UL1 - Muscles of the shoulder, arm & elbow Flashcards
which of the following muscles is attached to the coracoid process?
A) brachialis
B) pectoralis minor
C) subclavius
D) pectoralis major
E) deltoid
B: pectoralis minor
which of these muscles is innervated by the suprascapular nerve?
A) teres major
B) teres minor
C) rhomboid major
D) infraspinatus
E) latissimus dorsi
infraspinatus
the insertion of the biceps brachii muscle is on which structure?
radial tuberosity
what two structures pass through the quadrangular space?
axillary nerve
posterior circumflex humeral artery
what are the muscles of the anterior axioappendicular group? (4)
pectoralis major
pectoralis minor
serratus anterior
subclavius
what are the muscles of the posterior axioappendicular group? (5)
trapezius
latissimus dorsi
levator scapular
rhomboid major
rhomboid minor
what are the muscles of the scapulohumeral group?
supraspinatus
infraspinatus
subscapularis
teres minor
teres major
deltoid
what are the muscles of the anterior arm compartment? (3)
biceps brachii
coracobrachialis
brachialis
what are the muscles of the posterior arm compartment? (2)
triceps brachii
anconeus
what are the muscles of the rotator cuff muscle group?
supraspinatus
infraspinatus
subscapularis
teres minor
origins and insertion of the pectoralis major?
ORIGIN - pectoralis major has two heads:
- clavicular head from medial 1/3 of clavicle
- sternoclavicular head from superior 6 costal cartilages & sternum
INSERTION on the lateral lip of the intertubercular sulcus/ bicipital groove of the humerus
the pectoralis major consists of a clavicular head & sternocostal head? what are the actions of these heads individually? what happens when these heads work together?
sternocostal head contraction = shoulder extension
clavicular head = shoulder flexion
both = adduction & medial rotation of the shoulder
action of the pectoralis major when both heads work together?
adduction & medial rotation of the shoulder
innervation of the pectoralis major?
lateral & medial pectoral nerves
origin and insertion of the pectoralis minor?
ORIGIN - anterior surface of 3-5th ribs
INSERTION - coracoid process of scapula
action of the pectoralis minor?
depresses shoulder
stabilises scapula against thoracic wall
innervation of pectoralis minor?
medial pectoral nerve
origin & insertion of subclavius?
ORIGIN - junction of 1st costal cartilage of 1st rib
INSERTION - subclavian groove of clavicle
action of subclavius?
depresses clavicle
stabilises clavicle at sternoclavicular joint
(not for large movements)
innervation to subclavius?
nerve to subclavius - from the superior trunk of the brachial plexus
origin and insertion of serratus anterior?
ORIGIN - anterior aspect of first 9 ribs
INSERTION - medial border of scapula
action of serratus anterior?
protracts scapula & holds it against posterior thoracic wall
innervation to serratus anterior?
long thoracic nerve
what are the deep muscles of the posterior axioappendicular group?
levator scapulae
rhomboid major
rhomboid minor
what are the superficial muscles of the posterior axioappendicular group?
trapezius
larissimus dorsi
origin and insertion of the trapezius muscle?
ORIGIN - occipital bone, ligamentum nuchae, and spinous processes of C7–T12
INSERTION - lateral third of clavicle, acromion and spine of scapula
the trapezius muscle consists of three parts - what are they? what action are they each responsible for? what happens when they contract together?
descending - elevates scapula
transverse - retracts scapula
ascending - depresses scapula
together = forceful retraction & upwards rotation of scapula
action of the trapezius (all parts contracting together)?
forceful retraction & upwards rotation of scapula
innervation to trapezius muscle?
spinal accessory nerve
C3 & 4 cervical spinal nerves
what are the three parts of the trapezius muscle?
descending
ascending
transverse
(according to direction of fibres)
origin & insertion of latissimus dorsi?
ORIGIN - spinous processes of T7–T12, thoracolumbar fascia, iliac crest, and lower ribs
INSERTION - intertubercular sulcus of humerus
action of latissimus dorsi?
extension
adduction
medial rotation of humerus
innervation to latissimus dorsi?
thoracodorsal nerve from C6-8 nerve roots
what cervical vertebrae does the thoracodorsal nerve originate from? what muscle does it innervate?
C6-8 - innervates the latissimus dorsi
origin & insertion of the levator scapulae?
ORIGIN - transverse processes of C1–C4
INSERTION - medial border of scapula & superior angle
innervation of the levator scapulae?
dorsal scapular nerve (C5)
C3 & C4 cervical nerves
action of levator scapulae?
elevates scapula
origin & insertion of the rhomboid major?
ORIGIN - spinous processes of T2–T5
INSERTION - medial border of scapula
origin & insertion of the rhomboid minor?
