THIGH REGION

BY

GM MUWANGA The lower limb

• lower limb consists of the following components:

 leg 

• lower limb is connected to the trunk by pelvic girdle bones (i.e., hip bones)

The thigh

Fascial compartments of the thigh

• superficial is deep to the skin

• superficial fascia contains:

 fat

 superficial vessels, cutaneous nerves, & superficial lymphatics

Deep fascia of thigh

• is also called & surrounds all thigh muscles like an elastic sleeve

• is a dense CT layer between the superficial layer & the muscles

• separates groups of muscles from each other Thigh muscle compartments

An anterosuperior view of a transverse section through the thigh. Note superficial & deep fascia. Superficial fascia (subcutaneous tissue) has been invaded by fat & appears as a fatty layer. The deep fascia is the whitish membrane which has sent septa up to the bone, thus dividing muscles into various compartments (A, P & M). Also note some veins & nerves that run outside the deep fascia, and some that run within the deep fascia. Thigh muscle compartments Fascia lata (contn.)

• fascia lata sends 3 intermuscular septa:

 lateral intermuscular septum  medial intermuscular septum  posterior intermuscular septum

• septa attach to the linea aspera of the

Thigh muscle compartments

An anterosuperior view of a transverse section through the thigh. Note superficial & deep fascia. Superficial fascia (subcutaneous tissue) has been invaded by fat & appears as a fatty layer. The deep fascia is the whitish membrane which has sent septa up to the bone, thus dividing muscles into various compartments (A, P & M). Also note some veins & nerves that run outside the deep fascia, and some that run within the deep fascia. Fascia lata (contn.)

• septa thus divides the thigh into 3 muscle compartments:

 anterior compartment

 medial compartment

 posterior compartment

Muscle compartments

• muscles of anterior compartment:

 are all innervated by the femoral nerve

 act to extend knee joint & flex the hip

Fascia lata (contn.)

• medial or adductor compartment includes muscles that adduct the thigh

• muscles are innervated by the obturator, femoral, & deep femoral nerves Fascia lata (contn.)

• posterior compartment contains muscles:

 which extend the hip

 that are involved in flexing the knee

• muscles innervated by the sciatic nerve

Iliotibial tract

• fascia lata condenses & thickens laterally to form a broad band of fibers

• band called the

Iliotibial tract (contn.)

• tract extends from the iliac tubercle to the lateral condyle of the tibia

• tract receives insertions of the tensor fasciae latae & part of the muscles

Iliotibial tract Iliotibial tract Saphenous hiatus

• also known as fossa ovalis or

• is an opening in the fascia lata

• opening filled with loose called the cribriform fascia

Saphenous hiatus (contn.)

• pierces the cribriform fascia to drain into the

• superficial branches of & lymphatics also transmitted through saphenous opening

Saphenous opening

Femoral triangle

• is a fascia space in the superior-anterior one-third of the thigh

Femoral triangle (contn.) • is bounded:

 medially by the medial margin of the

 laterally by the medial margin of the

 superiorly by the inguinal ligament

Boundaries of femoral triangle Boundaries & floor of femoral triangle

Femoral triangle (contn.)

• floor consists of the adductor longus, pectineus, psoas tendon & iliacus

• roof of the triangle is formed by the fascia lata

Floor of femoral triangle Femoral triangle (contn.)

• when the hip joint is actively flexed, the femoral triangle appears as a depression inferior to the inguinal ligament

Femora triangle (contn.)

• from lateral to medial, contents of the femoral triangle are:

 femoral nerve

 femoral artery & its branches

 femoral vein & tributaries

• other contents = fat & lymphatics Femoral triangle (contn.)

• saphenous opening is located in the upper part of the triangle

• transversalis fascia & psoas fascia fuse & evaginate to form the below the inguinal ligament

Note origin & composition of femoral sheath Femoral sheath (contn.)

• sheath encloses:

 femoral artery  femoral vein 

• femoral nerve lies outside sheath on its lateral aspect

Compartments within the femoral sheath. Proximal end (abdominal opening) of the femoral canal is the . Femoral sheath (contn.)

