Quiz 3 Flashcards
Which wrist bone is most commonly fractured?
scaphoid
Which wrist bone is most commonly dislocated?
lunate
What is the sternoclavicular joint? Which ligaments stabilize and prevent excessive movement of it?
The sternoclavicular joint is:
- a fairly stable modified saddle joint
- Convex medial end of clavicle fits into concave manubrium.
- Fibrocartilagenous disc separates the articulating surfaces
- The sternoclavicular ligaments bind the clavicle to the manubrium on both anterior and posterior surfaces.
- The interclavicular ligament binds the medial ends of the right and left clavicles to each other just above the manubrium
- The costoclavicular ligament binds the clavicle to the first rib
What do the sternoclavicular ligaments do?
Part ofthe sternoclavicular joint, the sternoclavicular ligaments bind the clavicle to the manubrium on the anterior and posterior surfaces
What does the interclavicular ligament do?
Part of the sternoclavicular joint, the interclavicular ligament binds the medial ends of the right and left clavicles to each other just above the manubrium.
What does the costoclavicular ligament do?
The costoclavicular ligament binds the clavicle to the first rib in the sternoclavicular joint
Under which ligament can a branch of the brachial plexus get trapped? What happens as a result?
The costoclavicular ligament. It results in pain and muscle weakness, depending upon which branch is trapped.
Are dislocations of the sternoclavicular joint common? What results if there is a posterior dislocation?
No, they are not common. Posterior dislocation can result in trauma to the brachiocephalic veins that are located just posterior to this joint.
What innervates the sternoclavicular joint?
The nerve to the subclavius and the supraclavicular nerve
What supplies the blood to the sternoclavicular joint?
the suprascapular or internal thoracic arteries supply the blood to the sternoclavicular joint
What movements are associated with the sternoclavicular joint?
The sternoclavicular joint increases shoulder ROM and passively moves with scapular motion
Describe the acromioclavicular joint.
- -Synovial joint of Planar type between acromion of scapula and lateral end of clavicle.
- some movement here, but the main function is to bind the clavicle to the scapula in order to support the weight of the upper limb and keep the humerus suspended at the side without using a lot of muscle contraction energy.
What is the main function of the acromioclavicular joint?
bind the clavicle to the scapula in order to support the weight of the upper limb and keep the humerus suspended at the side without using a lot of muscle contraction energy
What provides the main stabilizing force to the acromioclavicular joint?
ligaments.– the acromioclavicular ligament that binds the clavicle to the acromion and the coracoclavicular ligaments, which bind the coracoid process of the scapula to the clavicle.
What two ligaments make up the coracoclavicular ligament?
the conoid and the trapezoid ligaments
When does shoulder separation occur? Describe shoulder separation.
When there is tearing of the coraclavicular ligaments and/or the acromioclavicular ligaments. A greater tear results in greater separation from the clavicle. When this happens, the weight of the upper limb pulls the scapula and the acromion downward. The result is that the clavicle overrides the acromion.
What is the innervation of the acromioclavicular joint?
suprascapular and lateral pectoral nerves
What is the blood supply of the acromioclavicular joint?
suprascapular and thoracoacromial arteries
Describe the glenohumeral joint.
- Most mobile joint in the human body.
- ball and socket synovial joint between head of humerus and concave glenoid fossa of the scapula.
- fibrous capsule that attached from the glenoid cavity to the anatomical neck of the humerus surrounds the joint.
- ligaments reinforce the capsule in all directions except for the inferior portion.
What are the ligaments that reinforce the glenohumeral joint?
1) coracoacromial ligament (which doesn’t actually attach to this joint) connects the coracoid process to the acromion. It reinforces the superior aspect of the shoulder joint and helps prevent upward displacement of the head of the humerus.
2) Coracohumeral ligament– strengenths the superior portion of the capsule and helps resist excessive abduction. It runs from the coracoid process to the lesser tubercle.
3) the transverse humeral ligaments holds the tendon of the long head of the biceps in the bicipital groove. This stabilizes the tendon so that it doesn’t pop out.
4) 3 parts of the glenohumeral ligament, which attach from the upper margin of the glenoid cavity and labrum, strengthen the anterior portion of the capsule.
