Upper limb 2 Flashcards
What shape is the scapula and what kind of bone is it?
Triangular flat bone
How many muscle attachments does the scapula have?
17
What are the 3 faces of the scapula?
- Costal surface
- Lateral surface
- Posterior surface
What is the costal surface of the scapula?
- Anterior surface
- Subscapular fossa (where subscapularis muscle originates)
- Coracoid process (provides attachment to the short head of biceps brachii, coracobrachialis and pec major)
What is the lateral surface of the scapula? What does it face? What tubercles does it contain? What muscles attach to the tubercles?
- Faces the humerus and glenoid fossa
- Supraglenoid tubercle = origin long head of biceps brachii
- Infraglenoid tubercle = origin of the long head of triceps brachii
What is the posterior surface of the scapula divided by? Gives rise to?
What other structure of the scapula does it give rise to?
- Posterior surface is divided by spine
- Gives rise to supraspinous fossa (where supraspinatus arsies)
- Gives rise to infraspinous fossa (where infraspinatus arises)
- Acromium is also present here, it articulates with the clavicle
What is subscapularis, supraspinatus and infraspinatus?
Look at picture
What are the other features of the scapula?
- Superior border
- Inferior border
- Suprascapular notch
- Medial border
- Lateral border
What can cause a scapular fracture?
Uncommon.
-Can be caused by chest trauma (high speed collisions, crushing injuries, sports injuries)
Why does a fractured scapula not need fixing?
The tone of the surrounding muscles hold the pieces in place for healing to occur.
What is winged scapula?
What can cause damage to that nerve?
- Damage of long thoracic nerve can cause paralysis of serratus anterior (origin ribs 1-8)
- Causes scapula to protrude out of the back when pushing with arm
- Long thoracic nerve can become damaged by shoulder trauma, repetitive movements at shpulder, pressing of nerve
What is the clavicle?
What does it attach?
- Long sigmoid bone
- Attaches upper limb to the trunk (torso)
What is the function of the clavicle?
- Protects neurovasculature
- Transmits forces from the upper limb to the axial skeleton
What are the key 5 characteristics of the clavicle?
- Sternal end
- Impression for costoclavicular ligament
- Conoid tubercle
- Trapezoid line
- Acromial end
Elaborate on the sternal end
- Has a large articular facet which articulates with the sternum (forming sternoclavicular joint)
- Has a depression for costoclavicular ligament (fibrous ligament that stabilises movement at the sternoclavicular joint - attached to first rib and borders of clavicle)
What is the costoclavicular ligament?
- The fibrous ligament that attaches from the first rib and its cartilage to the anterior and posterior borders of the clavicle
- stabilises the sternoclavicular joint
Why is the clavicular shaft important?
(Origin of which 6 muscles?)
Why does it have a depression?
- It’s the origin for deltoid, trapezius, subclavius, pec major, sternocleidomastoid and sternohyoid
- Has a depression for subclavius
Elaborate on the acromial end
- Has the acromial facet which articulates with the acromium
- Conoid tubercle = provide attachment for conoid ligament (medial part of the coracoclavicular ligament)
- Trapezoid line = attachment for lateral part of the coracoclavicular ligament = trapezoid ligament
What is the conoid tubercle?
-Allows attachment of conoid ligament which is the medial part of the coracoclavicular ligament
What is the trapezoid line?
Provides attachment to trapezoid ligament (lateral part of the coracoclavicular ligament)
Why is clavicle susceptible to fracture?
How do fractures happen?
- Because of its size
- Fall on shoulder or onto an outstretched hand
Which part of the clavicle fractures more common?
- 80% occur in the middle third
- 15% occur in the lateral third
- 5% occur in the medial third
What does the proximal humerus consist of?
- Head = articulates with the glenoid fossa
- Anatomical neck
- Surgical neck = axillary nerve wraps around here, circumflex humeral arteries are found here
- Greater tubercle = located laterally. Provides attachment for supraspinatus, infraspinatus and teres minor NOT subscapualris)
- Lesser tubercle = located medially. Provides attachment for subscapularus
Intertubercular (bicipital groove) = tendon of long head of biceps brachii runs; attachment points for pec major and lat dorsi
What is the greater tubercle?
- Located laterally
- Provides attachment for 3 rotator cuff muscles - infraspinatus, supraspinatus and teres minor
What is the lesser tubercle?
Located medially. Provides attachment for subscapularis
What is the intertubercular (bicipital groove)?
- Groove where tendon of long head of biceps brachii runs
- Attachment for pec major and lat dorsi
What are the key features of the shaft?
-Deltoid tuberosity = roughening for attachment of deltoid
Spiral groove = radial nerve and profunda brachii artery are found
- Anteriorly = coracobrachialis, deltoid, brachialis and brachioradialis attach
- Posteriorly = medial and lateral heads of triceps brachii attach above and below spiral groove
What are the features of the distal humerus?
- Medial supracondylar ridge (origin for brachialis, pronator teres and medial head of triceps brachii)
- Lateral supracondylar ridge (origin for common extensors and minor attachment for triceps brachii )
- Lateral epicondyle = provides attachment for supinator and some extensors, radial collateral ligament
- Medial epicondyle = ulnar nerve passes through inferiorly
- Trochlea = articulates with the trochlear notch of ulna
- Capitulum = articulates with radius
What is the medial supracondylar ridge?
Origin for brachialis and pronator teres and medial head of triceps brachii
What is the lateral supracondylar ridge?
Origin of the common extensors e.g brachioradilais, extensor carpi radialis
What is the lateral epicondyle?
-Provides attachment for supinator and some extensors (anconeus, extensor carpi ulnaris)
What is the medial epicondyle?
- Ulnar nerve passes through inferiorly
- Flexors attach here (common flexor origin)
What is the trochlea?
Articulates with the trochlear notch of ulna
What is the capitulum?
Articulates with the radius
What does the coronoid fossa do? What does the radial fossa do?
During flexion and extension:
- Coronoid fossa accommodates the ulna
- Radial fossa accommodates the radius
Olecranon fossa accommodates the olecranon of the ulna
What is surgical neck fracture of the humerus?
What is it caused by?
What key structures are at risk?
- Fracture at the surgical neck of the humerus
- Caused by direct flow to that area or falling onto an outstretched hand
- Axillary nerve and posterior circumflex artery are at risk
What muscles are at risk of paralysis due to surgical neck fracture of the humerus?
What movement will this affect?
- Axillary nerve damage will cause paralysis of deltoid and teres minor
- The axillary nerve also innervates the skin over the lower deltoid so sensation in this region may be lost
- Will affect abduction of the affected limb
Why may there be a loss in sensation of skin at the lower end of deltoid in a surgical neck fracture of the humerus?
Because the axillary nerve also supplies the skin there