UL extra Flashcards
What are the joints that make up the pectoral girdle?
- clavicle and sternum (sterno-clavicular)
- clavicle and scapular (acromio-clavicular)
- scapula + humerus (gleno-humeral)
- scapula + thoracic wall (scapulo-thoracic)
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What does the glenoid labrum do?
Deepens the glenoid fossa to stabilise the shoulder
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What are the different muscle compartments of the shoulder?
Anterior pectoral girdle
Posterior pectoral girdle
Intrinsic shoulder muscles
What muscles are contained in the anterior pectoral girdle?
pectoralis major
pectoralis minor
subclavius
serratus anterior
what muscles are contained in the posterior pectoral girdle?
trapezius
levator scapulae
latissimus dorsi
rhomboid major
rhomboid minor
what are the intrinsic shoulder muscles?
- deltoid
- teres major
- supraspinatus
- infraspinatus
- teres minor
- subscapularis
What are the two muscle groups that serve the shoulder region?
- pectoral girdle
- intrinsic shoulder muscles
What are the 4 surrounding ligaments that stabilise the glenohumeral joint?
glenohumeral ligaments
coracohumeral ligaments
transverse humeral ligaments
coracoacromial ligaments
What does the glenohumeral ligament do?
stabilises the anterior aspect of the joint and prevents it dislocating anteriorly
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what does the coracohumeral ligament do?
attaches the coracoid process to the greater tubercle of humerus, supporting superior part of joint capsule
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what does the transverse ligament do?
connects greater and lesser tubercles holding tendon of long head biceps brachia in place
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what does the coracoacromial ligament do?
spans between acromion and coracoid prcoess forming coracoacromial arch
overlies shoulder joint and prevents superior displacement of humeral head
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What is the pectoral region of the anterior chest wall?
contains 4 muscles that exert a force on the upper limb
pectoralis major, pectoralis minor, serratus anterior + subclavius
what is the pectoralis major muscle?
most superficial muscle in the pectoral region
large + fan shaped
has sternal head + clavicular head (sternal orginiates from anterior surface of the sternum, clavicle originates from the anterior surface of the medial clavicle)
distal attachment of both heads is into the intertubercular sulcus of humerus
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Function of pectoralis major + innervation?
adducts + medially rotates the upper limb
draws scapula anteroinferiorly
clavicular head acts individually to flex upper limb
innervated by medial and lateral pectoral nerves
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What is the pectoralis minor?
lies underneath the pectoralis major
both muscles form part of anterior wall of axilla region
originates from 3rd-5th ribs and inserts into coracoid process of scapula
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function + innervation of pectoralis minor?
stabilises scapula by drawing it anteroinferiorly against thoracic wall
median pectoral nerve
what is the serratus anterior?
located more laterally in chest wall
consists of several strips -> originate from lateral aspects of ribs 1-8 and attach to costal surface of medial border of scapula
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function + innervation of serratus anterior?
Rotates the scapula, allowing the arm to be raised over 90 degrees. It also holds the scapula against the ribcage.
long thoracic nerve
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What is the subclavius muscle?
small muscle directly underneath the clavicle -> offers minor protection to underlying neurovascular structures
originates from junction of 1st rib and its costal cartilage -> inserts into inferior surface of middle third of the clavicle
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function + innervation of subclavius?
anchors + depresses the clavicle
nerve to subclavius
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What can the muscles of the shoulder group be divided into?
extrinsic (from torso + attach to bones of the shoulder e.g. clavicle, scapula + humerus)
intrinsic (originate from scapula and/or clavicle + attach to humerus)
What can the extrinsic muscles of the shoulder be divided into?
- superficial (trapezius + latissimus dorsi)
- deep (levator scapulae + rhomboid minor and major)
what is the trapezius?
- broad, flat + triangular muscle
- most superficial of all back muscles
- originates from the skull, nuchal ligament and spinous processes of C7-T12
fibres attach to clavicle, acromion and scapula spine
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function + innervation of trapezius?
Motor innervation is from the accessory nerve. It also receives proprioceptor fibres from C3 and C4 spinal nerve
upper fibres of the trapezius elevate the scapula + rotates it during abduction of the arm.
middle fibres retract the scapula
lower fibres pull the scapula inferiorly
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what is the latissimus dorsi?
originates from lower part of the back
has a broad origin - spinous processes of T7-T12, iliac crest, thoracolumbar fascia and the inferior three ribs
fibres converge into a tendon that attaches to the intertubercular sulcus of the humerus
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function + innervation of latissimus dorsi?
extends, adducts + medially rotates the upper limb
thoracodorsal nerve
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what is the levator scapulae?
small + strap like muscle
begins in the neck + attaches to scapula
originates from transverse process of C1-4 vertebrae and attaches to medial border of the scapula
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function + innervation of levator scapulae?
elevates the scapula
dorsal scapular nerve
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What is the rhomboid major?
originates from spinous process of T2-6 vertebrae
attaches to medial border of scapula, between scapula spine +inferior angle
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function + innervation of rhomboid major
retracts + rotates the scapula
dorsal scapular nerve
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what is the rhomboid minor muscle?
Originates from the spinous processes of C7-T1 vertebrae.
Attaches to the medial border of the scapula, at the level of the spine of scapula
superior to the rhomboid major
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function + innervation of rhomboid minor?
dorsal scapular nerve
retracts + rotates the scapula
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label the diagram
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What are the 6 intrinsic muscles of the shoulder?
deltoid
teres major
4 rotator cuff group muscles (teres minor, supraspinatus, infraspinatus + subscapularis)
What is the deltoid muscle?
shaped like inverted triangle
can be divided into anterior, middle + posterior part
originates from lateral third of the clavicle, acromion + scapula spine
attaches to deltoid tuberosity on lateral aspect of humerus
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What is the function + innervation of the deltoid muscle?
Anterior fibres – flexion and medial rotation.
Posterior fibres – extension and lateral rotation.
Middle fibres – the major abductor of the arm (takes over from the supraspinatus, which abducts the first 15 degrees).
axillary nerve
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what is the teres major muscle?
Originates from the posterior surface of the inferior angle of the scapula
attaches to the medial lip of the intertubercular groove of the humerus
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function + innervation of teres major muscle?
Adducts and extends at the shoulder, and medially rotates the arm
lower subscapular nerve
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what are the highlighted structures?
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deltoid (orange)
teres major (yellow)
what are the rotator cuff group muscles?
4 muscles that originate from the scapula and attach to the humeral head
the resting tone of these muscles is to ‘pull’ the humeral head into the glenoid fossa
gives glenohumeral joint additional stability
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what is the supraspinatus muscle?
Originates from the supraspinous fossa of the scapula
attaches to the greater tubercle of the humerus
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function + innervation of supraspinatus?
suprascapular nerve
abducts the arm 0-15 degrees + assists deltoid for 15-90 degrees
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what is the infraspinatus muscle?
Originates from the infraspinous fossa of the scapula
attaches to the greater tubercle of the humerus
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function + innervation of infraspinatus muscle?
laterally rotates the arm
suprascapular nerve
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what is the subscapularis muscle?
originates from subscapular fossa on costal surface of scapula
attaches to lesser tubercle of humerus
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function + innervation of subscapularis muscle?
medially rotates the arm
upper + lower subscapular nerve
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what is the teres minor muscle?
originates from the posterior surface of the scapula adjacent to its lateral border
attaches to the greater tubercle of the humerus
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function + innervation of teres minor muscle?
laterally rotates the arm
axillary nerve
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label the diagram
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