Anatomy of the Lower Limbs

Question 1

The Bony Pelvis

Answer 1

The bony pelvis is comprised of the 2 hip bones (also called pelvic, coxal or innominate bones), the sacrum, and the coccyx. The sacrum and coccyx are part of the vertebral column, which is part of the axial skeleton.

Question 2

The Hip Bone

Answer 2

The hip bone is formed by three bones, the ilium the ischium and the pubis. At birth these bones are held together by hyaline cartilage. The inferior rami of the ischium and pubis are incompletely ossified by the age of 9. At puberty, their intersection at the acetabulum separated by a Y shaped triradiated cartilage. The bones begin to fuse at age 15-17 years.

Question 3

The Acetabulum

Answer 3

The ilium, ischium and pubis contribute to it. It has a smooth lunate or articular surface and a rough depression extending from the acetabular notch called acetabular fossa. It also contains the transverse acetabular ligament, the ligament of the head of the femur and Acetabular labrum that provides lubrication to the joint.

Question 4

The acetabular labrum

Answer 4

fibro cartilaginous annular lip. Deepens acetabular socket and adds to the area of contact between articulating bones. Some books say it may act as lubricant spreader.

Question 5

The hip joint

Answer 5

It is formed by the acetabulum and proximal femur. It is a synovial ball and socket joint. It is one of the most mobile joints in the body. Combining stability and mobility and it is designed for weight bearing. It is enclosed by a fibrous membrane, the hip joint capsule.

Question 6

Iliofemoral Ligament:

Answer 6

Strong triangular-shaped ligament anterior to the joint that extends from the ilium between A.I.I.S. and margin of acetabulum to the areas above and below the intertrochanteric line of femur. This results in an inverse Y-shaped appearance. Transverse part of this ligament limits lateral rotation and adduction and the descending part limits medial rotation. Together they limit hip extension.

Question 7

Pubofemoral Ligament:

Answer 7

Medially, it extends from iliopubic area of the acetabulum and superior pubic ramus. It blends inferior-medially with the fibrous capsule. laterally, it attaches to the intertrochanteric line of femur. Limits hip abduction, extension and internal (medial) rotation.

Question 8

Ischiofemoral Ligament

Answer 8

Reinforces posterior aspect of the fibrous capsule. Medially, attaches to the ischium, posteroinferior to the acetabulum. Laterally, attaches to the neck of femur and greater trochanter, deep to the iliofemoral ligament. Limits extension, abduction and internal (medial) rotation.

Question 9

Hip joint ligaments

Answer 9

Ischiofemoral Ligament, Pubofemoral Ligament, Iliofemoral Ligament.

The three ligaments are arranged in a spiral fashion around the hip joint. They become taught when hip joint is extended. Together they become taught, stabilising the joint and decreases the amount of muscle energy required to maintain standing posture.

Question 10

Hip joint bursae

Answer 10

Main bursae around hip joint are Iliopsoas, trochanteric, ischiogluteal and trochanteric bursae.

Question 11

Blood supply to the hip joint

Answer 11

Retinacular arteries from lateral and medial circumflex femoral arteries from deep femoral artery. Foveolar artery from obturator artery in round ligament (small in adults). There is a risk of avascular necrosis to the head of femur after proximal femoral neck fracture

Question 12

Hip joint movement

Answer 12

 Flexion (120 – 130º)
 Extension (20 - 30º)
 Abduction (40 - 50º)
 Adduction (20 – 30º)
 Internal (medial) rotation (45º) with hip and knee flexed to 90°
 External (lateral) rotation (45º) with hip and knee flexed to 90°
 Circumduction

Question 13

The knee joint

Answer 13

The knee joint is made out of the femur, tibia and patella bones. It is a modified synovial hinge joint: 1- Femorotibial –bicondylar 2- Femoropatellar – plane. (Note: proximal tibiofibular joint not part of knee joint).
Stability of the knee joint is dependent on ligaments and muscles, as there is almost no contribution from shape of bones and menisci.

Question 14

Knee menisci

Answer 14

Discs of fibrocartilage and fibrous tissue. There is one medial and one lateral. Its wedge shape helps to distribute compressive forces across wider surface area. Movement accommodates for changes in bone shape through range of motion.

Menisci are interconnected anteriorly by the transverse ligament. The medial meniscus attaches around its margins to the capsule via the coronary ligaments and also attaches to the tibial collateral ligament.

The lateral meniscus does not attach to the capsule, therefore more mobile than the medial.
Posteriorly it attaches to the tibia via the meniscofemoral ligament and also attaches to the tendon of the popliteus muscle.

