Lecture 1.4 Articulations

Body Motions

•  Classes of Body Motions –  Bones and muscles work together to

create movement –  Work like levers –  Disorders exist when movement is

impeded or painful

–  Remember Anatomical Position (AP) •  Movements are often described in relation to

AP; movement away from, or back to AP

Rheumatoid arthritis (U), anatomical position (L)

Body Motions

•  Classes of Body Motions –  These are important in the study

of muscles; all of these terms will be used in lab unit 2 extensively!

–  Rotation •  Movement of bone along its

longitudinal axis •  Medial rotation; e.g. leg in figure •  Lateral rotation; e.g. leg in figure •  Right or left rotation; e.g. head

Rotation; Marieb

Body Motions

•  Classes of Body Motions –  Circumduction

•  The distal end of the bone moves in a circle while the proximal end of the bone remains stationary

•  Like the baseball pitcher’s 360° windup •  Complex movement; requires flexion,

abduction, extension, and then adduction!

–  Practice: •  Rotate your torso right •  Medially rotate your ankle •  Laterally rotate your knee •  Circumduct your index finger

Circumduction; Marieb

Body Motions

•  Classes of Body Motions –  Abduct

•  Body part moved away from body midline

•  Abduct means to take away; to abduct takes away from the main body area

–  Adduct •  Body part moved towards body

midline •  Add means to increase– adduct adds

the body part to the main body area

Abduction, adduction; Marieb

Body Motions

•  Classes of Body Motions –  Be sure to pronounce abduct and

adduct carefully; they sound so close!

–  Practice: •  Abduct your arm •  Adduct your leg •  Abduct your fingers •  Can you adduct your head?

–  Many muscles have these words in their names, e.g. adductor magnus, abductor pollicis brevis

Abduction, adduction; Marieb

Body Motions

•  Classes of Body Motions –  Flex

•  Bend and decrease the angle between anterior surfaces of articulation

•  Exception: the knee and ankle; for these joints, flexion is a decrease in the angle between the posterior surface of the articulating bone

•  Long definition, but very functional!

–  Extend •  To return body part to anatomical

position after flexion

Flexion (U), flexion and extension (L); Marieb

Body Motions

•  Classes of Body Motions –  Hyperextension

•  Continuation of extension beyond anatomical position

–  Practice: •  Flex your arm, then extend it •  Flex your fingers, then extend them •  Can you flex your head? •  Are you ready to try out for Cirque du

Soleil? •  What body motion are the performers

exhibiting with their backs? Their heads?

Flexion by Cirque du soleil performers (U), hyperextension (L)

Body Motions

•  Classes of Body Motions –  Retract

•  Movement, such as the mandible or pectoral girdle (shoulders) backward parallel to ground

–  Protract •  Movement forward parallel to the

ground

–  Practice: •  Protract your mandible •  Retract your pectoral girdle

Protraction, retraction; Marieb

Body Motions

•  Classes of Body Motions –  Elevate

•  Raise the part; upward motion –  Depress

•  Lower the part; downward motion

–  Evert •  For the foot only; turn the sole laterally

–  Invert •  For the foot only; turn the sole medially

•  Practice –  Invert your foot –  Elevate your shoulders Elevate, depress (U), invert, evert (L); Marieb

Body Motions

•  Classes of Body Motions –  Dorsiflex

•  For foot, toes point upwards –  Like flexing the hand at the wrist

–  Plantar flex •  For foot, toes point downwards

–  Like extending the hand at the wrist •  Remember- the sole of the foot is called

the plantar surface •  Plantar warts (not planter warts!) are on

the bottom of the foot

•  Practice –  Dorsiflex your foot –  Feel the good stretch!

Dorsiflexion, plantar flexion (U); Marieb, plantar wart (L)

Body Motions

•  Classes of Body Motions –  Pronate

•  Palm pointing downward –  Supinate

•  Palm pointing upwards

•  Some use these terms for the ankle, showing poor ankle “posture”

•  Remember the musical “Oliver”? When Oliver asked for “more soup, please?” his hands are supinated. Get it? Soup-inate? Silly, but it works!

