitendinosus o Semimembranosus o Adductor magnus.

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