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Wineski - Upper Limb I
Shoulder and Arm
18
Anatomy
Professional
09/22/2008

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Cards

Term
How are the premuscle masses formed?
Definition
Embryonic premuscle mass in each bud splits around the central skeletal axis to form two separate premuscle masses, one dorsal and one ventral
Term
What nerves are present during differentiation of the muscle masses?
Definition
Embryonic ventral primary rami of spinal nerves C5-T1 penetrate limb bud mesenchyme, intermingle to form the trunks of the brachial plexus, which then split into dorsal and ventral divisions. The divisions enter the differentiating dorsal and ventral muscle masses.
Term
What forms out of the differentiating neuromuscular masses?
Definition

Individual muscles and nerves form out of these neuromuscular masses, and can be designated as dorsal or ventral limb muscles and dorsal or ventral nerves of the brachial plexus

 

All parts (dorsal and ventral) of the brachial plexus are derived from ventral primary rami of spinal nerves

Term
What are the characteristics of the ventral muscles?
Definition

Muscles derived from the embryonic ventral premuscle mass are located on the anterior (ventral) side of the adult upper limb

 

Ventral limb muscles are innervated by ventral divisions/nerves of the brachial plexus (remember: the brachial plexus is formed by ventral primary rami of spinal nerves C5-T1)

 

Ventral muscles act to flex and/or pronate

Term
What are the characteristics of dorsal muscles?
Definition

Muscles derived from the embryonic dorsal premuscle mass are located on the posterior (dorsal) side of the upper limb.

 

Dorsal limb muscles are innervated by dorsal divisions/nerves of the brachial plexus (remember: dorsal divisions/nerves of a plexus≠dorsal primary rami of spinal nerves)

 

Dorsal muscles act to extend and/or supinate

Term
What are the muscles that insert onto the clavicle/scapula unit and act upon the sternoclavicular and acromioclavicular joints?
Definition

trapezius

 

levator scapulae

 

rhomboid major and minor

 

pectoralis minor

 

serratus anterior

 

subclavius

Term
What are the muscles that insert onto the humerus or radius/ulna and act upon the glenohumeral joint?
Definition

Pectoralis major

 

Latissimus dorsi

 

Deltoid

 

Supraspinatus

 

Infraspinatus

 

Teres major and minor

 

subcscapularis

 

biceps brachii

 

coracobrachialis

 

triceps brachii

Term
What causes rotation of the scapula?
Definition
Trapezius and serratus anterior cause upward and downward rotation of scapula
Term
Explain wing scapula
Definition

Innervation for serratus anterior is long thoracic nerve

 

Blow to side wall of chest (stab, gun shot, radical mastectomy) can sever the long thoracic nerve

 

Full abduction will be weakened and not completely disabled because other muscles are recruited to help -A patient will not be able to elevate arm above 90 degrees

 

However, if try to do a push-up, the scapula will flare away from the chest wall = wing scapula

 

The serratus anterior is what holds the scapula in place

Term
Which muscles connect the shoulder to the vertebral column?
Definition

Trapezius

 

levator scapulae

 

rhomboid minor

Term
Which muscles connect the shoulder to the thoracic wall?
Definition

Pectoralis minor

 

serratus anterior

 

subclavius

Term
What are the muscles connecting the clavicle/scapula unit to the humerus or radius/ulna?
Definition

Pectoralis major

 

deltoid

 

supraspinatus (rotator cuff)

 

infraspinatus (rotator cuff),

 

teres major,

 

teres minor (rotator cuff)

 

subscapularis (rotator cuff),

 

biceps brachii,

 

coracobrachialis

 

triceps brachii

Term
Which shoulder muscle is not innervated by branches of the ventral primary rami of spinal nerves?
Definition
Trapezius is innervated by the accessory nerve (cranial XI)
Term
What is the function of the rotator cuff?
Definition

assist in holding the head of humerus in place

 

assist in stabilizing the glenohumeral joint

 

A group of four muscles that covers the glenohumeral joint on all side except inferior

 

-Supraspinatus - DOES NOT ROTATE It initiates abduction. There is a 90 degree angle btw. scapula and humerus. This means you can not get abduction unless you change the angle, which is done by the suprospinatus. Once get to horizontal plane, all the deltoid fibers are horizontal and can only drive humerus into scapula. Need upward rotation of scapula by trap and serratus anterior

 

-Infraspinatus

 

-Teres Minor

 

-Subscapularis

Term
What's the innervation of the rotator cuff?
Definition

Innervation

 

-Supraspinatus = suprascapular

 

-Infraspinatus = suprascapular

 

-Teres Minor = axillary nerve

 

-Subscapularis = upper and lower subscapular

Term
Explain the quadrangular space
Definition

Quadrangular ( = quadrilateral) space = lateral axillary hiatus

 

Boundaries

 

-Superior: teres minor

 

-Inferior: teres major

 

-Medial: long head of triceps

 

-Laterally: surgical head of humerus

 

Major contents

 

-Axillary nerve

 

-Posterior circumflex humeral artery

Term
Explain the triangular space
Definition

Boundaries

 

-Superior: teres minor

 

-Inferior: teres major

 

-Laterellay: long head of triceps

 

Major contents - Circumflex scapular artery

Term
What's the basic structure of the brachial plexus?
Definition

mnemonic - Robert Taylor Drinks Cold Beers

 

R - Rami (ventral primary) - C5-T1

 

T - Trunks - Upper (C5,6), Middle (C7), Lower (C8,T1)

 

D - Divisions - Anterior and Posterior

 

C - Chords - Lateral, Medial, and Posterior

 

B - Branches - major terminal branches

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