•  Practice –  Supinate your hand –  Pronate your ankle

Pronation, supination

Joints

•  Joints –  3 types of joints based on

structure •  Classified by the material that

holds the joints together, or the presence or absence of a joint cavity

–  3 types of joints based on their function

•  Classified by the amount of movement at the joint

Knee joint (Marieb)

Hip joint (L), knee joint (R)

Function •  Synarthroses

•  Amphiarthroses •  Diarthroses

(think S.A.D.)

Structure •  Fibrous

•  Cartilaginous •  Synovial

Joints

Joints •  Joints Classified by

Function –  Synarthroses

•  Immoveable joints •  Sing: synarthrosis

–  Amphiarthroses •  Slightly moveable joints

–  Diarthroses •  Freely moveable joints

Knee joint (U), Xray of teeth (L)

•  Joints Classified by Structure –  Fibrous joints

•  No joint cavity, bones held together by fibrous tissue

–  Cartilaginous joints •  Bones held together by

cartilaginous tissue

–  Synovial joints •  Has a joint cavity, ligaments,

and articular capsule

Remember- joints, or articulations are where bones come together. You’ll learn about many joints that you probably would not have thought of as a joint! Like this –>

Joints

Joint classes; Marieb

Joints

•  Joints Classified by Structure; Fibrous joints –  Sutures

•  Synarthrotic joints •  Irregular joints between the flat

bones of the cranium •  Strength is added by the

interlocking edges •  Fibrous connective tissue is

between bones, continuous with periosteum of the skull bone and the dura mater (tough membrane that surrounds brain ) in places

Sutures; Marieb

Joints

–  Sutures •  Some sutures fuse, to form one bone, called a synostosis

–  Frontal bone is example; was 2 bones in baby, 1 bone in adult

Suture types

– Various suture types seen: serrate, lap, and plane sutures

– Similar to the way woodworkers make wood joints

–  Syndesmosis •  Amphiarthrotic or diarthrotic •  Long bones held together with

interosseous ligaments/membrane

•  Example: articulation between tibia and fibula at distal end

•  Also found between radius and ulna for length of shaft

–  Is an attachment point for some deep muscles in the forearm

Joints

Syndesmosis, fibula and tibia (U), radius and ulna (L); Marieb

Joints

Gomphoses; Marieb

–  Gomphosis •  Teeth in alveolar sockets in mandible

and maxilla= dentoalveolar joint •  Synarthrotic joints •  Periodontal disease results in

loosening of teeth

Joints

Symphyses; Marieb

•  Joints Classified by Structure; Cartilaginous joints –  Symphysis

•  Pl: symphyses •  Amphiarthrotic joint held together with fibrocartilage

–  Of the 3 types of cartilage, this is the toughest •  All on the midline of the body

Joints

Symphyses; Marieb

–  Symphysis •  Fibrocartilage pad providing cushion between 2 bones

–  Intervertebral discs (below, left) between all vertebrae except C1 and C2

•  Ends of bones covered with hyaline articular cartilage, but the joint is held together with fibrocartilage capsule

–  Pubic symphysis (below, right) between 2 pubic bones

Joints

Synchondroses; Marieb

–  Synchondrosis •  Hyaline cartilage forms joint between bones •  Synarthrotic or amphiarthrotic joints •  Cartilage between growing bone segments (epiphyseal plate)

–  Synarthrotic –  After growth stops at maturity, becomes a synostosis

•  Between sternum and 1st rib

Synovial Joints

Diarthrotic joints; Marieb

•  Joints Classified by Structure; Synovial Joints –  Functionally diarthrotic

•  May be slightly moveable to very mobile

•  Space between articulating bones = joint cavity or synovial cavity

•  Bone ends covered with articular cartilage (hyaline cartilage)

•  Articular capsule surrounds the entire joint

–  Fibrous capsule: outer layer of dense irregular connective tissue (lots of tough collagen)

–  Inner synovial membrane, composed of areolar connective tissue*

*Don’t worry; you’ll learn these tissue types later!

