Lecture 14 - Musculoskeletal 3 Flashcards
what are the three parts of the deltoid?
anterior, posterior and middle fibres
what is the origin and insertion of the entire deltoid?
origin: the anatomical horseshoe
- anterior = clavicle, posterior fibres = scapula
insertion: the deltoid tuberosity of the humerus
what is the primary movement of the deltoid’s anterior fibres?
flex the shoulder
internal rotator of the humerus
what is the primary movement of the deltoid’s posterior fibres?
extend the shoulder (pulls humerus backwards)
externally rotates arm
what is the primary movement of the deltoid’s middle fibres and entire deltoid?
abducts humerus/arm, but does depend of where arm is and which fibres are activated
how do the anterior and posterior fibres of the deltoid relate to each other?
they are antagonists in rotation and flexion/extension.
but flexing them at the same time can cause adduction of the humerus at anatomical position, and assist in further abduction when arms are lifted
how does the supraspinatus assist in abduction?
the middle fibres of the deltoid would try to pull up on the humerus. The corcoacromial arch prevents this, so the supraspinatus starts abduction to take the humerus far enough away from your body so the middle fibres can start to contract
what is the origin and insertion of the teres major?
origin: inferior angle of the posterior scapula just below the teres minor
insertion: medial lip of the intertubercular groove on the anterior humerus
- goes from posterior side of body to anterior like lat dorsi
what is the primary movement of the teres major?
adductor of the shoulder
also an internal/medial rotator
what does a teres mean
the muscle is circular or round when cut in cross-section
what muscles form the anterior and posterior fold of the armpit?
anterior = pectoralis major
posterior = latissimus dorsi and teres major
what is the origin and insertion of the coracobrachialis?
origin: coracoid process
insertion: medial side of humerus (opposite the deltoid tuberosity)
what is the primary movement of the coracobrachialis?
adduction of shoulder
what is the insertion of the pectoralis major and what is its significance to the arm?
lateral lip of the intertubercular groove
- hold tendon of the biceps brachii in place
what do all components of a compartment share?
the same nerve supply, drained by the same vein and lymphatics
at what point in the arm can we begin to form compartments?
just under the insertion of the deltoid (deltoid tubercle) and the coracobrachialis, the lateral and medial intermuscular septa begin.
describe the comparment of the arm at the mid humerus (1)
there is a flexor compartment with 3 muscles and an extensor compartment with 1 muscle. these two are separated by the humerus and the lateral and medial intermuscular septa
true or false, the origin of muscles can be an intermuscular septum
true
what is the primary movement of the brachialis?
main elbow flexor
what is the origin and insertion of the brachialis?
origin is the anterior surface of the distal humerus (including intermuscular septa)
insertion is the tuberosity of the ulna
why do the long muscles of the hands and fingers attach to the side of the elbow/humerus?
- long muscles account for large range of motion and stronger movements
- It keeps the forearm compact, allowing the long tendons to run down the forearm into the hand without bulky muscle mass getting in the way of fine motor control.
In short: power at a distance with precision at the fingertips! 💪✋
how does muscle attachment on the elbow for hand movement change the structure of the upper arm/elbow compartment?
the lateral and medial intermuscular septa split to create another compartment on each side, where the muscles for hand movement can attach
- medial and lateral compartments created as well as flexor and extensor compartments for the common tendons
where do the majority of the muscles of the forearm originate?
on the lateral and medial epicondyles of the humerus/elbow via a common tendon
the lateral epicondyle shares a common __________ tendon of the forearm, and the medial epicondyle shares a common _________ tendon of the forearm
extensor, flexor
where does the common extensor tendon go/occupy?
from the lateral side of the humerus around to the posterior side of the forearm.
where does the common flexor tendon go/occupy?
from the medial side of the humerus around to the anterior side of the forearm.
what are the three muscles of the flexor compartment of the upper arm?
- biceps brachii
- brachialis
- coracobrachialis
what originates from the medial and lateral compartments OTHER than the common tendons?
medial: pronator teres on the supracondylar ridge
lateral: Brachioradialis and ECRL (extensor carpi radialis longus)
what muscle forms the extensor compartment of the upper arm?
the triceps brachii
what is the primary movement of triceps brachii?
elbow extensor
what are the two origins and two insertions of the biceps brachii?
long head origin: supraglenoid tubercle
short head origin: coracoid process
insertion 1: bicipital aponeurosis (not a bony insertion)
insertion 2: radial tuberosity (bump on inside of radius)
what is the primary movement of biceps brachii?
supinator (towards holding bowls of soup from spilt soup = supination)
and then elbow flexor
= pulls the radius back over the ulna to anatomical position
what is the primary movement of brachialis?
main elbow flexor
what is the origin and insertion of the brachialis?
origin: anterior surface of distal humerus
insertion: tuberosity of the ulna
how does supernation happen in terms of forearm bones?
the distal end of the radius crosses over the top of the ulna as the proximal end rotates against the humerus, and this brings the hand with it
random function of the tendon of the long head biceps tendon?
keeps the humerus against the glenoid as the humerus rotates
what is a problem with the biceps long head as we get older?
osteophytes can cause rupturing of the long head biceps - worn down tendon
which nerve innervates all three muscles of the anterior flexor compartment?
the musculocutaneous nerve
what are the head of the triceps?
lateral, medial, long heads
what is the insertion of the triceps heads?
olecranon of the ulna
what is the forearm muscle that assists triceps in elbow extension?
anchoneus
lateral epicondyle -> back of the ulna
what are shunt muscles?
prevent unwanted inferior movement/dislocation of the humeral head at the shoulder joint during loading (e.g carrying a heavy item).
but they are not shortening
what are the shunt muscles of the arm?
deltoid
short head biceps
coracobrachialis
long head triceps
