Lecture 2: The Pectoral Girdle and Shoulder Flashcards
what are the 4 anatomical regions of the upper limb?
Shoulder (pectoral)
Arm
Forearm
Hand
What are the 3 large joints in the upper limb?
shoulder, elbow, wrist
Where are the 3 neurovascular regions (spaces)?
Axilla (armpit)
Cubital fossa (anterior to the elbow)
Carpal tunnel (anterior wrist / hand)
Which is the most commonly dislocated joint in the body?
Shoulder joint.
what bones make up the pectoral girdle?
the clavicle ( = collar bone)
the scapula ( = shoulder blade)
Where does the pectoral girdle connect to?
Connects your upper limb to your thorax (or axial skeleton)
the clavicle is attached to your sternum (the sternoclavicular joint)
the scapula is anchored to the posterior chest wall by muscles and soft tissues
What is the glenoid fossa (Glenohumeral joint) ?
The proximal part of the humerus (the ‘head’) articulates with a socket on the scapula called the glenoid fossa = glenohumeral joint
What is the articulation of the shoulder joint?
Ball and socket joint, but the glenoid cavity is shallow
What is the shoulder joint referred to as in terms of fit?
Incongruent = poor fit
- thin and loose capsule
- Compromised stability
What does better stability mean for movement?
Better stability = decreased range of movement
Does the shoulder have good movement?
Yes
What features of the shoulder increase stability of the joint?
: the surrounding muscles, the tendon of biceps brachii, and the glenoid labrum (a rim of cartilage around the edge of the glenoid which deepens the glenoid fossa)
What is protraction of the scapula?
Protraction (forwards) – putting your arm out in front of you (e.g. pushing open a door)
What is retraction of the scapula?
Retraction (backwards) – ‘squaring the shoulders’
What is elevation of the scapula?
Elevation (shrugging your shoulders) and depression
What is rotation of the scapula?
Rotation – this moves the scapula so that the inferior angle is pointed either more medially or more laterally
What is the role of pectoralis major?
Pectoralis major adducts and medially rotates the shoulder
What is the role of pectoralis minor?
Pectoralis minor stabilises the scapula and assists in protraction
Where does the serratus anterior originate?
Ribs 1 - 8
What are the functions of the posterior pectoral girdle muscles?
Connect the axial skeleton to the bones of the pectoral girdle
Move the pectoral girdle (usually in combination with movement at the shoulder)
Are Trapezius and latissimus dorsi deep or superficial?
Trapezius and latissimus dorsi are superficial;
Are levator scapulae and the rhomboids deep or superficial?
levator scapulae and the rhomboids are deep
What is the lat dorsi?
originates from the axial skeleton and inserts directly onto the humerus (adducts, medially rotates, and extends the shoulder)
What is the basic function of deltoid and teres major?
Connect the humerus to the pectoral girdle > move the shoulder
Where is the deltoid located?
Connect the humerus to the pectoral girdle > move the shoulder
What innervates the deltoid?
Innervation: axillary n.
What movement in the deltoid involved in?
Abductor of the shoulder joint, extending and flexing
Where is the teres major located?
from the posterior scapula > inserts on the anterior humerus.
What movement is the teres major involved in?
Medially rotates and adducts the shoulder
Where does the rotator cuff originate from?
Originate from the scapula > insert on the humerus
What starts abduction?
Supraspinatus starts abduction (first ~15o )
Which muscles laterally rotate the shoulder?
Infraspinatus and teres minor laterally rotate the shoulder
What muscles medially rotates the shoulder?
Subscapularis adducts and medially rotates the shoulder
How are the rotator cuff muscles commonly injured?
tendons can be torn or become inflamed. Problems can be acute or chronic
Injury / disease > impaired movement, instability, pain
What are the major nerves and vessels of the pectoral region and shoulder?
Subclavian artery and vein
Enter axilla > axillary artery and vein
Give rise to the anterior and posterior circumflex humeral arteries > shoulder joint
The cephalic vein is a major superficial vein that drains into the axillary vein
Terminal branches of the brachial plexus
One of these, the axillary nerve, runs posteriorly, close to the surgical neck of the humerus > supplies deltoid and teres minor
Pathology of bones and joints:
can be fractured or dislocated, or less commonly, become infected (osteomyelitis). Joint surfaces can be come worn (osteoarthritis) – this is very common
Pathology of muscles and tendons
can be torn, become inflamed (tendonitis) or trapped (this is called impingement)
Pathology of the nerves:
can be injured in various ways (cut, torn, stretched, compressed, avulsed) or they may become inflamed (neuritis)
what is the most common muscle and joint injury in the shoulder?
