Lecture 20: arm and elbow Flashcards
Define arm
Brachium
Most proximal segment of free upper limb located between glenohumeral and elbow joints
Describe elbow joint- gen
Links arm - brachium - and forearm - antebrachium
More complex articulation between 3 bones = distal humerus, proximal humerus, proximal ulna
Describe humeral shaft distally
Widens mediolaterally
Distal humerus has 2 condyles = capitulum and trochlea
Adjacent medial and lateral epicondyles and supracondylar ridges = increase surface area for muscle attachments
Describe coronoid fossa humerus
Deeper
Describe radial fossa humerus
Shallow
Describe capitulum humerus
Articular surface for radius
Describe trochlea humerus
Articular surface for ulna
(Spool/pulley shaped)
Describe olecranon fossa humerus
Deepest
Reciprocal surface for capitulum of humerus
Radial head
Reciprocal surface for trochlea of humerus
Trochlear notch
Descrie radius features
Radial head, radial neck, radial tuberosity, shaft
(Proximal)
Describe ulna features
Tochlear notch = articulates with humerus
Conoid process - makes c shape = with olecranon process makes wrench shape
Ulnar tuberosity
Shaft
What type of joint is elbow
Synovial hinge - flex/ext
Compound joint = 3 bones with 3 articulations = humeroradial, humeroulnar and radioulnar
Describe purpose of 3 fossae on distal humerus
Accommodate processes on radius and ulna =
to prevent excessive flexion = coronoid and radial fossae
Prevent excessive extension = olecranon fossa
= act as stoppers, 180 degress rom max, locks radial head against fossa, = makes perfect hinge joint when olecranon locked in olecranon fossa
Describe humeroradial articulation
Capitulum
Head of radius
Describe humeroulnar articulation
Trochlea
Trochlear notch
Name elbow joint ligaments
Reinforcing/stabilizing structures =
Radial collateral ligament (lateral)
Ulnar collateral ligament (medial)
Annular ligament
Describe annular ligament
Stabilizes radioulnar joint and enables pronation/supination - lect 4
Ring shapen, keeps radial head in place against ulna, facilitates rotation of radial head against ulna
Describe nursemaids elbow
Radial head subluxation = occurs in children when radial head splits out of annular ligament - dislocates
Causes painful impingement of ligament, child refuses to promnate/supinate or flex elbow
Treatment = reduction = pop back in so fit radial head back into annular lig
What does humerus do to brachium
Divides brahcium into 2 musculofascial compartments, each dedicated to antagonists movements and interacted by own terminal branch brachial plexus
Describe anterior compartment of brachium = gen
Flexor compartment
Control elbow flexion
Describe anterior compartment of brachium = innervation
Innervated by musculocutaneous nerve c5-c7
Lateral cord brachial plexus
Describe posterior compartment of brachium = gen
Extensor compartment
Control elbow extension
Describe posterior compartment of brachium = innervation
Innervated by radial nerve - c5-t1
Name muscles of anterior compartment
Biceps brachii
Coracobrachialis
Brachialis
What does biceps brachii stand for
2 heads of arm
Proximal scapular attachment biceps brachii long head
Supra genloid tubercle of scapula
Proximal scapular attachments biceps brachii Short head
Coracoid process
Distal radial attachments biceps brachii
As conjoined tendon of 2 heads = radial tuberosity (halfway down arm)
As bicipital aponeurosis = deep fascia of medial forearm - flap ct over cubital fossa, soft tissue attachment
Functions of biceps brachii
Flexion elbow joint
Accessory flexor of glenohuemral joint bc proximal attachments on scapula
Supination
Bicipital aponeurosis covers and protects contents of cubital fossa
biceps brachii Describe long head tendon
Runs over humeral head in fibrous capsule (tendon integrated into fibrous capsule) through intertuberular bicipital groove = another passive stabilizer of shoulder- tension helps keep head opposed to genloid facet
Where are brachialis and coracobrachialis
Under biceps brachii
Attachments Coracobrachialis
Coracoid process of scapula to medial/anterior humeral shaft
