GENERAL CONSIDERATIONS ON JOINTS & MUSCLES

Painting by Danny Quirk

Kaan Yücel M.D., Ph.D. 2. October.2012 Tuesday

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1. GENERAL CONSIDERATIONS ON JOINTS1.1. CLASSIFICATION OF JOINTS

1.2. STABILITY OF JOINTS

1.3. JOINT VASCULATURE AND INNVERVATION

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2. GENERAL CONSIDERAITONS ON MUSCLES2.1. TYPES OF MUSCLES 2.2. SKELETAL MUSCLES2.2.1. Features of muscles 2.2.2. Muscle terminology2.3. CONTRACTION OF MUSCLES2.4. FUNCTIONS OF MUSCLES2.5. FASCIA2.6. NERVES AND ARTERIES OF MUSCLES

science concerned with the anatomy, function, dysfunction and treatment of joints.

ARTHROLOGY GREEK A RQRON JOINT –LOGY

according to the tissues that lie between the bones:

1) Fibrous joints

2) Cartilaginous joints

3) Synovial joints

Classification of Joints

Fibrous jointsBones are united by fibrous tissue. Sutures of the cranium

Fibrous jointsSyndesmosis type of fibrous joint unites the bones with a sheet of fibrous tissue either a ligament or a fibrous membrane partially movableThe interosseous membrane in the forearm is a sheet of fibrous tissue that joins the radius and ulna in a syndesmosis.

Fibrous jointsSyndesmosis type of fibrous joint unites the bones with a sheet of fibrous tissue either a ligament or a fibrous membrane partially movableThe interosseous membrane in the forearm is a sheet of fibrous tissue that joins the radius and ulna in a syndesmosis.

Cartilaginous joints

Bones are united by hyaline cartilage or fibrocartilage.

Cartilaginous joints

Pimary cartilaginous joints-synchondroseshyaline cartilage- growth of a bone during early life

Secondary cartilaginous joints-symphyses strong, slightly movable joints united by fibrocartilage

Synovial joints Most common type of joints

Bones united by a joint capsule enclosing an articular cavity.

Provide free movement between the bones they join.

Joint cavity potential space contains lubricating synovial fluid, secreted by the synovial membrane.

Articular cartilagearticular surfaces are covered by hyaline cartilage

Articular capsulesurrounds the joint and formed of two layers.

Articular capsule: surrounds the joint two layers. Fibrous capsuleSynovial membrane

Some synovial joints have other distinguishing features, such as a fibrocartilaginous articular disc or meniscus, which are present when the articulating surfaces of the bones are incongruous.

Ligamentsa cord or band of connective tissue uniting two structures.

Articular capsules are usually strengthened by articular ligaments.

Connect the articulating bones to each other.

limit the undesired and/or excessive movements of the joints.

Articular disc: Help to hold the bones together.

Labrum: A fibrocartilaginous ring which deepens the articular surface for one of the bones.

Bursa

Flattened sacs that contain synovial fluid to reduce friction.

Walls are separated by a film of viscous fluid.

Found wherever tendons rub against bones, ligaments, or other tendons.

Stability of Joints1) Negative pressure within the joint cavity

2) Shape, size, and arrangement of the articular surfaces

3) Ligaments

4) Tone of the muscles around the joint

Joint vasculature and innvervation

Joints receive blood from articular arteries that arise from the vessels around the joint.

Articular veins are communicating veins that accompany arteries (L. venae comitantes) and, like the arteries, are located in the joint capsule, mostly in the synovial membrane.

Joints have a rich nerve supply provided by articular nerves with sensory nerve endings in the joint capsule.

Types of synovial jointsaccording to shape of articulating surfaces- type of

movement they permit

1.Plane joints uniaxial joints- gliding or sliding acromioclavicular joint

2. Hinge joints uniaxial joints- flexion & extensionknee & elbow joints

Types of synovial joints3. Saddle jointsbiaxial joints- flexion & extension, abduction & adductioncarpometacarpal joint at the base of the 1st digit (thumb)

4. Condyloid (ellipsoid type) biaxial joints- flexion & extension, abduction & adductionmetacarpophalangeal joints (knuckle joints)radiocarpal joint (wrist)

Types of synovial joints5. Ball and socket joints (spheroidal joints)

multiple axes and planes: flexion and extension, abduction and adduction, medial and lateral rotation, and circumductionhip & shoulder joints

Types of synovial joints6. Pivot jointsuniaxial joints- rotation around a central axisproximal & distal radioulnar joints

Tendon Sheath

A layer of the synovial membrane around a tendon.

Permits the tendon to move.

EXAMINATION OF JOINTS

.The clinician should assess the normal range of movement of all joints.

When the bones of a joint are no longer in their normal anatomic relationship with one another, then the joint is said to be dislocated.