• sheath divided into 3 compartments:

 lateral compartment contains the femoral artery

 intermediate compartment contains the femoral vein

 medial compartment contains deep lymph nodes

Compartments of retro-inguinal space & structures traversing them to enter femoral triangle Femoral sheath (contn.)

• medial compartment is called the femoral canal

• opens into the abdominal cavity superiorly at the femoral ring

• femoral canal contains deep (glands of Cloquet) Femoral sheath (contn.)

• femoral canal is also the site at which a loop of the gut can herniate through ()

• femoral hernia can become strangulated & can lead to gangrene of stangulated part

Anterior (extensor) compartment

• contains the following muscles:

 sartorius

 quadriceps femoris

 psoas major

 Iliacus

Anterior (extensor) compartment (contn.)

• each of these muscles is innervated by the femoral nerve

Sartorius

Origin: anterior superior iliac spine

Insertion: medial surface of the tibia

Sartorius (contn.)

• Action:

 abducts thigh at hip joint & laterally rotates the thigh

 also flexes the knee joint

• muscle is the longest one in the body Sartorius

• Action (contn.)

 muscle also responsible for our being able to place our leg in a “cross-leg” position

• Innervation: femoral nerve

Quadriceps femoris

• consists of 4 heads, hence the name quadriceps

 rectus femoris

 vastus lateralis

 vastus intermedialis

Quadriceps femoris Quadriceps femoris (contn.)

(a) Rectus femoris

Origin: the anterior inferior iliac spine; upper lip of the acetabulum

(b) Vastus medialis

Origin: the medial lip of the linea aspera

Quadriceps femoris (contn.)

(c) Vastus lateralis

• Origin: lateral lip of the linea aspera

(d) Vastus intermedius

• Origin: lateral & anterior surfaces of the femur

Quadriceps femoris: rectus femoris Quadriceps femoris: most of rectus femoris has been removed Quadriceps femoris: v. intermedius v. lateralis v. medialis Quadriceps femoris (contn.)

• Insertion: all the 4 parts of quadriceps insert into the patella &, from here, to the tubercle of the tibia

 patella is thus a sesamoid bone in the tendon of quadriceps femoris

Quadriceps femoris (contn.)

• Action:

 extension & stabilization of knee joint

 rectus femoris also a weak flexor of the hip joint

• Innervation: femoral nerve

Psoas major

Origin: transverse processes of lumbar vertebrae

Insertion: lesser trochanter of femur along with via the tendon

Psoas major (contn.)

• Action:

 in the lower limb it to flexes the hip joint

 in trunk, flexes & laterally bends the lumbar vertebral column

• Innervation: femoral nerve

Iliacus (contn.)

Origin: iliac fossa, iliac crest as well as the ala of the sacrum

Insertion: lesser trochanter of femur with via the iliopsoas tendon

Iliacus (contn.)

• Action:

• has the same action as the psoas major muscle

• Innervation: femoral nerve

Tensor fasciae latae

• muscle does not belong to anterior compartment

• however, it assists muscles of this compartment in:

 extending knee joint

 flexing hip joint

Tensor fasciae latae (contn.)

• Origin:

 anterior iliac crest outer lip  anterior border of  outer surface of anterior superior iliac spine

Tensor fasciae latae

• Insertion: between the two layers of the iliotibial band, about one-third of the way down

Tensor fasciae latae (contn.)

Action:

 tenses fascia lata

 i.e., the iliotibial tract moves forward in extension & backward in flexion but is tense in both positions

 flexes hip joint

Tensor fasciae latae (contn.)

• Action (contn.):

 abducts & medially rotates thigh

 stabilizes knee joint in extension

• Innervation: superior gluteal nerve

Nerves of the anterior compartment

• is innervated by femoral nerve which has:

 muscular branches

 anterior & lateral femoral cutaneous branches

 a branch

Note muscular branches of femoral nerve Note anterior & lateral femoral cutaneous nerves Note branches of lateral cutaneous nerve Note course of lateral cutaneous nerve and territory of skin it is responsible for Some clinical aspect

• lateral femoral cutaneous nerve enters the thigh just inferior to the inguinal ligament

• an underwear which has a tight-fitting waist- band may compress the nerve at this point

Some clinical aspect (contn.)