(Passes deep to Pectoralis major)
Coracobrachialis Function
Flexion, weak adduction and medial rotation of glenohumeral joint
(Does not cross elbow)
Attachments Brachialis
Anterior shaft of humerus to ulnar tuberosity
Fusiform muscle
Function Brachialis
Flexion of elbow joint - synergist of biceps brachii
(Nothing ELSE)
Innervation of anterior arm = motor
All 3 muscles of ant arm Innervated by musculocutaneous nerve c5-c7 from lateral cord, pierces coracobrachialis
After innvervating muscles = becomes entirely cutaneous as lateral cutaneous nerve of forearm (runs between brachialis and biceps brachii then comes out on lateral side as cutaneous nerve )
Sensory innervation anterior arm = name all nerves and general areas
From brachial plexus = mixed spinal nerves and named cutaneous nerves - sensory only
Lateral = axillary c5-6, radial nerve c5-t1
Lateral cutaneous nerve of forearm c5-7
Medial = medial brachial cutaneous and medial antebrachial cutaneous (both from medial cord c8-t1)
Triceps brachii
3 heads fo arm
Name muscles of posterior compartment of arm
Triceps brachii
Anconeus
Triceps brachii Proximal attachment long head
Infraglenoid tubercle of scapula (crosses shoudler joint)
Triceps brachii Proximal attachment lateral and medial heads
Lateral head = posterior shaft of humerus above radial groove (for radial nerve)
medial head = posterior shaft of humerus below radial groove (for radial nerve)
Triceps brachii Distal attachments
As one big single tendon = to olecranon process of ulna
Triceps brachii Functions
Elbow extension = major antagonist of biceps brachii and brachialis
Long head only = adduction (from abducted position) and extension of glenohumeral joint (from flexed position)
Anconeus attachments
Posterior aspect of lateral epicondyle of humerus (dorsal) to olecranon process
Anconeus Functions
Elbow extension weak
Dynamic stabilization
Describe innervation of posterior arm - Motor
All posterior muscles Innervated by single brachial plexus nerve
Radial nerve c5-t1, travels in radial groove on posterior humerus, spirals arounf shaft, to end anterior to lateral epicondyle
= invert and triceps and Anconeus
(Radial nerve and deep brachial artery visible on triangular interval between long head and lateral head triceps)
Sensory innervation posterior arm = name all nerves and general areas
Cutaneous innervation from multiple nerves
Lateral = axiallary nerve c5-6, radial nerve c5-t1, lateral cutaneous nerve of forearm
Medial = medial brachial cutaneous and medial antebrachial cutaneous (both c8-t1)
What blood supplies posterior arm
Deep brachial artery (first branch brachial artery, in radial groove with radial nerve) aka profunda brachii
What blood supplies anterior arm
Brachial artery - medially
Runs with median nerve
Describe brachial artery
Inferior to Teres major axillary artery becomes brachial artery
Terminal branches brachial artery
Radial artery
Ulnar artery
What forms axillary vein
Brachial veins and basilic vein join to form axillary vein
What runs with brachial artery
Paired brachial veins
If see superficial vein = …
It’s basilic vein
Not brachial veins
What is cubital fossa
Triangular space in anterior elbow, apex pointing distally, forming 2nd funnel for passage of n/v structures from arm into forearm
Name the 3 funnels of arm
Axilla - funnel 1
Cubital fossa - funnel 2
Carpal tunnel - funnel 2
Superior border cubital fossa
Imaginary line between humeral epicondyles
Lateral border cubital fossa
Brachioradialis
Floor cubital fossa
Brachialis -deep to biceps brachii
Medial border cubital fossa
Pronator Teres
Roof cubital fossa
Bicipital aponeurosis - protects its contents
Name an describe what contents of cubital fossa
From lateral to medial = tan
Biceps brachii Tendon
Brachial Artery (before splitting), also venae comitantes of brachial artery also run in cubital fossa
Median Nerve
Are the superficial veins = cephalic, basilic and median cubital veins = inside cubital fossa
Nahhhhh
In area of cubital fossa but not part of it
Are above bicipital aponeurosis - roof cubital fossa