ORIGIN - nuchal ligament and spinous processes of C7–T1
INSERTION - medial border of scapula
action of rhomboid major & minor?
retraction & downwards rotation of scapula
innervation to rhomboid major & minor?
dorsal scapula nerve (C4 & 5)
what common nerve innervates the deep muscles of the posterior axioappendicular group? what are its nerve roots?
dorsal scapular nerve - C4-5 nerve roots
what axioappendicular muscles insert on the intertubercular sulcus? (3)
pectoralis major - on the lateral lip
latissimus dorsi - on the floor
teres major - on the medial lip
(“a lady between two majors”)
which of the following muscles is NOT part of the anterior axioappendicular group?
a) Pectoralis Major
b) Pectoralis Minor
c) Subclavius
d) Levator Scapulae
D: levator scapulae
what is the primary action of the pectoralis minor?
a) Adduction of the humerus
b) Elevation of the ribs during forced inspiration
c) Depression and protraction of the scapula
d) Retraction of the scapula
C: depression & protraction of the scapula
which nerve is responsible for innervating the latissimus dorsi?
a) Thoracodorsal nerve
b) Lower subscapular nerve
c) Long thoracic nerve
d) Axillary nerve
A: thoracodorsal nerve (C6 & 8)
The trapezius is responsible for all the following actions EXCEPT:
a) Elevation of the scapula
b) Retraction of the scapula
c) Depression of the scapula
d) Medial rotation of the scapula
D: medial rotation of the scapula
TRUE/FALSE: the rhomboid major and minor are both innervated by the dorsal scapular nerve
TRUE
TRUE/FALSE: the trapezius is innervated by the accessory nerve (cranial nerve XI)
TRUE
Which of the following combinations of origin and insertion is correct for the levator scapulae?
a) Origin: Spinous processes of C7-T5, Insertion: Medial border of scapula
b) Origin: Transverse processes of C1-C4, Insertion: Superior angle & medial border of scapula
c) Origin: Clavicle, Insertion: Acromion process of scapula
d) Origin: Ribs 3-5, Insertion: Coracoid process of scapula
B: Origin: Transverse processes of C1-C4, Insertion: Superior angle & medial border of scapula
The pectoralis major has two heads. What is the correct pairing of origins for these heads?
a) Clavicular head: Anterior sternum, Sternocostal head: Medial clavicle
b) Clavicular head: Medial clavicle, Sternocostal head: Anterior sternum and first six costal cartilages
c) Clavicular head: Lateral clavicle, Sternocostal head: Ribs 3-5
d) Clavicular head: Acromion, Sternocostal head: Superior angle of scapula
B: Clavicular head: Medial clavicle
Sternocostal head: Anterior sternum and first six costal cartilages
which muscle can both protract and rotate the scapula upwards during overhead movements of the arm?
serratus anterior
the latissimus dorsi performs which combination of movements at the shoulder joint?
a) Flexion, abduction, lateral rotation
b) Extension, adduction, medial rotation
c) Flexion, adduction, medial rotation
d) Extension, abduction, lateral rotation
B: extension, adduction & medial rotation of the shoulder
when both the upper and lower fibres of the trapezius contract simultaneously, what is the resulting movement of the scapula?
forceful retraction & upwards rotation of the scapula
which muscle opposes the action of the rhomboids in scapular movement?
serratus anterior
(rhomboids retract the scapula, serratus anterior protracts it)
what movement occurs when the clavicular head of the pectoralis major contracts alone?
flexion of the shoulder joint
what would happen to scapular movements if the long thoracic nerve was damaged?
serratus anterior would be paralyzed - leads to winged scapula & impaired upward rotation and protraction of the scapula
which muscle is primarily responsible for initiating abduction of the arm at the shoulder joint?
a) Deltoid
b) Supraspinatus
c) Serratus anterior
d) Pectoralis major
B: supraspinatus
what is the main action of the serratus anterior?
a) Retracts and elevates the scapula
b) Protracts and rotates the scapula upward
c) Depresses and retracts the scapula
d) Stabilizes the scapula by downward rotation
B: protracts and rotates the scapula upward
which muscle retracts the scapula and rotates it downward?
a) Rhomboid major
b) Latissimus dorsi
c) Trapezius (middle fibres)
d) Pectoralis minor
A: rhomboid major
the pectoralis major muscle produces which of the following movements at the shoulder joint?
a) Extension, lateral rotation, and adduction
b) Flexion, medial rotation, and adduction
c) Abduction, flexion, and lateral rotation
d) Extension, medial rotation, and abduction
B: flexion, medial rotation, and adduction
what three muscles of the rotator cuff insert on the greater tubercle of the humerus? what is their common function?
supraspinatus
infraspinatus
teres minor
lateral rotation of shoulder joint
origin & insertion of the supraspinatus?