Ligaments reinforce the fibrous capsule that attaches from the glenoid cavity to the anatomical neck of the humerus in all directions except?
inferior portion
What are the three parts of the glenohumeral ligament?
1) The superior part, which runs over the humeral head to a depression above the lesser tuberosity.
2) The middle part, which runs from in front of the humerus to lower lesser tuberosity
3) the inferior part, which runs to a lower part of the anatomical neck. This ligament is a key stabilizer of the anterior shoulder.
Weakness of which part of the glenohumeral ligament often leads to anterior glenohumeral instability?
The inferior part
What is the glenoid labrum?
rim of fibrocartilage attaching to the outer rim of the glenoid fossa. Superior attachment of the labrum includes the supraglenoid tubercle and the origin of the tendon of the long head of the biceps.
What does the glenoid labrum do?
helps deepen the articulation between the head of the humerus and the glenoid fossa of the scapula. Provides stability to this articulation.
Tears of the glenoid labrum often are associated with…?
glenohumeral dislocations
Describe the capsule of the glenohumeral joint.
It is very thin and lax. It attaches to the glenoid beyond the labrum and to the anatomical neck of the humerus. It is strengthened by the muscles of the shoulder: supraspinatus, infraspinatus, teres minor, subscapularis, and the long head of the biceps brachii
What are the openings of the capsule of the glenohumeral joint?
1) between greater and lesser tubercles that allows passage of the long head of the biceps brachii through the shoulder joint.
2) below and anterior to coracoid process, which allows the joint to communicate with the subscapular bursa
3) between joint and bursa under infraspinatus tendon
What bursae are associated with the glenohumeral joint?
1) subscapular, which is between the muscle and the neck of the scapula. It communicates with the shoulder joint.
2) Subacromial or subdeltoid, which is inferior to the acromion and extending distally to area deep to the deltoid muscle, but superficial to the supraspinatus. This normally does not communicate with the joint.
3) above acromion,
4) others with tendons
5) between the coracoid and the capsule
What innervates the glenohumeral joint?
the suprascapular nerve, lateral pectoral nerve, posterior cord of the brachial plexus, and axillary nerve
What arteries supply the glenohumeral joint?
the anterior and posterior humeral circumflex, which goes through the quandrangular space, and the suprascapular artery, which innervates from the posterior.
How would you characterize the stability of the glenohumeral joint?
Very mobile, so stability is reduced.
What muscles/structures contribute to the passive stability of the glenohumeral joint?
The trapezius acts as a postural muscle, keeping the shoulder joint in a retracted and upwardly rotated position. The deltoid prevents dislocation of the humerus from the glenoid cavity by gravity. The ligaments (especially glenohumeral ligament and coracohumeral ligament and glenoid labrum) help stabilize the joint.
If the shoulder droops, which muscle that stabilizes the glenohumeral joint is likely to have been damaged?
trapezius
What is the difference between passive and active stability?
Passive stability involves the factors that keep it stable when it is at rest. Active stability involves those structures that stabilize the joint when motion occurs.
Describe very simply how the structures involved in active stability of the glenohumeral joint do their job.
they pull the head of the humerus into the fossa and pulls the head of the humerus downward, counteracting the tendency of the head of the humerus to move up towards the acromion and compression of the structures between the humeral head and the acromion.
What muscles are responsible for active stability of the glenohumeral joint?
the rotator cuff muscles– a series of 4 muscles that arise from the scapula and insert into the proximal end of the humerus. They rotate the humerus and are active during all types of shoulder joint movements.
What does weakness of rotator cuff muscles result in?
impingement of structures between acromion and head of humerus.
Which rotator cuff muscles is most likely to get injured?
supraspinatus.
what are the movements of the glenohumeral joint?
