S3L1 - Anatomy Of The Hip

Question 1

What is the pelvic girdle?

Answer 1

A collection of bones (the right and left hip bones and the sacrum) that attaches the axial skeleton to the lower limbs

Question 2

What are the 3 main articulations of the hip bones?

Answer 2

1) Sacroiliac joint : articulation with the sacrum
2) Pubic symphysis: articulation between the left and right hip bones
3) Hip joint : articulation with the head of the femur

Question 3

What 3 bones fuse to form the hip bone?

Answer 3

Ilium, pubis and ischium

Question 4

During childhood, what separates the 3 bones of the hip bone? When do the bones fuse?

Answer 4

Triradiate cartilage

Fusion of the 3 bones (ilium, ischium and pubis) begins at 15 to 17 years and finishes at 20-25 years.

Question 5

What is the acetabulum?

Answer 5

A c -shaped socket on the inferno lateral aspect of the pelvis formed by the ilium, pubis and ischium converging. The margin of the acetabulum is incomplete inferiorly forming the acetubular notch. The head of the femur articulates within the acetabulum to form the hip joint.

The inferior acetabular notch contains fibroelastic fat covered with synovial membrane.

Both the acetabulum and the head of the femur is covered in hyaline cartilage.

Question 6

What is the ilium?

Answer 6

1 of the 3 parts that are fused to form the hip bone. Widest and largest. Located superiorly forming the superior part of the acetabulum. Superior to the acetabulum, the ilium forms the wing. The wing of the ilium has 2 different surfaces

Question 7

Describe the 2 different surfaces of the ilium.

Answer 7

Internal surface = concave, produces iliac fossa ( site of origin of the iliac muscle )

External surface = gluteal surface, convex, provides attachments to the gluteal muscles

Question 8

What is the iliac crest?

Answer 8

Thickened superior margin of the iliac wing. Extends from the anterior iliac spine (ASIS) to the posterior superior iliac spine (PSIS)

Question 9

Describe the structure and location of the pubis.

Answer 9

Most anterior part of the hip bone. Consists of a body, a superior ramus and an inferior ramus. (Ramus = branch)
Superior pubic ramus = extends laterally from the pubic body to the acetabulum
Inferior pubic ramus = extends laterally from the pubic body to form the inferior ischial ramus. They join together to form the ischiopubic ramus.

Pubic body is located medially and articulates with the opposite pubic body at the pubic symphysis. Rounded superior thickening of the pubic body is called pubic crest, which extends laterally as far as the pubic tubercle

Question 10

What is the obturator foramen?

Answer 10

The hole within the hip bone, located inferiorly to the acetabulum. Enclosed by the superior and inferior rami and the ischial tuberosity. Obturator nerve artery and vein pass through to reach the lower limb.

Question 11

Describe the structure and location of the ischium.

Answer 11

Ischium forms the posterior inferior part of the hip bone. Composed of a body and a superior and inferior ramus. The posteroinferior aspect of the ischium forms the ischial tuberosity.
The ischial spine is a projection of bone on the ischium body and superior ischial ramus.

Question 12

What 2 important ligaments attach to the ischium?

Answer 12

1. Sacrospinous ligament - Runs from the ischial spine to the sacrum, thereby creating the greater sciatic foramen.
2. Sacrotuberous ligament - runs from the sacrum to the ischial tuberosity, forming the lesser sciatic foramen.

Question 13

Describe the structure of the hip joint

Answer 13

A ball and socket synovial joint. Consists of the articulation of the head of the femur and the pelvic acetabulum.

Question 14

Describe the function of the hip joint

Answer 14

Enables mobility of the lower limbs without weakening the ability of the lower limbs to support the weight of the body. Is a very stable joint that takes a lot to disrupt.

Question 15

What is the acetabular labrum?

Answer 15

A fibrocartilaginous collar that encircles the margin of acetabulum. This deepens the acetabulum, providing a more secure fit for the hemispherical femoral head. Increases the Articular contact area by 10%. 50% of the femur head in contact with the socket.

Question 16

What strengthens the hip joint?

Answer 16

1) Acetabular labrum - increased Articular contact area by 10%
2) Transverse acetabular ligament - strengthens inferior portion of acetabulum where the acetabular notch is.
3) Joint capsule - capsular fibres take a spiral course. In extension capsule helps pull the femoral head into the acetabulum.

Question 17

Describe the structure of the femur

Answer 17

Articulates with the acetabulum to form the hip joint, and with the tibia and patella dismally to form the knee joint. Longest bone in the human body. Femoral head covered with hyaline cartilage.
Fovea capitis is a small depression in the centre of the femoral head. Ligamentum teres attaches here.
Neck of the femur attaches the head to the femoral shaft. It passes posteriorly, laterally and inferiorly.

Question 18

What are the greater and lesser trochanters?

Answer 18

Large bony prominences at proximal end of the femoral shaft.
The greater trochanter is located superiorly and anteriorly, with the lesser trochanter being located inferiorly and posteriorly.
On the anterior aspect they are connected by the intertrochanteric line and on the posterior aspect they are connected by the interchanteric crest.

