MS1 B4W2L1 - Shoulder Region, Axilla & Posterior Triangle

Where Does the Phrenic Nerve Travel in the Posterior Triangle?

(C3-5) travels on the anterior surface of the anterior scalene through the posterior triangle on its way to the superior & middle mediastinum to innervate the diaphragm.

What are the Muscles in the Posterior Group of the Extrinsic Muscles of the Shoulder?

(a.k.a. the superficial "back" muscles) includes the trapezius, levator scapulae, rhomboids, latissimus dorsi. (Block 4, Week 1)

What are the 3 Parts of the Axillary Artery and What do they Do?

- 1st part ( medial ) - 2nd part ( deep ) - 3rd part ( lateral )

Components of the Shoulder

- 6 instrinsic muscles = 4 + 2 (rotator cuff + delt & tmaj) - 2 extrinsic muscles = groups (ant. & post.) - 2 spaces = (triangular & quadrangular) - 2 nerves = (suprascapular & axillary)

Suprahumeral "Joint" Space

- Not a true joint This space contains the: - biceps long head tendon - rotator cuff tendons - subacromial/subdeltoid bursa - gleno-humeral joint capsule *Inflammation in this space can impinge or otherwise affect these structures. See frozen shoulder syndrome

What Was the Axillary Artery Name before and Where Did it Change?

- The axillary a. is a continuation of the subclavian a. - It changes names at the 1st rib. - Once it passes the teres major, it enters the arm and becomes the brachial a. (brachium = "arm" in latin)( Green Part)

Ligaments of The Acromioclavicular (AC) Joint

- acromioclavicular ligament - coraco- clavicular ligament - coracoacromial ligament

What Makes Up the Boundaries of the Posterior Triangle?

- anterior margin of the trapezius, posterior margin of the sternocleido-mastoid and the clavicle. - the posterior triangle is posterior to the anterior triangle of the neck

What is the 2nd Part of the Axillary Artery and What does it Do?

- deep to pec. minor and has 2 branches. - The thoraco-acromial artery is related to the superior margin of pec. minor. It has pectoral, deltoid, acromial, and clavicular branches. - lateral thoracic a. runs along the lateral border of pec. minor. It supplies the breast.

Components of the Humerus from Superior to Posterior

- head - greater tuberosity - lesser tuberosity (tubercle)(anterior side) - anatomical neck - surgical "neck" - intertubercular ( bicipital ) groove (anterior side) - radial groove(posterior side) - deltoid tuberosity (anterior side)

What is the 3rd Part of the Axillary Artery and What does it Do?

- lateral to the pec. minor and has 3 branches. - The anterior circumflex humeral artery goes lateral and anterior to the neck of the humerus. - The posterior circumflex humeral artery goes lateral and posterior to the humerus. - These two will anastomose. - The subscapular artery goes medial and quickly divides into the circumflex scapular and thoracodorsal arteries.

What is the 1st Part of the Axillary Artery and What does it Do?

- medial to the pec. minor. - It has 1 branch called the supreme thoracic artery which supplies the 1st intercostal space

What Forms the Walls of the Axilla?

- posterior wall is formed the the latissimus dorsi, teres major, and subscapularis muscles. - lateral wall is formed conceptually by the bicipital groove of the humerus - anterior wall is formed by the pec. major, pec. minor, the clavicle & subclavius muscle. - medial wall is formed the thorax and serratus anterior.

Components of the Posterior Scapula

- scapular notch - spine of scapula - supraspinous fossa -infraspinous fossa - glenoid fossa - acromion

What is Frozen Shoulder Syndrome?

- sequelae of shoulder tendinitis, bursitis, or partial tear - A shoulder that is initially painful but which gradually becomes more restricted in motion in all directions is considered "frozen." - Many tissues of the suprahumeral "joint" space may be involved

Components of the Anterior Scapula

- superior border - acromion - coracoid process - lateral border - inferior angle - medial border - superior angle

What is in the Posterior Triangle of the Neck?

- supraclavicular part of the brachial plexus - phrenic nerve - accessory nerve - subclavian artery *Therefore, the control of the upper limb, diaphragm, and trapezius involves pathways through this region.

Components of the Lateral Scapula

- supraglenoid tubercle - glenoid fossa - infraglenoid tubercle

The Sternoclavicular (SC) Joint

- synovial joint (subtype: saddle-type). (but it functions like a ball & socket joint). - It has an articular disk dividing the joint into 2 separate joint cavities - The SC joint is very strong, dislocation is rare

The Acromioclavicular (AC) Joint

- synovial, plane-type jt. which allows gliding movements - relatively weak jt and has an incomplete articular disk. *This is the joint involved in shoulder separation injuries.

