Shoulder and arms Flashcards
What is the glenoid cavity?
The socket for the shoulder joint on the scapula
What is the costal surface of the scapula?
The front of the scapula - pressed against the posterior chest wall
What does the spine of the scapula divide the scapula into?
The supraspinous and infraspinous fossae
What is the name of the tubercle of the scapula?
deltoid tubercle of scapula
What is the name of the bony process on the end of the scapula?
acromion
What is the coracoid process?
the hook like structure of the scapula
What are the 2 articulations of the clavicle?
acromial end
sternal end
What does the acromial end of the clavicle articulate with?
the acromial end of the scapula
What causes the impressions on the posterior surface of the clavicle?
muscle attachments
What are the three main bones of the shoulder?
clavicle, humerus and scapula
What are the 2 necks of the humerus?
Anatomical - real head
Surgical - most commonly damaged
What is the deltoid tuberosity of the humerus?
It is a bump halfway down the humerus where the deltoid muscle attaches
What are the main parts of the humerus?
head, shaft, distal region with articulating surfaces (trochloea and capitulum)
What are the compartments of the shoulder and arm?
Anterior pectoral girdle muscles
Posterior pectoral girdle muscles
Intrinsic shoulder muscles
Anterior compartment of the upper arm
Posterior compartment of the upper arm
What does proximal attachment (of a muscle ) mean?
closer to the trunk
What is the arm (anatomically not when talking to patients)?
Between the elbow and shoulder
What are the anterior pectroral girdle muscles?
- pec major
- pec minor
- sublcavius
- serratus anterior
What are the proximal and distal attachments of pectoralis major?
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proximal - on the medial third of the clavicle, sternum and costal cartilages (hence two heads; sternal, clavicular and also has an abdominal part)
distal - lateral lip of the intertubercular sulcus (groove in humerus)
What does the pectoralis major do?
Adducts and medially rotates the humerus (punching muscle), little extension
Less effects on the scapula
What are the attachments of pectoralis minor?
Originates at the caracoid process of the scapula and
attaches to ribs 2,3,4,5
What is the role of pectoralis minor?
Moves scapula forward and down maintaining the mobility of the shoulder joint
What are the attachments of the subclavius?
Attaches from the first rib the the under surface of the clavicle
What does the subclavius do?
Stabilises the clavicle and SCJ
What are the attachments of serratus anterior?
Attaches up to 9 ribs and comes posteriorly from the medial edge of the scapula. The muscle runs around the side of the chest and divides into finger like parts
What is the role of serratus anterior?
Holds and stabilises the scapula, protraction at STJ and elevate the glenoid fossa
What are the posterior pectoral girdle muscles?
trapezius, latissimus dorsi, levator scapulae and rhomboids
What are the attachments of the trapezius?
A triangular muscle that attaches to the base of the skull (supeior nuchal line) and at all of cervical and thoracic vertebrae. Has an attachment from the spine of the scapula. It goes anteriorly onto the lateral/posterior third of the clavicle, acromion and scapular spine
What nerve innervates the trapezius?
spinal accessory nerve
What is the role of the trapezius muscle?
Acts on the scapula - different fibres of muscle contract to have different effects
What are the proximal and distal attachments of the latissimus dorsi?
Big triangular muscle that attaches from T8 to connective tissue in posterior pelvic region. Fibres from the distal attachment form a trap which attaches to the floor of the intertubercular groove.
What are the roles of latissimus dorsi?
- Extends, adducts and rotates the humerus
- Pulls the body up to the arms during climbing and also important in rowing
- In 4 legged animal important in running
What is the nerve supplying the latissimus dorsi?
Thoracodorsal nerve
What are the attachments of the rhomboids?
2 muscles (major and minor)
- Minor is one strap
- They attach to the medial border of the scapula and spinous process at lower end of neck and upper part of thorax
What nerve supplies the rhomboids?
The dorsal scapular nerve
What are the roles of the rhomboid?
Retracts the scapula and stabilises it
What are the attachments of levator scapulae?
Comes from the transverse processes of C1-4 and attaches to superior angle of the scapula (top corner)
Which nerve innervates levator scapulae?
Dorsal scapula nerve and C3/4
What are the roles of levator scapulae?
It is involved in retracting and elevating and rotating the scapula (e.g. shrugging your shoulders upwards).
