Introduction to arthrology and bones of the shoulder WK 1 PDF

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INTRO TO ARTHROLOGY At the end of this topic you should be able to understand the: a) definition and functions of a joint b) system of joint classification c) terms used to describe movement at joints d) structure and function of the components of synovial joints 2.1 Define a joint (articulation) and its components. - A joint is where two or more bones interconnect. - Two major classification systems: ➔ Structure: fibrous, cartilaginous, synovial ➔ Amount of movement: immovable, slightly movable and freely movable 2.2 Describe 2 main functions of a joint. - Determines the type of movement (eg plane/axis) - Determines the amount of movement 2.3 Describe the general structure of, and the relative amount of movement available at, each of the following types of joints: i) fibrous- Bones joined by dense connective tissue - suture ➔ Exist between bones of a skull ➔ No movement as the edges of the articulating bones are highly serrated(ridged bones), as well as being joined together by an intermediate layer of fibrous tissue

- syndesmosis ➔ The bones are connected by ligaments, cords, or bands of fibrous tissue ➔ Slightly immoveable/ restricted and controlled. ➔ Eg interosseous membrane(fibrous tissue) between the radius and the ulna ➔ Eg inferior tibiofibular joint where the two bones held together by an interosseous ligament.

ii) cartilaginous - Joints  that are attached by hyaline cartilage and Fibrocartilaginous have fibrous tissue in between cartilage - primary cartilaginous or synchondrosis ➔ Immoveable ➔ Rigid, hyaline cartilage between articulating bones ➔ Eg epiphyseal growth plates (children)- the plate of hyaline cartilage is relatively rigid it exhibits no movement. ➔ Eg joint between the costal cartilage of the first rib and the manubrium of the sternum

- secondary cartilaginous or symphysis ➔ A joint where fibrocartilage unites the bones ➔ Some mobility

➔ Eg pubic symphysis or intervertebral joints iii) synovial - Freely mobile joints - Articulating bones are separated by a fluid containing joint cavity. Have six distinguishing features: - Articular cartilage: hyaline, glassy, smooth which covers the opposing bone surfaces as articular cartilage, contains collagen (high tensile and compressive strength), contains elastin (some elasticity) - Joint (articular) cavity: a potential space that contains a small amount of synovial fluid

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Articular capsule: covers the bones ends within joint capsule, allows the bones to slide on one another without friction Synovial fluid: a small amount of slippery synovial fluid occupies all free spaces within the joint capsule Reinforcing ligaments: synovial joints are reinforced and strengthened by a number of bandlike ligaments Nerves and blood vessels: richly supplied with sensory nerve fibers that innervate the capsule (detects pain or monitors joint position or stretch)

2.4 Describe the factors which determine the amount of friction occurring between articular surfaces during movement at synovial joints. -

Coefficient of friction: resistance due to friction depends on ➔ Compressive load: more compression → more friction & less compression → less friction ➔ Surfaces involved: The articular surfaces of the bones in synovial joints are covered with articular cartilage due to its hardness and smoothness→ bones to move ➔ Synovial fluid (lubrication): Acts as lubrication for the opposing joints surfaces and so friction is greatly reduced ➔ Health of articular cartilage: As the health deteriorates, the coefficient of friction increases

2.5 Describe the 3 principal axes of movement about synovial joints. plane

Axis

Movements

Sagittal

Transerve

Flexion/extension

Passes Side to side

Transverse

Vertical

medial /lateral

Passes top to bottom

Coronal

Anteroposterior

abduction/adduction

Passess front to back

2.6 Classify synovial joints according to: i) degrees of freedom - uniaxial: movement can occur along only one axis (eg elbow, knee, ankle joint) ➔ Hinge and pivot - biaxial: movement can occur along two axes (eg wrist joint)

➔ Aq , condyloid and saddle - multiaxial: movement can occur along three axes (eg shoulder and hip joint) ➔ Ball and socket and plane ii) structure Type of synovial joint

description

Movement

Example

Hinge

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Snugs fit in the two articular surfaces

Uniaxial

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Elbow joint Knee joint (modified hinge joint as it does allow movement about a second axis)

Pivot

-

Articular surfaces arranged so that one bone rotates with a fibro-osseous ring

Uniaxial

-

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Atlantoaxial joint(upper part of the neck between the first and second cervical vertebrae) Proximal radioulnar joint

-

radiocarpal joint atlanto-occipital joint

-

Metacarpophalangeal

Ellipsoid

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Another form of ball and socket joint but the surfaces are ellipsoid in nature

