A&P I - Chapter 9

Gomphoses

"peg in a socket", articulation of teeth with sockets of mandible and maxillae, tooth held in place by fibrous periodontal membranes,

Into what functional category is a symphysis placed?

A symphysis is an amphiarthrosis. It has a pad of fibrocartilage that allows for slight mobility.

What are the basic characteristics of all types of synovial joints?

All are freely mobile articulations with articular capsule, joint cavity, synovial fluid, articular cartilage, ligaments, nerves, and blood vessels.

Structures of Knee Joint

Articular capsule, quadriceps femoris muscle tendon, patella ligament: extends from patella to tibial tuberosity, tibial collateral ligament: reinforces medial surface of knee joint, extends from femur to tibia, prevents hyperabduction of leg at knee

Articular Cartilage

Articulating bone covered by this hyaline cartilage, reduces friction during movement, acts as a cushion to absorb joint compression, prevents damage to articulating ends of bones, lacks a perichondrium, avascular (like all cartilage)

Characteristics of Fibrous Joints

Connected by dense regular connective tissue, have no joint cavity, immobile or only slightly mobile (teeth in sockets, sutures between skull, between radius and ulna)

Saddle Joint

Convex and concave surfaces resembling saddle shape, biaxial, greater range of movement than condylar or hinge joint (carpometacarpal joint of thumb)

Tendon Sheath

Elongated bursa, wraps around tendons where there may be excessive friction, especially common in wrist and ankle

Structural Classification of Joints

Fibrous, cartilaginous, synovial

How does the position of the fulcrum, resistance, and effort vary in first-class, second-class, and third-class levers?

First-class lever: fulcrum is between the effort and the resistance Second-class lever: resistance is between the fulcrum and the effort Third-class lever: effort is applied between the resistance and the fulcrum

How do flexion and extension differ?

Flexion is movement in an anterior-posterior position that decreases the angle between the bones. Extension is movement in an anterior-posterior direction that increases the angle between the bones.

Hinge Joint

Formed by convex surface fitting into concave depression, movement confined to a single axis (uniaxial), like the hinge of a door (elbow joint, knee and interphalangeal joints)

Where in the body are gomphoses and sutures found?

Gomphoses are found in the articulations of teeth roots with the sockets of the mandible and maxillae. Sutures are found between certain bones of the skull.

Common Types of Fibrous Joints

Gomphoses, sutures, syndesmoses

Fibrous Joint

Has no joint cavity, bones held together by dense connective tissue (lambdoid suture)

Cartilaginous Joint

Has no joint cavity, bones joined by cartilage (intervertebral dis articulations)

Properties of Cartilaginous Joints

Have cartilage between articulating bones, lack a joint cavity, immobile or slightly mobile, synchondroses or symphyses

Intracapsular ligaments

Iliofemoral ligament, ischiofemoral ligament, pubofemoral ligament

Synarthrosis

Immobile joint, can be fibrous of cartilaginous joint (tooth to jaw)

What is the composition of a synchondrosis?

In a synchondrosis, bones are joined by hyaline cartilage.

What is the difference between inversion and eversion, and which joints allow these movements?

Inversion and eversion occur at the intertarsal joints of the foot only. The sole of the foot turns medially during inversion and laterally during eversion

What is the function of the anular ligament in the elbow joint?

It surrounds the neck of the radius and binds the proximal head of the radius to the ulna. It can be subluxed in young children.

Synovial Joint Development

Laterally placed mesenchyme, mesenchyme in region medially, centrally located mesenchyme

Three Functions of Synovial Fluid

Lubricates articular cartilage on articulating surfaces, nourishes and removes wastes from articular cartilage's chondrocyes, acts as a shock absorber

Range of Motion at Joints

Motion ranges from no movement to extensive movement, structure of each joint determines mobility and stability, inverse relationship between mobility and stability

Sensory Nerves and Blood Vessels

Numerous in synovial joints, innervate and supply articular capsule and ligaments, detect painful stimuli in joint, report on movement and stretch within joint

Extrinsic Ligaments

Physically separate from joint capsule

For the six kinds of joints, tell whether they are uniaxial, biaxial, or multiaxial.

Plane joint, hinge joints, and pivot joints are considered uniaxial. Condylar and saddle joints are considered biaxial. Ball-and-socket joints are multiaxial.

Amphiarthrosis

Slightly mobile joint, can be fibrous or cartilaginous joint (articulation between tibia and fibula)

Are all fibrous joints also synarthroses?

