Week 3: Hip Joint, Gluteal Region, Posterior Thigh

Short Head of the Biceps Femoris

originates at the lateral lip of the linea aspera. Insertion: Head of the fibula. Innervated by the common peroneal division of the sciatic nerve (L5, S1, S2).

Long Head of the Biceps Femoris

originates in the infer medial part of the upper area of the ischial tuberosity. Insertion: Head of the fibula. Innervated by the tibial division of the Sciatic nerve (L5, S1, S2).

Intertrochanteric Crest

On the POSTERIOR surface of the femur and descends medially across the bone from the posterior margin of the greater trochanter to the base of the lesser trochanter. Is a broad smooth ridge of bone, with a prominent tubercle on its upper half (quadrate tubercle). Remember: crest, is behind the femur, (cushy tushie)

Obturator Internus

A muscle of the pelvic wall and gluteal region. A flat fan shaped muscle. Laterally rotates extended femur at hip, abducts flexed femur at hip. Origin: Anterolateral wall of true pelvis. Deep surface of obturator membrane and surrounding bone. Insertion: Medial side of greater trochanter of the femur Innervation: Nerve to Obturator Internus (L5, S1)

Gluteal Tuberosity

A broad linear roughening that curves laterally to the base of the greater trochanter. Attachment site for gluteus maximus.

Neck of the Femur

A cylindrical strut of bone that connects the head to the shaft of the femur. It projects superomedially from the shaft at an angle of 125 degrees, and projects forward. This increases range of motion of the hip joint.

Gluteus Medius

A fan shaped muscle that overlies the gluteus minimus. Abducts the lower limp at the hip joint, helps reduce pelvic drop over the opposite swing limb during walking by securing the position of the pelvis on the stance limb- also medially rotates thigh. Origin: External surface of the allium between the anterior and posterior gluteal lines. Insertion: Elongate facet on the lateral surface of the greater trochanter. (MORE POSTERIOR FEMUR) Innervation: Superior Gluteal Nerve (L4, L5, S1)

Gluteus Minimus

A fan shaped muscle. Abducts the lower limp at the hip joint, helps reduce pelvic drop over the opposite swing limb during walking by securing the position of the pelvis on the stance limb- also medially rotates thigh. Origin: External surface of the illium between the inferior and anterior gluteal lines. Insertion: Linear facet on the anterolateral aspect of the greater trochanter. (ANTERIOR FEMUR) Innervation: Superior Gluteal Nerve (L4, L5, S1)

The Ligament of The Head of Femur

A flat band of delicate connective tissue that attaches at one end to the fovea of the femur, and on the other end to the acetabular fossa, transverse acetabular ligament, and margins of the acetabular notch. Carries a small branch of the obturator artery, which contributes to blood supply for the head of the femur.

Acetabulum

A large cupped shaped area on the pelvis where the illium, pubis, and ischium fuse.

Lateral Supracondylar Line

A line on the POSTERIOR surface of the femur at the distal end, lateral.

Medial Supracondylar Line

A line on the POSTERIOR surface of the femur. Terminates on the distal end of the femur at a prominent tubercle (adductor tubercle). Just lateral to the lower end of this line is the attachment area for the proximal attachment of the medial head of the gastrocnemius.

Intertrochanteric Line

A ridge of bone on the ANTERIOR surface of the upper margin of the shaft that descends from a tubercle on the anterior surface of the base of the greater trochanter just anterior to the base of the lesser trochanter. An oblique line that travels lateral to medial. Is continuous with pectineal line, which curves medially under the lesser trochanter, and around the shaft of the femur to merge with the linea aspera on the posterior femur.

Hip Joint

A synovial articulation between head of femur and acetabulum. A ball and socket joint that allows flexion, extension, abduction, adduction, medial and lateral rotation, and circumduction.

Quadrate Tubercle

A tubercle on the POSTERIOR aspect of the femur. Is located on the upper half of the intertrochanteric crest.

Obturator Externus

Functions to adduct the thigh at the hip joint, and laterally rotate the thigh. Origin: Obturator membrane and surrounding bone Insertion: Trochanteric fossa of greater trochanter Innervation: Posterior branch of the obturator nerve (L3, L4).