Examination of the shoulder joint

Knee examination

DISLOCATION OF JOINTS

.Some joints are particularly susceptible to dislocation because of:1. lack of support by ligaments2. the poor shape of the articular surfaces, 3. the absence of adequate muscular support. The shoulder joint, temporomandibular joint, & acromioclavicular joints

DAMAGE TO LIGAMENTS

.Ligaments prone to excessive stretching & even tearing and rupture.

If possible, the apposing damaged surfaces of the ligament are brought together by positioning and immobilizing the joint.

In severe injuries, surgical approximation of the cut ends may be required.

OSTEOARTHRITIS

.Synovial joints are well designed to withstand wear, but heavy use over several years can cause degenerative changes.

Some destruction is inevitable during such activities as jogging, which wears away the articular cartilages and sometimes erodes the underlying articulating surfaces of the bones.

OSTEOARTHRITIS

.The normal aging of articular cartilage begins early in adult life and progresses slowly thereafter, occurring on the ends of the articulating bones, particularly those of the hip, knee, vertebral column, and hands.

OSTEOARTHRITIS

. Degenerative joint disease or osteoarthritis is often accompanied by stiffness, discomfort, and pain.

Osteoarthritis is common in older people and usually affects joints that support the weight of their bodies (e.g., the hips and knees).

ARTHROSCOPY

.Cavity of a synovial joint can be examined by inserting a cannula and an arthroscope (a small telescope) into it.

Enables to examine joints for abnormalities, such as torn menisci (partial articular discs of the knee joint).

Some surgical procedures can also be performed.

GENERAL CONSIDERATIONS ON MUSCLES

interested in all the muscles in the body

Musculus (muscle) mus-mouse; musculus- little mouse.

So called because the shape and movement of some muscles (notably biceps) were thought to resemble mice. If you bend and straighten your arm at the elbow, you should see the front of the upper arm move under the skin. To the ancient Romans this movement resembled a little mouse scurrying beneath the skin.

myology

Skeletal muscles move the skeleton, as a result the body.

Types of Muscles based on distinct characteristics

Functionalvoluntary vs. involuntary

Histological striated vs. smooth or unstriated

Anatomical (location)@ body wall (soma) and limbs @ hollow organs (viscera) or blood vessels

Skeletal striated muscle voluntary somatic muscle

gross skeletal muscles that compose the muscular system

moving or stabilizing bones and other structures (e.g., the eyeballs).Innervated by the somatic nervous system.

Cardiac striated muscle involuntary visceral muscle

forms the walls of the heart and adjacent parts of the great vessels.

pumps blood.

Smooth muscle (unstriated muscle) involuntary visceral muscle

forms part of the walls of most vessels and hollow organs (viscera)moving substances through them

coordinated sequential contractions (pulsations or peristaltic contractions).

Innervated by the autonomic nervous system.

FEATURES OF SKELETAL MUSCLES

HEAD OR BELLY fleshy, reddish, contractile portions

TENDON white non-contractile portions composed mainly of organized collagen bundles, that provide a means of attachment.

Most skeletal muscles attach toDirectly or indirectly to bonesCartilagesLigamentsFasciasor combinations of the ones above

Some to organs (eyeball)/skin (facial muscles)/mucous membranes(intrinsic tongue muscles)

Muscles are organs of locomotion (movement) also:

provide static support give form to the body

provide heat

Some tendons form flat sheets aponeuroses

anchor the muscle to the skeleton to deep fascia to aponeurosis of another muscle

Many terms provide information about a structure's ShapeSizeLocationFunction Resemblance of one structure to another

Basis of function Bones attached to

Abductor digiti minimi muscle abducts the little finger.

Sternocleidomastoid muscle (G. kleidos, bolt or bar, clavicle) attaches inferiorly to the sternum and clavicle and superiorly to the mastoid process of the temporal bone of the cranium.

Levator scapulae elevates the scapula (L. shoulder blade).

Descriptive namesDeltoid muscle triangular, like the symbol for delta, the fourth letter of the Greek alphabet. -oid “like”; deltoid means like delta.

Position medial, lateral, anterior, posterior

Length brevis, short; longus, long

Shape piriformis musclepear shaped (L. pirum, pear + L. forma, shape or form).

Locationtemporalis muscle in the temporal region (temple) of the cranium (skull).

CLASSIFICATION OF MUSCLESaccording to their shapes

Flat musclesparallel fibers often with an

aponeurosisExternal oblique muscle broad flat muscle

Sartoriusnarrow flat muscle with parallel fiberslongest muscle in the body

feather-like (L. pennatus, feather), arrangement of fasicles

Unipennate

Extensordigitorumlongus

Bipennate Rectusfemoris

Pennate muscles

Multi-pennate

Deltoid

spindle shaped with a round, thick belly (or bellies) and tapered ends

Fusiform muscles

arise from a broad area converge to form a single tendon

four equal sides (L. quadratus, square)

rectus abdominis between its tendinous intersections.

