Lecture 10: acapulocostal, sternoclavicular, acromioclavicular, & shoulder joints & asynchronous lecture Flashcards
Scapulothoracic joint:
Physiological joint:
scapula w/Thoracic cage
Movements: provided by the muscles attached to scapula
(dependent on acromioclavicular, and sternoclavicular articulations)
Any movement at the scapulothoracic joint will cause movement at these two joints.
What is the role of the scapulothoracic joint?
-Provides a moveable base for the humerus, hence increasing arm ROM at shoulder joint
-Helps deltoid function w/ proper tension w/arm above 90 degrees
-Provides glenohumeral stability for overhead work
-Absorbs shocks to outstretched arms
Actions of the scapulothoracic joint:
Protraction: abduction away from midline
Retraction: adduction towards midline
Elevation: upward sliding on rib cage
Depression: downward sliding on rib cage
Rotation of scapula: reference is glenoid cavity and inferior angle
-Upward rotation: glenoid rotates superiorly, inferior angle rotates away from the midline
-Downward rotation: glenoid rotats inferiorly, inferior angle rotates towards midline
Sternoclavicular joint:
Articular surfaces =>
Type of joint =>
Movement=>
Articular surfaces:
1)Facet on the lateral end of the clavicle (acromial facet)
2)Facet on the medial end of the acromion
Type of joint: Plane synovial joint
Movement: slide & glide
Identify the ligaments:
1) Sternoclavicular ligament w/capsule
2) Interclavicular ligament
3) Costoclavicular ligament
Sternoclavicular joint movements:
1) Elevation of clavicle: 60 degrees
2) Depression of clavicle: 5-10 degrees
3) Protraction: 25-30 degrees
4) Retraction: 25-30 degrees
5) Rotation of clavicle: 30 degrees
Acromioclavicular joint:
Articular surface=>
Type of Joint=>
Movement=>
Articular surface:
-Facet on the lateral end of the clavicle (acromial facet)
-Facet on the medial end of the acromion
Type of joint: Plane synovial joint
Movement: Slide and glide
Note: AC joint moves as a result of scapular movement
Acromioclavicular joint:
Ligaments=>
Acromioclavicular ligament: A strong fibrous band that reinforces the superior aspect of the acromioclavicular joint
Trapezoid ligament: Extends from the coracoid process of the scapula to the trapezoid line on the inferior lateral end of the clavicle
Conoid ligament: Extends from the base of the coracoid process of the scapula to the conoid tubercle on the inferior aspect of the lateral clavicle
The trapezoid and the conoid ligaments make up the ____________________________, which anchors the lateral end of the clavicle and prevents superior dislocation of the AC joint.
Coracoclavicular ligament
Glenohumeral (shoulder) joint:
Articular surfaces=>
Type of joint=>
AS: The glenoid fossa of the scapula and the head of the humerus
(covered by hyaline cartilage)
Joint Type: Ball & socket synovial joint (multi-axial-3 degrees of freedom)
Physiology of the glenohumeral joint:
-Proximal joint of the upper limb (most mobile joint)
-Has 3 DOF;
1) Medial-lateral axis: flexion & extension
2) Anteroposterior axis: abduction & adduction
3) Vertical axis; rotational movement
Only _____ of the head of the humerus fits into the glenoid fossa.
1/3
Glenoid labrum:
A ring of fibrocartilage attached to the margins of the glenoid cavity. Widens the cavity slightly but deepends it appreciably so as to make the articular surfaces congruent.
Capsule of the glenohumeral joint:
-Attaches to the margins of the glenoid cavity medially & neck of the humerus laterally.
-Covered by synovial membrane (inside)
Glenohumeral ligaments:
Capsular ligaments: Joint is very loose and permits free movements. Least supported inferiorly (where most dislocations may damage the axillary nerve)
Superior, middle, and inferior glenohumeral ligaments: Anteriorly reinforce the joint capsule
Transverse humeral ligament:
Bridges the upper part of the humeral groove into a canal.
(functions as a retinaculum for long head of bicep brachii tendon)
-Holds synovial sheath & tendon in place during movement.