The most common problem is the supraspinatus tendon getting trapped (impinged) between the humeral head and the acromion and becoming inflamed
What is winged scapula?
can be caused by injury to the long thoracic nerve, which innervates serratus anterior
The nerve is vulnerable during surgery in the axilla, to penetrating chest wounds, during chest drain insertion, or can become inflamed (neuritis)
What would a paralysed serratus anterior mean for the body?
A paralysed serratus anterior cannot hold the scapula onto the posterior chest wall > the medial border ‘lifts off’
This patient would also have difficulty protracting the scapula
What is the brachial plexus?
the nerve network that innervates the upper limb
Where is the brachial plexus located?
Located in the neck and axilla (armpit)
The nerve comes from the spinal chord
What does the brachial plexus give rise to?
Gives rise to 5 major branches that provide the motor and sensory innervation of the upper limb
Where is the axilla neurovascular bundle found?
in the armpit
Where is the cubital fossa neurovascular region found?
anterior to the elbow
Where is the carpal tunnel neurovascular region found?
anterior to the write/ hand
Where is the carpal tunnel neurovascular region found?
anterior to the write/ hand
What connection does the pectoral girdle provide?
it connects your upper limb to the thorax/ axial skeleton
What is the axial skeleton?
skull, vertebral column, rib cage
What is the joint called where the clavicle attaches to the sternum?
sternoclavicular joint
What structures anchor the scapular to the posterior chest wall?
muscles and soft tissues
What is the name of the joint where the clavicle attaches to the scapula?
acromioclavicular joint
What is the name of the joint where the head of the humerus articulates with the scapula?
glenohumoral joint
Where on the scapula does the head of the humorous articulate?
glenoid fossa
What is the name of the superior most point on the scapula body?
superior angle
What is the name of the most inferior point on the scapula body?
inferior angle
What is the name of the posterior structure that forms the head of the spine of the scapula?
acromion
What is the name of the bony landmark anterior to the acromion of the scapula?
coracoid process
What is the name of the large ridge round extending on from the acromion on the posterior surface of the scapula?
spine of the scapula
Is the spine of the scapula found on the anterior or posterior side?
posterior
What is the name of the indent on the anterior surface of the scapula?
subscapular fossa
What is the name of the indent found above the spine on the posterior side of the scapula?
supraspinous fossa
What is the name of the indent found below the spine on the posterior side of the scapula?
infraspinous fossa
What is the glenoid fossa and head of humerus covered in?
cartilage
What is the name of the smooth, uppermost region of the humerus that articulates with the glenoid fossa?
head of the humerus
What is the name of the bony landmark found on the lateral side of the upper humerus?
greater tubercle
What is the name of the bony landmark found on the anterior side of the upper humerus?
lesser tubercle
What is the name of the ridge that marks where cartilage ends on the head of the humerus?
anatomical neck
What is the name of the imaginary line found below the tubercles of the humerus that is a common site of fractures?
surgical neck
What type of joint is the glenohumeral joint?
ball and socket
Describe the incongruence in the glenohumeral joint:
the glenoid fossa socket is shallow, meaning the joint surfaces are a poor fit
Give two structures that increase the stability of the glenohumeral joint and prevent the humorous dropping out:
1) glenoid labrum
2) long tendon of biceps brachii
What is the glenoid labrum?
an extra lip of cartilage around the edge of the glenoid fossa which deepens it
Where does the long tendon of biceps bracii run to and from?
it runs through the intertubercular sulcus of the humerus and wraps along the top of the glenohumeral joint, coursing across the glenoid labrum
Give the four main movements of the scapula:
1) protraction
2) retraction
3) elevation and depression
4) rotation
Give the three major muscles of the anterior pectoral girdle:
1) pectoralis major
2) pectoralis minor
3) serratus anterior
What are the two parts of the pectoralis major?
1) sternal
2) clavicular
Where does the pectoralis major insert onto the humurus?
intertubercular sulcus 1
What movement does the pectoralis major allow for the shoulder? (2)
1) adduction
2) medial rotation
Where does pectoralis minor originate?
ribs 3-5
Where does the pectoralis major insert?
intertubercular groove of humerus and coracoid process
Where does the serratus anterior originate?
anterior surface of ribs 1-8
Where does the serratus anterior originate?
anterior surface of ribs 1-8
What nerve innervates serratus anterior?
long thoracic nerve (courses down the lateral surface of the nerve)
