Pectoral Girdle/ Should/Arm/Elbow Flashcards
Describe the bony features shown on the image
What does tenderness at the two bony points on proximal humerus indicate?
What does tenderness inbetween these bony points indicate?
- Shown is the costal surface of the scapula which faces the ribcage
- Contains large concave depresssion = subscapular fossa, subscapularis originates here
- Originating superolaterally is the corcaoid process which is a hook like projection lying underneath the clavicle, palpable below lateral clavicle
- The acromion is the large palpable bony shelf felt above the shoulder
- On the humerus have the greater and lesser tubercles which serve as attachment points for the rotator cuff muscles
- Tenderness at the greater and lesser tubercles indicates potential injury to the rotator cuff muscles
- In between the greater and lesser tubercles is the intertubecular groove, where the biceps tendon sits.
- Tenderness here indicates biceps tendon inflammation
Describe the bony landmarks of the posterior scapula and humerus
- Posterior surface of the scapula faces outwards, it is the site of origin for the majority of the rotator cuff muscles of the shoulder
- Most prominent feature is the spine of the scapula running transversely across
- The acromion is seen laterally, is a projection of the spine that arches over the glenohumeral joint and articulates with the clavicle at the acromioclavicular joint
- above the spine of the scapula is the supraspinous fossa, supraspinatus muscle originates here
- inferiorly is the infraspinous fossa in which infraspinatus muscle originates
- medially is the medial border of the scapula and laterally see the lateral border
- Inferiorly see the inferior angle
What is the triangle of ausculation?
- Triangle of ausculatation of a relative thinning of the musculature on the back
- It lies medially to the medial border of the scapula at the inferior angle (medial border of the scapula forms the lateral boundary)
- inferiorly it is bordered by the superior portion of latissimus dorsi
- superiorly and medially it is bound by the inferior portion of trapezius
What vertebral spinous processes are marked by the:
superior angle
spine
inferior angle
- Superior angle marks the T2 spinous process
- inferior angle marks the T7 spinous process
- the Medial portion of the spine marks the T3 spinous process
What does the medial border of the abducted scapula mark?
- Medial border of the abducted scapula helps mark the oblique fissue of the lungs
What does the clavicle act as in the upper limb?
Clavicle acts as a strut to support the upper limb and transmit forces from the upper limb to the axial skeleton.
Forces move through the humerus, shoulder joint, into the scapula region, with forces passing through the clavicle into the manubrium of the sternum.
It also acts as a guide to keep the scapula away from the axial skeleton which allows the scapula to move freely around the wall of the thorax.
Why is the clavicle at high risk of fracture?
- Clavicle is at high risk of fracture as it acts as a strut that connects the upper limb to the axial skeleton
- Forces are transmitted from the upper limb, into the glenohumeral joint, across into the scapula region and into the clavicle where it articulates with the manubrium of the sternum at the manubrioclavicular joint.
- Clavicle can be fractured by a direct blunt force trauma, or by a fall onto an outstretched hand, transmitting forces to the clavicle.
What the two main joints of the clavicle?
What type of joints are they?
What is the likelihood of dislocation of these joints?
- The acromioclavicular joint --> between the acromion of the scapula and the clavicle, plane synovial joint that permits sliding. AC joint can dislocate and is relatively common
- the sternoclavicular joint --> between the clavicle and the manubrium of the sternum. Functions more like a ball and socket joint. Dislocation of the sternoclavicular joint is rare.
What is the clinical relevance of the sternoclavicular joint?
- Clinical relevance: Sternoclavicular joint:
- When injection or aspiration needs to take place at this site it must be done under ultrasound guidance
- This is due to the proximity of the apex of the lung and the high risk of pneumothorax
- There is also the risk of damaging the internal jugular vein and brachiocephalic vein.
What ligaments support the acromioclavicular joint?
Three main ligamnets that strengthen the acromioclavicular joint:
1) Acromioclavicular ligament runs horizontally from the acromion to the lateral clavicle, covers joint capsule reinforcing it superiorly.
2) Conoid ligament runs vertically from the coracoid process of scapula to the conoid tubercle of the clavicle
3) Trapezoid ligament runs from the coracoid process of the scapula to the trapezoid line of the clavicle.