Biaxial

Condyloid

-

Modified form of a ball and socket joint

Biaxial

Saddle

-

Two surfaces are reciprocally concavo-convex

biaxial

-

carpometacarpal joint of the thumb

Ball and socket

-

‘Ball’ of one bone fits into the ‘socket’ of the other

multiaxial

-

hip joint Shoulder joint

plane (gliding)

-

Surfaces are flat

Multiaxial

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Acromioclavicular joint Sternoclavicular joints Vertebrocostal joint

2.7 List and identify examples of each type of joint in objectives 2.3 and 2.6 LISTED ABOVE 2.8 Define and demonstrate the following types of movement about synovial joints: i) active : produced by muscles- normal movement - Active Assisted :Produced by muscles and an external force – to assist normal movement

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Angular movements ➔ flexion/extension ➔ abduction/adduction ➔ Circumduction ( movement of a part in a circular direction) Rotational movements ➔ Medial(internal) and lateral(external) rotation

ii) passive: movement is produced by external force not muscle activation - physiological: produced by an external force to mimic normal movement / can be produced actively - accessory: produced by an external force( in a single plane- not normal movement) ➔ Movement of articular surfaces within joint capsule ➔ Cannot be produced actively ➔ Rolling and gliding of joint surfaces

2.9 Define and demonstrate the terms used to describe active movement about joints: i) flexion; extension Flexion: - Movement in a sagittal plane that reduces the angle between two adjacent body segments - Eg bending the elbow so that the anterior surfaces of the forearm and the arm are closer Extension: - Movement in a sagittal plane that increases the angle between two adjacent body segments - Eg straightening the flexed elbow ii) abduction; adduction Abduction: - Movement in the coronal plane that moves a body segment away the midline of the body - Movement of the arm away from the side of the trunk Adduction: - Movement in the coronal plane that moves a body segment away from the midline of the body - Movement of the arm towards from the side of the trunk iii) medial (internal) rotation; lateral (external) rotation Medial: - Rotation of a limb segment about it longitudinal axis such that the anterior surface comes to face towards the longitudinal axis of the body - Eg turning lower limb so the toes points towards the longitudinal axis of the body Lateral: - Rotation of a limb segment about it longitudinal axis such that the anterior surface comes to face away the longitudinal axis of the body - Eg turning lower limb so the toes points away the longitudinal axis of the body 2.10 Relate active movements about joints to the anatomical planes and axes for movement. Plane

Axis

movement

Sagittal

Transerve

extension/flexion

Coronal

anteroposterior

abduction/adduction

transerve

vertical

Medial and lateral rotation

2.11 Explain the functions of ligaments: Ligaments are bands of fibrous tissue connecting bones, serving to stabilise joints i) mechanical Ligaments provide mechanical restraints acting at the end of physiological joint range to: - prevent unwanted movements at joints ➔ Ligaments are restrictive → prevent unwanted movement that could cause injury - limit wanted movements at joints ➔ Ligaments are assistive→ limited wanted movements at the joints in order to allow movement to prevent injury or damage ii) sensory (proprioceptive) - Are sensory organs for the perception of joint movement and position 2.12 Define and give an example of each of the following types of ligament: i) capsular - Form a part of the capsule( supports it) - Localised thickening of joint capsule - Eg glenohumeral ligament in the shoulder

ii) extracapsular - Cross the joint completely outside the capsule - Eg coracoacromial ligament in the shoulder (strengthens upper capsule of the shoulder)

iii) intracapsular - Wholly within the capsule - Eg anterior cruciate ligament in the knee (stop shin bone sliding out in front of thin bone)

2.13 Define and list five (5) possible functions of articular discs. - Pad of fibrous cartilage situated between opposing bones within some synovial joints - Eg knee joints, acromioclavicular joint, sternoclavicular joint Functions: - Acts as a shock absorber - Aids in mechanical fit between articular surfaces - Restrain movement - Assist in lubrication - Allows movement to occur in different directions on either side of the disk (occurs at SC joint)

2.14 Define and list the functions of bursae. - A fibrous sac lined with synovial membrane and containing synovial fluid; occurs between bones and muscle tendons (or other structures) Function: - Decrease friction during movement between muscle and bones (to prevent inflammation → loss of function) - Acts as a shock absorber 2.15 Identify examples of different ligament and disc types as listed in 2.12 and 2.13. Refer to 2.12 and 2.13 Disc types: - intra-articular disc (e.g. sternoclavicular joint) - Intervertebral discs found in the vertebrae - Triangular articular disc in the wrist joint

BONES OF THE SHOULDER REGION Aims At the end of this topic you should be able to: a) identify and classify the bones of the shoulder region b) state the functions of markings on the bones of the shoulder region c) orientate (side) the bones of the shoulder region using bony markings 3.1 Identify and classify the humerus.

