Bones, Joints, Capsules and Ligaments of the Lower Limb Flashcards
The hip bone
The hip 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 nine. At puberty, the intersection of the threebones at the acetabulum is separated y a Y shaped triradiated cartilage. The bons begin to fuse at age 15-17 years and completely fuse at about the age of 25.
The bony pelvis
The bony pelvis is comprised of two 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.
The acetubulum
The ilium, ischium and pubis contribute to it. It has a smooth lunate or articular surface and a rough depression extending from the acetubular notch called acetabular fossa. The fossa contains synovial membrane that provides lubrication to the joint, the transverse acetabular ligament and the ligament of the head of the femur.
The acetabular labrum
Fibrocartilaginous annular lip. It deepens the acetabular socket and adds to the area of contact between articulating bones. Some books say it may act as lubricant spreader.
The hip joint
Acetabulum and proximal femur. Synovial joint, ball and socket joint. It is one of the most mobile joins in the body. It combines stability and movility and is designef for weight bearing. It is enclosed by a fibrous membrane, the hip joint capsule.
Hip joint ligaments
Iliofemoral ligament, pubfemoral ligament and ischiofemoral ligrament.
Iliofemoral ligament
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 abduction and the descending part limits medial rotation. Together limit hip extension.
Pubofemoral ligament
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 the femur. Limits hip extension, abduction and external rotation.
Ischiofemoral ligament
Reinforces posterior aspect of the fibrous capsule. Medially, attaches to the ischium, posterior to the acetabulum. Laterally, attaches to the nech of the femur and greater trochanter, deep to the iliofemoral ligament. Limits extension, abduction and later rotation. The three ligaments are arranged in a spiral fashion around the hip joint. They become taught when hip joint is extended. Together they stabilise the joint and decrease the amount of energy required to maintain a standing posture.
The hip joint bursae
A bursa is a small fluid-filled sac lined by synovial membrane. Filled with synovial fluid and usually occurs in locations subject to friction. Allows free movement of surfaces. Bursae associated with the hip joint include iliopsoas, trochanteric, ischiogluteal and trochanteric bursae.
Hip joint movements
Flexion (120-130) Extension (20-30) Abduction (40-50) Adduction (20-30) Internal (medial) rotation (45) with hip and knee flexed to 90 External (lateral) rotation (45) with hip and knee flexed to 90 Circumduction
The knee joint
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 the knee joint. The stability of the knee joint is dependent on ligaments and muscles, as there is almost no contribution from shape of bones and minisci.
Knee joint menisci
Disc of fibrocartilage and fibrous tissue. There is one medial meniscus and one lateral meniscus. Their 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 it is more mobile than the medial. Posteriorly it is attached to the femur via the meniscofemoral ligament and also ttaches to the tendon of the popliteus muscle.
Ligaments of the knee
Intracaosular ligaments: anterior cruciate ligament (ACL), posterior cruciate ligament (PCL). Extracapsular ligaments: patellar ligament (tendon), tibial (medial) collateral ligament (MCL), lateral (fibular) collateral ligament (LCL).
Anterior cruciate ligament (ACL)
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.