Collectively conoid and trapezoid = coracoclavicular ligament
Label the image
What is each joint supported by? Name the ligaments.
- Top arrow (Left) –> Acromioclavicular joint (AC joint). Passes from anterior to posterior, dislocation of this joint leads to visibile deformity.
- Next arrow down –> coracoacromial ligament between the coracoid process and the acromium. It supports the shoulder joint superiorly. It can be ruptured by superiorly directed forces. Can impinge the supraspinatus/ subacromial bursa.
- Next arrow along –> coracoclavicular ligaments, formed of the trapzoid and conoid ligaments from coracoid process to clavicle. If the AC joint is dislocated these ligaments can be torn.
- Last arrow –> Sternoclavicular joint, only joint between upper limb and axial skeleton, supported by the costoclavicular ligament running from the 1st costal cartilage to the clavicle.
What can rupture the coracoclavicular ligaments?
- coracoclavicular ligaments run from the coracoid process to the clavicle, formed of trapezoid and conoid.
- They can be ruptured by acromioclavicular joint dislocation.
What is the pathology shown?
- Top image = normal acromioclavicular joint
- acromioclavicular joint = plane synovial joint, ends of the bone are covered in fibrocartilage (not hyaline) which absorbs xrays less than bone hence gap
- Bottom image = dislocated acromioclavicular joint, ends of the clavicle and acromion are not longer aposed.
- Will mean coracoclavicular ligaments are sprained/ torn, once ligaments are damaged at increased risk of damage recurring.
What are the most common sites of clavicular fracture? (in order of frequency)
What is the weakest point of the clavicle?
- in order of frequency the most common sites of clavicular fracture occur middle third > lateral third > medial third
- Weakest point of the clavicle is reported between the middle and lateral thirds.
- Note the fracture shown in image is a multifragmented, comminuted type fracture. (break of bone into two or more fragments).
How might a fractured clavicle present and why?
- Fractured clavicle presents as a distinct step often seen proximal to the individuals neck.
- Separated parts of a fractured clavicle move in opposite directions due to muscle contractions and gravity
- The sternocleidomastoid pulls the proximal fragment superiorly, wherease the weight of the upper limb pulls the distal fragment downwards.
Label the image
What is the clinical relevance of two of the bony landmarks of the humerus?
- Top arrow pointing to the articular head
- Then anatomical neck
- neck surgical neck = most common site for proximal humerus fracture, the axillary nerve is at risk of damage here
- shaft of humerus –> the radial nerve runs down the posterior of the humeral shaft in a spiral groove and is at risk of damage in a shaft fracture, along with profunda brachii artery.
Which nerve is at risk during a fracture of the surgical neck of the humerus?
- The surgical neck runs distal to the greater and lesser tubercles of the humerus to the shaft of the humerus
- The axillary nerve and posterior circumflex artery lie against the surgical neck at are at risk of damage
- surgical neck = frequent site of fracture either due to direct blow or fall on outstretched hand
- axillary nerve damage will result in paralysis to the deltoid and teres minor muscles
- patient will have difficulty performing abduction of affected limb
- axillary nerve also innervates skin over the deltoid, resulting in impaired sensation.
What type of joint is the shoulder joint?
What is it formed between?
what are the ends of the bones covered with?
how does the size of the humeral head compare to the glenoid fossa?
What function does this allow and at what cost?
what structure stabilised the joint?
- shoulder joint = ball and socket joint formed by the head of the humerus and the glenoid cavity/ fossa of the scapula (hence glenohumeral joint).
- Articulating surfaces are covered in hyaline cartilage
- head of humerus much larger than glenoid fossa giving wide range of movement at the cost of inherent stability
- Glenoid fossa is deepened by fibrocartilage rim called glenoid labrum.
What ligaments reinforce the glenohumeral joint?
- The glenohumeral ligaments (superior, middle and inferior) form the joint capsule and connect the humerus to the glenoid fossa. Main source of stability preventing anterior dislocation.