Some fibrous joints are synarthroses (immobile) and some are amphiarthrosis (slightly mobile).

Functional Classification of Joins

Synarthrosis, Amphiarthrosis, Diarthrosis

What bones articulate the talocrural joint, and what movements are permitted at this joint?

The ankle joint has one articulation between the distal tibia and the talus and another articulation between the distal fibula and talus. It permits dorsiflexion and plantar flexion.

What adverse effects might arise from a fractured epiphysis in a young person?

The bone may not reach its potential full length. The individual may develop arthritic-like changes in the joint.

What is the difference between the effort arm and the resistance arm in a lever?

The effort arm is the part of the lever from the fulcrum to the point of effort. The resistance arm is the part of the lever from the fulcrum to the point of resistance.

What is the purpose of the fibular collateral ligament and the tibial collateral ligament?

The fibular collateral ligament reinforces the lateral surface of the joint and prevents hyperadduction of the leg at the knee. The tibial collateral ligament reinforces the medial surface of the joint and prevents hyperabduction of the leg at the knee.

What is the relationship between mobility and stability in a joint?

The greater the mobility, the lesser the stability (and vice versa).

How do the glenohumeral and hip joints compare with respect to their mobility and stability?

The hip joint is more stable and less mobile than the glenohumeral joint.

The glenohumeral joint is considered the most unstable joint in the human body. What about its structure makes this so?

The joint is a ball-and-socket joint, the joint type with the most mobility but least stability. Ligaments strengthen the joint only minimally.

What is the purpose of synovial fluid in the joint?

The synovial fluid lubricates articular cartilage (reducing friction), nourishes chondrocytes, and acts as a shock absorber.

Fat Pads

act as packing material, provide some joint protection, often distributed along periphery of a synovial joint, often fill spaces formed when joint shape changes

Hip Joint

articulation between head of the femur and acetabulum of the os coxae, acetabular labrum, more stable and less mobile than glenohumeral joint

Condylar Joint

biaxial joint, moving in two planes; oval, convex surface articulating with concave surface (metacarpophalangeal joint or fingers 2 to 5)

Uniaxial Joint

bone moves in just one plane or axis

Multiaxial Joint

bone moves in multiple planes or axes

Biaxial Joint

bone moves in two planes or axes

Pivot Joints

bone with rounded surface, fits into ring formed by ligament from another bone, rotates on longitudinal axis relative to second bone, uniaxial (proximal radioulnar joint)

Synchondrosis

bones joined by hyaline cartilage, all immobile

Glenohumeral (Shoulder) Joint

commonly referred to as the should joint, ball-and-socket joint, formed by head of humerus and gleaned cavity of scapula, permits greatest range of motion of any joint in the body, most unstable and most frequently dislocated

Tendons

composed of dense regular connective tissue, not part of synovial joint itself, attached muscle to bone, help stabilize joints, sometimes limit range of movement permitted at a joint,

Hip Joint gets stability from:

deep bony socket, strong articular capsule, supporting ligaments, muscular padding

Cruciate ligaments

deep to articular capsule of knee joint, limit anterior and posterior movement of femur on tibia, cross each other in an X

Ligaments

dense regular connective tissues, connect one bone to another bone, stabilize/strengthen/reinforce most synovial joints

Joint Capsule

double-layed capsule termed articular capsule, outer layer termed fibrous layer: formed from dense connective tissues, strengthens joints to prevent bones being pulled apart; inner layer termed synovial membrane: composed primarily of areolar connective tissue, covers all internal joint surfaces not covered by cartilage, helps produce synovial fluid

Third-Class Levers

effort applied between resistance and fulcrum (picking up an object with forceps), most common in body

Lever definitions

effort applied to one point, resistance located at some other point, movement if effort exceeds resistance, effort arm: part of level from fulcrum to point of effort, resistance arm: part of level from fulcrum to point of resistance

Lever

elongated, rigid object; rotates around fixed point (fulcrum); has ability to change: speed and distance of movement produced by a force, direction of applied force, force strength

Movements of TMJ

exhibits hinge, gliding and pivot joint movements, functions like a hinge during jaw depression and elevation, glides during protection for biting, glides side to side to grind food

Anterior Cruciate Ligament (ACL)

extends from posterior femur to anterior tibia, prevents hyperextension, prevents tibia moving too far anteriorly on femur

Bursa

fibrous, saclike structure containing synovial fluid, lined internally by synovial membranes, associated with most synovial joints, found where bones/ligaments/muscles/skin/tendons rub together, connected to the joint cavity or separate from it, alleviate friction resulting from body movements

