Lower Limb 1 - MEDIUM

Lower Limb

• The lower limb includes the gluteal region, hip, thigh, leg, and foot.
• Muscles in the gluteal region relate to movements of the lower limb.

Gluteal Region

• Refers to the posterior part of the pelvis.
• Extends between the iliac crest and the inferior border of the gluteus maximus muscle.
• Muscles are organized in two layers; superficial and deep.

Superficial Layer

• Gluteus maximus muscle is included.
• Gluteus medius muscle is included.
• Gluteus minimus muscle is included.
• Tensor fascia lata muscle, located on the lateral thigh, is included.

Deep Layer

• Piriformis muscle is included.
• Obturator internus muscle is included.
• Superior and inferior gemelli muscles are included.
• Quadratus femoris muscle is included.

Gluteus Maximus Muscle

• Originates from the outer surface of the ilium, dorsal surface of the sacrum and coccyx, and the sacrotuberous ligament.
• The iliotibial tract is attached to the lateral condyle of the tibia, and the gluteal tuberosity of the femur.
• Functions to extend and laterally rotate the thigh at the hip.
• Extends the knee joint through the iliotibial tract.
• Inferior gluteal nerve provides the innervation.

Fascia Lata

• Deep fascia of the thigh.
• Divides postero-superiorly into two layers that cover the superficial and deep surfaces of the gluteus maximus muscle.
• Forms a thickening at the inferolateral part of the thigh called the the iliotibial tract, which inserts to the lateral condyle of the tibia.

Gluteus Medius Muscle

• Originates from the outer surface of the ilium.
• Inserts on the greater trochanter of the femur.
• Abducts and medially rotates the thigh at the hip joint, tilting the pelvis when walking.
• During walking, the gluteus medius and minimus of the opposite side contract when one foot rises.
• Prevents sagging of the pelvis is prevented and keeps tilted by the muscle contraction.
• The superior gluteal nerve innervates it.

Gluteus Minimus Muscle

• Originates from the outer surface of the ilium.
• Inserts on the greater trochanter of the femur.
• Abducts and medially rotates the thigh at the hip joint, tilting the pelvis when walking.
• Function as described for the gluteus medius.
• Innervated by the superior gluteal nerve.

Tensor Fascia Lata Muscle

• Originates from the anterior superior iliac spine and iliac crest.
• Insert into the iliotibial tract attaches to the lateral condyle of the tibia.
• Abducts, medially rotates, and flexes the thigh.
• Helps to keep the knee extended during standing by tensing the iliotibial tract.
• Innervated by the superior gluteal nerve.

Clinical Note: Injury to the Superior Gluteal Nerve

• Causes weakened abduction and medial rotation of the thigh.
• The pelvis sags on the side when the foot of the opposite side is raised.
• When the right gluteal nerve is damaged, the left pelvis sags when the patient raises the left foot
• The described issue is known as the "positive Trandelenburg sign."
• Patients may lean away from the sagging side or raise the foot higher than normal to prevent foot rubbing during walking.

Piriformis Muscle

• Originates from the anterior surface of the sacrum and sacrotuberous ligament.
• Inserts on the greater trochanter of the femur.
• Laterally rotates the extended thigh and abducts the flexed thigh.
• Innervated by the nerve to priformis.
• Passes through the greater sciatic foramen and divides it into suprapiriform and infrapiriform parts.

Obturator Internus Muscle

• Originates from the pelvic surface of the obturator membrane and surrounding bone.
• Inserts on the greater trochanter of the femur, passing through the lesser sciatic foramen.
• Functions as a lateral rotator of the thigh
• Innervated by the nerve to obturator internus.

Gemellus Superior and Gemellus Inferior Muscles

• Gemellus Superior originates from the spine of the ischium, while Gemellus Inferior originates from the ischial tuberosity.
• Both insert on the trochanteric fossa of the femur.
• Both gemelli laterally rotate the thigh.
• Nerves to each gemellus provides the innervation to the superior and inferior muscles respectively.

Quadratus Femoris Muscle

• Originates from the lateral border of the ischial tuberosity.
• Inserts on the quadrate tubercle on the intertrochanteric crest of the femur.
• Functions as a lateral rotator of the thigh.
• The nerve to quadratus femoris provides the innervation.

Obturator Externus Muscle

• Lies deep at the medial thigh region.
• Originates from the outer surface of the obturator membrane surrounding bone.
• inserts on the trochanteric fossa of the femur.
• Acts as a lateral rotator of the thigh.
• Innervated by the obturator nerve.

Greater Sciatic Foramen

• Greater sciatic notch, sacrospinous ligament and sacrotuberous ligament border the foramen.
• Priformis muscle further divides the greater sciatic foramen into suprapiriform and infrapriform parts.

Supraspiriform Foramen Structures

• Superior gluteal artery and vein pass through.
• Superior gluteal nerve passes through.

Infrapriform Foramen Structures

• Inferior gluteal artery and vein pass through.
• Inferior gluteal nerve passes through.
• Sciatic nerve passes through.
• Posterior femoral cutaneous nerve passes through.
• Internal pudendal artery and vein pass through.
• Pudendal nerve passes through.