• compression of the nerve results in paraesthesia (altered sensation). This includes:

 feeling of pin pricks

 having burning sensation

 feeling sharp pain Saphenous nerve:

• travels along with great saphenous vein

• continues anterior to medial malleolus at the ankle joint

• here it supplies articular branches to ankle joint

Territory of skin innervated by saphenous nerve *

Note point where saphenous nerve pierces deep fascia to reach superficial fascia & hence skin* Note saphenous nerve & muscular branches of femoral nerve Saphenous nerve (contn.)

• nerve innervates skin along medial side of the foot

• innervation extends as far anteriorly as the head of the first metatarsal

Saphenous nerve

• extends:

 superiorly to the apex of the femoral triangle

 inferiorly to the

Femoral triangle, adductor canal & adductor hiatus Adductor canal (contn.):

• contains:

 femoral artery & vein

 saphenous nerve

 nerve to the vastus medialis

 lymphatics

Adductor canal: note femoral vessels running in canal Adductor canal (contn.)

• adductor hiatus is the location where femoral vessels pass to reach the

• adductor hiatus is an opening in the tendon of the adductor magnus muscle

Adductor magnus – adductor & parts: note adductor hiatus Note adductor hiatus Adductor hiatus: note femoral vessels running thru hiatus to become popliteal vessels Medial (adductor) compartment

• muscles arise mainly from the external surfaces of pubic rami

• main action is to adduct the thigh & hence are generally referred to as adductor group of muscles

Adductor compartment muscles Medial (adductor) compartment (contn.)

• muscles are:

(i) Gracilis (ii) Pectineus

(iii) Adductor longus (iv) Adductor brevis

(v) Adductor magnus (vi) Obturator externus

Medial (adductor) compartment (contn.)

• all adductor muscles except pectineus are innervated by the obturator nerve

• pectineus is supplied by the femoral nerve

Gracilis

• long, slender & thin muscle located superficially on medial aspect of the thigh

Origin: body & inferior ramus of pubis

Insertion: tendon crosses the knee joint to insert on the upper part of the shaft of tibia

•

• this insertion is part of the pes anserinus (= duck’s foot]

• it is a common tendon of insertion for 3 muscles (sartorius, gracilis & semitendinosus)

• pnemonic = “girl between two surgeons”

Pes anserinus

Note components of pes anserinus Gracilis (contn.)

• Action:

• it adducts the thigh & assists flexing the knee joint

• may participate in flexion of the hip joint & medial rotation of the thigh

• Innervation: obturator nerve

Gracilis muscle Pectineus

• a short, flat & quadrangular muscle

• forms the medial part of the floor of the femoral triangle

Origin: pubic pectin

Insertion: pectineal line of femur

Pectineus Pectineus (contn.)

• Action:

 adducts the thigh & rotates it medially

 also assists flexion of the hip joint

Pectineus (contn.)

• Innervation:

 femoral nerve

• may also be supplied by a branch of the obturator nerve (accessory obturator nerve) when present (i.e., in about 9% of cases)

Adductor longus

• a triangular muscle that forms the medial boundary of the femoral triangle

Origin: body & superior ramus of pubis

Insertion: middle one-third of the linea aspera of femur

Adductor longus (contn.)

• Action:

 adducts the thigh & rotates it medially

 also assists in flexion of the hip joint

• Innervation: obturator nerve

Adductor longus Adductor brevis

• lies deep to pectineus & adductor longus muscles

Origin: body & inferior ramus of pubis

Insertion: lower two-thirds of pectineal line & proximal part of linea aspera of femur

Adductor brevis (contn.)

• Action:

 adducts the thigh

 may assist medial rotation of thigh & flexion of hip joint to a lesser degree

• Innervation: obturator nerve

Adductor brevis – adductor longus has been cut Superficial group of adductors Adductor magnus

• largest muscle of the adductor group

• triangular in shape

• formed by a combination of two muscles with differing innervation

Adductor magnus (contn.)

