Joints of the Skeletal System Advanced Biology Fall 2012

Vocab Development Anul- ring Arth- joint Burs- bag, purse Glen- joint socket Labr- lip Ov- egg-like Sutur- sewing Syn- with, together Syndesm- band, ligament

Introduction Joints or articulations- functional junctions between bones – Bind parts of the skeletal system – Allow for bone growth – Permit parts of the skeleton to change shape during childbirth – Enable the body to move in response to skeletal muscle contractions

Introduction cont… Joints vary in structure and function – Classified both structurally and functionally Structurally by the type of tissue that binds the bones at each junctions Functionally by the degree of movement possible

Introduction cont… Structural joint classifications – Fibrous – Cartilaginous – Synovial Functional joint classifications – Immovable (synarthrotic) – Slightly movable (amphiarthrotic) – Freely movable (diarthrotic)

3 types of Fibrous Joints Syndesmosis – bones are bound by a sheet or bundle of dense connective tissue – Flexible & may be twisted – Permits slight movement (amphiarthrotic) – Ex: lies between the tibia & fibula

3 types of Fibrous Joints Sutures – Only between the flat bones of the skull – Bones are united by a thin layer of dense connective tissue – Immovable (synarthrotic)

3 types of Fibrous Joints Gomphosis – Formed by the union of a cone-shaped process in a bony socket – Ligament surrounds the root & firmly attaches it – Synarthrotic – Ex: teeth

2 types of Cartilaginous Joints Synchondrosis – Bands of hyaline cartilage unite the bones – Many are temporary & disappear during growth – Synarthrotic – Ex: epiphyseal plates – Ex: between manubrium & first rib

2 types of Cartilaginous Joints Symphysis – Covered by a thin layer of hyaline cartilage & the cartilage is attached to a pad of fibrocartilage – Limited movement – Ex: pubic symphysis – Ex: intervertebral discs

Synovial Joints Most joints of the skeleton are synovial Allow free movement (diarthrotic) Consist of: articular cartilage, a joint capsule, & a synovial membrane

Synovial Joints General Structure – Articular cartilage- covers the ends of the bones – Joint capsule- has 2 layers that hold together the bones of the joint – Synovial membrane-covers all surfaces with in the joint capsule (only a few cell layers thick) – synovial fluid- lubricates articular surfaces – Menisci- divide the synovial joints into some small compartments

Synovial Joints General Structure cont… – purpose of the menisci is to help cushion the joint – Bursae (bursa sacs)- found in certain types of synovial joints Help cushion and provide protection for bones that are close to the skins’ surface Helps ligaments and tendons glide smoothly over bones

Synovial Joints 6 types of synovial joints – Ball-and-socket joints- hip joint & shoulder joint – Condylar joint- where your finger bend (in between the phalanges) – Plane joints (gliding joints)- found in between your carpals & tarsals – Hinge joints- elbow & knee – Pivot joint- between the axis and atlas, between your radius and ulna – Saddle joint- where the thumb joins the carpals

Types of Joint Movements Flexion- bending parts of a joint so that the angle between them decreases and the parts come closer together – Ex: bending knee Extension- moving parts of a joint so that the angle between them increases and the parts move farther apart – Ex: straightening the knee

Types of Joint Movements Hyperextension- used to describe the extension of the parts at a joint beyond the normal range of motion (usually causes injury) Dorsiflexion- movement at the ankle that brings the foot closer to the shin – Ex: rocking back on your heels Plantar Flexion- movement at the ankle that brings the foot farther from the shin – Ex: standing on your toes or walking

Types of Movements Abduction- moving a part away from the midline or the axial line of the limb – Ex: spreading your fingers or toes Adduction- moving a part toward the midline or toward the axial line of the limb – Ex: moving your fingers or toes closer together

Types of Movements Rotation- moving a part around an axis – Medial rotation- turning of a limb toward the midline – Lateral rotation- turning of a limb away from the midline Circumduction- moving part so that its end follows a circular path – Ex: moving a finger in a circular motion without moving your hand

