Lecture 9: Joints and Movement

Joint (articulation)

point where two bones meet

Arthrology

study of joint structure and function

Kinesiology

study of musculoskeletal movement; a branch of biomechanics

What are the two classification schemes we use to classify joints?

1. By their anatomy; three categories: fibrous, cartilaginous, and synovial

2. By their mobility; three categories: synarthroses (immovable
   ), amphiarthroses (slightly moveable), and diarthroses (most moveable)

What are fibrous joints?

joint where adjacent bones bound by collagen fibers; include sutures, syndesmoses, and gomphoses

In terms of fibrous joints, what are sutures? What do they do? Are there different types?

Sutures closely bind bones to each other, and they are immobile or slightly mobile. There are three different types of sutures. The first is serrate sutures, which join bones with serrated margins. The second is lap (squamous) sutures, which join bones that have overlapping beveled edges. The third is plane (but) sutures, which join bones that have straight, nonoverlapping edges.

In terms of fibrous joints, what are syndesmoses? What do they do? Give an example.

Syndesmoses bind bones with relatively long collagen fibers, and they have more mobility than sutures. An example of this would be the radius and ulna joined by interosseous membrane.

In terms of fibrous joints, what are gomphoses? What do they do?

Gomphoses bind teeth to jaw.

What are cartilaginous joints?

joint where adjacent bones bound by cartilage; include synchondroses and symphyses

In terms of cartilaginous joints, what are synchondroses? What do they do? Give an example.

They’re bones bound by hyaline cartilage; immoveable or slightly moveable. An example of this would be the joint between the first rib and sternum.

In terms of cartilaginous joints, what are symphyses? What do they do? Give an example.

They’re bones joined by fibrocartilage; slightly moveable. An example of this would be the pubic symphysis.

What are synovial joints?

bones separated by join (articular) cavity containing lubricating synovial fluid

In synovial joints, what are the bones surfaces covered in?

They’re covered in articular cartilage, composed of hyaline cartilage. Additionally, a double layered joint (articular) capsule encloses the joint cavity.

What makes up the joint cavity in synovial joints?

The synovial membrane (inner layer; secretes synovial fluid) and fibrous capsule (outer layer; dense fibrous connective tissue).

Tendon

cord or sheet of fibrous connective tissue connecting muscle to bone (ex: collagen; dense regular connective tissue)

Ligament

similar to tendon, but connects bone to bone

True or False: Tendons and ligaments cross synovial joints and stabilize them.

True

Bursa

fibrous sac external to joint cavity and between moving parts; filled with synovial fluid (sit in places where there might be excess friction)

Bursitis

inflammation of a bursa

Tendon sheath

elongated bursa wrapped around a tendon

Tendinitis

inflamed tendon sheath

What are the classes of synovial joints?

(classified by their planes of mobility)

• Monaxial - joint moves in one place (ex: elbow, knee)

• Biaxial - joint can move in two planes

• Multiaxial - joint can move in any of these three planes of space (ex: shoulder, hips, wrist, ankle)

What are the six types of synovial joints?

Flexion

movement decreases joint angle

Extension

Movement increases joint angle

Abduction

movement of body part in the frontal place away from midline of the body

Adduction

movement of body part in the frontal place toward midline of the body

Elevation

movement raises body part in frontal plane

Depression

movement lowers body part in frontal plane

Protraction

anterior movement of body part in transverse plane

Retraction

posterior movement of body part in transverse plane

Circumduction

one end of appendage is stationary while other end makes a circular motion

Rotation

bone spins on its longitudinal axis

Medial (internal) rotation

bone spins toward midline of body

Lateral (external) rotation

bone spins away from midline of body

Supination

forearm movement where palm turns to face anteriorly or upward

Pronation

forearm movement where palm turns to face posteriorly or downward

What are some special movements of the head and trunk?

• flexion of spine is forward bending movement

• extension of spine straightens trunk or neck

• Lateral extension: tilting head or trunk to right or left

• Twisting at waist or turning head is called right or left rotation

Range of Motion (ROM)

Number of degrees through which one bone can move relative to anther at that joint (degrees of arch your joint can go through)

What are some factors that affect ROM?

What are some special movements of the mandible?

• capable of protraction and retraction

• Lateral and medial excursion: side-to-side movements of mandible

What are some special movements of the hands and fingers?

• Radial and ulnar flexion of hand: hand tilts toward thumb or little finger, respectively

• Fingers capable of flexion, extension, abduction, and adduction

• Thumb capable of radial and palmar abduction, opposition and reposition

What are some special movements of the foot?

• Dorsiflexion: movement of foot so toes are elevated

• Planar flexion: movement of foot so toes point downward

• Inversion: foot movement that moves soles medially

• Eversion: foot movement that moves soles laterally