Anatomy And Physiology: Exam 3

Articulation

site where two or more bones meet

Functions of Joints

1. Give skeleton mobility
2. Hold skeleton together

Synarthroses

immovable joints

amphiarthroses

slightly movable joints

Diarthroses

freely movable joints

Fibrous Joints

bones connected by fibrous CT; most synarthrotic (no joint cavity)

* Sutures
* Syndesmoses
* Gomphoses

Sutures

Immovable joints for protection of brain; allow for growth during youth

* Contain short CT fibers
* In middle age, they ossify and fuse completely

Fontanelles

“soft spots” between skull bones. These are wider areas of connective tissue

Syndesmoses

2 Parallel bones connected by ligaments (bands of fibrous tissue)

* Fiber length varies, therefore movement varies
* Ex. tibiofibular joint, and interosseous membrane connecting radius and ulna

Gomphoses

Specialized fibrous joint that anchors root of tooth into its alveolar socket

* Fibrous connection is called the periodontal ligament

Cartilaginous Joints

Bones connected by cartilage; not highly movable (no joint cavity)

* Synchondroses
* Symphyses

Synchondroses

Hyaline Cartilage unites bones; all are synarthrotic

* Ex. temporary epiphyseal plate joints or cartilage of 1st rib with manubrium

Symphyses

Fibrocartilage unites bones; hyaline cartilage is present as articular cartilage

* Some movement (amphiarthroses)

Synovial Joints

bones separated by fluid-filled joint cavity; all are diarthrotic

* most common joints in the body (all limbs)

6 Distinguishing Features of Synovial Joints

1. Articular cartilage
2. Joint (synovial) cavity
3. Articular (joint) capsule
4. Synovial Fluid
5. Different types of reinforcing ligaments
6. Nerves and Blood Vessels

Fatty Pads

For cushioning between fibrous layer and synovial membrane

Articular Discs

Fibrocartilage separates articular surfaces to improve “fit” of bone ends, stabilize joint, and reduce wear and tear

* Ex. menisci

Bursae

Sacs lined with synovial membrane; contain synovial fluid

* Reduce friction where ligaments, muscles, skin, tendons or bones rub together

Tendon Sheaths

Elongated bursae wrapped completely around tendon subjected to friction

Pivot Joint

rounded portion of a bone is enclosed within a ring formed partially by the articulation with another bone and partially by a ligament

* C1-C2

Hinge Joint

The convex end of one bone articulates with the concave end of the adjoining bone

* Elbow, knee

Condyloid Joint

The shallow depression at the end of one bone articulates with a rounded structure from an adjacent bone or bones

* Wrist, knuckles

Ball and Socket Joint

The rounded head of one bone fits into the convoke articulation of the adjacent bone

* Greatest range of motion
* Hip and shoulder only

Plane Joint

The articulating surfaces of the bones are flat or slightly curved and of approximately the same size, which allows the bones to slide against each other

* Feet, vertebrae

Saddle Joint

both of the articulating surfaces for the bones have a saddle shape, which is concave in one direction and convex in the other

* Hand

Origin

attachment to immovable bone

Insertion

attachment to movable bone

Nonaxial

gliding movements only; no axis to move around

* Small carpal bones

Uniaxial

movement in one plane

* pivot and hinge joints

Biaxial

movement in two planes

* saddle joint

Multiaxial

movement in or around all three planes

* ball and socket

Gliding Movements

one flat bone surface glides or slips over another similar surface

* Intercarpal, intertarsal joints or between articular processes of vertebrae

Angular Movements

Increase or decrease angle between two bones

* Movement along sagittal plane

Flexion

decreases the angle of joint

Extension

increases the angle of joint

Hyperextension

excessive extension beyond normal range of motion

Rotation

Turning of bone around its own axis (towards midline or away from it)

* C1-C2 or rotation of humerus or femur

Supination and Pronation

Radius and Ulna

Dorsiflexion and plantar flexion; Inversion and eversion

foot

protraction and retraction, elevation and depression

mandible

Opposition

thumb

What are the five main synovial joints?

1. jaw
2. shoulder
3. knee
4. elbow
5. hip

Temporomandibular joint (jaw)

Modified hinge joints mandible articulates with temporal bone

* Has two types of movement: hinge (up and down) and gliding (side to side)

What is the most easily dislocated joint in the body?

Jaw or temporomandibular joint

Glenohumeral Joint (shoulder)

Ball and socket joint where head of humerus fits in shallow, small glenoid cavity

* Largest range of motion

What I the most freely moving joint in the body?

shoulder or glenohumeral joint

Glenoid Labrum

fiqrocartilogenous rim around glenoid cavity that helps add depth to the shallow cavity

Corcarohumeral ligament

Ligament that helps support weight of upper limb

* On shoulder joint

Where does primary support come from on the shoulder joint?

Muscle tendons

* Rotator cuff tendons: SITS

Humeroulnar Joint (Elbow)

Hinge joint where the ulna articulates with the humerus (flexion and extension only)

Anular ligament

surrounds head of radius in the elbow joint

What are the two capsular ligaments that restrict side-to-side movement?

