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Chapter Eight 1 Joints and Movements Major Types of Joints Three types based on tissue type connecting bones and presence or absence of a fluid filled joint capsule Fibrous – connection of bones with fibrous connective tissue, no joint capsule Cartilaginous – two bones connected by hyaline or fibrocartilage Synovial – joints with fluid filled capsules 2 Fibrous Joints Sutures – joints between bones of the skull. Dense regular connective tissue plus periosteum of bone along with interdigitations of bone make these very strong joints. Fontanels – regions between sutures of newborn skulls. Sutures may fuse completely in older adults (synostosis) 3 1 4 5 6 2 Other Fibrous Joints Syndesmosis – the joining of two bones by ligaments as seen between the radius & ulna Gomphoses – specialized fibrous joints between peg-like structures and sockets. Example: teeth fitting in sockets (fibers connect root to socket) 7 Cartilaginous Joints Joining of two bones by either fibrocartilage or hyaline cartilage: Synchondroses – joined with hyaline cartilage – little movement e.g. 1st rib & sternum Sympheses – joined by fibrocartilage, may show slight movement. e.g. pubic symphysis, manubrium/body of sternum 8 9 3 10 Synovial Joints Characterized by having a fluid filled joint capsule. These are complex joints. Articular cartilage - covers surface of both bones Fibrous capsule - makes up outer layer of joint capsule (may also form ligaments inside the capsule) Synovial membrane - makes up inner surface of capsule, not present on articular cartilage surfaces Synovial fluid – lubricant produced by synovial membrane 11 12 4 Six Types of Synovial Joints !Plane/Gliding !Saddle !Hinge !Pivot !Ball & Socket !Ellipsoid see table 8.2 (pg 247 6th ed.) for details 13 Plane or Gliding Joints Slight movement occurs at most of these e.g. carpals, ribs/vertebrae 14 Saddle Joints Movement in two axes Thumb (only joint of this type in body) between carpal & metacarpal of thumb 15 5 Hinge Joint Movement predominantly in one axis e.g. elbow, knee, ankle 16 Pivot Joint Rotation around an axis e.g. radius/ulna and atlas/axis 17 Ball & Socket Joint Multiple axes e.g. hip and shoulder 18 6 Ellipsoid Joint may move in multiple axes, one axis or two depending on particular joint (see 8.6 for examples) e.g. Atlas/Skull, metatarsals/phalanges 19 Angular Movements Flexion – moving a body part toward anterior/ventral Extension – moving a body part toward posterior/dorsal 20 21 7 Angular Movements Abduction – movement away from midline Adduction – moving toward midline 22 23 Circular Movements Rotation – Turning around a long axis 24 8 Circular Motions Pronation – turning palm toward posterior Supination - turning palm toward anterior 25 Circular Movements Circumduction – combined flexion, extension, abduction & adduction of freely moveable joints. This movement outlines a cone shaped space. 26 Special Movements Elevation – raising or moving a structure in a superior direction Depression – lowering or moving a structure in an inferior direction 27 9 Special Movements Protraction – moving a body part toward anterior (thrusting forward) Retraction – moving a part toward posterior 28 Special Movements Excursion – moving lower jaw in a side-to-side fashion Lateral Excursion – moving jaw away from midline Medial Excursion – moving jaw toward midline 29 Special Movements Opposition – unique motion touching thumb & little finger Reposition – returning thumb to original postion 30 10 Special Movements Inversion – turning ankle so plantar surface (sole) of foot faces medial (towards opposite foot) Eversion – turning ankle so plantar surface of foot faces laterally (away from opposite foot) 31 Temporomandibular Joint Synovial joint between mandible and temporal bone supported by lateral ligament and accessory ligaments (e.g. stylomandibular ligament) both plane and ellipsoid motions (mostly ellipsoid) Depression of the mandible opens the mouth See figure 8.8 for anatomy Malfunctions of this joint often lead to jaw pain and or ‘clicking’. Pain may be ‘referred’ and felt in the ear rather than at the joint 32 33 11 Study All of those bones ….. 34 Shoulder Joint Head of humerus fits into the glenoid fossa of the scapula. The glenoid labrum a ring of fibrocartilage helps hold the humerus in the fossa. The entire joint is enclosed by a bursa Shoulder held stable by a series of ligaments and four muscles (rotator cuff muscles) and one tendon Review ligaments of shoulder from table 8.2 – The tendon of the biceps brachii holds the anterior face of the humerus. 35 36 12 37 Hip Joint Head of femur fits into acetabulum Acetabulum labrum – ring of fibrocartilage which helps retain the femur. Ligamentum teres – ligament at center of the femur’s ball attaches inside the acetabulum, providing some help to retain the femur and in some people contains an artery. This joint is supported by several external ligaments – see figure 8.10 and table 8.3 for details. 38 39 13 Knee Joint A complex ellipsoid joint that moves in a hinge-like fashion 11 ligaments support the knee (see table 8.4) Two large condyles of femur articulate with… … the articular cartilage of the tibia which forms lateral and medial menisci (singular = meniscus). These dense fibrocartilage disks may be torn and often present with symptoms of a ‘clicking’ knee. See Clinical Notes for some common knee problems. 40 Tendon Groups of Knee Cruciate – Two ligaments that cross internally between condyles ! Anterior ! Posterior Collateral – two ligaments providing side support ! Medial ! Lateral Popliteal – two ligaments providing posterior support ! Oblique ! Arcuate Patellar – large ligament which contains patella (knee cap) see others in table 8.4 41 42 14 43 44 45 15 Ankle Joint The distal ends of tibia and fibula articulate with the talus to form this joint. Calcaneofibular ligament attaches calcaneous (heel bone) to fibula Medial ligament – from fibula to calcaneous Anterior talofibular from fibula to talus 46 47 48 16