Lesser Sciatic Foramen

• Bordered by the lesser sciatic notch, sacrospinous ligament, and sacrotuberous ligament.
• Internal pudendal artery and vein pass through.
• Pudendal nerve passes through.

Internal Pudendal Vessels and Pudendal Nerve

• Leave the pelvis through the greater sciatic foramen.
• Reenter through the lesser sciatic foramen.
• Pass through the pudendal canal (Alcock's canal) in the pelvis.

Pudendal Canal

• Lies in the lateral wall of the ischiorectal fossa.
• It is between the obturator internus muscle and the fascia covering its medial surface.
• Internally contains the internal pudendal vessels, the pudendal nerve, and the nerve to obturator internus muscle.

Clinical Note: Intramuscular Injections to Gluteal Region

• The gluteal region is a common site for intramuscular injections.
• This because the muscles there are large, which provides a large surface area for absorption of the given medication.
• The safest area for IM injections is above the horizontal line passing through the greater trochanter of femur - upper lateral quadrant of the buttock
• Other regions may be dangerous since a number of vessels and nerves are present.

Anterior Thigh

• The fascia lata (deep fascia) superiorly attaches to the inguinal ligament.
• Inguinal ligament extends between the anterior superior iliac spine and the pubic tubercle.
• It is the most inferior part of the aponeurosis of the external oblique muscle.

Fascia Lata (Opening)

• The opening on the fascia lata inferior to the inguinal ligament is the saphenous opening .
• The cribriform fascia covers the area.
• The great saphenous vein penetrates this fascia and passes through the hiatus saphenus to drain into the femoral vein.

Anterior Thigh - Muscles

• The main functions of the muscles in this region are to flex the thigh at the hip joint and extend the knee.
• Six muscles are considered: pectineus, psoas major, iliacus, psoas minor, quadriceps femoris, and sartorius.

Pectineus Muscle

• Originates from the superior ramus of the pubis.
• Inserts on the pectineal line of the femur.
• Flexes and adducts thigh and assists in its medial rotation.
• Innervated by the femoral nerve.

Iliopsoas Muscle

• Refers to the psoas major, psoas minor, and iliacus muscles collectively.
• Psoas major and iliacus muscles act together in flexing the thigh and laterally rotating it.
• All three muscles can flex the trunk when the lower limb is fixed and contracting bilaterally.
• Helps control the deviation of the trunk and is active during standing. Is a postural muscle.

Psoas Major Muscle

• Originates from the bodies and transverse processes of T12 – L5 vertebrae and the intervertebral discs between them.
• Inserts on the lesser trochanter of the femur.
• Innervated by direct branches from the lumbar plexus.

Psoas Minor Muscle

• Originates from the bodies of T12 – L1 vertebrae and the intervertebral discs between them.
• Inserts on the pectineal line of the pubic bone and iliopubic eminence.
• Innervated by direct branches from the lumbar plexus.

Iliacus Muscle

• Originating from the iliac fossa.
• Inserts on the lesser trochanter of the femur.
• Innervated by the femoral nerve.

Quadriceps Femoris Muscle

• Has four heads with distinct origins
• Rectus femoris originates from the anterior inferior iliac spine and ilium just above the acetabulum.
• Vastus lateralis originates from the greater trochanter and linea aspera.
• Vastus medialis originates from the intertrochanteric line and linea aspera.
• Vastus intermedius originates from the anterior and lateral surfaces of the body of femur.
• All heads insert to the base of the patella via the quadriceps tendon.
• Some fibers extend as the patellar ligament and inserts to the tibial tuberosity.
• All heads are innervated by the femoral nerve.
• Rectus femoris helps with flexing the thigh and extend the knee.

Sartorius Muscle

• Originates from the anterior superior iliac spine.
• Inserts on the superior part of the medial surface of the tibia.
• Flexes, abducts, and laterally rotates the thigh at the hip joint; flexes the leg at the knee joint.
• Innervated by the femoral nerve.

Medial Thigh

• The muscles in this region are called the adductor group.
• The muscles are adductor longus, adductor brevis, adductor magnus and gracilis.

Adductor Longus Muscle

• Originates from the body of the pubis inferior to the pubic crest.
• Inserts on the middle third of the linea aspera.
• Adducts the thigh and assists in lateral rotation.
• Innervated by the obturator nerve.

Adductor Brevis Muscle

• Originates from the inferior ramus of the pubis.
• Inserts on the posterior surface of the body of the femur.
• Adducts the thigh and assists in flexion.
• Innervated by the obturator nerve.

Adductor Magnus Muscle

• Has two parts with differing origins and insertions.
• The adductor part originates from the inferior ramus of the pubis and ramus of ischium.
• The hamstring part originates from the ischial tuberosity.
• Adductor part inserts on the gluteal tuberosity, linea aspera, and medial supracondylar line.
• Hamstring part inserts on the adductor tubercle of the femur.
• Adductor part is innervated by the obturator nerve.
• Hamstring part is innervated by the tibial nerve.
• The gap between attachments of adductor and hamstring parts is the adductor hiatus.
• The adductor hiatus transmits the femoral artery and vein, transitioning through it from the adductor canal to the popliteal fossa.