ORIGIN - supraspinous fossa of scapula
INSERTION - greater tubercle of humerus
actions of the supraspinatus?
initiates shoulder abduction - the first 15 degrees (deltoid takes over with the rest)
innervation of the supraspinatus?
suprascapular nerve
origin & insertion of the infraspinatus?
ORIGIN - infraspinous fossa
INSERTION - greater tubercle of the humerus
origin & insertion of the teres minor?
ORIGIN - middle part of lateral border of scapula
INSERTION - greater tubercle of humerus
innervation of the infraspinatus?
suprascapular nerve
innervation of the teres minor?
axillary nerve (one of the terminal branches passes out of the quadrangular space to supply Tminor)
actions of the infraspinatus?
lateral rotation of the shoulder
actions of the teres minor?
lateral rotation of the shoulder
what rotator cuff muscle inserts on the lesser tubercle of the humerus? what is its action?
subscapularis - from the subscapular fossa to the lesser tubercle
action - medial rotation of shoulder joint
innervation to subscapularis?
upper & lower/ superior & inferior subscapular nerves
origin and insertion of teres major?
ORIGIN - lateral border of scapula & inferior angle
INSERTION - medial lip of intertubercular sulcus
innervation to teres major?
lower/ inferior subscapular nerve
actions of the teres major?
extension
adduction
medial rotation of the shoulder
the deltoid muscle consists of three parts. what is the origin & insertion of these parts?
ORIGIN:
- anterior fibres = lateral third of clavicle
- middle fibres = acromion
- posterior fibres = spine of scapula
INSERTION - deltoid tuberosity of humerus
what are the three parts of the deltoid muscle?
anterior, middle, posterior
actions of the three different parts of the deltoid muscle?
anterior fibres - shoulder flexion & medial rotation
middle fibres - shoulder abduction
posterior fibres - shoulder extension & lateral rotation
what happens to the humerus during shoulder flexion?
humerus is pulled upwards
what action is performed when all three part of the deltoid muscle contract together?
powerful shoulder abduction - anterior and posterior fibres counteracting each other to stabilize movement
action of the anterior part of the deltoid muscle?
shoulder flexion & medial rotation
action of the posterior part of the deltoid muscle?
shoulder extension & lateral rotation
action of the middle part of the deltoid muscle?
shoulder abduction
innervation to the deltoid muscle?
axillary nerve - branches pass through quadrangular space to reach deltoid muscle
what separates the arm muscles into their anterior & posterior compartments?
intermuscular septum - derived from the brachial fascia
what nerve innervates all the muscles of anterior/ flexor compartment of the arm?
musculocutaneous nerve
what nerve innervates all the muscles of posterior/extensor compartment of the arm?
radial nerve
muscles of the same arm compartment share the same neurovascular supply. what is the clinical importance of this?
important for monitoring the spread of infection & haemorrhage
origin of the long head of the biceps brachii?
supraglenoid tubercle of the scapula
origin of the short head of the biceps brachii?
coracoid process of the scapula
insertion point of the biceps brachii?
radial tuberosity & fascia of the forearm via the bicipital aponeurosis
actions of the biceps brachii at the shoulder joint?
flexion of shoulder
actions of the biceps brachii at the elbow joint?
supinates forearm - once supinated, flexes the elbow
origin & insertion of the coracobrachialis?
ORIGIN - coracoid process of the scapula
INSERTION - middle third of the medial humerus
actions of the coracobrachalis?
shoulder flexion & adduction
origin & insertion of the brachialis?
ORIGIN - distal half of the anterior humerus
INSERTION - ulnar tuberosity & coronoid process of the ulna
action of the brachialis?
elbow flexion
describe the course of the long head of the biceps brachii
originates from the supraglenoid tubercle of the scapula - through glenoid cavity & joint capsule of the glenohumeral joint
runs through bicipital groove & merges with short head to form one muscle belly - runs over elbow
inserts on radial tuberosity & gives off a tendon to insert via the bicipital aponeurosis
the triceps brachii consists of 3 heads - what are they? their origins?
long - infraglenoid tubercle of scapula
lateral - posterior humerus, superior to radial groove
medial - posterior humerus, inferior to radial groove
does the lateral head of the triceps brachii originate superior or inferior to the radial groove?
SUPERIOR
insertion point of the triceps brachii?
olecranon process of ulna
actions of the triceps brachii?
shoulder extension (via long head)
elbow extension
origin & insertion of the anconeus?
ORIGIN - lateral epicondyle of humerus
INSERTION - lateral olecranon and proximal ulna
actions of the anconeus?
stabilises elbow joint
helps with elbow extension
(small muscle)
