Lect 2 Shoulder Part 2

What is the depression below the lateral third of the clavicle?

deltopectoral groove

What is the superior border of the deltopectoral groove?

the clavicle

What is the lateral border of the deltopectoral groove?

deltoid muscle

What is the medial border of the deltopectoral groove?

pec major

What passes through the deltopectoral groove?

cephalic vein

Which teres (minor or Major) is NOT a rotator cuff?

teres Major ≠ a rot cuff

minor is a rotator cuff

What does the cephalic vein join with after passing through the deltopectoral groove?

axillary vein

What is the large, fan shaped muscle that covers the superior part of the thorax?

pectoralis major (pec major)

What are the two heads of the pec major?

clavicular head and sternal head

What head of the pec major is larger?

sternal head is larger

What does the sternal head of the pec major form?

anterior wall of the axilla

What does the pec major form with both the deltoid and clavicle?

the deltopectoral groove

What is the OAIN of the pectoralis major?

O:

• clavicular head: 1/2 of clavicle

• sternal head: anterior sternum + superior 6 costal cartilages

I: lat lip intertuberc groove

A: shoulder add + IR

N: lat AND med pect nerves

What part of the pec major does the lateral pectoral nerve supply?

clavicular head

What part of the pec major does the medial pectoral nerve supply?

sternal head

What muscle lies in the anterior wall of the axilla?

pectoralis minor

What muscle is largely covered by the pectoralis major?

pectoralis minor

What shape is the pectoralis minor?

triangular

The pectoralis minor forms a _______________ with the _________ under which ______________ & __________ pass through

pec minor

• forms a bridge

• with the coracoid process

• bridge; vessels; nerves; corcacoid

What is the origin, insertion, action, and innervation of the pectoralis minor?

O: medial ribs 3-5

I: coracoid process

A: scapular protraction + depression

N: medial pectoral nerve

What muscle lies almost horizontally when the arm is in the anatomical position?

subclavius

What is the main function of the subclavius muscle?

protects the subclavian artery when the clavicle fractures

What is the origin, insertion, action, and innervation of the subclavius?

O: junction 1st rib & its costal cart

I: inferior surf middle 1/3 clavicle

A: anchors + depresses the clavicle

N: nerve to subclavius

What muscle overlies the lateral part of the thorax?

serratus anterior

What wall of the axilla does the serratus anterior form?

medial wall

What is the meaning behind the serratus anterior's name?

the muscle looks serrated and has a saw-tooth appearance

When is the serratus anterior muscle used? What is it’s nickname?

when punching or reaching anteriorly

(also Known as the Boxer’s muscle!)

What causes scapular winging?

issue with serratus anterior

long thoracic nerve - succeptible to damage in radical mastectomy

Why is the serratus anterior known as the boxer's muscle?

it is the muscle responsible for forced protraction of the scapula, which occurs when throwing a punch

What is the origin, insertion, action, and innervation of the serratus anterior?

O: ext surf of the lateral parts of ribs 1-8

I: ant surf of the medial border of the scapula

A: protraction of the scapula

N: long thoracic nerve

What are the two heads of the biceps brachii muscle?

long head and short head

What is an important function of the biceps brachii as humans age?

stabilizes the anterior capsule

as the capsuloligamentous stability decreases (S/M/I-GH ligg decrease stability with age)

biceps become anterior capsular stabilizer

What are the ligaments that typically decrease in stability, causing the biceps brachii to become an anterior capsular stabilizer?

SGHL

MGHL

IGHL

What muscle is the strongest elbow supinator?

biceps brachii

What is the origin, insertion, action, and innervation of the long head of the biceps brachii?

O: supraglenoid tubercle (IN capsule)

I: radial tuberosity + bicpital aponeurosis

A: shoulder flex, elbow flex, supination!

N: musculocutaneous nerve

What is the origin, insertion, action, and innervation of the short head of the biceps brachii?

