Anatomy and Physiology
Synovial Joint Assignment
Friday 13th March
“Synovial joints are characterized by the presence of synovial fluid within a space that encapsulates the articulating surfaces (surfaces that touch each other) of the joint.” (Joints, 2012) There are 6 different types of synovial joints: Plane joint/gliding, hinge, pivot, condyloid, saddle, and ball and socket.
Features of a Synovial Joint: (See image 1 for placements in a knee joint)
Joint Capsule (1): A sac of the fibrous and synovial membrane that surround a joint to enclose a space (called the joint cavity), if there was no capsule, the joint would have nothing to hold the protective fluid which plays a big part in protecting joints from injury.
Joint Cavity (2): The space between articulating bones that is lined with the synovial membrane. The joint capsule surrounding the joint cavity provides support for the delicate synovial membrane where it is not in contact with bone, also preventing injury.
Synovial Membrane Lining (3): The function of the lining is to provide lubrication for the movement of the bones in a joint, if there was no lining, the cartilage on the bones would wear quickly causing a lot of pain.
Articular Cartilage (4): Articular cartilage covers ends of bones that articulate with one another, it is a smooth surface to reduce friction in the joint
PART A, B, AND C
Ball and Socket Joint
Ball and socket joints are multi axial, they allow movements in several different directions (see image 2), an example of this is the hip joint. The surface of the epiphysis, of one bone fits in the cup-shaped socket of the other, ball of the femur into the acetabulum of the hipbone. (See Image 3)
Image 3: Where the femur and the hip bone join forming a ball and socket joint.
A rim of cartilage lines the socket and aids the firm grip on the femur.
Rounded head of the femur and the
Cup-like acetabulum of the pelvis.
These form the primary connection between the bones of the lower limb and the axial skeleton and pelvis. Both are covered with articular hyaline cartilage.
Muscles on the joint:
Muscles of the hip joint work together to provide the hip movement in all directions, as well as stabilising the entire lower body during weight-bearing activities. These muscles include:
“Muscles that work as Extensors: Gluteus Maximus, hamstrings (long head of biceps femoris, semitendinosus, semimembranosus).
Muscles that work as Flexors: Iliopsoas (iliacus and psoas), rectus femoris, tensor fasciae latae, sartorius.
Muscles that work as Adductors: Pectineus, adductor brevis, adductor longus, gracilis, adductor Magnus.
Muscles that work as Abductors: Gluteus medius, gluteus minimus, tensor fasciae latae.
Muscles that work as External Rotators: Obturatorius internus and externus, gemellus superior and inferior, quadratus femoris, piriformis.
Muscles that work as Internal Rotators: The anterior portion of the gluteus medius and the tensor fasciae latae contribute to this action, but no muscle does internal rotation as its primary function” (Moore 1992).
Ligaments and tendons:
The strong ligaments increase stability within the hip. The two main ligaments, ilio-femoral, and pubofemoral ligaments encompass the hip joint and form the joint capsule. The ilio-femoral ligament is the strongest in the body. Rectus femoris tendon, is the largest tendon, which runs from the knee to the hip (see image 4).
The knee joint is classified as a hinge joint because it is uni-axial, as it links to two rounded bulbs of the femur with the condyles of the tibia. It is located where the femur and the tibia meet. The articular cartilage (See in image 5) allows the bones to glide over one another as we straighten and bend our knees; it is also used as a shock absorber.
The knee joint is where the femur and the tibia meet,…