Iliofemoral Ligament

ANTERIOR to the hip joint. Triangular in shape, with apex attaching to the ilium b/w the anterior inferior iliac spine and to the margin of the acetabulum, with its base being attached along the intertrochanteric line of the femur. There is a Y-shaped appearance due to parts of the ligament being attached either above or below the intertrochanteric line.

Epicondoyles

Act as attachment site for collateral ligaments of the knee joint. Are bony elevations on the non articular outer surface of the condoyles. Two facets separated by a groove are just posterior to the lateral *blank*. The upper facet is for attachment of the lateral head of the gastrocnemius. The inferior facet is for attachment of the popliteus. The tendon of the popliteus lies in the groove separating the two facets. Are most visible anteriorly.

Pubofemoral Ligament

Anteroinferior to the hip joint. Also triangular in shape, with base attached medially to the iliopubic eminence, adjacent bone, and the obturator membrane. Laterally, it blends with the fibrous membrane and deep surface of the iliofemoral ligament.

Femoral Condoyles

Articulate with the tibia. On each *blank*, a shallow oblique groove separates the surface that articulates with the tibia from the anterior surface that articulates with the patella (anteriorly).

Intercondylar Fossa

At the distal end of the femur. On the POSTERIOR side, this structure separates two condoyles. Bears two facets for superior attachment of the cruciate ligaments, which stabilize the knee joint.

Synovial Membrane of the Hip Joint

Attaches to the margins of the articular surfaces of the femur and acetabulum. Forms a tubular covering around the ligament of the head of the femur. Lines the fibrous membrane of the hip joint. Covers the neck of femur as well.

Shaft of the Femur

Bears the greater and lesser trochanters, makes up the length of the bone. Descends from lateral to medial in the coronal plane at an angle of 7 degrees from the vertical axis. The distal end of the femur ends up being closer to the midline than the upper end of the femur. Is triangle in shape. Posterior margin is broad, and forms raised crest (linea aspera).

Posterior Cutaneous Nerve of the Thigh

Enters the gluteal region through the greater sciatic foramen inferior to the piriformis muscle and immediately medial to the sciatic nerve. It descends through the gluteal region deep to the gluteus maximus, and enters the posterior thigh. Has number of gluteal branches that loop over lower margin of gluteus maximus in order to innervate skin in gluteal fold. A small perineal branch passes medially to contribute to innervation of skin of scrotum/labia majora. The main trunk passes inferiorly, giving rise to branches the innervate skin on the posterior thigh and leg. S1, S2, S3 (anterior rami)

Nerve to Obturator Internus

Enters the gluteal region through the greater sciatic foramen inferior to the piriformis, and between the posterior cutaneous nerve of the thigh and the pudendal nerve. Supplies a small branch to gemellus superior, and passes over the ischial spine and through the lesser sciatic foramen to innervate the obturator internus via the perineum. L5, S1

Nerve to Quadratus Femoris

Enters the gluteal region through the greater sciatic foramen inferior to the piriformis, and deep to the sciatic nerve. Lies anterior to the deep muscles. It descends along the ischium to the tendon of the obturator internus to penetrate and innervate the quadratus femoris. It also supplies a small branch to the gemellus inferior. L5, S1

Sciatic Nerve

Enters the gluteal region through the greater sciatic foramen inferior to the piriformis. It descends in the plane between the superficial and deep group of gluteal muscles, crossing the posterior surfaces of first the obturator internus, gemellus muscles, and quadratus femoris. It lies just deep to the gluteus maximus at the mid point between the ischial tuberosity and the greater trochanter. At the lower margin of the quadratus femoris, this nerve enters the thigh. This is the largest nerve in the body, and innervates muscles in the posterior thigh that flex at the knee, and all muscles that work the ankle and foot. It also innervates skin on the lower limb. L5, S1, S2

Inferior Gluteal Nerve

Enters the gluteal region through the greater sciatic foramen inferior to the piriformis. It runs along the posterior surface of the sciatic nerve, and then penetrates and supplies the gluteus maximus muscle. (L5, S1, S2)

Greater Trochanter

Extends superiorly from the shaft of the femur lateral to the region where the shaft joins the neck of the femur. It continues to the posterior of the femur, where the middle surface has a deep groove to form the trochanteric fossa. Has an elongated ridge on the front lateral surface for attachment of the gluteus minimus, and a similar ridge posteriorly for attachment of the gluteus medium. Between these two points,*blank* is palpable. Also bears attachment sites for obturator externus +internus, gemelli muscles, piriformis.