• the two components are:

 (a) the adductor part

 (b) the hamstring part

Adductor magnus (contn.)

• Origin:

 adductor part – from the inferior ramus of pubis, & ramus of ischium

 hamstring part – from ischial tuberosity

Adductor magnus (contn.)

Insertion:

 adductor part – gluteal tuberosity, linea aspera & supracondylar line of femur

 hamstring part – adductor tubercle of the medial epicondyle of femur (by a rounded tendon)

Adductor magnus – anterior view: note the hamstring component*

* Adductor magnus – * posterior view: note origin of the hamstring component* from the ischial tuberosity in common with other hamstring muscles Adductor magnus (contn.)

• Action:

 adductor part is a powerful adductor of the thigh

 also assists in medial rotation of the thigh & flexion of the hip joint

 hamstring part extends the hip joint & also rotates thigh medially

Adductor magnus (contn.)

• Innervation:

 adductor part – obturator nerve

 hamstring part – tibial division of the sciatic nerve

Obturator externus

• lies deep to the origins of the adductor group of muscles

• a relatively small, triangular muscle

Origin: external aspect of the margins of obturator foramen & obturator membrane

Obturator externus Obturator externus & adductor magnus Obturator externus (contn.)

Insertion:

• tendon of insertion crosses the back of the neck of femur & posterior capsule of the hip joint

 then inserts on the trochanteric fossa of the femur Obturator externus (contn.)

• Insertion (contn.)

 synovial membrane of the hip joint descends below the edge of the posterior capsule

 acts as a bursa separating the tendon from the neck of femur

Obturator externus (contn.)

Action:

• it is a lateral rotator of the thigh

• may help to steady the head of femur in the acetabulum

Innervation: obturator nerve Posterior compartment of the thigh

• muscles in this compartment flex the knee joint & extend the hip joint

• muscles are:

 Semitendinosus

 Semimembranosus

 Biceps femoris

Posterior compartment muscles (hamstring muscles) Posterior compartment of the thigh (contn.)

• muscles collectively referred to as the “hamstring muscles”

• have a common origin from the ischial tuberosity

Hamstring muscles- note common origin from ischial tuberosity Posterior compartment of the thigh (contn.)

• muscles innervated by tibial division of the sciatic nerve

• biceps femoris has an additional origin from the femur

 this part of the muscle is supplied by the common fibular (peroneal) nerve

Hamstring muscles (contn.)

• because of their attachment, they act on both the hip & knee joints

• ischiocondylar part of the adductor magnus muscle also belongs to this group of muscles

Semitendinosus

• muscle is tendinous in about half of its length

• is a fusiform muscle having a long tendon

Semitendinosus (contn.)

Origin: ischial tuberosity

Insertion: medial surface of superior part of tibia [part of pes anserinus]

Semitendinosus (contn.)

• Action:

 extends the hip joint & flexes the knee joint

 may rotate the flexed leg medially

• Innervation: tibial nerve

Semimembranosus

• a broad muscle located deep to the semitendinosus

• Origin: ischial tuberosity

• Insertion: posterior part of medial condyle of tibia

Semimembranosus (contn.)

• Action:

 extends the hip & flexes the knee joint

 may rotate the flexed leg medially

• Innervation: tibial nerve

Biceps femoris

• has 2 heads – a long and short head

Origin: (a) long head – ischial tuberosity

(b) short head – linea aspera & supracondylar line of femur

Insertion: lateral head of fibula (by a heavy rounded tendon)

Hamstring muscles – note heads of origin of biceps muscle. Part long head of biceps has been removed. Biceps femoris (contn.)

• Action:

 it flexes the knee joint & rotates the leg laterally

 long head extends the hip joint

Biceps femoris (contn.)

• Innervation:

 long head – tibial nerve

 short head – common fibular (peroneal) nerve

Hamstring muscles & sciatic nerve Assignment –

• read about hamstring injuries, e.g.,

 pulled hamstring [muscle pull]

 hamstring strain, etc.