1) elevation and depression of scapula. Elevation is like shrugging your shoulders. 2) protraction and retraction of scapula– former moves medial part of scapula away from midline, while latter moves medial part of scapula toward midline , 3) upward rotation of scapula (glenoid cavity and acromion face up), downward rotation occurs when inferior angle moves in a medial direction or acromion is drawn downward. 4) flexion/extension, wherein the humerus moves on the glenoid cavity in a sagittal plane. During flexion, the humerus moves anteriorly, while during extension, the humerus moves posteriorly up to 90 degrees , 5) abduction/adduction, wherein the humerus moves away from/toward the midline, 6) inward/medial rotation or outward/lateral rotation. Inward rotation occurs when the anterior portion of the humerus turns toward the midline of the body, outward rotation is the movement of turning the humerus away from the midline. 7) scapulohumeral rhythm– coordinated movements between scapula and humerus to abduct arm (2:1 ratio humeral abduction to scapula upward rotation). First 30 degrees humerus abducts and scapula remains stable, as motion continues scapula undergoes upward rotation. Upward rotation of scapula is result of the combined actions of the trapezius and serratus anterior. Damage to either the trapezius or serratus anterior results in the person not being able to fully abduct the arm, despite the fact that the deltoid is working to raise the humerus.
When the arm is abducted 180 degrees, how much occurs by rotation of the scapula, and how much by rotation of the humerus at the shoulder joint?
60 degrees by scapula rotation and 120 degrees by rotation of humerus at the shoulder joint.
At what degree would extension of the humerus in the glenohumeral joint be considered hyperextension?
beyond 90 degrees behind the body
What is shoulder impingement?
– overuse injury in which repetitive motion results in fatigue of rotator cuff muscles.
What type of movement reduces the contact between the humeral head and the glenoid fossa and makes the glenohumeral joint less stable than it is at rest?
any type of movement.
What type of motion renders the glenohumeral joint particulary unstable and why? Which muscles are especially responsible for counteracting this instability? What does their action in particular prevent?
abduction (especially full abduction), because there is minimal contact between the articulating bones. The rotator cuff muscles (especially subscapularis, infraspinatus, and teres minor) become active during shoulder abduction. They pull the head of the humerus downward and into the glenoid cavity. Their action prevents the humerus from riding up and pressing the supraspinatus tendon between the acromion and greater tubercle of the humerus.
What happens when the teres minor, subscapularis, and infraspinatus fatigue? What is the primary symptom of this?
The humerus moves towards the acromion and the supraspinatus tendon becomes rubbed between the acromion and greater tubercle, irritating the tendon. The primary symptom is pain posterior to and below the acromion in the vicinity of the greater tubercle, especially when attempting to abduct, flex, or adduct the humerus.
What are some special tests for shoulder impingement?
1) painful arc– abduct arm (pain present from 60 to 120 degrees abduction). 2) Can tests– to assess impingement or damage to the supraspinatus tendon. Full can is with abduction of arm to shoulder level and outwardly rotate humerus, press down on shoulder, if pain or difficulty then supraspinatus tendon is affected. Empty can test is abduction of arm to shoulder level and inwardly rotate humerus, press down on shoulder. If pain or difficulty then supraspinatus tendon is affected.
How does the anatomy of the can test positions differ and what does this mean?
Full can (outward rotation) moves the greater tubercle and attached supraspinatus tendon away from acromion. No irritation of this tendon and it can withstand pressing downward on the arm. Empty can (inward rotation) moves the greater tubercle and supraspinatus tendon directly under the acromion. In this position it is easy to have the supraspinatus tendon irritated by the acromion so it is a lot more difficult/painful for the patient to resist when you are pushing down on arm. Hence, impingement sign indicated by empty can.
What type of joint is the elbow joint?
synovial hinge joint betwen the distal humerus and proximal ulna and radius.
What are the joints of the elbow joint?
humeroradial joint– capitulum and head of radius
humeroulnar joint– trochlea and trochlear notch of ulna
Describe the capsule of the elbow joint
thin anteriorly and posteriorly, attaches anteriorly to the area proximal to coronoid and radial fossae and to the annular ligament. Attaches posteriorly to the olecranon fossa and trochlear notch. The synovial capsule is continuous with that of the proximal radioulnar joint.
What are the ligaments of the elbow joint?
1) radial or lateral collateral– fan shaped and attaches to the lateral epicondyle of the humerus and distally blends with the annular ligament of the radius.
2) ulnar or medial collateral– three bands. anterior from front of medial epicondyle of humerus to tubercle on medial margin of coronoid. Posterior from lower, back part of medial epicondyle to medial margin of the olecranon.
3) oblique connects to distal attachments of the other two
What are the bursa of the elbow joint?