O: coracoid process (Not in capsule)

I: radial tuberosity + bicpital aponeurosis

A: shoulder flexion, elbow flexion, and powerful supinator

N: musculocutaneous nerve

Where is the origin of the long head of the biceps brachii located?

located WITHIN the capsule

(supraglenoid tubercle)

Where is the origin of the short head of the biceps brachii located?

located OUTSIDE of the capsule

(coracoid process)

What muscle does the musculocutaneous nerve pierce?

coracobrachialis

What is the origin, insertion, action, and innervation of the coracobrachialis?

O: coracoid process

I: middle 1/3 of the medial humerus

A: shoulder flexion and adduction

N: musculocutaneous nerve (pieced by!)

What muscle is the coracobrachialis deep to?

short head of the biceps brachii

What are the 2 layers of the posterior thoracoappendicular musculature?

• superficial posterior muscles (traps + lats)

• deep posterior muscles (levat scap, rhomboids M/m, long head triceps*)

What muscles make up the superficial posterior muscles of the posterior thoracoappendicular musculature?

trapezius

latissimus dorsi

What muscles make up the deep posterior muscles of the posterior thoracoappendicular musculature?

levator scapulae

rhomboid major

rhomboid minor

long head of triceps

What muscle provides direct attachment of the pectoral girdle to the trunk?

trapezius

What is the shape of the trapezius muscle?

large, triangular shaped muscle

How many parts is the trapezius muscle divided into?

3 different parts- each with own action

• scap elevation

• scap retraction

• scap depression

Each part of the trapezius has a ___________________ action.

different

What is the origin, insertion, action, and innervation of the trapezius?

O: ext occipital protuberance + nuchal lig + SP C7-T12

I: lat 1/3 of clavicle + acromion process + spine of scapula

A: scapula elevation, retraction, and depression

N: CN XI (spinal accessory)

What is the action of the upper part of the trapezius?

scapular elevation

What is the action of the middle part of the trapezius?

scapular retraction

What is the action of the lower part of the trapezius?

scapular depression

What nerve innervates the trapezius?

spinal accessory nerve (CN XI)

What does latissimus dorsi mean?

widest of the back

What is the shape of the latissimus dorsi muscle?

large fan shaped muscle

What is the origin, insertion, action, and innervation of the latissimus dorsi?

O: SP T6-T12 + iliac crest + thoracolumbar fascia

I: floor of intertubercular groove

A: shoulder extension, adduction, internal rotation

N: thoracodorsal nerve

“Latissimus Dorsi = Lady between two majors”

(Pec major lat lip intertubercular groove, teres Major medial lip & Lady Lat in the middle: floor of intertub groove)

What muscle lies deep to the SCM in the neck?

levator scapula

What is the shape of the superior third of the levator scapula?

straplike

What muscle is the inferior third of the levator scapula deep to?

trapezius

What is the origin, insertion, action, and innervation of the levator scapula?

O: transverse provesses of C1-C4

I: superiomedial border of scapula

A: elevates + rotates scapula (tilts the glenoid cavity inferiorly)

N: dorsal scapular nerve

(sup 1/3 straplike, inf 1/3 is deep to trap)

Wat muscles is the levator scapuli surrounded by?

• inf 1/3 deep to trap

• ant to splenius capitis

The levator scapula rotates the scapula so that the glenoid cavity is tilted _________________.

inferiorly

What muscle is the levator scapula posterior to?

middle scalene

What muscle is the levator scapula anterior to?

splenius capitis

What muscles form an oblique equilateral parallelogram?

rhomboids

What muscle are the rhomboids deep to?

trapezius

What are the two rhomboids?

rhomboid major

rhomboid minor

What is the origin, insertion, action, and innervation of rhomboid major and minor?

O:

minor: SP C7-T1

major: SP T2-T5

I: medial border of scapula

A: scapular retraction and downward rotation

N: dorsal scapular nerve

Where do the fibers of eac rhomboid insert at on the scapula?

minor: above the spine of the scapula

Major: below

What is the origin, insertion, action, and innervation of the long head of the triceps brachii?