- Coroacohumeral ligament which attaches at coracoid process to greater tubercle of humerus supporting superiorly
- coracoclavicular ligament composed of trapezoid and conoid ligaments runs from clavicle to coracoid process of scapula.
- coracoacromial ligament from coracoid process to acromium, forms coracoacromial arch, prevents superior displacement of humeral head.
Label the image and describe the joint capsule of the glenohumera joint
- Top –> 3 x glenohumeral ligaments, form the joint capsule, support the joint anteriorly, projects from the glenoid to the humerus
- Bottom –> lax lower part of the joint capsule, permits range of movement -> to allow abduction
- Downward force applied at the joint capsule can lead ot dislocated shoulder.
Label the shoulder joint and describe the relevance of these features
- Top –> glenoid fossa = shallow socket that articulates with the head of the humerus, allows wide range of movement
- glenoid labrum surrounds the glenoid fossa, formed of fibrocartilage and deepens the socket to stabilise it. It can tear from overuse injury, producing a snapping sensation or pain on abduction or lateral rotation.
- superiorly the shoulder joint is supported by the coracoacromial arch, formed between the acromion, coracoid process and coracoacromial ligament
- The coracoid process acts as anatomical landmark, can access the shoulder joint via needle 2cm inferiorly to the coracoid process. Angle needle superolaterally.
What structures are present in the shoulder joint that reduce friction of the shoulder joint?
What is the clinical relevance of these structures?
Joint capsule = fibrous sheath that encloses the shoulder joint and extends from the anatomical neck of the humerus to the border of the glenoid fossa. It is lined with synovial membrane which produces synovial fluid to reduce friction between articular surfaces.
Several synovial bursae are present:
- Subacromial bursa –> deep to deltoid and acromion, superficial to supraspinatus tendon and joint capsule. Subarcomial bursa reduces friction beneath deltoid, promotes free motion of rotator cuffs.
- Subacromial bursitis can be cause of shoulder pain
- Subacromial bursa is subject to wear/ impingement and inflammation, especially in people with high level of upper arm activity.
- Subscapular located between subscapularis tendon and scapula.
Where can you inject the subacromial bursa?
- injection into subacromial bursa can take place via acromiodeltoid groove
Label the image and state the function of the superficial muscles shown
Left hand side = superficial muscles
- Top three arrows pointing to Trapezius:
- origin: base of skull, cervical vertebrae C7 and thoracic vertebrae down to T12 vertebra.
- Insertion: scapula, spine and acromium
- Action: upper fibres elevate the scapula, medial fibres retract the scapula, lower fibres depress the scapula
- Innervation: CN IX Accessory nerve
-
Latissimus dorsi:
- origin: from spinous processes of T6-T12, inferior 3 ribs
- Insertion: fibres converge into a tendon that attaches to intertubercular sulcus of humerus
- Action: extends, adducts and medially rotates the upper limb. Can raise the trunk to the arm during climbing.
- Innervation: Thoracodorsal nerve
Label the image and state the function of the deeper muscles
What are they innervated by?
-
Top arrow –> Levator scapulae:
- from the transverse processes of C1- C4 and inserts onto the medial border of the scapula
- Innervated by the dorsal scapular nerve
- elevates the scapula
-
Rhomboid major and minor:
- minor superior to major
- from spinous processes to medial border of the scapula, scapula spine and the inferior angle.
- innervated by the dorsal scapular nerve
- retract and rotate the scapula.
-
Teres major:
- adduction and medial rotation of the humerus
- innervated by the lower scapula nerve
Describe the muscles of the pectoral region:
What are their origins/ insertions/ actions/ innervations? :
Largest and most superificial muscle
-
Pectoralis major:
- most superfical large and fan shaped, composed of sternal head and clavicular head
- clavicular head from anterior clavicle
- sternocostal head from anterior sternum and superior 6 costal cartilages
- inserts onto the intertubercular sulcus of the humerus
- adducts and medially rotates the upper limb
- innervation: Medial and lateral pectoral nerves
Describe the muscles of the pectoral region:
What are their origins/ insertions/ actions/ innervations? :
muscle directly beneath pectoralis major
-
Pectoralis minor:
- lies directly underneath the pectoralis major
- originates from ribs 3-5 inserts onto the coracoid process of the scapula
- stabilises the scapula drawing it anteroinferiorly against thoracic wall (depresses and protracts scapula).