Lesser Trochanter

Feature that projects posteromedially from the shaft of the femur just inferior to the junction with the neck. Has a blunt conical shape. Is the attachment site for the combined tended of the psoas major and iliacus muscles.

Superficial Gluteal Muscles

Gluteus Maximus, medius, and minimus, as well as tensor fasciae latae (connecting to illiotibial tract). Are abductors and extensors of the hip.

Ligaments of the Hip Joint Capsule

Illiofemoral, pubofemoral, and ischiofemoral ligaments. The fibres of these ligaments are oriented in a spiral orientation around the hip joint so that they become taut when the hip extends. This stabilizes the joint, and reduces energy required for standing. Remember L-P-I for anterior to posterior order.

The Lesser Sciatic Foramen

Inferior to the greater sciatic foramen. Inferior to the lateral attachment of the pelvic floor (levator ani and coccygeus muscles), so is the passageway from the gluteal region to the perineum. (Structure D). -Tendon of obturator internus passes from lateral pelvic wall through this structure into the gluteal region to insert on the femur -Pudendal nerve and vessels exit the pelvis by passing through the greater sciatic foramen, then entering the perineum below the pelvic floor by passing around the ischial spine and sacrospinous ligament, and medially through this structure.

Common Peroneal Division of Sciatic Nerve

Innervation of short head of biceps femoris. Nerve Root L5, S1, S2

Gluteus Maximus

Largest muscle of the gluteal region. Overlies other gluteal muscles. It mainly extends the flexed thigh at the hip joint. Through insertion into the iliotibial tract, it also stabilizes the knee and hip joints. Origin: Fascia covering gluteus medius, external surface of the allium behind the posterior gluteal line, fascia of erector spine, dorsal surface of lower sacrum, lateral margin of coccyx, external surface of sacrotuberous ligament. Insertion: Posterior aspect of illiotibial tract of fascia latae, and gluteal tuberosity of proximal femur. Innervation: Inferior Gluteal Nerve (L5, S1, S2).

Biceps Femoris

Lateral in the posterior compartment of the thigh. Has two heads. Flexes leg at knee joint, extends and laterally rotates thigh at the hip joint, and laterally rotates leg at the knee joint. Origin: Long head originates in the infer medial part of the upper area of the ischial tuberosity. The short head originates at the lateral lip of the linea aspera. Insertion: Head of the fibula. Innervation: Sciatic Nerve (L5, S1, S2). Long head innervated by the tibial division, vs. the short head which is innervated by the common peroneal division.

Semimembranosus

Lies deep to the semitendinosus muscle in the posterior compartment of the thigh. It flexes the leg at the knee joint, and extends the thigh at the hip. Along with the semitendinosus, it medially rotates the thigh at the hip joint and the leg at the knee joint. Origin: Superolateral impression of the ischial tuberosity Insertion: Groove and adjacent bone on the medial and posterior surface of the medial tibial condoyle. Innervation: Sciatic nerve, tibial division. (L5, S1, S2).

Adductor Tubercle

Located at the medial end of the linea aspera, or medial supracondylar line. It is the site of attachment for the adductor magnus.

Semitendinosus

Medial to the Biceps femoris in posterior compartment of the thigh. Flexes the leg at the knee joint and extends the thigh at the hip joint. Working with the semimembranosus, it also medially rotates the thigh at the hip joint, and medially rotates the leg at the knee joint. Origin: Inferomedial part of the upper area of the ischial tuberosity. Insertion: Medial surface of the proximal tibia. Innervation: Sciatic Nerve, tibial division (L5, S1, S2).

Muscles of Gluteal Region

Muscles of the gluteal region are composed of two groups: 1) Deep group of small muscles, which are lateral rotators of the femur at the hip joint (piriformis, obturator internus, gemellus superior and inferior, and quadratus femoris) 2) Superficial group of larger muscles, which abduct and extend the hip, and include the gluteus medius, minimus, and maximus, as well as the tensor fasciae latae (stabilizes knee in extension by acting on longitudinal band of deep fascia (illiotibial tract). Many nerves in gluteal region lie between the plane of superficial and deep groups of muscles.