Possible Hip Joint Movement

flexion, extension, abduction, adduction, rotation, circumduction

Synovial Joint

fluid-filled joint cavity separating articulating surfaces of bones, surfaces enclosed within connective tissue, bones attached by ligaments (elbow joint)

Synovial Joints

freely mobile articulation, include most joints in the body, bones separated by a space (the joint cavity), all diarthroses, articular capsule and joint cavity, synovial fluid, articular cartilage, ligaments, nerves, blood vessels

Diarthrosis

freely mobile joints, all synovial joints (knee joint)

First-Class Levers

have fulcrum in the middle, between effort and resistance (pair of scissors); effort applied to handle of scissor, fulcrum along the middle of scissors (atlanto-occipital joint of neck)

Features of Temporomandibular Joint

head of mandible articulation with temporal bones, only mobile joint between bones in skull, has loose articular capsule, has articular disc

Talocrural Joint

highly modified hinge joint, permits dorsiflexion and plantar flexion includes two articulations within one joint capsule

Elbow Joint

hinge joint composed of two articulations: humeroulnar joint and humeroradial joint, both enclosed within a single articular capsule

Sutures

immobile fibrous joints, found only between certain bones of the skull, have interlocking usually irregular edges, permit skull to grow as brain increases in size during childhood, become ossified in older adults, when obliterated become synostoses

Syndesmoses

joined by long strands of dense regular connective tissue, allow for slight mobility, found between radius and ulna and tibia and fibula, bound by interosseous membrane, provides a pivot

Knee Joint

largest and most complex diarthrosis, primarily a hinge joint, capable of slight rotation and lateral gliding when flexed, composed of two separate articulations: tibiofemoral joint, patellofemoral joint

Supination

lateral rotation of forearm so palm of the band anterior

Pronation

medial rotation of forearm so palm of the hand posterior

Ball-And-Socket Joint

multiaxial joints, permitting movement in 3 planes; spherical head of one bone fitting into cupcake socket (coxal and glenohumeral joints)

Symphysis

pad of fibrocartilage between articulating bones, all symphyses allow slight mobility

Joint (Articulation)

place of contact between bones, bone and cartilage, or bones and teeth; bones said to articulate at a joint

Acromioclavicular Joint

plane joint, formed from acromion and lateral end of clavicle, fibrocartilaginous articular disc, works with sternoclavicular and glenohumeral joint, joint capsule strengthened superiorly by acromioclavicular ligament, clavicle bound to coracoid process by coracoclavicular ligament

Joints: Least to Most Mobile

plane, hinge, pivot, condylar, saddle, ball-and-socket

Biomechanics

practice of applying mechanical principles to biology (comparing joint movement and muscle contraction to a lever)

fibular collateral ligament

reinforces lateral surface of joint, extends from femur to fibular, prevents hyper adduction of leg at knee;

Second-Class Levers

resistance between the fulcrum and effort (lifting handles of wheelbarrow), fulcrum farther from effort, small force able to balance larger weight, rare in body

Posterior Cruciate Ligament (PCL)

runs from anteroinferior femur to posterior tibia, prevents hyper flexion, prevents posterior displacement of tibia on femur

Sternoclavicular Joint

saddle joint, formed by manubrium and sternal end of clavicle, articular disc, elevation/depression/circumduction possible, stability provided by fibers and ligaments, makes joint very stable and difficult to dislocate

Arthrology

scientific study of joints, classified by structural characteristics and type of movement allowed

Support of Hip Joint

secured by articular capsule, ligaments, muscles; articular capsule, retinacular fibers

Plane Joint

simplest synovial articulation, least mobile type of diarthrosis, uniaxial joint, limited side-to-side movement in a single plane, articular surfaces flat (intercarpal and intertarsal joints)

Joint Cavity

space permitting separating of articulating bones, lined by synovial membrane secreting synovial fluid

Joint Development

start to form by 6th week of development, differentiate during fetal period, mesenchyme around fibrous/cartilaginous joints

Injuries to Epiphyseal Plate

subluxation or fracture with adverse effects

Ligaments of TMJ

supported by several ligaments, sphenomandibular ligament, temporomandibular ligament

Intrinsic Ligaments

thickening of articular capsule itself, include ligaments outside and within joint capsule

Lateral Rotation

turns anterior surface of femur or humerus laterally

Medial Rotation

turns anterior surface of femur or humerus medially