What are the different parts of the trazpezius?
superior (descending), middle and inferior (ascending)
What are the intrinsic shoulder muscles?
deltoid, teres major and rotator cuff muscles
What are the attachments of the deltoid muscle?
- Posteriorly attaches to the scapular spine, and also the acromial region and the clavicle
- The deltoid therefore has a clavicular part, a middle part and a posterior, spinous part
- The fibres coming from these converge onto the deltoid tuberosity
What is the nerve supplying the deltoid?
Axillary nerve
What is the role of the deltoid muscle?
- Adduction of arm
What is included in the rotator cuff muscles?
supraspinatus, infraspinatus, teres minor and subscapularis
What are the attachments of the rotator cuff muscles?
They come off at the scapula in different places and cross the shoulder joint to attach around the head of the scapula. Muscles on posterior and anterior surface of scapula.
What are the roles of the rotator cuff muscles?
- Involved in holding the head of humerus into the socket -as socket is shallow so lots of muscle needed to stabilise joint
- They fix the head of the humerus into glenoid fossa.
- Supraspinatus is involved in abduction of arm for first 15 degrees
What are the attachments of teres major?
- Comes off the inferior angle of the scapula
- It passes laterally and inserts (along with latissimus dorsi) into the floor and medial lip of intertubercular sulcus of humerus
Which nerve innervates teres major?
lower subscapular nerve
What does teres mean?
straight
What does teres major do?
Medial rotator and adductor of the humerus
It also helps stabilise the humeral head in the glenoid cavity
What is included in the anterior compartment of the arm?
biceps, brachialis and corabrachialis
What is the biceps and what are the attachments?
- Two-headed muscle of the arm
short head from the coracoid prcoess and long head from the supraglenoid tubercle to the tuberosity on the radius
Which nerve supplies the anterior compartment of the arm?
musculocutaneous nerve
What are the attachments of the brachialis?
It has an attachment at the middle and distal parts of the humeral shaft. It attaches to the coronoid process of the ulna.
What is the role of the brachialis muscle?
Major contributor to flexion of the elbow joint
What are the attachments of the coracobrachialis muclse?
Comes from the carcoid process and attaches to shaft of humerus
What is the role of the coracobrachialis muscle?
Involved in flexion of the shoulder join
What is included in the posterior compartment of the arm?
triceps and anconeus
Which nerve supplies the posterior compartment of the arm?
radial nerve
What is the structure of the triceps?
Triceps have a long head, a lateral head and a medial head
What are the attachments of the triceps?
The long head covers the other heads (it crosses the shoulder group, towards the infraglenoid tubercle). The other proximal attachments are posterior to the shaft of the humerus. These heads converge to form the triceps tendon, which crosses over the elbow joint and attaches to the olecranon process of the ulna.
What are the attachments of the anconeus muscle?
Anconeus is a small muscle that attaches from the lateral epicondyle of the humerus, to the upper part of the posterior of the ulna bone
List the joints of the shoulder and arm
- sternoclavicular
- acromioclavicular
- gleno-humeral
- scapulothoracic (virtual)
- elbow
What kind of joint is the sternoclavicular joint?
pivot joint
What kind of joint is the gleno-humeral joint?
synovial
What is the rim of cartilage that deepens the glenoid fossa?
glenoid labrum/lip
What are the names of the ligaments associated with the clavicle and scapula?
capsular ligaments
What does the intertubercular groove refer to?
The space between the two tubercles of the heads of the humerus
What is the subacromial bursa?
synovial cavity located just below the acromion - bursas are found at joints with lots of movement to cushion them (can become inflamed and painful)
What is the main function of the rotator cuff muscles?
To hold the humeral head in the glenoid
Where are the supraspinatus and infraspinatus muscles?
supra - in the supraspinous fossa
infra - infraspinous fossa
Where does the teres minor come off from?
the inferior part of the scapula
Where does the subscapularis come off?
deep surface of scapula
What are the different movements of the scapulothoracic joint?
- Elevation/Depression of the scapula
- Protraction/Retraction of the scapula
- Rotation of the scapula
What is found in the axilla?
- pyramid shaped
- arteries (axilla and branches)
- veins (axillary and tributaries)
- lymphatic vessels and nodes
- nerves (brachial plexus)
What are the arteries of the shoulder and arm?
- subclavian artery
- axillary artery
- brachial artery
- ulnar and radial arteries
Describe venous drainage in the limbs
superficial and deep (deep mirrors the arterial supply, often venae comitantes)
What are the superficial veins in the arm?