1) 2 associate with olecranon– one subctaneous and one deep to the tendon of the triceps. 2) radioulnar bursa is between the extensor digitorum, supinator, and the radiohumeral joint. 3) interosseal bursa behind the supinator, lateral to the biceps 4) bicipitoradial bursa is between the biceps and tuberosity of the radius.
What innervates the elbow joint?
the musculocutaneous (terminal branch of the lateral cord), the radial nerve on the posterior cord, and some ulnar (funny bone), median, and anterior interosseous nerves (branch off of median nerve)
What supplies blood to the elbow joint?
The components of the anastomosis of the elbow– the brachial artery (2 ulnar collateral arteries off of brachial), the deep brachial, the ulnar (recurrant), and the radial.
What are the movements available at the elbow joint?
Flexion and extension. The axis for these movments is a horizontal line through the epicondyles of the humerus. Flexion involves bringing the radius and ulnar to approximate the humerus. Extension involves bringing the radius and ulna away from the humerus.
What is the proximal radioulnar joint?
Synovial pivot joint between the convex head of the radius and a concavity on the ulna. Formed by the head of the radius with the radial notch of the ulna. It contains a synovial cavity that communicates with the elbow joint.
What are the ligaments of the proximal radioulnar joint?
The annular ligament circles the head of the radius,forming 4/5 of the ring. Allowing for pronation and supination.
What does the synovial cavity of the proximal radioulnar joint do?
Communicates with the elbow joint
What innervates the proximal radioulnar joint?
the musculocutaneous, median, and radial nerves.
What is the blood supply to the proximal radioulnar joint?
the same as the elbow joint– brachial artery, the deep brachial artery, the ulnar, and the radial.
Describe the anastomosis of the elbow. What does it do?
Anastomosis of the elbow– brings brachial artery in anastomotic connection with the radial and ulnar arteries. It permits circulation to the forearm and wrist even with complete elbow flexion.
What is Nursemaid’s Elbow?
Happens in children often, when swinging or pulling on their arm the radius is pulled out of the annular ligament.
What are the movements of the proximal radioulnar joint?
pronation and supination. Pronation involves the radius moving on a fixed ulna. The radius rotates, bringing the hand and palm in a downward facing position. Supination involves the radius moving on a fixed ulna. The radius rotates, bringing the hand in a palm-up position.
What is Tommy John surgery?
Famous baseball pitcher who tore his ulnar collateral ligament. They drilled holes in his humerus and ulna and sewed the tendon through to sew his joint back together.
glenohumeral ligaments support in all directions except?
inferiorly
what is the key stabilizer of the anterior capsule?
inferior glenohumeral ligament
Which ligaments are especially involved with passive stability of the glenohumeral joint?
the coracohumeral ligament, the glenoid labrum, and the inferior glenohumeral ligament.
What happens regarding the glenohumeral joint if the SITS muscles are weak?
the humerus moves upward, pushing against the acromion, causing impingement of the supraspinatous tendon/muscle.
Describe humeral abduction and what muscles are involved.
Initiation of abduction is a function of the supraspinatus muscles. Bringing the arm to shoulder level is the action of the deltoid. Completing abduction to 180 degrees requires the synergistic action of the deltoid, trapezius, and serratus anterior muscles. The rotator cuff muscles (especially the infraspinatus, subscapularis, and teres minor) become very active during shoulder abduction. These muscles pull the head of the humerus downward and inward against the glenoid cavity. This action prevents the humerus from riding up and pressing the supraspinatus tendon between the acromion and greater tubercle of the humerus.
Which muscles are responsible for just abducting the humerus? Which are responsible for upward rotation of scapula?
1) Supraspinatus and deltoid.
2) Serratus anterior and trapezius.
Which muscle is the strongest flexor of the elbow joint when it is pronated? Supinated?
Pronated = brachialis. Supinated = biceps brachii
What must the biceps brachii first do before flexing the elbow joint?
supinate forearm. If the radioulnar joint is kept in a prone position, the biceps cannot act to flex the elbow.
Where is the brachialis in relation to the biceps brachii?
flat beneath
Where is the coracobrachialis in relation to the biceps?
beneath the short head
What is the main contributor to the musculocutaneous?