Coracohumeral ligament:
Coracoid process of the scapula to greater tubercle of the humerus (intrinsic ligament)
Coracoacromial arch:
Protective structure formed by the smooth inferior aspect of the acromion & coracoid processes of the scapula.
Coracoacromial ligament: bridges gap between these structures.
Overlies the head of the humerus , preventing it’s superior displacement from the glenoid cavity.
Position of the rotator cuff muscles tendon around the joint capsule:
Note the position of the biceps brachii tendon.
Subscapular bursa:
Overlies anterior joint capsule and lies beneath the subscapularis muscle
Subacromial bursa:
between acromion and the tendon of the supraspinatus muscle.
Facilitates movements of the supraspinatus tendon under the coracoacromial arch & deltoid over the fibrous capsule & greater tubercle of humerus.
Subject to impingement beneath the acromial arch if inflamed & swollen.
Subdeltoid bursa:
Between the deltoid and the fibrous capsule
(may be continuous with the subacromial bursa)
Flexion & extension of the glenohumeral joint:
Performed in a sagittal plane, about a transverse axis.
a) Extension: 45 degrees-50 degrees
b) Flexion to 180 degrees
Adduction of glenohumeral joint:
Adduction of the frontal plane : adduction is only possible when combined with:
a) Extension, which allows a bit of adduction
b) Flexion, in this case adduction can reach 30 degrees to 45 degrees
Abduction of the glenohumeral joint:
The movement of the upper limb away from the midline, frontal plane movement, anteroposterior axis.
1) After the 90 degree position, abduction again brings the arm closer to the sagittal plane of the body.
2) Final position is 180 degrees
Scapulohumeral rhythm:
Rotation of the shoulder joint:
Occurs on longitudinal axis of humerus
Elbow must be bent to 90 degrees, and forearm lying at sagittal plane.
Lateral rotation: to 80 degrees
Medial rotation: to 95 degrees
Medial rotation to reach this far, the forearm must be pulled behind the trunk
Transverse movements of the trunk:
Horizontal movements: vertical axis & involve shoulder joint & scapula. Total range falls short of 180 degrees.
-Position of reference 90 degree abd of shoulder joint in frontal plane.
Horizontal adduction: 140 degree
-Muscles involved; ant.deltoid, subscapularis, pec. major, pec. minor, serratus anterior, coracobrachialis, & short head of biceps
Horizontal abduction: 30 degree
-Muscles involved; post. deltoid, infraspinatus, teres major, teres minor, rhomboid muscles, trapezius, latissimus dorsi.
Main muscle actions on the shoulder joint:
Elbow complex:
Three bony articulations:
1) Humeroulnar: trochlea of humerus articulates with the trochlear notch of ulna
-synovial hinge joint (one degree of freedom)
2) Humeroradial: Capitulum of humerus articulates w/ the head of the radius
-synovial hinge joint (one degree of freedom)
3) Proximal radioulnar
Actions:
-Flexion
-Extension
Strong joint due to the bony configuration (mainly between humerus & ulna) & collateral ligaments (radial collateral & ulna collateral)
Elbow joint articulat surfaces & capsule:
Distal end of humerus has two articular surfaces:
Figure A) Trochlea (2)
Figure A) Capitulum (3)
Proximal ends of the two bones of the forearm have two surfaces corresponding to those of the humerus:
-Trochlear notch of the ulna; articulates w/ the trochlea
Figure C) Coronoid fossa (5) above the trochlea & the radial fossa (6), medial epicondyle (7), lateral epicondyle (8)
Figure F) olecranon fossa (17), which receives the olecranon process (20)
Figure D) (coronal section through joint)
Capsule (17): invests a single anatomical joint cavity w/ two functional joints:
True elbow joint (vertical strips) Figure E.
Superior radioulnar joint (horizontal strips)
Olecranon process (11) lying inside the olecranon fossa during extension
Elbow axis of motion:
Can be approximately located on humans slightly distal to the epicondyles of the humerus.
Carrying angle of elbow joint:
With the elbow at full extension and the forearm supinated, the forearm deviates laterally in relation to the humerus.