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Sole bone of the arm, largest bone in the upper limb Round head at the proximal end articulates with the scapula (glenohumeral joint) Articulates distally with the radius and ulna forming the elbow joint

3.2 On the humerus identify: i) proximal end - head : smooth rounded articular surfaces facing upwards, medially and backwards. - anatomical neck: margin of joint capsule - surgical neck: the narrow part distal to the tubercules - greater tubercle(most lateral bone of the shoulder as it extends laterally past the shoulder): Rounded projection on the lateral surface of the epiphysis (site attachment) - lesser tubercle: smaller projection that lies on the anterior, medial surface of the epiphysis - intertubercular (bicipital) groove : narrow channel between the two tubercles on the anterior surface - medial lip of intertubercular groove - lateral lip of intertubercular groove ii) shaft - (spiral) groove for radial nerve: follows the deltoid tuberosity on the posterior surface (path of the radial nerve) - deltoid tuberosity:is a large, rough process on the lateral surface of the shaft (attaches to deltoid muscle) iii) distal end - medial epicondyle : posterior surface → smooth with a shallow groove for the ulnar nerve - medial supracondylar ridge - lateral epicondyle: small tuberculation projection - lateral supracondylar ridge - capitulum: smooth rounded projection articulates with the head of the radius - trochlea: medial portion of the articular surface articulates with the trochlear notch on the ulna

3.3 Relate the markings of the humerus (objective 3.2) to the planes of the body in order to side (orientate) a disarticulated humerus. The process to orientate the humerus is to identify all 3 planes (i.e. superior/inferior, anterior/posterior, medial/lateral) -

head is superior end trochlea is anterior side medial epicondyle is medial side

3.4 Identify and classify the other bones of the shoulder girdle: clavicle and scapula. Scapula: - Large, flat triangular plate of the bone on the posterolateral aspect of the thorax. - Articulates with the humerus at the glenoid fossa (on the scapula) forming the shoulder (glenohumeral) joint - Articulates with the clavicle at acromion (on the scapula) forming acromioclavicular joint Clavicle: - Is a subcutaneous bone running horizontally from the sternum to the acromion - Acts as a strut holding the scapula laterally - Long, curved S-shaped bone - Smooth, superior surface; roughened inferior surface - Medial 2/3rds is convex forward with expanded medial end - Lateral 1/3rd is concave forward with flattened lateral end - Originates at the manubrium of the sternum (sternal end); sternoclavicular (SC) joint - Articulates with the acromion of the scapulae (acromial end); acromioclavicular (AC) joint

3.5 On the scapula identify: i) costal surface : anterior side/ smooth and concaves with depression called the subscapular fossa ii) dorsal surface: p  osterior side/ the smooth, convex posterior (dorsal) surface is divided by the spine into the superior Supraspinous fossa and the inferior Infraspinous fossa (supraspinous = superior to spine, infraspinous = inferior to spine iii) superior, medial and lateral borders iv) superior, inferior and lateral angles v) spine and root of the spine: S  capular spine runs from the medial border, crossing the posterior scapular body to the lateral acromion

vi) acromion process: e  xpanded lateral end of the spine, is large and quadrilateral, projecting forwards at right angles to the spine vii) coracoid process: h  ook like projection with a broad base directed upwards and forwards from the upper part of the body viii) glenoid fossa: slight concavity at the lateral angle, forms a socket for the glenoid fossa viii) subscapular, supraspinous and infraspinous fossae:

ix) suprascapular notch: a  notch just next to the base of the coracoid process where the superior border joins the base of the coracoid process x) supraglenoid and infraglenoid tubercles: s upraglenoid and infraglenoid tubercles are small projections above and below the glenoid fossa respectively

3.6 Relate the markings of the scapula (objective 3.5) to the planes of the body in order to orientate a disarticulated scapula. Must identify all three planes e.g. - superior angle is superior - coracoid process is anterior to acromion process - glenoid fossa faces laterally

3.7 On the clavicle identify: i) acromial end - lateral and superior end; most flattened part and has a deltoid tubercle on its anterior border ii) sternal end: enlarged and faces downwards and medially/ pyramidal iii) superior surface : smooth iv) inferior surface: rough with prominent lines and tubercules v) roughened area for costoclavicular ligament: inferior/medial/ roughened process vi) trapezoid line: oblique ridge running laterally from the conoid tubercle vii) conoid tubercle: lateral and inferior/less lateral than a trapezoid line viii) curvatures: - Lateral ⅓- concaves forwards - Medial ⅔- convex forwards

3.8 Identify the bony features listed above on radiographic images of the shoulder region....