- also divides the axillary artery into 3 parts
- innervation: medial pectoral nerve
Describe the muscles of the pectoral region:
What are their origins/ insertions/ actions/ innervations? :
muscle that lies underneath pectoralis minor, forms the medial border of the axilla region
- serratus anterior forms the medial border of the axilla region and lies under pectoralis minor
- consists of several strips originating from ribs 1-8 inserting onto costal surface of the medial border of the scapula
- action: rotates the scapula, allowing the arm to raise over 90 degrees, holds scapula against ribcage, protracts it.
- innervation is the long thoracic nerve
What is clinically relevant about the innervation to serratus anterior muscle?
How can the function of the serratus anterior muscle be tested clinically?
- serratus anterior is innervated by the long thoracic nerve.
- Normally muscles are innervated deep, the long thoracic nerve runs superficially over the serratus anterior and is ar risk of damage during axillary or breast surgery with node clearance.
- Clinical test for serratus anterior:
- from ribs 1-8 and inserts onto medial border of scapula, holds scapula against ribcage and prevent winging of the scapula
- test clinically by asking patient to put their hands against a wall and lean into the wall, if the scapula lifts suggests weakness in serratus anterior.
What is the main muscle that forms the bulk of the shoulder?
what is its orgin/ insertion/ action/ innervation?
How can it be tested clinically?
- main muscle forming the bulk of the shoulder is the Deltoid muscle.
- Originates: from lateral clavicle, scapula spine, acromion
- Inserts: onto the deltoid tuberosity on the lateral humerus
- Innervation: Axillary nerve
-
Actions: All movements of the shoulder except adduction:
- anterior fibres flexion and medial rotation
- posterior fibres - extension and lateral rotation
- middle fibres major abduction of the arm
- Tested clinically by getting patient to abduct and raise arm at shoulder against resistance.
Where can the axillary nerve be found?
What can damage it?
How will the patient present?
- Axillary nerve found 5cm below the acromium, passes around the surgical neck of the humerus
- supplies the deltoid muscle and if damaged the patient will have a limited range of shoulder movement
- damage to the axillary nerve can be caused by:
- fracture of the surgical neck of the humerus
- damage caused by IM injection
- shoulder dislocation
Which direction is the most likely direction of shoulder dislocation?
What can it result in?
What nerve is at risk?
What would that damage cause?
- Shoulder dislocations occur most often anteriorly and result in a loss of normal contour
- the axillary nerve is at risk of damage
- damage can cause paralysis and wasting of the deltoid and teres minor muscles
- the upper limb to hand limp by the side
- loss of shoulder contour
- sensory loss of lateral shoulder (regimental badge region).
Describe the rotator cuff muscles
Their origins, insertions, actions and innervations
- 3 rotator cuffs posteriorly:
-
supraspinatus:
- Originates in the supraspinous fossa superior to the scapular spine, inserts onto the greater tubercle of the humerus
- assists with initial part of arm abduction to around 20 degrees, and assists deltoid with abduction 20-90 degrees
- innervated by the suprascapular nerve
-
Infraspinatus:
- in the infraspinous fossa inferior to the spine of the scapula, inserts into the greater tubercle of the humerus
- lateral shoulder rotation
- innervated by suprascapular nerve
-
Teres minor:
- originates from the posterior scapula attaches to the greater tubercle of the humerus
- innervated by the axillary nerve
- laterally rotates the arm
-
supraspinatus:
- Anteriorly:
-
Subscapularis:
- originates from the subscapular fossa on the costal surface of the scapula
- attaches to the lesser tubercle of the humerus
- innervation via upper and low subscapular nerves
- medially rotates the arm.
-
Subscapularis:
What fills the axilla and what are the boundaries?
- The axilla is a fat filled region located superior to the armpit skin.
- Bordered anteriorly by the axillary fold and pectoral muscles
- bordered posteriorly by the posterior axillary fold, subscapularis and the scapula
- its medial border is formed by serratus anterior and lateral thoracic wall
- laterally it is bordered by the intertubercular groove
What are the main lymph nodes of the axilla?