Question 19

Describe the structure of the femoral shaft.

Answer 19

Smooth and rounded. Posteriorly there is a ridge called the linea aspera, Intermuscular septa and muscles of the thigh attach here.
Gluteal tuberosity lies between the upper end of the linea aspera and the intertrochanteric crest. This is the site of insertion of the gluteus maximus.
Inferiorly, the linea aspera splits to form the lateral and medial supracondylar lines.

Question 20

Describe the path of the supracondylar lines down the femur.

Answer 20

The 2 supercondylar lines begin as the linear aspera divides to form the lateral and the medial supracondylar lines.
The medial supracondylar line continues inferiorly and terminates at the adductor tubercle on the medial femoral condole.
The lateral supracondylar line continues inferiorly and terminates at the lateral femoral condyle.
The condyles are separated by the intercondylar notch posteriorly, and the Articular surface for the patella anteriorly ( known as the trochlear groove)
Both the lateral and the medial condyles take part in the formation of the knee joint.

Question 21

Where does the hip joint capsule attach?

Answer 21

Proximally : to the edge of the acetabulum, outside the labrum.
Distally: attaches to the intertrochanteric line of the femur anteriorly and the femoral neck posteriorly.

Anteriorly the capsular fibres ascend along the neck as the longitudinal retinacula

Question 22

What intracapsular and extracapsular ligaments are present in the hip joint?

Answer 22

Intracapsular: ligamentum teres

Extracapsular: iliofemoral, pubofemoral, ischiofemoral.

Question 23

What is the strongest ligament is the body?

Answer 23

Iliofemoral ligament. Inverted y shape, lies superior and anterior to the hip joint. Blends with the capsule of the hip joint.

Question 24

What is the function of the iliofemoral ligament?

Answer 24

It screws the head of the femur into the acetabulum.

Prevents hyperextension of the hip.

Question 25

What is the function and extension of the pubofemoral ligament?

Answer 25

Lies inferior and anterior to the hip joint. Base is attached to the superior pubic ramus and its apex to the inferior part of the interchanteric line arteriorly.

Roles it to prevent excessive abduction and extension of the joint.

Question 26

What is the location and function of the ischiofemoral ligament?

Answer 26

Location : Spiral shaped, attached to the body of the ischium posteriorly. Inferior fibres spiral superolaterally from the body of the ischium to attach to superolateral end of the interotrochanteric line of the femur, anteromedial to the greater trochanter. Weakest of the three ligaments.

Function : prevents excessive internet/medial rotation.

Question 27

What is the transverse acetabular ligament?

Answer 27

Formed by the acetabular labrum, this small ligament bridges the acetabular notch, converting it into a tunnel through which the blood vessels and nerve enter the hip joint.

Question 28

What stabilising factors increase the stability of the hip joint.

Answer 28

1. The cup chapped acetabulum
2. The acetabular labrum, which deepens the acetabulum
3. The capsule
4. The ligamentum teres
5. Extracapsular ligaments (iliofemoral, pubofemoral and ischiofemoral)
6. Muscles surrounding the hip joint.

Question 29

What muscles cause flexion in the hip?

Answer 29

Iliopsoas (iliacus and psoas major)

Assisted by rectus femoris, sartorius, pectineus

Question 30

What muscles cause hip extension?

Answer 30

Gluteus maximus

Hamstrings (semimembranosus, semitendinosus, biceps femoris)

Question 31

What muscles cause hip abduction?

Answer 31

Gluteus medius, gluteus minimus.

Assisted by sartorius, tensor fascia lata

Question 32

What muscles cause hip adduction?

Answer 32

Adductor longus, adductor breves, adductor Magnus.

Assisted by pectineus, gracious, obturator externus

Question 33

Which muscles are involved in lateral rotation?

Answer 33

Obturator externus, piriformis, obturator internus, superior and inferior gemelli, quadratics femoris. Assisted by the gluteus maximus and sartorius.

Question 34

Which muscles are used in medial rotation of the hip?

Answer 34

Anterior fibres of the gluteus medius and minimus, tensor fascia lata. Assisted by adductor brevis, adductor longus, superior portion of adductor magnus, pectineus.

Question 35

What nerves innervate the hip joint?

Answer 35

Posteriorly = sciatic nerve

Anteriorly = femoral nerve

Inferiorly = obturator nerve

Question 36

Describe the blood supply to the femoral head and neck

Answer 36

Extracapsular arterial ring at the base of the femoral neck.
Formed posteriorly by large branch of the medial femoral circumflex artery (MFCA)
Formed anteriorly by smaller branches of the lateral femoral circumflex artery.

Question 37

Describe blood supply to the femoral head

Answer 37

Ascending cervical arteries crossing the surface of the femoral neck send numerous small branches into the metaphysis of the femoral neck. (Main blood supply in adults).
The ligamentum teres (extracapsular ligament) contains within it the artery of the ligamentum teres, which arises commonly from the obturator artery. (Major blood supply in children, less important after fusion of the epiphysial plates)