C6
Which cord is musculocutaneous nerve derived from?
lateral
Which nerve supplies motor innervation to the muscles in the anterior brachial compartment?
musculocutaneous
Which nerve supplies sensory information from the lateral portion of the forearm?
musculocutaneous
What supplies the blood to the anterior compartment of the arm?
brachial artery, a continuation of the axillary artery
What are the two compartments of the arm?
anterior/flexor– which contains muscles that flex the elbow joint and supinate the proximal radioulnar joint.
posterior/extensor– which contains muscles that extend the elbow joint
What are the two compartments of the forearm?
anterior/flexor – contains muscles that flex the wrist joint, pronate the radioulnar joint, and flex the digits.
posterior/extensor– contains muscles that extend the wrist joint, supinate the radioulnar joint, and extend and abduct the digits
What are transition zones?
Areas that connect one region to another in the compartments of the arm– in close proximity to moveable joints and therefore are subject to injuries.
What are the important transition zones in the arm and forearm?
Axilla (passageway for nerves and vessels that original in the neck to enter the axilla and upper limb), cubital fossa (anterior to elbow joint; provides passageway for nerves and vessels travelling from arm to forearm); wrist (connects and provides passageway for contents of forearm into hand)
What are the branches of the brachial artery?
1) muscular branches to the muscles in the anterior compartment of the arm, 2) collateral branches that participate in elbow anastomosis, 3) deep brachial artery that supplies the extensor compartment.
Which branches of the brachial artery participates in the elbow anastomosis?
collateral branches
Which branch of the brachial artery supplies the extensor compartment?
deep brachial artery branch
Which part of the triceps brachii forms the triangular space?
long head
What are the muscles in the posterior compartment of the arm primarily responsible for?
extending the elbow joint
What is the nerve of the posterior compartment of the arm?
the radial nerve (derived from the posterior cord of the brachial plexus)
What contributes the majority of the axons to the radial nerve?
C5-C7
The musculocutaneous nerve is part of which dermatome?
C6
Radial nerve is part of which dermatome?
C5
What is the cubital fossa?
region anterior to elbow joint. Region provides passageway for nerves and vessels travelling from the arm to the forearm.
where is venapuncture usually performed?
cubital fossa
What are the boundaries of the cubital fossa?
superior– imaginary line connecting epicondyles, medial– pronator teres, lateral – brachioradialis
What forms the roof and floor of cubital fossa?
roof– skin, fascia, biciptial aponerosis; floor – medial - brachialis, lateral- supinator
what are the contents of the cubital fossa from lateral to medial?
- radial nerve
- biceps tendon
- brachial artery and vein (v. is deep to a. with terminal branches of 1) radial artery and 2) ulnar artery)
- median nerve
Describe the venous contributions to the cubital fossa region and their clinical significance.
2 main cutaneous veins that drain the upper limb are derived from a venous arch on the dorsum of the hand. The basilic vein drains the skin on the ulnar portion of the forearm into the axillary vein in inferior axillary region. The cephalic vein drains skin on radial side of forearm and also drains into axillary vein (near apex, so more superior). The median cubital vein connects the basilic and cephalic veins in the cubital fossa and is the site for venapuncture.
What is the most common point of origin for the flexor muscles of the forearm?
medial epicondyle of humerus
pronation of forearm occurs by rotating which bone?
rotation of radius upon fixed ulna
which joints do the pronator teres and pronator quadratus act upon?
pronator teres = proximal radioulnar joint; pronator quadratus = distal radioulnar joint
What are the wrist flexors of the forearm?
flexor carpi radialis, palmaris longus, and flexor carpi ulnaris
where do the wrist flexors attach?
medial epicondyle of the humerus.
What is the main function of the palmaris longus?
keeping the palmar aponeurosis tight. It is a weak wrist flexor
which muscles of the forearm are considered extrinsic hand muscles and why?
flexor digitorum superficialis, flexor digitorum profundus, flexor pollicis longus. These muscles have their bellies of origin in the forearm, but exert their actions on the wrist and hand.
Which is the only extrinsic hand muscle of the forearm that proximally attaches to the medial epicondyle of the humerus?
flexor digitorum superficialis
Do the tendons of the flexor digitorum superficialis and flexor digitorum profundus both pass through the carpal tunnel and deep to the flexor retinaculum?
yes
Which muscle is the prime flexor of the PIP?
flexor digitorum superficialis
Which muscle is the prime flexor of the DIP?
flexor digitorum profundus