What are the two superficial posterior axioappendicular (extrinsic shoulder) muscles?
lattissimus dorse
trapezius
What nerve supplies the latissimus dorsi?
thoracodorsal nerve
What are the 3 functions of the latissimus dorsi?
extends, adducts, and medially rotates the humerus at the shoulder joint
What nerve supplies the trapezius?
Accessory nerve (CN XI)
and C3, C4 spinal nerves
What are the three functions of the trapezius?
upper fibers?
middle fibers?
lower fibers?
Upper fibers: Elevate scapula
Middle fibers: Retract scapula
Lower fibers: Depress scapula
What does paralysis of the trapezius muscle result in and why?
It causes droopy shoulder - the upper trap helps the serratus anterior in making possible abdution of the humerus of more than 90 degrees
What are the 3 deep axioappendicular (extrinsic shoulder) muscles?
- Levator scapulae
- Rhomboidei (major and minor)
- Serratus anterior
What nerve supplies the levator scapulae?
dorsal scapular nerve
What is the function of the levator scapulae?
elevates and fixes the scapula
What nerve supplies the major and minor rhomboidei?
dorsal scapular nerve
What are the main function of the major and mino rhomboidei?
retracts and elevates the scapula
WHat nerve supplies the serratus anterior?
the long thoracic nerve
What are the functions of the serratus anterior?
- protracts the scapula and holds it against the thoracic wall
- positions the glenoid cavity
What are the 6 scapulohumeral (intrinsic shoulder) muscles?
- Deltoid
- Teres major
- Supraspinatus
- Infraspinatus
- Teres minor
- Subscapularis
WHat nerve supplies the deltoid?
axillary nerve
What are the three functions of the deltoid?
Anterior fibers: Flex and medially rotate the humerus
Middle fibers: Chief abductor of the humerus
Posterior fibers: Extend and laterally rotate the humerus
What nerve supplies the teres major?
lower subscapular nerve
What is the function of the teres major?
adducts and medially rotates the humerus
What nerve supplies the supraspinatus?
Suprascapular nerve
What is the main function of the supraspinatus?
abducts the humerus
What nerve supplies the infraspinatus?
suprascapular nerve
What is the function of the infraspinatus?
laterally rotates the humerus
WHat nerve supplies the teres minor?
axillary nerve
What is the function of the teres minor?
laterally rotates the humerus
What nerves supplies the subscapularis?
the upper and lower subscapular nerves
What is the function of the subscapularis?
medially rorates the humerus
What are the two attachments of the omohyoid muscle?
the inferior attachment is the superior border of the scapula near the suprascapular notch
the superior attachment is to the hyoid bone on which the muscle acts
What 3 nerves supply the omohyoid muscle?
CN 1, 2, and 3
What is the funciton of the omohyoid bone
It depresses, retracts, and steadies the hyoid bone
What three arteries are involved in blood cirulation of the upper limb?
transverse cervical artery (deep branch)
dorsal scapular artery
suprascapular artery
circumflux scapular artery
What muscle of the back connects the upper limb with the thoracic wall? What is its nerve supply?
How would one clinically test the function of the deltoid?
The examiner resists the patient’s abduction of the limb by the deltoid. If the deltoid is acting normally, contraction of the middle part of the muscle can be palpated.
What muscles form the posterior axillary fold? What is their nerve supply?
What muscles form the rotator cuff?
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
What is the most common site of clavicular fracture?
At the junction of its middle and lateral thirds
this is especially weak in children and often breaks when they catch themsevles with an outstretched hand in a fall
Why does the shoulder droop following clavicular fracture?
When the clavicle breaks, the sternocleidomastoid pulls the broken piece up
the trapezius is not strong enough to hold up the limb by itself, so the shoulder droops
patients with broken clavicles will often support the arm with the other hand to keep it from drooping too low
it’s kept from dislocating at the AC joint by the strong coracoclavicular ligament
What is a ‘greenstick’ fracture?
A fracture of the clavicle is often incomplete in younger children—that is, it is a greenstick fracture, in which one side of a bone is broken and the other is bent. This fracture was so named because the parts of the bone do not separate; the bone resembles a tree branch (greenstick) that has been sharply bent but not disconnected.
What is “winged scapula” and how does it usually occur?
WHen a patient pushes against a wall, the scapula will “wing” out
This is caused by damage to the long thoracic nerve which innervates the serratus anterior
What is the triangle of auscultation? When using a stethoscope and listening for lung sounds, what intercostal space would the triangle expose?
Triangle of auscultation formed by the trapezius, rhomboid major and latissimus dorsi.
6th and 7th intercostal space
What clinical deficit would be apparent with injury to the thoracodorsal nerve?
With paralysis of the latissimus dorsi, the person is unable to raise the trunk with the upper limbs, as occurs during climbing.
What happens with respect to “chinning” one’s self and the use of crutches with paralysis of the latissimus dorsi?
With paralysis of the latissimus dorsi, the person is unable to raise the trunk with the upper limbs, as occurs during climbing. Furthermore, the person cannot use an axillary crutch because the shoulder is pushed superiorly by it. These are the primary activities for which active depression of the scapula is required; the passive depression provided by gravity is adequate for most activities.
How would injury to the dorsal scapular nerve effect the position of the scapula?
Injury to the dorsal scapular nerve, the nerve to the rhomboids, affects the actions of these muscles. If the rhomboids on one side are paralyzed, the scapula on the affected side is located farther from the midline than that on the normal side.
When is injury to the axillary nerve most likely to occur? What would be the appearance of the patient’s shoulder sometime following axillary nerve injury?
Because it passes inferior to the humeral head and winds around the surgical neck of the humerus (Fig. B6.8A), the axillary nerve is usually injured during fracture of this part of the humerus. It may also be damaged during dislocation of the glenohumeral joint and by compression from the incorrect use of crutches.
As the deltoid atrophies, the rounded contour of the shoulder is flattened compared to the uninjured side. This gives the shoulder a flattened appearance and produces a slight hollow inferior to the acromion.
Which muscle of the rotator cuff is most commonly torn?
Trauma may tear or rupture one or more of the tendons of the SITS muscles. The supraspinatus tendon is most commonly ruptured
When is dislocation of the shoulder joint most likely to occur? Where would the head of the humerus usually move with a shoulder dislocation?
Anterior dislocation of the glenohumeral joint occurs most often in young adults, particularly athletes. It is usually caused by excessive extension and lateral rotation of the humerus
inferoanteriorly, so down and forward
When would a patient most likely experience shoulder pain (subacromial bursitis)?
Calcification of the supraspinatus tendon leads to inflammation of the bursa, causing pain on abduction of the upper extremity (painful arc syndrome).
From where does the accessory nerve take origin? Is it a spinal or cranial nerve?
It takes origina from C1-C6
However, it is considered a cranial nerve because it first travels up into the cranium through the fossa magnum and then back down through the neck
What muscles are innervated by the dorsal scapular nerve?
the rhomoides and the levator scapulae
What muscle is innervated by the thoracodorsal nerve and supplied by the thoracodorsal artery?
latissimus dorsi
Through what space does the axillary nerve pass through?
the quadrilateral/quadrangle space
Why is the long thoracic nerve unusually susceptible to injury?
While nerves usually run deep to the muscles they supply, the long thoracic nerve runs superiorly to the seratus anterior, so it’s more readily exposed when the limb is elevated