The Shoulder and Arm Flashcards
where does the clavicle extend?
between the manubrium of the sternum and the acromion of the scapula
what are the 3 main functions of the clavicle?
1) attaches upper limb to trunk
2) protects underlying neurovascular structures supplying the upper limb
3) transmits force from upper limb to axial skeleton
what shape is the clavicle?
s shape
how many parts can the clavicle be divided into and what are they?
3 - sternal (medial) end, shaft, acromial end
describe the sternal end of the clavicle
contains large facet for articulation with manubrium of sternum at STERNOCLAVICULAR joint
describe the shaft of the clavicle
acts as a point of origin for several muscles eg deltoid, trapezius, subclavius, pectoralis major
describe the acromial (lateral) end of the clavicle
- small facet for articulation with acromion of scapula at acromioclavicular joint
- serves as an attachment point for 2 ligaments
what is the function of the scapula?
connects the upper limb to the trunk via glenohumoral joint and acromioclavicular joint.
site of attachment for 17 muscles
how many surfaces of the scapula are there and what are their names?
3 - costal (anterior), lateral, posterior
what does the costal surface face?
ribcage
what does the costal surface contain?
the subscapular fossa = large concave depression
what originates from the superolateral surface of the costal surface of the scapula and what is it?
the coracoid process - a hook like projection which lies just underneath the clavicle.
what does the lateral surface of the scapula face?
humerus
describe the lateral surface of the scapula
- site of the glenohumoral joint
- contains 3 important body landmarks = glenoid fossa, supraglenoid tubercle, and the infraglenoid tubercle
what is the glenoid fossa?
- shallow cavity
- located superiorly
- forms glenohumoral joint
what is the supraglenoid tubercle of the scapula?
a roughening immediately superior to the glenoid fossa
what is the infraglenoid tubercle?
a roughening immediately inferior to the glenoid fossa
what does the posterior surface of the scapula face and what is it a site of origin for?
outwards.
most of the rotator cuff muscles of the shoulder originate here
what can the muscles of the shoulder be split into?
2 groups - intrinsic and extrinsic
describe the extrinsic muscles of the shoulder
originate from the torso, and attach to bones of the shoulder
describe the intrinsic muscles of the shoulder
originate from the scapula, and / or clavicle, and attach to the humerus
how many groups can the extrinsic muscles be split into?
2 - superficial and deep
what are the 2 superficial extrinsic muscles
the trapezius and latissimus dorsi
describe the trapezius
long, flat triangulr muscle
what are the actions of the fibres in the trapezius?
- upper fibres = elevate scapula
- middle fibres = retract the scapula
- lower fibres = pull scapula inferiorly
how is the trapezius innervated?
accessory nerve
describe the latissimus dorsi
originates from lower part of the back
what are the actions of the latissimus dorsi?
extend, abduct, and medially rotate the upper limb
how is the latissimus dorsi innervated?
the thoracodorsal nerve
what are the 3 deep extrinsic muscles?
levator scapulae, rhomboid minor, rhomboid major
describe the levator scapulae
small strap like muscle
what are the actions of the levator scapulae?
elevates the scapula
what innervates the deep extrinsic muscles in the shoulder?
dorsal scapula nerve
what are the actions of the rhomboids?
retract and rotate the scapula
what are the 6 intrinsic muscles of the shoulder?
deltoid, teres major, and 4 rotator cuff muscles
describe the deltoid, its actions, and innervation
- inverted triangle shape
- anterior fibres = flexion and medial rotation
- posterior fibres - extension and lateral rotation
- middle fibres = major abductor of the arm
- axilliary nerve
what are the actions of the teres major and how is it innervated?
- abducts and extends at the shoulder
- medially rotates the arm
- lower subscapular nerve
what are the rotator cuff muscles?
group of 4 muscles that originate from the scapula and attach to humeral head. collectively act to give glenohumeral joint stability
the suprascapular nerve innervates which 2 rotator cuff muscles?
supraspinatus, infraspinatus
what is the subscapularis innervated by?
the upper and lower subscapular nerves
what is the teres minor innervated by?
axilliary nerve
what are the 4 muscles in the pectoral region?
- pectoralis major
- pectoralis minor
- serratus anterior
- subclavius
describe the pectoralis major, its actions, and innervation
- most superficial muscle in pectoral region
- large and fan shaped
- abducts and medially rotates the upper limb
- clavicular head acts to individually flex the upper limb
- lateral and medial pectoral nerves
describe the pectoralis minor, its actions, and innervation
- lies underneath major
- stabilises the scapula by drawing it anteroinferiorally against thoracic wall
- medial pectoral nerve
describe the serratus anterior, actions, and innervation
- located more laterally on chest wall
- rotates scapula, allowing arm to be raised over 90 degrees
- holds scapula against rib cage
- long thoracic nerve
describe the subclavius, action, and innervation
- small muscle located underneath the clavicle, running horizontally
- anchors and depresses the clavicle
- nerve to subclavius
what is the glenohumeral joint?
the shoulder joint
how is the shoulder joint formed?
articulation between humerus and scapula
what is the joint capsule of the shoulder joint and where does it extend from?
fibrous sheath enclosing structures of the joint. extends from the anatomical neck of the humerus to the rim of the glenoid fossa
what lines the inner surface of the joint capsule in the shoulder joint?
synovial membrane - produces synovial fluid to reduce friction between surfaces
how many ligaments are there in the shoulder joint and what are they?
4 - glenohumeral , coracohumeral, transverse humeral, coracoacromial
describe glenohumeral ligament in the shoulder joint
- humerus to glenoid fossa
- stabilises anterior aspect
describe the coracohumeral ligament in the shoulder joint
- coracoid process to greater tubercle of humerus
- supports superior part
describe the transverse humeral ligament in the shoulder joint
- extends from 2 tubercles of humerus
- holds tendon of long head in biceps
describe the coracoacromial ligament in the shoulder joint
- extends between acromion and coracoid process of scapula
- resists superior displacement of humeral head
how many muscles are there in the upper arm, and how many are posterior and anterior
4
3 anterior = biceps brachii, brachialis, coracobrachialis
1 posterior = triceps brachii
how is the anterior compartment of the upper arm innervated?
musculocutaneous nerve
what is the arterial supply to the anterior compartment of the upper arm?
brachial artery
describe the biceps brachii and its function
- 2 headed muscle
- long originates from supraglenoid tubercle of scapula
- short originates from glenoid process in scapula
- supination of the forearm
- flexes arm at elbow and shoulder
describe the brachialis and its function
- lies deep to biceps brachii and found more distally
- originates from medial and lateral humeral shaft surfaces
- inserts into ulnar tuberosity, distal to elbow
- flexion of elbow
describe the coracobrachialis and its function
- lies deep to biceps brachii
- originates from coracoid process in scapula
- flexion of the arm at shoulder, and weak adduction
what is the arterial supply to posterior compartment of upper arm?
profunda brachii artery
describe the triceps brachii and its function
- 3 heads
- medial lies deepest
- extension of the arm at elbow
what is the innervation of the triceps brachii?
radial nerve