Ranges from: 5 degrees- 19 degrees
Women typically have more pronounced carrying angle by 0 degrees- 6degrees due to wider pelvic girdle.
Carrying angle allows the arm to be swung without contacting the hips.
Trochlea extends more distally than the capitulum; does not allow it to be fully perpendicular to the humeral shaft
Cubitus Varus:
Varus = deformity of limb; deviated towards the midline
Common deformity in which the extended forearm is deviated towards midline of the body.
Cubitus Valgus:
medical deformity in which the elbow is turned in.
Elbow Joint ligaments:
Keeps articular surfaces in apposition:
Medial (ulnar) collateral ligament: (Figure A: 1,2 ,3)
Lateral (radial) collateral ligament(Figure B: 10,11,12)
The ligaments will keep the half-ring (figure C) fitted to the pulley & prevent all sideways movement (Figure E).
Capsule is strengthened anteriorly by:
Anterior ligament (14)
Oblique anterior ligament (15)
Identify the structures:
1) Radial collateral ligament
2) Ulnar collateral ligament
3) Lateral epicondyle
4) Medial epicondyle
5) Joint capsule
Flexor & extensor muscles of the elbow:
Extension of the elbow depends on one muscle:
-Triceps brachii (A)
-Anconeus exerts minor action
-Lateral head of the triceps (2) is the strongest of the three heads
3 Major flexor muscles:
-Brachialis (B,1)
-Brachioradialis (B,2)
Above two muscles act exclusively as elbow flexor
-Biceps brachii (C): keeps shoulder in opposition but main action is flexion at the elbow. (main supinator of forearm)
Elbow joint AROM & PROM:
Figure C: when arm & forearm are in a straight line
-Women & children have great laxity of the ligaments allow hyperextension of 5 degree-10 degree
Figure A: active flexion, range of 145 degrees and a range of passive flexion is 160 degrees
(W/ the fist width separating the wrist from the shoulder)
Proximal (superior) radio-ulnar joint:
Type: Synovial pivot joint
-cylindrical surfaces
Movement: rotation about the axis of the two cylinders in contact
Two cylinders in contact:
Head of the radius (C: 1)
-covered by articular cartilage
-The cupped surface of the (fovea) head also articulates w/ the capitulum of the humerus
A fibro-osseous ring(A): consists of the following:
1) Radial notch of the ulna(6) is covered by the articular cartilage, concave anteroposteriorly
2) Annular ligament: (5) consists of a strong fibrous band attached by it’s ends to the anterior & posterior margins of the radial notch of the ulna & lined internally by cartilage continuous w/ that lining the radial notch
Inferior (Distal) Radio-ulnar joint:
Has cylindrical surfaces:
Type: synovial pivot joint;One degree of freedom (rotation)
At the distal edge of the ulnar notch is inserted the articular disc(5); attached above the base(9) of the styloid process of the ulna (B).
The purpose of the disk is to bind the radius & ulna together & seperate the distal radioulnar joint & ulna from the radiocarpal joint.
The proximal & distal surfaces of the disc: covered by articular cartilage.
The thickening of the capsule as the palmar (anterior) and posterior or dorsal radioulnar ligaments support the joint anteriorly & posteriorly.
Identify the structure:
Palmar radioulnar ligament
Identify the structure:
Dorsal radioulnar ligament
Middle radioulnar joint:
A ligamentous connection:
Interosseous membrane, lies between the bodies of the radius & ulna
Type of joint: amphiarthrosis syndesmosis joint
Supinator & pronator muscles:
Supination: 90 degrees
Pronation: 80 degrees
Articular complex of wrist:
Figure A:
1) Radiocarpal joint: detween the distal end of the radius, disc of the distal radiocarpal joint (proximally), & the proximal row of carpal bones (except pisiform) distally.
-condyloid (ellipsoid) joint (B) w/ anterior & posterior axis (flexion & extension)
2) midcarpal joint: between proximal and distal rows of carpal bones (except pisiform)
3) Intercarpal joints: between proximal or distal carpal bones.