Synovial Joints

Diarthrotic joints; Marieb

•  Synovial Joints •  Articular capsule

–  Fibrous capsule; the outer connective tissue layer adds strength

–  Inner synovial membrane produces the fluid

–  Synovium is the fluid in the joint »  Synovium lubricates the joint; the

fluid is viscous (meaning slippery), acts as a shock absorber, nourishes the tissues

»  In the knee, which is the largest joint in the body, there’s less than 3 mL of synovium

•  Bursae –  Sacs of fluid within the joint capsule,

outside the joint cavity

Synovial Joints

Tendon sheaths in shoulder joint (U), fat pads seen under patella in knee joint (L); Marieb

•  Synovial Joints •  Tendon Sheaths

–  Tubular or elongated bursae which surround the tendons where they pass bony surfaces

–  On tendons that are subject to much friction, or pass through narrow spaces

•  Fat pads –  Cushions joint structures –  Also fills spaces created when

joint changes shape

Synovial Joints

Synovial joints; Marieb

•  6 Types of Synovial Joints:

–  Gliding or Plane –  Hinge –  Condyloid or Ellipsoidal –  Saddle –  Pivot –  Ball and Socket

Some large and/or complicated joints may have some components of more than one joint type; e.g. may be primarily ball and socket, but have some gliding components

Synovial Joints

Gliding joints; Marieb

•  Gliding or Plane Joints –  Articular surfaces are nearly flat (e.g. the facets) allowing gliding

only –  Allows nonaxial or translational movement.

•  Nonaxial means having no axis of movement; flat bones moving side to side

–  Found between carpals, tarsals, articular processes of vertebrae –  Also between ribs and the facets of the thoracic vertebrae

Synovial Joints

Hinge joints; Marieb

•  Hinge Joints –  Allows uniaxial movement; movement in one axis only –  Allows simple flexion and extension movement at joint –  Ankle, elbow, knee joints, finger and toe joints (not knuckles),

temporomandibular joint (hinge of jaw)

Synovial Joints •  Examples of Complex Hinge Joints

Hinge joints; elbow (UL), knee (UR),; Marieb

Synovial Joints

Condyloid joints; Marieb

•  Condyloid or Ellipsoidal Joints –  Angular movement in 2 directions; moves back and forth and side

to side (biaxial) (abduct/adduct and flex/extend) –  Characterized by a condyle of one bone in a fossa or elliptical

cavity of the other –  Wrist joint; articulation between radius and proximal carpals, as

well as metacarpals and proximal phalanx (knuckles) –  Atlas-occipital articulation

Synovial Joints

Saddle joints; Marieb

•  Saddle Joints –  Angular movement in 2 directions; (biaxial) –  Differs from condyloid joint in the shape of the articulating bones;

saddle joints have saddle-shaped bones, but movement is same –  Trapezium and thumb metacarpal

•  Our opposable thumb is made possible by this joint; what makes us and other great apes able to do what we do with our hands!

Synovial Joints

Saddle joints; Marieb

•  Saddle Joints •  Also includes the sternoclavicular joint

–  Put your left hand fingers on your clavicular notch. Put your finger slightly lateral to the notch to feel the prominent right sternoclavicular joint. Move your right arm around, shrug your shoulders. Feel the wide range of motion allowed at this joint?

Synovial Joints

Pivot joints; Marieb

•  Pivot Joints –  Allows rotary movement in one

plane (uniaxial) –  Atlas-axis (C1 and C2)

articulation (no disc between) –  Radius and ulna at proximal end,

allowing supination/pronation

Synovial Joints

Ball and Socket joints; Marieb

•  Ball and Socket Joints –  Angular movement in all directions (biaxial), combined with

pivotal rotation = multiaxial –  Shoulder and hip joints both have a rounded head (ball) which fits

into a socket in the articulating bone

Synovial Joints •  Examples of Ball and Socket Joints

Ball and Socket joints, shoulder (L), hip (R), ; Marieb

Note the smooth, rounded heads of both the humerus (L) and the femur (R),

covered with hyaline cartilage

Synovial Joints

•  The Knee Joint –  A hinge joint, but not simple

•  Rounded femoral condyles allow some rolling and gliding movements

•  Rotary movement due to alignment of hip and foot

–  Largest joint in the body, and probably the most highly stressed joint in the body

•  Less stable than other hinge joints, due to the rotation

Xray of the knee

Synovial Joints

•  The Knee Joint –  3 joints:

•  Patellofemoral joint –  Partly synovial-gliding

•  Lateral tibiofemoral joint –  Synovial hinge type

•  Medial tibiofemoral joint –  Synovial hinge type

The knee; Marieb

This is one of the best knee diagrams; study it well! Which leg is it- right or left?