O: infraglenoid tubercle

I: olecranon process

A: shoulder extension, adduction, and elbow extension

N: radial nerve

What is the origin, insertion, action, and innervation of the lateral head of the triceps brachii?

O: superior to radial groove

I: olecranon process

A: shoulder extension, adduction, and elbow extension

N: radial nerve

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CHANGE PICTURE

What is the origin, insertion, action, and innervation of the medial head of the triceps brachii?

O: inferior to radial groove

I: olecranon process

A: shoulder extension, adduction, and elbow extension

N: radial nerve

What is the primary action of the triceps brachii?

elbow extension

What muscles make up the scapulohumeral musculature?

• deltoids

• teres major

• rotator cuff muscles (SITS- supra, infraspin, teres minor, subscap)

What muscles make up the rotator cuff?

SITS

supraspinatus

infraspinatus

teres minor*

subscapularis

What scapulohumeral muscle is thick and powerful?

deltoid

What is the texture of the deltoid?

coarse textured

What does the deltoid muscle form?

rounded contour of the shoulder and the deltopectoral groove

What is the origin, insertion, action, and innervation of the deltoid?

O: distal 1/3 of clavicle + acromion + spine of scapula

(ant, middle, post)

I: deltoid tuberosity

A: shoulder abduction

(ant- s flex + IR) (middle- s abd) (post- s ext + ER)

N: axillary nerve

What are the different parts of the deltoid muscle?

anterior delt

middle delt

posterior delt

What is the action of the anterior deltoid?

shoulder flexion and internal rotation

What is the action of the middle deltoid?

shoulder abduction

What is the action of the posterior deltoid?

shoulder extension and external rotation

What scapulohumeral muscle is thick and rounded?

teres minor

What does the teres minor form?

the inferior border forms the inferior border of the axilla and quadrangular space

What is the origin, insertion, action, and innervation of the teres major?

O: dorsal surface of inferior angle of scapula

I: medial lip intertuberc groove

A: shoulder internal rotation and adduction

N: lower subscapular nerve

What is the origin, insertion, action, and innervation of the supraspinatus?

O: supraspinatus fossa

I: superior facet of the greater tubercle

A: assists deltoid in shoulder abduction

N: suprascapular nerve

*first 15` abd

What amount of shoulder abduction does the supraspinatus muscle contribute?

the first 15 degrees of abduction

What bony structure does the supraspinatus go under to insert on the superior facet of greater tubercle of the humerus?

acromion process

What is the origin, insertion, action, and innervation of the infraspinatus?

O: infraspinatus fossa

I: middle facet of the greater tuberosity

A: shoulder external rotation

N: suprascapular nerve

What is the origin, insertion, action, and innervation of the teres minor?

O: superior part of the lateral border of the scapula

I: inferior facet of the greater tubercle

A: shoulder external rotation

N: axillary nerve

(inferior border forms the inferior border of the axilla and quadrangular space)

What is the lateral margin of the humerus that has three facets?

greater tubercle of the humerus

What muscles attach to the greater tubercle of the humerus?

supraspinatus (sup facet)

infraspinatus (mid facet)

teres minor (inf facet)

(subscap attaches to lesser tubercle)

What projects anteriorly from the humerus bone?

lesser tubercle of the humerus

What muscle attaches to the lesser tubercle of the humerus?

subscapularis

What is the origin, insertion, action, and innervation of the subscapularis?

O: subscapular fossa

I: lesser tubercle

A: shoulder internal rotation

N: upper and lower subscapular nerves

What is it called when muscles are able to produce one movement when acting alone, but then produce different movements when acting together?

force couples

What is the purpose of force couples in the GH joint?

muscles balanced against one another ensure that the humeral head stays centered in the glenoid fossa

What do force couples prevent in the GH joint?

subacromial impingement

What are the general force couples of the shoulder?

• frontal plane force couples (deltoid + rot cuff) (upwward migration)

• transverse plane force couples (ant vs post rot cuf) (ant/post disp > kinematics)