- 5 main lymph nodes named according to their position
- Humeral lymph node within the humeral portion
- subscapular and pectoral lymph nodes
- humeral, subscapular and pectoral all drain into a central axillary lymph node
- this central lymph node then drains into an apical lymph node
- this apical lymph node drains into the supraclavicular lymph node
- Lymph from the upper limb, pectoral region and breast tissue all drain to the axillary lymph nodes, lymphadenopathy can be a non specific sign of breast cancer.
- Note in the picture below the base of the breast has an axillary tail that passes along the anterior axillary fold
What are the muscles in the anterior compartment of the arm?
what are their origins/ insertions/ innervations/ blood supply/ actions
plus any roots tested by reflexes
- three main muscles: biceps brachii, brachialis and coracobrachialis, all innervated by the musculocutaneous nerve, all supplies by brachial artery. (BBC - biceps, brachoradialis, coracobrachialis).
-
Biceps brachii:
- long head originates from the supraglenoid tubercle of the scapula, short head originates from coracoid process
- both heads insert onto radial tuberosity, and into the bicipital aponeurosis
- Flexes and supinates the forearm at the elbow, flexes shoulder
- bicipital aponeurosis is a connective tissue sheet connecting biceps brachi to deep fascia of forearm
- biceps tendon reflex tests C5/C6
-
Coracobrachialis:
- lies deep to the biceps brachii
- originates from coracoid process and passes through axilla attaching to medial side of humerus
- flexes arm at shoulder and weak adduction
-
Brachialis:
- lies deep to biceps more distally
- forms floor of cubital fossa
- originates from humeral shaft, inserts onto ulna tuberosity distal to elbow joint
- flexion of elbow
- innervated by musculocutaneous and some radial nerve
label image
What can happen to the biceps brachii tendon?
- Long head of biceps brachii is a more common tendon to rupture
- It produces flexing of the elbow and a bulge of the muscle belly called the “Popeye sign”.
- common in patients with ageing and long term steroid treatment that weakens bone and soft tissue
What are the muscles in the posterior compartment of the arm?
- Triceps brachii:
- long head is from the infraglenoid tubercle of the scapula, lateral head from the humerus superior to radial gtoove and the medial head originates from the humerus inferiorly to the radial groove
- distally inserts onto the olecranon of the ulna
- extends arm at elbow
- innervated by radial nerve
- triceps tendon reflex tests C7/8
What are two spaces formed in the posterior arm compartment?
- quadrangular space under teres major, medial to long head of triceps and medial to humerus:
- axillary nerve and posterior circumflex artery travels through here and around surgical neck of humerus
- Triangular interval and spiral groove: between long and lateral heads to tricps and humerus.
- radial nerve and profunda artery travel through this space and groove
Describe the superficial venous drainage of the upper limb
- superficial drainage via the cephalic (lateral) and basilic (more medial) veins
- basilic vein originates in the dorsum of the hand, travels medially and at the border of teres major dives deep to combine with the brachial vein to form the axillary vein
- The cephalic vein also arises in dorsum of the hand, ascends laterally, at the shoulder travels between deltoid and pectoralis major to enter axilla. In axilla vein empties into axillary vein.
Describe deep venous drainage of upper limb
- sits underneath deep fascia, formed by paired veins that sit either side of an artery, and share name of the artery they accompany
- Brachial veins sat either side of brachial artery, pulsations of brachial artery assist venous return
- Brachial veins becomes axillary veins, becomes the subclavian vein
Describe the arterial supply to the arm
Begins at the subclavian artery –> becomes axillary –> becomes brachial –> splits into radial and ulnar arteries in cubital fossa
Axiallary artery runs from 1st rib to teres major
Brachial artery gives off profunda brachii which travels with the radial nerve in the radial groove of the humerus and supplies the triceps and elbow joint.
Note there are rich anastomoses that surround the scapula and join the subclavian and axillary arteries –> this can be exploited surgically as parts of the axillary artery can be clamped or removed without compromising blood supply to the upper limb.