Question 15

Knee joint capsule

Answer 15

Extensive fibrous membrane formed and reinforced by extensions from tendons of surrounding muscles. Blends medially with MCL and attaches to Med. Meniscus. Laterally, separate from LCL and does not attach to Lat. Meniscus. (3)

Question 16

Synovial membrane

Answer 16

Attaches to the margins of the articular surfaces and menisci. Lines internal surfaces of capsule. ACL, PCL excluded from synovial cavity (intracapsular but extra synovial)

Question 17

Anterior cruciate ligament (ACL)

Answer 17

attaches to tibia anteriorly and to the femur at the intercondylar fossa on the lateral side. Prevents anterior displacement of tibia relative to femur, and posterior displacement of femur relative to tibia, also prevents hyperextension

Question 18

Posterior cruciate ligament (PCL):

Answer 18

attaches to tibia posteriorly and to the femur at the intercondylar fossa on the medial side. Prevents posterior displacement of tibia relative to femur, and anterior displacement of femur relative to tibia (e.g., during walking downhill)

Question 19

Patellar ligament (Tendon):

Answer 19

Continuation of quadriceps tendon from patella to tibial tuberosity. Vastus medialis (oblique fibres) balance lateral forces of rest of quadriceps muscle. The patella improves line of pull of quads, reduces wear and tear of quadriceps tendon on femur.

Question 20

Tibial (Medial) collateral ligament (MCL):

Answer 20

Broad ligament, attached to femur, tibia and medial meniscus. Receives fibres from adductor Magnus. Prevents abduction of tibia (<5o of passive abduction normal) and hyperextension. More often injured ligament in the knee.

Question 21

Fibular (Lateral) collateral ligament (LCL):

Answer 21

Strong, cord-like ligament, attached to femur, head of fibula, but not lateral meniscus. Not often injured. Prevents adduction of tibia (<5o of passive adduction normal), hyperextension. (3)

Question 22

Ligaments of the knee

Answer 22

(1) Extracapsular ligaments: Fibular (Lateral) collateral ligament (LCL), Tibial (Medial) collateral ligament (MCL), Patellar ligament (Tendon).
(2) Intracapsular ligaments: Anterior cruciate ligament (ACL), Posterior cruciate ligament (ACL)

Question 23

Knee joint bursae

Answer 23

Suprapatellar bursa. Prepatellar bursa. Subcutaneous and deep infrapatellar bursae. Pes Anserinus bursa. Popliteal bursa. Medial and lateral collateral ligament bursae.

Question 24

Blood supply around the knee

Answer 24

There are 10 vessels form the Genicular anastomoses around the knee that provide blood supply. The genicular branches of the femoral, popliteal, and anterior and posterior recurrent branches of the anterior tibial recurrent and circumflex fibular arteries.

Question 25

Tibiofibular joints

Answer 25

 Proximal tibiofibular: synovial plane.
 Distal tibiofibular: fibrous syndesmosis
 Tibiofibular – interposes membrane – fibrous syndesmosis

Question 26

Movement at the knee joint

Answer 26

 Flexion 135º
 Extension 0º
 Hyperextension 5 – 10º
 Lateral rotation 30-40º
 Medial rotation 10º

Question 27

The Ankle (Talocrural) joint

Answer 27

The ankle joint is made out of the talus (trochlea, dome), tibia and fibula. It is a synovial hinge joint. Movements at ankle joint are plantarflexion / dorsiflexion.

Question 28

Subtalar Joint

Answer 28

Also called talocalcaneal joint (anterior and posterior parts), is a synovial plane joint. Movements at subtalar joint are Inversion and eversion.

Question 29

Transverse tarsal (midtarsal, Chopart’s) Joint

Answer 29

1- talonavicular (talocalcaneonavicular) jont is a synovial plane (or ball and socket) joint
2- Calcaneocuboid Joint is a synovial plane joint
Movements at transverse tarsal joint are inversion / eversion (supination / pronation)

Question 30

Medial Collateral (Deltoid) Ligament

Answer 30

Contributes to stability of ankle, subtalar, and talonavicular joints. Preventsover-eversion. It has three parts: anterior and posterior tibiotalar, tibiocalcaneal, tibionavicular.

Question 31

Lateral Collateral Ligament

Answer 31

Contributes to stability of the ankle and subtalar joints. Preventsover-inversion. It has three parts: anterior and posterior talofibular, calcaneofibular

Question 32

Interosseus Talocalcaneal Ligament

Answer 32

Contributes to stability of subtalar joint. Located within tarsal canal/sinus (not tunnel)

Question 33

What type of joints are the intertarsal joints?

Answer 33

synovial plane

Question 34

What type of joints are the Tarsometatarsal (Lisfranc’s) joints?

Answer 34

synovial plane

Question 35

What type of joints are the Intermetatarsal joints

Answer 35

synovial plane

Question 36

What type of joints are the Metatarsophalangeal (MTP) joints, and what movement do they provide?

Answer 36

• synovial condyloid
  – Abduction/adduction, flexion/extension
  – Plantar plates (ligaments)

Question 37

What type of joints are the Interphalangeal (IP) joints and what movement do they provide?

Answer 37

• synovial hinge

– Flexion / extension