1. Ulnar collateral ligament (Tommy John surgery)
2. Radial Collateral Ligament

Hip Joint

Ball and socket joint that carries body weight so it is deigned for strength and stability

* More restricted movement; less range of motion
* Head of femur articulates with acetebum of hip

Acetabular Labrum

rim of fibrocartilage that enhances depth of hip socket

* Makes hip dislocations rare

Reinforcing ligaments of hip joint:

Isciofemoral, ilifemoral, pubofemoral ligaments

Knee Joint

Largest, mot complex joint in the body

* Three articulations surrounded by a singular cavity; at least 12 bursae
* Hinge Joint that allow flexion, extension and some rotation when knee is partly flexed

What are the three articulations that make up the knee joint?

1. Femoral-patellar Joint
2. Medial Tibiofibular Joint
3. Lateral Tibiofibular Joint

Anterior Cruciate Ligament (ACL)

Prevents forward sliding of tibia and stops hyperextension of knee

* Attaches to anterior tibia

Posterior Cruciate Ligament (PCL)

Prevents backward sliding of tibia and forward sliding of femur

* Attaches to posterior tibia

What do common knee injuries involve?

Collateral ligaments, cruciate ligaments, and cartilages (Menisci)

What does the “unhappy triad” consist of?

1. Tibial (medial) collateral ligament
2. Medial meniscus
3. Anterior cruciate ligament (ACL)

Who is mot susceptible to injuries in just the ACL?

Runners

What are the three types of muscle in the body?

Skeletal, smooth, and cardiac

Characteristics of Skeletal Muscles

* Striated, non-branching
* Voluntary (conscious control)
* Contract rapidly, tire easily; powerful
* Require nervous system stimulation

Characteristics of Cardiac Muscles

* Only in heart; bulk of heart walls
* Striated, branching
* Can contract without nervous system stimulation (involuntary)

Characteristics of Smooth Muscle

* In walls of hollow organs
* Ex. Stomach, Urinary Bladder, Airways
* Not striated
* Involuntary

What is each skeletal muscle comprised of?

Skeletal muscle tissue, nervous tissue, blood, and other connective tissues

Fascia

Layers of dense connective tissue that surround and separate each muscle

* Gives rise to tendons by extending beyond ends of muscle

Aponeuroses

Broad sheets of connective tissue that connect muscles to each other

Epimysium

Layer of connective tissue around each whole muscle

Perimysium

Layer of connective tissue that surrounds individual bundles (fascicles) within each muscle

Endomysium

Layer of connective tissue that cover each muscle cell (fiber)

Sarcolemma

specialized cell membrane

What does the sarcoplasm contain?

Myofibrils, T tubules, and sarcoplasmic reticulum

Myosin

Thick filaments of myofibrils

Actin

Thin filaments of myofibrils

Sarcomere

The basic unit of striated muscle tissue

* Extend from one Z line to the next

I Bands

Light bands made up of actin filaments anchored to Z lines

A Bands

Dark band made up of overlapping thick and thin filaments

H Zone

Myosin filaments only

* In the center of A bands

Sarcoplasmic Reticulum

Membraneous tubules surrounding each myofibril

* Function to release (into sarcoplasm) and take up calcium

T-Tubules

Allow an electrical signal to be delivered quickly into the cell

* Invaginations of the sarcolemma

Neuromuscular Junction

Site where motor neuron and muscle fiber meet

Motor end plate

formed by the muscle fiber membrane in which the sarcolemma is tightly folded and where nuclei and mitochondria are abundant

What is actually happening in a muscle contraction?

Shortening of a sarcomere

Myosin structure

consists of two twisted strands with globular cross bridges projected outward along the strands

Actin structure

globular protein with myosin binding sites; tropomyosin and troponin are two proteins associated with the surface of actin filaments

Sliding Filament Theory

The myosin cross-bridge attaches to the binding site on the actin filament and bends, pulling on the actin filament; it then releases and attaches to the next binding site on the actin, pulling again

What causes the cross-bridges to be in a ‘cocked’ position?

energy from the conversion of ATP to ADP provided from the enzyme ATPase

What is the stimulus for contraction?

* Acetylcholine being released from its synaptic vesicles into the synaptic cleft
* Receptors in the motor end plate detect the ACH and a muscle impulse spreads over the surface of sarcolemma into the T tubules, where it then reaches the sarcoplasmic reticulum

Calcium and Troponin/Tropomyosin

When the S.R. receives the muscle impulse, it releases its stored calcium into the sarcoplasm.

* The calcium binds to the troponin, causing the tropomyosin to move aside, exposing the myosin binding sites on actin filaments

Achtylcholinsterase

Rapidly decomposes acetylcholine, signaling the end of the muscle contraction

Where does energy for contraction come from?

molecules of ATP (limited and must be regenerated often)

What regenerates the ATP needed for contraction?

Creatine phosphate, which stores excess energy released by the mitochondria

Oxygen Supply

Muscle has a high requirement for oxygen, which enables the complete breakdown of glucose in the mitochondria

Hemoglobin

in red blood cells carries oxygen to muscle

Myoglobin

Stores oxygen in muscle tissue

Lactic Acid

forms when body is running out of oxygen

* accumulates as an end product of anaerobic respiration
* diffuses out of muscle cells and is carried in the bloodstream to the liver

Oxygen Debt

the amount of oxygen that the liver cells require to convert the accumulated lactic acid into glucose

* may take several hours

Muscle Fatigue

When a muscle loses its ability to contract during strenuous exercise; usually from an accumulation of lactic acid in muscle

* Lowered pH prevents muscle from contracting