Synovial Joints •  The Knee Joint

–  Semilunar cartilages (menisci) are pads of fibrocartilage –  They absorb some of the stress, padding the condyles of the femur

where they meet the tibia •  Lateral meniscus between lateral condyle of femur and tibia •  Medial meniscus between medial condyle of femur and tibia

–  Transverse ligament connects the two menisci anteriorly and posteriorly. It’s not labeled on this diagram. You label it!

Menisci; Marieb

Synovial Joints •  The Knee Joint

–  Cruciate ligaments form an X in the interior of the knee joint

–  Are intracapsular ligaments (within the joint capsule)

–  Anterior cruciate ligament (ACL)

–  Posterior cruciate ligament (PCL)

–  They act as restraining straps, preventing undesirable movements

–  Lock knees when standing Cruciate ligaments; Marieb

Synovial Joints

Cruciate ligaments; Marieb, X-ray of repair

•  The Knee Joint –  Cruciate ligament damage –  Anterior cruciate is more

commonly damaged; is just weaker

ACL tear heals slowly if at all. Often need graft from Achilles tendon or patellar ligament to replace/repair

Synovial Joints

Collateral ligaments; Marieb

•  The Knee Joint –  Collateral ligaments

•  Extracapsular ligaments; outside of the joint capsule

–  Fibular collateral ligament

•  On lateral surface; also called lateral collateral ligament

–  Tibial collateral ligament •  On medial surface, also

called medial collateral ligament

•  Most common football injury, torn when hit/tackled on side of knee

Synovial Joints

Collateral ligaments; Marieb

•  The Knee Joint –  Fibular collateral ligament

•  Lateral surface; run from lateral epicondyle of femur to head of fibula

–  Tibial collateral ligament •  On medial surface; run from

medial epicondyle of femur to medial surface of tibia

–  Both reinforce and stabilize the knee only at full extension

•  Also limit anterior and posterior movement of femur, align femur and tibia, prevent hyperextension of knee

Synovial Joints

The knee; Marieb

•  The Knee Joint –  Quadriceps tendon

•  Upper; runs from quadriceps muscle to patella

–  Patellar ligament •  Lower portion; runs from

patella to tibial tuberosity –  These two structures are

continuous

Why does a single stretch of connective tissue have two names? Because tendons connect _____ to _____ and ligaments connect _____ to _____.

Synovial Joints

Bursae of knee joint; Marieb

•  The Knee Joint –  Bursae of knee

•  Sacs of fluid which reduce friction •  Composed of a sac of CT with an

inner synovial membrane •  Keep tendons from rubbing on

bones; note placement between tendons/ligaments and underlying bones

•  At least a dozen bursae associated with each knee

Joint cracking does not cause arthritis or enlarged joints. Does aggravate those around you. When two opposing bones are pulled apart, a vacuum is created. The gas in the fluid forms a bubble that then immediately collapses, creating the noise.

Synovial Joints

Pre-patellar bursitis (UL), olecranon bursitis (UR), and fat pads of knee joint (L); Marieb

•  The Knee Joint •  Bursitis

–  Chronic inflammation of bursae by trauma, infection such as TB or syphilis, or RA

–  Olecranon bursitis, or “student’s elbow” occurs from repeatedly leaning on the elbow on hard surfaces

–  Long ago, bursitis was common in the knee of women who scrubbed floors for a living, hence the colloquial name “washer-woman’s knee”)

–  Infrapatellar fat pad •  Infra- means ‘below;’ is deep and

inferior to the patella

End 1.4 Next: 1.5 Muscle Anatomy