Gemellus Superior

One of a pair of triangular muscles associated with the upper and lower margins of the obturator internus tendon. Laterally rotates extended femur at hip, abducts flexed femur at hip. Origin: External Surface of ischial spine Insertion: Along length of superior surface ofobturator internus tendon and into medial side of greater trochanter of femur with the obturator internus. Innervation: Nerve to obturator internus (L5, S1)

Gemellus Inferior

One of a pair of triangular muscles associated with the upper and lower margins of the obturator internus tendon. Laterally rotates extended femur at hip, abducts flexed femur at hip. Origin: Upper aspect of ischial tuberosity Insertion: Along the length of inferior surface of the obturator internus tendon and into the medial side of the greater trochanter of the femur with the obturator internus tendon. Innervation: Nerve to quadratus femoris (L5, S1)

Profunda Femoris Artery

Originates from deep artery of the thigh as it descends anterior to the adductor brevis muscle. There are three. All three penetrate the adductor magnus near its attachment to the linea aspera to enter and supply the posterior compartment of the thigh. The vessels have ascending and descending branches that interconnect to form a longitudinal channel.

The Greater Sciatic Foramen

Pelvic opening formed by the greater sciatic notch of the hip bone, the sacrum, and the sacrospinous and sacrotuberous ligament (structure A). Major route to the gluteal region from the pelvis. The piriformis passes out of the pelvis into the gluteal region through this structure, and separates the foramen into two parts that structures pass through: Above Piriformis: -Superior gluteal nerve + Vessels Below Piriformis: -Sciatic nerve, inferior gluteal nerve +vessels, pudendal nerve +vessels, posterior cutaneous nerve of the thigh, nerve to the quadratus femoris and gemellus inferior

Deep Gluteal Muscles

Piriformis, quadratus femoris, obturator internus, and gemellus superior + inferior. Are lateral rotators of the hip, and function to stabilize hip (prevent internal rotation) during walking and running.

Ischiofemoral Ligament

Reinforces POSTERIOR aspect of the fibrous membrane. It is attached medially to the ischium, posteroinferior to the acetabulum, and laterally to the greater trochanter deep to the iliofemoral ligament.

Head of the Femur

Spherical. Articulates with acetabulum of pelvic bone. Characterized by a non-articular pit called the fovea on the medial surface for ligament attachment to the acetabulum. Covered in hyaline cartilage, with exception of the fovea.

Fibrous Membrane of Hip Joint

Strong thick membrane that encloses hip joint. Medially attached to the margin of the acetabulum on the pelvis, the transverse acetabular ligament, and the adjacent margin of the obturator foramen. Laterally, it is attached to the intertrochanteric line on the anterior aspect of the femur, and the neck of the femur just proximal to the intertrochanteric crest on the posterior surface. Three ligaments reinforce the external surface of this structure and stabilize the joint (iliofemoral, pubofemoral, and ischiofemoral ligaments).

Linea Aspera

The *blank* is a prominent longitudinal ridge or crest, on the middle third of the bone, presenting a medial and a lateral lip, and a narrow rough, intermediate line. It is an important insertion point for the adductors and the lateral and medial intermuscular septa that divides the thigh into three compartments. On the POSTERIOR femur. In the proximal femur, it splits medially and laterally as the pectineal line (medial femur) and gluteal tuberosity (posterolateral femur).

Femur

The bone of the thigh, is the longest bone in the body. Proximal end characterized by a head and neck, and two large projections called the greater and lesser trochanters on the upper shaft.

popiteal fossa

The depression in the posterior region at the back of the knee. Contains all the main neurovascular structures that travel into the lower leg. It is diamond shaped, and is formed by the borders of the biceps femoris and semimembranosus above, and the medial and lateral heads of the gastrocnemius below. It contains the tibial and common peroneal nerves, the popliteal artery, and the popliteal vein. From most superficial to deepest structure, it goes tibial and peroneal nerves, popliteal vein, popliteal artery.