Gracilis Muscle

• Originates from the inferior ramus of the pubis.
• Inserts on the superior part of the medial surface of the tibia.
• Adducts the thigh and flexes the leg.
• Innervated by the obturator nerve.

Femoral Triangle

• Located at the upper part of the anterior thigh.
• Superior border is the inguinal ligament.
• Medial border is the medial margin of the adductor longus muscle.
• Lateral border is the medial margin of the sartorius muscle.
• Medially, the floor is the adductor longus and pectineus muscles and, laterally, the iliopsoas muscle.
• The roof is deep and superficial fasciae, and skin.

Femoral Triangle - Contents (Lateral to Medial)

• Femoral nerve (and its branches)
  • Saphenous nerve (sensory branch of the femoral nerve)
• Femoral artery (and its several branches)
  • Deep femoral artery (deep artery of the thigh).
    • Medial and lateral circumflex femoral arteries and perforating branches.
• Femoral vein (and veins draining to its proximal part.
  • The great saphenous vein and deep femoral vein form it.
• Deep inguinal lymph nodes

Muscular and Vascular Compartments

• Located posterior to the inguinal ligament.
• Is divided into two compartments by a septum: the muscular (lateral) and vascular (medial) comparment.
• This septum is a thickening of the iliac fascia covers anterior surface of the iliacus muscle.
• Thickening extends between posterior surface of inguinal ligament and the iliopubic eminence.

Muscular Compartment

• Contains the iliacus and psoas muscles and the femoral nerve.

Vascular Compartment

• Femoral artery and vein pass through.
• The femoral branch of the genitofemoral nerve.
• Lymph vessels.

Femoral Sheath

• Is formed by the transversalis fascia of abdominal wall and iliac fascia.
• A tubular sheath encloses the vascular lacuna.
• Septa divide the sheath into compartments, lateral (femoral artery), intermediate (femoral vein), and an opening (femoral canal).

Femoral Canal

• The smallest compartment of the femoral sheath, approximately 1-1.5 cm long.
• Contains loose connective tissue, fat, and usually a deep inguinal lymph node.
• Is only a potential canal and is not normally open but closed with tissue.
• The proximal opening of the femoral canal is referred to as the "femoral ring", which is closed by extraperitoneal fatty tissue named "femoral septum."
• Borders of the canal includes the femoral vein(laterall), Lacunar ligament (medially), Inguinal ligament (anterior) and Pectineus muscle and its fascia (posterior)

Clinical Note: Femoral Hernia

• The protrusion of any abdominal organ is called ""femoral hernia"", normally involving a part of the small intestine.
• Femoral ring is a weak area in the interior abdominal wall.
• The hernia can pass through the femoral canal, and reaches ""femoral triangle"", where is usually palpable as a tender mass.
• Passing through ""femoral triangle"" allows the hernia to travel to saphenous opening in subcutaneous tissue.
• Femoral hernias occur more commonly in females.
• The relatively weak femoral ring causes more hernias.
• Strangulation may occur, interfering with blood supply and cause necrosis to part of the small intestine.

Adductor (Subsartorial) Canal

• A long canal which extends to 15cm middle third of anterior.
• Extends between the apex of the triangle and adductor hiatus.
• The Adductor hiatus separates heads and separates adductor magnus muscle.
• Borders include vastus medialis (Antero-lateral), Sartorius muscle, and vastoadductor fascia (anteromedial.)
• The adductor longus ad adductor magnus muscles (posterior).

Structures passing through the canal

• Femeral artery and vein. (Enter and exit the area after passing through adductor hiatus. Become popliteal)
• Saphenous nerve = sensory, pass no through the canal but exit to go posterior at the region of knee.
• Nerve to vastus. Does no go through, instead innervates vastus region.

Posterior Thigh - Muscles

• Three muscles known collectively as the hamstring muscles are considered: semitendinosus, semimembranosus, and biceps femoris.

Semitendinosus Muscle

• Originates from the ischial tuberosity.
• Inserts on the medial surface of the tibia on its upper part.
• Flexes and medially rotates the flexed leg, and extends the thigh.
• Innervated by the tibial nerve.

Semimembranosus Muscle

• Originates from the ischial tuberosity.
• Inserts on the posterior part of the medial condyle - reflected part its insertion tendon. _ Forms the oblique ligament in the knee.
• Exact function as semitendinosis, extension of the thigh and flexion of the leg
• Innervated by the tibial nerve

Biceps Femoris Muscle

_ Long head originates at the ischial tuberosity. _ Short head is the linea aspera and lateral epicondyloard.

• The heads insert on the fibula. Is the only muscle of the hamstrings to attach to the bone.
• The functions include flexión then leg and it rotates it, thigh extensions.
• Long head Is inervantes by tibial , Short head, Is innervated by common peroneal.