- Cephalic vein runs up lateral border of arm
- Basilic vein runs up the medial border of arm
- The cephalic and basilic veins are often joined by a median cubital vein
How do the superficial veins in the arm drain into the subclavian vein?
- Basilic veins joins the venae comitantes (a bit deeper) to form the axillary vein in the arm
- Cephalic vein continues up the arm into the delto-pectoral groove and joins the axillary vein in the axilla
- Axillary vein becomes the subclavian vein at the level of the first rib
Describe the venous drainage of the arm into the subclavian vein
- Axillary vein (deep v) is formed as basilic vein passes through the deep fascia to join the brachial veins at the level of the lower border of teres major
- The axillary vein receives a large number of tributaries, including the cephalic vein and the lateral thoracic vein.
- The axillary vein becomes the subclavian vein at the level of the 1st rib
What are some lymph nodes of the shoulder and arm?
- Superficial and deep systems, run with veins
- Cubital lymph nodes
- Delto-pectoral lymph nodes
- Axillary lymph nodes – particularly important in breast cancer
- Subclavian lymph trunk
Where does the brachial plexus pass under?
clavicle
Describe the brachial plexus and what the terminal branches are
- The nerves mix and swap and branch off
- Some branches come off early and some later
- The terminal branches include the radial nerve, ulna nerve, median nerve, axillary nerve and musculocutaneous nerve
What are some nerves that are more prone to damage?
Funny bone
When you bang the funny bone, you are banging the ulna nerve (where it’s quite superficial) wrapping around the medial epicondyle of the humerus.
Axillary nerve
Similarly, the axillary nerve is just below the shoulder joint. This can be damaged in shoulder dislocation.
Radial nerve
The radial nerve wraps very closely is opposed to the shaft of the humerus. If this is broken, we may see radial nerve damage.
Explain the aterial supply of the arm from the subclavian artery
Subclavian artery -> in axilla become axillary artery (divides into 3 parts in relation to pex minor: superior, deep and inferior) -> in upper arm becomes brachial artery (major branch is profunda brachii artery coming off) -> at elbow divides into ulnar and radial artery -> main branch of ulnar artery is the common interosseous artery -> anterior and posterior branch -> ulnar and radial anastamose in the end at superficial and deep palmar arch to give off metacarpal and digital arteries to fingers
- extensive anastomosis at the elbow
- extensive collateral circulation around scapula
- extensive anastomosis in the axilla
What are some ligaments of the acromio-clacivular joint?
Acromio-clavicular ligament
Coraco-clavicular ligament: runs from the coracoid process of the scapula to the clavicle. There are two main sections to this ligament, the conoid and the trapezoid ligaments.
Coraco-acromial ligament: this is not particularly strong, but it is clinically important in that it is often a cause of impingement of the gleno-humeral joint.
How is the ACJ often injured?
fall onto outstretched hands
What are the extensions of the shoulder joint capsule? (ligaments encapsulating the joint)
- from glenoid to humerus
- subacromial bursa (capsule extends above humeral head to form bursa between the humeral head and acromial process)
- extends around long head of biceps
What is the coraco-acromial arch?
- It consists of the acromion, the coracoid process and a strong ligament running between the two
- This ligament is the coraco-acromial ligament
- Arch prevents the humerus rising above acromion
What are some ligaments blending in with the capsule of the gleno-humeral joint?
- Gleno-humeral
- Coraco-humeral
- Transverse-humeral
Which muscle cause which movements at the gleno-humeral joint?
Flexion – clavicular head of pectoralis major, anterior fibres of deltoid, coracobrachialis, biceps
Extension – latissimus dorsi
Abduction – supraspinatus (first 15 degrees), central fibres of deltoid (after 15 degrees)
Adduction – pectoralis major, latissimus dorsi
Internal rotation – subscapularis
External rotation – infraspinatus, teres minor
Circumduction – i.e. a combination of movements
Which muscles resist dislocation at the gleno-humeral joint?
- Rotator cuff muscles – hold the humeral head against the glenoid cavity
- Deltoid
- Coracobrachialis
- Short head of biceps
- Long head of bicep
What are the main movements of the scapula at scapulo-thoracic joint?
