Chapter 9 , Chapter 8 Anatomy JCCC

Joints

Joints occur where two bones meet (articulations).

Joint Classification

The functional classification of joints includes Synarthrosis (immovable joint, no movement), Amphiarthrosis (a slightly movable joint), and Diarthrosis (a freely movable joint).

Fibrous Joints

Fibrous joints are bones held together by dense collagen fibers, with no joint/synovial cavity.

Cartilaginous Joints

Cartilaginous joints are bones held together by cartilage, with no joint/synovial cavity.

Synovial Joints

Synovial joints are bones held together by ligaments, fluid, capsules, and have a joint cavity.

Sutures

Sutures are synarthrotic joints only between bones of the skull, with short CT fibers and irregular, interlocking edges that increase strength.

Syndesmoses

Syndesmoses are amphiarthrotic joints that permit more or less movement depending on fiber length, such as the tibiofibular ligament and interosseous membrane.

Gomphoses

Gomphoses are synarthrotic peg-in-socket joints, such as the articulations of the teeth with the sockets of the maxillae and mandible.

Synchondroses

Synchondroses are synarthrotic joints where connecting tissue is hyaline cartilage, such as the epiphyseal plate and the 1st rib and manubrium of sternum.

Symphyses

Symphyses are amphiarthrotic joints where the ends of the articulating bones are covered with hyaline cartilage, connected by a disc of fibrocartilage, such as the pubic symphysis and intervertebral disks.

Articular Cartilage

Articular cartilage is hyaline cartilage that covers the ends of bones in synovial joints.

Synovial Cavity

The synovial cavity allows free movement and is characteristic of diarthrotic joints.

Articular Capsule

The articular capsule is a sleeve-like capsule that encloses the joint/synovial cavity, consisting of an outer fibrous capsule and an inner synovial membrane.

Synovial Fluid

Synovial fluid is secreted by the synovial membrane, lubricates the joint, prevents erosion, reduces friction, acts as a shock absorber, and supplies oxygen/nutrients while removing CO2/metabolic wastes.

Reinforcing Ligaments

Reinforcing ligaments are several layers that stabilize the joint.

Nerves and Blood Vessels

Nerves detect pain and monitor joint position and stretch, while capillary beds supply filtrate for synovial fluid.

Fatty Pads

Fatty pads cushion between the capsule fibrous layer and synovial membrane or bone.

Articular Discs (Menisci)

Articular discs are fibrocartilage structures that separate articular surfaces to improve the fit of bone ends, stabilize the joint, and reduce wear and tear.

Bursae

Bursae are bags of synovial fluid that reduce friction where ligaments, muscles, skin, tendons, or bones rub together.

Tendon Sheaths

Tendon sheaths are elongated bursae wrapped completely around tendons subjected to friction.

Factors Influencing Synovial Joint Stability

Three factors determine the stability of joints to prevent dislocations: shape of articular surface, ligament number and location.

Shape of Articular Surface

The shape of the articular surface plays a minor role in joint stability; shallow surfaces are less stable than ball-and-socket joints.

Ligament Number and Location

The number and location of ligaments play a limited role in joint stability; the more ligaments, the stronger the joint.

Muscle tone

Keeps tendons taut as they cross joints, extremely important in reinforcing shoulder and knee joints and arches of the foot.

Origin

Attachment to immovable bone.

Insertion

Attachment to movable bone.

Muscle contraction

Causes insertion to move toward origin.

Transverse plane

One of the planes along which movements occur.

Frontal plane

One of the planes along which movements occur.

Sagittal plane

One of the planes along which movements occur.

Planar/Gliding Joints

Allow back-and-forth and side-to-side movements; examples include intercarpal and intertarsal joints.

Hinge Joints

Produce an opening and closing motion like that of a hinged door; examples include knee (femur & tibia) and elbow (humerus & ulna).

Flexion

Bending movement that decreases angle of joint and brings 2 articulating bones closer together.

Extension

Bending movement that increases angle of joint and takes 2 articulating bones further away.

Pivot Joints

Allow rotation; examples include head of radius on ulna and atlas/axis.

Condyloid Joints

Permit angular movements such as circumduction, adduction, and abduction; examples include wrist and metacarpophalangeal joints.

Circumduction

Combination of flexion/extension and abduction/adduction, resembling a circular motion.

Abduction

Movement along frontal plane away from midline of body.

Adduction

Movement along frontal plane toward midline of body.

Saddle Joints

Articular surface of one bone is saddle-shaped, fitting into the saddle of another; example includes the thumb.

Ball-and-Socket Joints

ball-like surface of one bone fits into a cuplike depression of another; most freely moveable; examples include shoulder (humerus, scapula, & clavicle) & hip (pelvis & femur).

Elevation

upward movement of a part of the body; example includes closing the mouth; its opposing movement is depression.

Depression

downward movement of a part of the body; example includes opening the mouth.

Protraction

movement of a part of the body anteriorly; example includes thrusting the mandible forward; its opposing movement is retraction.

Retraction

movement of a protracted part of the body back to normal.

Inversion

movement of the sole medially; its opposing movement is eversion.