What are the Extrinsic Muscles of the Shoulder?

- two groups of muscles that attach the upper limb (via the pectoral girdle) to the axial skeleton. In general, these muscles act upon the scapula (except pec. major and lat. dorsi) - groups :anterior and posterior

Where does the Ext. Jugular V. Drain?

- will drain into the subclavian vein or the junction of the internal jugular and subclavian veins)

Movements at the Shoulder Joint II

-flexion - extension - circumduction

What are the 5 Regions of the Brachial Plexus?

1. 5 roots 2. 3 trunks 3. 2 kinds of divisions (6 total divisions) 4. 3 cords 5. 5 terminal branches

What are the Attachments of the subclavius Muscle?

1st rib and its costal cartilage , clavicle (inferior surface)

What Spinal Cord Segments Contribute Fibers to the axillary Branch?

C5 - C6

What Spinal Cord Segments Contribute Fibers to the Musculocutaneous Branch?

C5 - C7

What Spinal Cord Segments Contribute Fibers to the median Branch?

C5 - T1

What Spinal Cord Segments Contribute Fibers to the radial Branch?

C5 - T1

What Spinal Cord Segments Contribute Fibers to the ulnar Branch?

C8, T1

What are the Intrinsic Muscles of the Shoulder

Group of 6 muscles that attach from the pectoral (shoulder) girdle to the humerus. These include the deltoid m., teres major m., and the 4 rotator cuff muscles: Supraspinatus, Infraspinatus, Teres minor, and Subscapularis (S.I.T.S.). The rotator cuff muscles form a common tendon ("cuff") which is contained within the suprahumeral "joint" space. These muscles are all involved in some kind of rotation.

What Are the Contents of the Axilla?

Infraclav. Brachial Plexus - axillary a.,the axillary v. and distal part of the brachial plexus (cords & terminal branches) - Axillary Vessels and axillary lymph nodes - tendons of the biceps and coracobrachialis.

What Muscles Make Up the Quadrangular Space?

Lat. Border: lat. head of triceps Med. Border: long head of triceps Sup. Border: teres minor Inf. Border: teres major long head & lateral head of triceps m.

The Movements of the Scapula

Protraction: The scapula moves laterally (and anteriorly). Retraction: The scapula moves medially Elevation: The scapula moves superiorly Depression: The scapula moves inferiorly. Superior (Upward) Rotation: means the scapula rotates so that the glenoid cavity points upward. Inferior (Downward) Rotation: means the scapula rotates so that the glenoid cavity points downward.

What are the Rotator Cuff Muscles?

S.I.T.S. supraspinatus, infraspinatus, teres minor, subscapularis

The Glenohumeral Joint: Intrinsic Ligaments

The glenohumeral joint capsule thickens in certain places to form 3 ligaments (superior, middle, and inferior). The most frequently injured of these ligaments in shoulder dislocation is the inferior glenohumeral ligament (IGHL).

What are the Components of The Cervical Fascia

The investing fascia forms the roof of the posterior triangle and surrounds the SCM and trapezius. The prevertebral fascia covers the muscular floor of the triangle and surrounds the prevertebral and true, deep back muscles. The pretracheal fascia surrounds the thyroid gland, trachea, and esophagus.

What are the Floor Muscles of the Posterior Triangle?

The prevertebral fascia covers the muscular floor muslces - levator scapulae - middle scalene - anterior scalene the accessory nerve travels across the floor of the posterior triangle on the levator scapulae as it dives deep to trapezius to innervate it.

What are the Rotator Cuff Tendons

The rotator cuff itself is actually the conjoined tendon of the supraspinatus, infraspinatus, teres minor, and subscapularis muscles which forms a "cuff" around the fibrous joint capsule of the humerus. Note that the shoulder joint is not reinforced by the cuff inferiorly and thus is weak inferiorly.

Where Does the Brachial Plexus and Subclavian Artery Travel in the Floor of the Posterior Triangle?

The supraclavicular part of the brachial plexus - roots and trunks - is in-between the anterior and middle scalene muscles. The brachial plexus divisions are deep to the clavicle. The subclavian artery is also in-between the anterior and middle scalene muscles. However, it is inferior to the brachial plexus roots & trunks.

Other Articulations of the Shoulder Girdle

The suprahumeral "joint" is not a true joint, but a space - the space superior to the humerus and below the acromion. The scapulothoracic "joint" is also not a true joint. It is a term that describes the close approximation of the scapula and the ribs.