- Elevation and depression of the scapula
- Protraction of the scapula i.e. forward and lateral movement of the scapula against the chest wall
- Retraction of the scapula i.e. backward and medial movement of the scapula against the chest wall
- Rotation of the scapula
What forms the borders of the axilla?
- The base is composed of skin, subcutaneous tissue and fascia extending from the arm to the chest
- The apex lies between the first rib, the clavicle and the superior border of the subscapularis muscle
- The anterior wall is formed by pectoralis major and pectoralis minor
- The posterior wall is formed by the scapula and subscapularis (superiorly) and the teres major and latissimus dorsi (inferiorly)
- The medial wall is formed by the chest wall (1st to 4th ribs) and the serratus anterior
- The lateral wall is formed by the intertubercular groove of the humerus
What are the 5 axillary lymph nodes?
Apical, pectoral, subscapular, humeral and central - all drain to apical which goes into subclavian lymphatic duct into the right/left duct
Describe the lymphatic drainage of the arm
- Lymph drains from the hand via superficial lymphatics, which run alongside the cephalic and basilic veins
- Some lymphatics pass directly and superficially up the arm
- But there are also some cubital lymph nodes at the elbow
- Similarly there are some delto-pectoral lymph nodes alongside the cephalic vein
- Ultimately lymph from the superficial system drains to the axillary lymph nodes
Which nerves are at risk of damage during axillary node dissections?
long thoracic and thoracodorsal
Why is the clavicle unusual?
It is the first long bone to ossify (5th week of intra uterine life) in humans. It does so by intramembranous ossification rather than endochondral ossification that is common to most long bones.
Which nerves can be damaged during fractures or dislocations of the humerus?
- axillary
- radial
- ulnar
- median
Where can the subclavian artery pulse be found?
The subclavian artery pulse is just above and behind the medial end of the clavicle
Superior/inferior angle and medial end of the scapula are at which vertebral levels?
superior- T2
medial - T3
inferior - T7
Delto-pectoral groove landmarks
Is a triangle bounded by the clavicle superiorly, the deltoid laterally and the pectoralis major medially
What is a prime mover or agonist?
Main muscle responsible for a specific movement
How can the sternocleidomastoid be tested and which nerves are responsible?
turn the head against resistance
spinal accessory nerve, C3, C4
How can the trapezius be tested and which nerves are responsible?
raise both shoulders against resistance
spinal accessory nerve, C3, C4
How can pec major be tested and which nerves are responsible?
adduct the abducted arm against resistance
lateral and medial pectoral C5-8, T1
How can serratus anterior be tested and which nerves are responsible?
both arms of subject are outstretched with palms against wall, and asked to press forward strongly
long thoracic nerve, C5, C6
How can teres major be tested and which nerves are responsible?
adduct arm against resistance
lower subscapular nerve, C5, C6
How can latissimus dorsi be tested and which nerves are responsible?
abduct arm to 90 degrees, then adduct against resistance
thoracodorsal nerve, C6-8
How can the deltoid be tested and which nerves are responsible?
abduct the upper arm against resistance
axillary nerve, C5, C6
What is circumduction
combination of flexion/extension and abduction/adduction so that the distal part of the upper limb moves in a circle
What is opposition?
OPPOSITION: Bringing the pad of the thumb towards the pad of another digit.
What is protraction and retraction?
PROTRACTION: an anterior movement of a body part.
RETRACTION: a posterior movement of a body part.
What is pronation and supination?
PRONATION: rotation of the forearm along its long axis so that the palm faces posteriorly.
SUPINATION: rotation of the forearm along its long axis so that the palm faces anteriorly.
Which muscles cause elevation, depression, protraction, retraction, rotation of the scapulo-thoracic joint?
Elevation: Superior trapezius, levator scapulae, rhomboids
Depression: Inferior trapezius, pectoralis minor, serratus anterior
Protraction: Pectoralis minor, serratus anterior
Retraction: Rhomboids, middle trapezius, latissimus dorsi
Rotation: Glenoid fossa faces upwards or downwards as scapula rotates
Rotation-up: Superior trapezius, inferior trapezius, serratus anterior
Rotation down: Pectoralis minor, latissimus dorsi, rhomboids and levator scapulae
What is the scapulo-thoracic joint?
Convex surface of the posterior thoracic cage and the concave surface of the anterior scapula (at the back)
What causes flexion and extension of the elbow joint?
Flexion:s Biceps, brachialis, brachioradialis (pronator teres)
Extension: Triceps (anconeus