Types of Movements Supination- rotation of the forearm so the palm is upward Pronation- rotation of the forearm so the palm is down Eversion- turning the foot so the plantar surface faces laterally – Ex: big toe pushed down, little toe up Inversion- turning the foot so the plantar surface faces medially – Ex: big toe up, little toe down

Types of Movements Protraction- moving a part forward Retraction- moving a part backward Elevation- raising a part Depression- lowering a part

Shoulder Joint Ball and socket joint – Consists of the humerus & glenoid cavity Ligaments – Coracohumeral ligaments Connects the coracoid process of the scapula to the humerus – Glenohumeral ligaments (3) Connect the glenoid cavity to the neck of the humerus

Ligaments… – Transverse Humeral Ligament Across the humerus several bursae Labrum Can perform: flexion, extension, adduction, abduction, rotation, and circumduction

Elbow Joint 2 articulations – Hinge joint between the humerus & ulna – Planar joint between the ulna and humerus (only when elbow is bent, not when in anatomic position) Ligaments – Ulnar collateral ligament Connects the humerus to the ulna – Radial collateral ligament Connects the humerus to the radius – Anular ligament Connects the ulna to the radius at the head of the radius Movements: flexion & extension – Supination and pronation of forearm is allowed by the anular ligament

Hip Joint Ball and socket joint Consists of: – Head of the femur – Acetebulum of the hip bone Major Ligaments – Iliofemoral ligament Strongest ligament in the body Connects the iliac spine to the femur – Pubofemoral ligament Runs from the superior pubis to the iliofemoral ligament – Ischiofemoral ligament Runs from the ischium to the joint capsule

Hip Joint Movements: – Flexion, extension, adduction, abduction, rotation, and circumduction

Knee Joint Largest and most complex synovial joint Consists – Femur – Tibia – Patella – Lots of ligaments

Knee Joint Ligaments (these strengthen the joint capsule) – Patellar ligament Extends from the patella to the tibia – Oblique popliteal Connects the lateral condyle of the femur to the head of the tibia – Arcuate popliteal Extends from the lateral condyle of the femur to the head of the fibula – Tibial collateral (MCL) Connects the medial condyle of the femur to the medial condyle of the tibia – Fibular Collateral (LCL) Connects the lateral condyle of the femur and the head of the fibula

Knee Joint Cruciate ligaments – Help prevent displacement of the articulating surfaces – Stretch upward and cross between the tibia and femur – Anterior cruciate ligament (ACL) Runs from the anterior side of the tibia to the lateral condyle of the femur – Posterior cruciate ligament (PCL) Connects the posterior side of the tibia to the medial condyle of the femur

Knee Joint 2 menisci – Separate the articulating surfaces of the femur and tibia & help keep them aligned Several bursae Movement: flexion, extension, and some rotation

Joint Disorders Sprains – Overstretching or tearing of connective tissues associated with a joint – Painful & swollen, restricts movement Bursitis – Inflammation of the bursa – Caused by overuse or a sudden increase in activity – Ex: tennis elbow

Joint Disorders cont… Arthritis – Causes inflamed, swollen, and painful joints – More than 100 different types – Can be part of other syndromes – Most common types are: rheumatoid, osteo, Lyme

Joint Disorders cont… Rheumatoid Arthritis (RA) – Autoimmune condition – Painful & debilitating – Synovial membrane becomes hard and forms a mass – Over time joints can ossify – Usually a systemic illness

Joint Disorders cont… Osteoarthritis – Degenerative disorder – Most common type of arthritis – Usually occurs with aging – Articular cartilage disappears slowly – Painful & restricts movement – NSAIDS are used to treat it along with regular exercise

Joint Disorders cont… Lyme Arthritis – Caused by lyme disease and is intermittent – Antibiotic treatments early on can help treat it Arthritis may also be associated with other bacterias like strep, staph, gonorrhea, tuberculosis AIDS may also be associated with arthritis because it is an autoimmune disorder

Joint Disorders cont… Other types of arthritis – Gout – Juvenile RA – Scleroderma – Systemic lupus erythemoatosus – Kawasaki disease – Strep A infection

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