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The Joints and Muscular System

What are the 4 types of joints?

1. Fibrous Joints
2. Cartilaginous Joints
3. Synovial Joints
4. Bony Joints

What is a joint?

Any point where two bones meet, also known as an articulation

What is arthrology?

The science of joint structure, function, and dysfunction

Fibrous Joints

-Synarthrosis
-Bones are fused together by collagen fibers
-Fibers are short, little no movement
-3 kinds of fibrous joints

What are the 3 kinds of fibrous joints?

1. Sutures
2. Gomphoses
3. Syndesmoses

What are sutures?

-Immobile or slightly moveable fibrous joints that closely bind the bones if the skull to each other
-only found in the skull

What are the classifications of sutures?

1. Serrate-wavy lines along which the adjoining bones firmly lock with each other by their serrated margins
2. Lap (squamous)- occur where 2 bones have overlapping edges, relatively smooth
3. Plane (butt)-occur where 2 bones have straight nonoverlapping edges. The 2 bones just overlap each other.

Give an example of serrate, lap, and plane sutures.

1. Serrate-coronal, sagittal, and lambdoid sutures
2. Lap (squamous)-squamous suture between parietal and temporal lobe
3. Plane (butt)- suture between palantine process and maxillae in roof of mouth

What are Gomphoses?

-attachment of a tooth to a socket
-tooth held in place by a fibrous peridontal ligament, which consists of collagen fibers that extends from the bone matrix of jaw into dental tissue

What are Syndesmoses?

-fibrous joint at which 2 bones are bound by relatively long collagenous fibers.
-separation between the bones and length give more mobility
-ex: shafts of radius and ulna, joined by broad fibrous interosseous membrane; especially moveable; allows supination and pronation

Bony Joints

-Synostosis
-formed by either fibrous or cartilaginous joints
-old age: parietal bones fuse
-immovable joint formed when the gap between two bones ossifies and they become a single bone

Give an example of a bony joint

The epiphses and diaphyses of the long bones become synotoses

Cartilaginous Joints

-Amphiarthroses
-two joints linked by cartilage
-slight amount of movement

What are the 2 types of cartilaginous joints?

1. Synchondrosis: bones bound by hyaline cartilage
2. Symphysis: bones bound by fibrocartilage

What are examples of Synchondrosis and Symphysis?

1. Sychondrosis-1st rib to sternum, epiphyseal plate
2. Symphysis- Pubic Symphysis, intervertebral discs`

Synovial Joints

-Diarthroses
-freely moveable

Give examples of synovial joints

Elbows, knees, knuckles

What are accessory structures associated with synovial joints?

1. Tendons
2. Ligaments
3. Bursa-saclike extension of a joint capsule that extends between nearby structures, allowing them to slide more easily past each other

What are Tendon Sheaths?

-layer of membrane around a tendons
-allows tendon to move
-elongated cylinders of connective tissue lined with synovial membrane

What are the functions of muscles?

-movement of body parts and organ contents-breathing, blood circulation, feeding
-maintain posture and prevent unwanted movement
-communication-speech, expressions and writing
-control of openings and passageways
-body heat production; 85% of ones body heat; glycemic control

Connective Tissue Components from Deep to Superficial

-Endomysium- thin sleeve of loose connective tissue that surrounds each muscle fiber. Creates room for blood capillaries and nerve fibers.
-Perimysium- thicker connective tissue sheath that wraps muscle fibers together in bundles called fascicles
-Epimysium- fibrous sheath that surrounds entire muscle
-Fascia- sheet of connective tissue that separates neighboring muscles or muscle groups from each other and subcutaneous tissue

What are the 2 types of skeletal muscle fibers?

1. Red muscle Fibers
2. White muscle Fibers

Red Muscle Fibers

-slow oxidative
-great endurance
-less powerful, fatigue resistant
-high myoglobin content
-high oxygen content
-lots of mitochondria
-lots of blood capillaries

White Muscle Fibers

-fast glycolytic
-low in oxygen supply
-high power output, fatigues quickly
-low myoglobin content
-few mitochondria
-few blood capillaries
-contract rapidly
-paler appearance

What do the arrangement of fascicles affect?

1. Power-depends on the # of fibers connected to the tendons
2. Range of motion-the desire to which a joint can move; muscle fibers contract to about 70% of their resting length; the longer the muscle fibers the > ROM

Muscle Shapes

-Fusiform-thick in the middle and tapered at the end, strong;biceps brachii
-Parallel-uniform width and parallel fascicles; rectus abdominus; satorious of thigh
-Convergent (Triangular)-fan shaped; pectoralis major
-Unipennate-all fascicles approach tendon from one side
-Bipennate- fascicles approach tendon from both sides
-Multipennate-shaped like a bunch of feathers w/quills converging on single point
-Circular (sphincters)-rings around certain body openings

What are Origins of muscles?

the bony site of attachment at the stationary end of muscle

What is the Belly of muscles?

The thicker, middle region of muscle

What Insertion of muscles?

The attachment at the mobile end

Functional Groups of Muscles

1. Agonist-the prime mover, the muscle that produces the most force during a particular joint action
2. Antagonist- a muscle that opposes the prime mover; prevents excessive movement
3. Antagonistic Pairs- produces opposite effects on a joints, such as flexion and extension
4. Synergist- a muscle that aids that prime mover
4. Fixator- a muscle that prevents a bone from moving during joint action

What are the 3 things involved in lever systems?

1. Resistance (load)-what you are moving
2. Fulcrum-where movement occurs (joints)
3. Effort-causes movement (muscle)

What are 1st Class levers?

-has fulcrum in middle (EFR)
-resistance and effort arm are same length
-rocking of the foot on tibia
-SEE-SAW
-Atlanto-occipital joints-muscles of the back of neck pull down on occipital bone and oppose the tendency of head to tip forward

What are 2nd Class levers?

-has resistance in middle (FRE)
-WHEELBARROW
-sitting in chair raising one knee up

What is Mechanical Advantage?

-Ratio of its output force to input force
-If MA>1 lever produces more force less speed/distance
-If MA<1 lever has more speed/distance less force
-MA=Le/Lr

What are 3rd Class levers?

-has effort in midde (REF)
-Resistance arm is longer that fulcrum
-Most musculoskeletal levers
-Forearm when you flex elbow

What are the 6 types of Synovial Joints?

1. Ball and Socket Joint
2. Pivot Joint
3. Saddle Joint
4. Condylar (ellipisoid) joint
5. Plane (gliding) joint
6. Hinge Joint

What are Synovial Joints distinguised by?

-articular surfaces
-degrees of freedom

Ball-and-Socket Joints

-Multiaxial
-shoulder and hip joints
-has smooth hemispherical head that fits into cuplike socket

Condylar Joints

-Biaxial
-oval convex surface on one bone that fits into another complementary shaped depression
-radiocarpal joint of wrist and metacarpophelangeal joint
-capable of movement in two planes

Saddle Joints

-Biaxial
-both bones have saddle shaped surfaces, concave in one direction and convex in other
-trapeziometacarpal joint

Plane Joints

-bone surfaces are flat or only slightly concave or convex
-found between bones of wrist and tarsal bones of ankles
-slightly complex movements

Hinge Joints

-Monoaxial
-moving freely in one plane with very little movement in another
-elbow, knee

Pivot Joints

-Monoaxial
-Bone spins on its longitudinal axis
-atlantoaxial joint between first two vertebrae and radioulnar joint at elbow

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