Convergent muscles

Quadrate muscles

orbicularis oculi closes the eyelids

Circular or sphincteral muscles surround a body opening or orifice,

constricting it when contracted

more than one head of attachment or more than one contractile belly

Biceps muscles two heads of attachment triceps muscles three heads

Two belliesdigastric musclegastrocnemius muscle

Multi-headed or multi-bellied muscles

Skeletal muscles function by contracting they pull and never push.

When a muscle contracts and shortensone of its attachments usually remains fixed the other attachment (more mobile) pulled toward it

movement

CONTRACTION OF MUSCLES

Attachments of muscles origin & insertion Origin proximal end of the muscleremains fixed during muscular contraction.

Insertion distal end of the musclemovable

This is not always the case. Some muscles can act in both directions under

different circumstances.

Reflexive Contractionautomatic (reflexive) contraction, not voluntarily

controlled

Respiratory movements of the diaphragm

Myotatic reflex

Muscle tone (tonus)No movement, but

Certain firmness in musclesAssistance to the stability of jointsMaintenance of postureKeeping the muscles ready to respond to stimuli

Absent only when? unconscious (during deep sleep or under general anesthesia) after a nerve lesion resulting in paralysis

Tonic Contractionslight contraction@ rest

Phasic Contraction: There are two main types of phasic (active) muscle contractions:

(1) isotonic contractions, in which the muscle changes length in relationship to the production of movement.

(2) isometric contractions, in which muscle length remains the same—no movement occurs, but the force (muscle tension) is increased above tonic levels to resist gravity or other antagonistic force.

When a muscle contracts its length decreases by 1/3 or ½.

Whereas the structural unit of a muscle is a skeletal striated muscle fiber, the functional unit of a muscle is a motor unit, consisting of a motor neuron and the muscle fibers it controls.

When a motor neuron in the spinal cord is stimulated, it initiates an impulse that causes all the muscle fibers supplied by that motor unit to contract simultaneously.

The number of fibers varies according to the size and function of the muscle.

Large motor units, in which one neuron supplies several hundred muscle fibers, are in the large trunk and thigh muscles.

Functions of muscles

Prime mover (agonist) main muscle responsible for producing a specific movement of the body.

Does most of the work (expending most of the energy) required. In most movements, there is a single prime mover, but some movements involve two prime movers working in equal measure.

Fixator steadies the proximal parts of a limb through isometric contraction while movements are occurring in distal parts.

Synergist complements the action of a prime mover. Usual to have several synergists assisting a prime mover in a particular movement.

Antagonist a muscle that opposes the action of another muscle. A primary antagonist directly opposes the prime mover, synergists may also be opposed by secondary antagonists.

The same muscle may act as a prime mover, antagonist, synergist, or fixator under different conditions.

Nerves and arteries to muscles Variation in the nerve supply of muscles is rare; it is a nearly constant

relationship.

In the limb, muscles of similar actions are generally contained within a common fascial compartment and share innervation by the same nerves.

Nerves and arteries to muscles

Nerves supplying skeletal muscles (motor nerves) usually enter the fleshy portion of the muscle (vs. the tendon), almost always from the deep aspect (so the nerve is protected by the muscle it supplies).

The blood supply of muscles is not as constant as the nerve supply and is usually multiple.

Fascia (L. fasciae) wrapping, packing, and insulating materials of the deep

structures of the body

Underlying the subcutaneous tissue superficial fascia

Deep fascia dense, organized connective tissue layer, devoid of fatcovers most of the body deep to the skin and subcutaneous tissue

In the limbs, groups of muscles with similar functions sharing the same nerve supply are located in fascial compartments, separated by thick sheets of deep fascia, called intermuscular septa, that extend centrally from the surrounding fascial sleeve to attach to bones.

These compartments may contain or direct the spread of an infection or a tumor.

Subserous fascia between the internal surfaces of the musculoskeletal walls and the serous membranes lining the body cavities. These are the endothoracic, endoabdominal, and endopelvic fascias; the latter two may be referred to collectively as extraperitoneal fascia.

lateral side of the abdomen

MUSCLE TONE

.Determination of the tone of a muscle is an important clinical examination.

If a muscle is flaccid, then either the afferent, the efferent, or both neurons involved in the reflex arc necessary for the production of muscle tone have been interrupted.

If, conversely, the muscle is found to be hypertonic, the possibility exists of a lesion involving higher motor neurons in the spinal cord or brain.

MUSCLE SHAPE AND FORM

.The general shape and form of muscles should also be noted, since a paralyzed muscle or one that is not used (such as occurs when a limb is immobilized in a cast) quickly atrophies and changes shape.

ELECTROMYOGRAPHY (EMG)

.a technique for evaluating & recording electrical activity produced by skeletal muscles

A diagnostic procedure to assess the health of muscles and the nerve cells that control them (motor neurons). Can reveal nerve dysfunction, muscle dysfunction or problems with nerve-to-muscle signal transmission. Performed using an instrument called an electromyograph, to produce a record called an electromyogram.