Obturator Canal

The gateway through the obturator through the obturator formen. Connects the abdominopelvic region with the thigh. The obturator nerve and vessels pass through here.

Acetabular Notch

The inferior margin of the acetabulum. Provides area for blood vessels and nerves to pass through and out of the pelvis,

Quadratus Femoris

The most INFERIOR of the deep gluteal muscles. A flat rectangular muscle located below the obturator internus and associated gemellus muscles. Laterally rotates the femur at the hip joint. Origin: Lateral aspect of the ischium just anterior to the ischial tuberosity. Insertion: Quadrate tubercle on the intertrochanteric crest of the proximal femur. Innervation: Nerve to the quadratus femoris (L5, S1).

Piriformis

The most SUPERIOR of the deep group of muscles. Is a muscle of the pelvic wall, and of gluteal region. Laterally rotates extended femur at hip, abducts flexed femur at hip. Origin: Anterior Surface of sacrum b//w anterior sacral foramina Insertion: Medial side of superior border of greater trochanter of the femur Innervation: Branches from Anterior Rami of S1 and S2

Tensor Fasciae Latae

The most anterior of the superficial muscles in the gluteal region. Overlies the gluteus minimus and part of the gluteus medius. Origin: Lateral aspect of the crest of the illium between the ASIS and the tubercle of the crest Insertion: Illiotibial Tract of fascia lata. Innervation: Superior Gluteal Nerve (L4, L5, S1). Stabilizes the knee in extension, and stabilizes the hip joint along with the gluteus maximus muscle by holding the femur in the acetabulum.

Superior Gluteal Nerve

The nerve that passes above the piriformis. After entering gluteal region, it loops up over the inferior margin of the gluteus minimus, and travels anteriorly and laterally between the gluteus minimus and medius. Supplies branches to the gluteus minimus and medius muscles, and terminates by innervating the tensor fasciae latae muscle. (L4, L5, S1)

Acetabular Fossa

The non-articular area of the acetabulum. Is rough, forms a shallow circular depression in the middle of the acetabulum. Marked inferiorly by the acetabular notch. Provides attachment for ligaments of the head of the femur. Contains loose connective tissue, and a fat pad.

Acetabular labrum

The rim of the acetabulum is raised slightly by a fibrocartliaginous collar called the *blank*. This structure bridges across the acetabular notch as the transverse acetabular ligament, converting the notch into a foramen.

Lunate Surface of Acetabulum

The smooth crescent shaped surface on the acetabulum. Broadest superiorly where all the weight is transmitted through the pelvis to the femur. Covered with hyaline cartilage.

Nerves of Hip Joint

This structure is innervated by articular branches from the femoral, obturator, and superior gluteal nerves, as well as the nerve to the quadratus femoris.

Shape of Femur

Trianglar in shape, with smooth lateral and medial margins (corners.) The third corner forms the linea aspera in the posterior margin. There are anterior, posterolateral, and medial (posteromedial) surfaces in between these corners.

Vascular Supply to Hip Joint

Vascular supply to this structure is through branches of the obturator artery, medial and lateral circumflex femoral arteries, superior and inferior arteries, and first perforating branch of the deep artery of the thigh (profundis femoris)

Posterior Muscles of the Thigh

biceps femoris, semitendinosus, semimembranosus. Collectively known as the hamstrings. As a group, flex the leg at the knee, and extend the thigh at the hip.

Transverse acetabular ligament

bridges a gap in the inferior margin of the acetabular labrum.

Popliteal Artery

deepest structure in the popliteal fossa. A deep continuation of the femoral artery after it passes through the adductor hiatus. It supplies the knee's ligaments and capsule with blood.

Trochanteric Fossa

depression on medial surface of greater trochanter. The lateral wall of this fossa has a distinct oval depression for attachment of obturator externes muscle. Just above this feature, there is a small impression for attachment of the obturator internus and associated gemelli muscles. Above the attachment for the obturator internus, the margin of the trochanter bears an impression for attachment of the piriformis. Most of these attachment sites are best viewed medially.

Tibial Division of the Sciatic Nerve

innervation of semitendinosus, semimembranosus, and long head of the biceps femoris. Nerve root L5, S1, S2