-small synovial planar joints
-synovial planar joint
The ligaments of the radiocarpal joint are arranged in two groups:
1) Collateral ligaments
2) radiocarpal & ulnocarpal ligaments
1) collateral ligaments (C):
-The lateral (1) is attached to the styloid process of the radius & scaphoid bone
-The medial (2) is attached to the styloid process of ulna and the pisiform & triquetrum bones
2) Anterior and posterior ligaments (C):
-Radiocarpal ligament(3): with it’s expansion to the carpal bone.
-Ulnocarpal ligament (4):
Identify the structures:
1) Radioscaphoid & radiocapitate part of the radiocarpal ligament
2) Radial collateral ligament
3) Ulnolunate & ulnotriquetral part of the ulnocarpal ligament
4) Ulnar collateral ligament
Identify the structure:
1) Dorsal ulnocarpal ligament
2) Dorsal radiocarpal ligament
Radiocarpal joint:
Action of the ligament varies w/the type of movement performed.
Adduction & abduction: (C,D,E), the collateral ligaments are active so that the lateral (radial) collateral ligament becomes taut & the medial (ulnar) collateral ligament relaxes during adduction, and vice versa.
Flexion & extension: (F,G,H) The anterior & posterior ligaments; posterior ligament becomes taut in flexion &the anterior ligament in extension.
Radiocarpal joint AROM adduction & abduction:
Range of adduction and abduction is minimal when the wrist is in flexion & extension.
It is maximal when the hand is slightly flexed because the ligaments are relaxed.
The axis of these motions is through the head of the capitate, located proximally to the base of MC III.
Radial deviation: 15 degrees
Ulnar deviation: 30 degrees
Radiocarpal joint AROM flexion & extension:
Wrist flexion: 85 degrees
wrist extension: 85 degrees
Carpometacarpal (CMC) joint:
1st CMC joint: synovial saddle joint, with 3 DOF, with the surfaces of the 1st metacarpal & trapezium both having convex & concave characteristics.
The joint capsule is thick, but loose.
Motions include abduction/adduction (in a right angle to the palm), and flexion/extension (parallel to the palm), and opposition (a rotation of the 1st metacarpal on the trapezium)
Due to the laxity of the joint, 15 to 20 degrees of rotation is possible.
1st CMC flexion = 15 degrees
1st CMC extension = 20 degrees
1st CMC abduction = 70 degrees
2nd to 5th carpometacarpal (CM) joints:
The distal row of carpal bones articulate with the bases of the 2nd to 5th metacarpals in an irregular manner.
A common joint cavity is found between the four distal carpals, the CMC joints, and into the intermetacarpal joints.
The 2nd & 3rd CMC joints have a motion of 2 degrees or less.
The 4th CMC joint has 10-15 degrees of dorso-volar movement.
The 5th CMC joint is the most flexible, with 25-30 degrees of motion.
These movements are important to hand function w/ relation to the transverse arch of the hand from the closed fist to the open hand.
Metacarpophalangeal (MCP) joints:
Synovial condyloid joints between the heads of the metacarpal bones & the base of the proximal phalanges of the digits w/ 2DOF
Medial & lateral collateral ligaments: attach the heads of the metacarpals to the bases of the phalanges. They are also supported by the palmar plates (ligaments) ventrally.
Movements and ROM-MCP joints: digits II-V: when MCP joint is in 90 degree flexion, the collateral ligaments are taut:
Movement:
1) MCP flexion: 90 degrees
2) MCP hyperextension: 0-45 degrees
3) MCP abduction: 20 degrees
4) MCP adduction: 20 degrees
5) MCP abd. (w fingers flexed): 0 degrees
6) MCP add. (w fingers flexed): 0 degrees
Interphalangeal (IP) joints:
Digits II to V have two interphalangeal joints; the proximal interphalangeal (PIP) joint and the distal interphalangeal (DIP) joint.
Thumb only has one IP joint
Classified as hinge joints w/ 1 DOF
PIP flexion: 120 degrees
DIP flexion: 90 degrees
PIP & DIP extension: 0 degrees
Thumb IP hyperextension: 5-10 degrees