Eversion

movement of the sole laterally.

Dorsiflexion

bending of the foot at the ankle in an upward direction; its opposing movement is plantar flexion.

Plantar flexion

bending of the foot at the ankle in a downward direction.

Pronation

movement of the forearm so that the palm is turned downward; its opposing movement is supination.

Supination

movement of the forearm so that the palm is turned upward.

Opposition

movement of the thumb across the palm to touch the tips of the fingers on the same hand.

Temporomandibular Joint

the articulation between the head of the mandible and the articular tubercle of the temporal bone anteriorly and mandibular fossa posteriorly; it is a diarthrotic, synovial hinge joint.

Intervertebral Articulations

amphiarthroses between vertebral bodies; diarthroses between articular processes; vertebral bodies separated by intervertebral discs.

Sternoclavicular Joint

diarthrotic saddle joint between manubrium of sternum and sternal end of the clavicle; articular disc separates two joint cavities.

Acromioclavicular Joint

diarthrotic plane joint between acromial end of clavicle and acromion of scapula; articular disc within joint cavity.

Glenohumeral (Shoulder) Joint

diarthrotic ball-and-socket joint between head of humerus and glenoid cavity of scapula; greatest range of movement but also the most unstable.

Elbow Joint

diarthrotic hinge joint composed of humeroulnar and humeroradial joints; both joints enclosed in a single articular capsule.

Radiocarpal (Wrist) Joint

diarthrotic condylar joint between the three proximal carpal bones (scaphoid, lunate, triquetrum), the distal articular surface of radius, and an articular disc.

Hip (Coxal) Joint

diarthrotic ball-and-socket joint between head of femur and acetabulum of os coxae; features include fibrocartilaginous acetabular labrum.

Knee Joint

diarthrotic hinge joint containing two articulations: tibiofemoral joint and patellofemoral joint; largest and most complex diarthrosis of body.

Talocrural (Ankle) Joint

diarthrotic hinge joint composed of two articulations between distal end of tibia and the talus, and between distal end of fibula and the lateral aspect of the talus.

Intertarsal Joint

plane joint between tarsals.

Tarsometatarsal Joint

plane joint between distal tarsal bones and metatarsals.

Metatarsophalangeal (MP) Joint

condylar joint between metatarsal and proximal phalanges.

Interphalangeal (IP) Joint

hinge joint between phalanges.

Arthritis

a common inflammatory or degenerative disease that comes in many forms, including gouty arthritis, osteoarthritis, and rheumatoid arthritis.

Appendicular Skeleton

Includes bones of the limbs and the girdles of bones that attach limbs to axial skeleton.

Pectoral Girdle

Articulates with the trunk and supports the upper limbs; consists of the clavicles and scapulae.

Clavicle

S-shaped bone with a sternal end that articulates medially with the manubrium of sternum and an acromial end that articulates laterally with the acromion of the scapula.

Scapula

Shaped like a broad, flat triangle with three borders and three angles; glenoid cavity articulates with head of humerus.

Upper Limb

Consists of 30 bones including the humerus, radius, ulna, carpal bones, metacarpals, and phalanges.

Humerus

Proximal features include a head that articulates with scapula and greater and lesser tubercles for muscle attachment.

Radius

Bone of the forearm that is lateral to the ulna in the anatomic position.

Ulna

Bone of the forearm that is medial to the radius in the anatomic position.

Carpals

Eight wrist bones arranged in two rows of four.

Metacarpals

Five bones in the palm of the hand.

Phalanges

Fourteen bones in the fingers.

Glenoid Cavity

Articulates with the head of the humerus.

Intertubercular Sulcus

Passage for biceps brachii tendon and site for muscle attachment.

Capitulum

Round, lateral projection of the humerus for articulation with the radius.

Trochlea

Pulley-shaped, medial projection of the humerus for articulation with the ulna.

Olecranon Fossa

Large basin on the posterior humerus that accommodates the olecranon of ulna.

Styloid Process (Radius)

Lateral 'wrist bump' at the distal end of the radius.

Trochlear Notch

Accommodates the trochlea of the humerus.

Olecranon

Projection that forms the posterior 'bump' of the elbow; attachment site for triceps brachii.

Coronoid Process

Inferior lip of the trochlear notch of the ulna.

Scaphoid

First bone in the proximal row of carpals.

Lunate

Second bone in the proximal row of carpals.

Triquetrum

Third bone in the proximal row of carpals.

Pisiform

Fourth bone in the proximal row of carpals.

Trapezium

First bone in the distal row of carpals.

Trapezoid

Second bone in the distal row of carpals.

Capitate

Third bone in the distal row of carpals.

Proximal Phalanx

The first phalanx in a finger, closest to the hand.

Middle Phalanx

The second phalanx in a finger, located between the proximal and distal phalanges.

Distal Phalanx

The last phalanx in a finger, furthest from the hand.

Pollex

The thumb, which has only two phalanges (proximal and distal).

Pelvic Girdle

The pelvis is composed of left and right ossa coxae, as well as the sacrum and coccyx.

Os Coxae

The 'hip bone', a fusion of ilium, ischium, and pubis between 13 and 15 years of age.