Tendon of Biceps Long Head

The tendon invaginates the joint capsule (so it is intracapsular), but does not enter the synovial cavity The tendon is held in the bicipital groove by the transverse humeral ligament

What is the Origin of the suprascapular n.?

a branch of the upper trunk of the brachial plexus.

Glenohumeral Joint

a synovial joint (subtype: ball & socket) that allows flexion, extension, abduction, adduction, medial and lateral rotation, and circumduction of the humerus It is reinforced by rotator cuff tendons and anteriorly by the glenohumeral ligaments (which are thickenings of the joint capsule).

Where is the Brachial Plexus Located?

across two different anatomical regions: the posterior triangle and axilla.

What is the Action of the Teres Major Muscle?

adducts & medially rotates humerus

What is the Action of the Pectoralis Major Muscle?

adducts & medially rotates humerus; clavicular head (acting alone) - flexes humerus; sternocostal head (acting alone) - extends humerus from flexed position

What is the Action of the deltoid Muscle?

ant. fibers - flex & medially rotate arm mid. fibers - abduct arm post. fibers - extend & laterally rotate arm

What Arteries of the Shoulder Region Travel Across the Floor of the Posterior Triangle?

as they proceed posteriorly to the shoulder region: the transverse cervical a. (superior to the suprascapular a.)(to trapezius) and the suprascapular a. (deep to the clavicle) (to supraspinatus They originate from the thyrocervical trunk (of the subclavian a.)

What is the Origin of the posterior circumflex humeral a.?

axillary a. (3rd part)

What is the Innervation of the teres minor Muscle?

axillary n.

What is the Innervation of the deltoid Muscle?

axillary nerve

axial skeleton

bones of the head (skull), neck (hyoid bone and cervical vertebrae), and trunk (ribs, sternum, vertebrae, and sacrum).

The Appendicular Skeleton

bones of the limbs (extremities, appendages) including those forming the pectoral (shoulder) and pelvic girdles.

Where does the Blood Supply of the Shoulder Region Originate From?

branches of the subclavian and axillary arteries

What Structures would be Compromised if There was a Fracture of the surgical neck of the humerus?

can endanger the axillary n. & posterior circumflex humeral a.

What are the Attachments of the deltoid Muscle?

clavicle (lateral 1/3), scapula (acromion & spine), humerus (deltoid tuberosity)

Pectoral (or Shoulder) Girdle

comprised of the clavicle, proximal humerus, and scapula Muscles that have all their attachments on these bones are "intrinsic shoulder muscles."

Where are the suprascapular nerve and artery found?

deep to both the supraspinatus and infraspinatus muscles. They travel together from the supraspinous fossa, then around the scapular spine, and then to the infaspinous fossa.

Which Non-Terminal Branches of The Brachial Plexus Come from the Roots?

dorsal scapular n. (innervates the rhomboids & levator scapulae) long thoracic n. (innervates the serratus anterior.)

What is the Action of the subclavius Muscle?

draws clavicle inferiorly and anteriorly; protects structures deep to clavicle

Joints of the Shoulder Girdle

glenohumeral, acromioclavicular, and sternoclavicular joints. the sternocostal joints and costovertebral joints provide the functional linkage of the upper limb to the support of the vertebral column.

Lateral View of the Glenohumeral Joint

glenoid labrum is a fibrocartilagenous ring that surrounds the glenoid fossa and helps deepen the socket of the shoulder joint

What is the Action of the supraspinatus Muscle?

initiates abduction; laterally (externally) rotates humerus

What Branche(s) Does the Axillary Nerve Give Off?

lat. brachial cutaneous n.

What is the Innervation of the Pectoralis Major Muscle?

lateral & medial pectoral nerves

Which Non-Terminal Branches of The Brachial Plexus Come from the Lateral Cord?

lateral pectoral n. - innervates the pectoralis major.

What is the Action of the infraspinatus Muscle?

laterally (externally) rotates arm

What is the Action of the teres minor Muscle?

laterally rotates arm

What muscles are responsible for inferior rotation?

lev. scapulae, rhomboids

What is the Innervation of the Serratus Anterior Muscle?

long thoracic n. (C5-C7)

What is the Innervation of the Teres Major Muscle?

lower subscapular n.

Which Non-Terminal Branches of The Brachial Plexus Come from the Medial Cord?

medial pectoral n. - innervates the pectoralis major & pec. minor.

What is the Innervation of the Pectoralis Minor Muscle?

medial pectoral nerve

What is the Action of the subscapularis Muscle?

medially (internally) rotates arm, adducts arm

What are the Termial Branches of the Brachial Plexus ?

musculocutaneous - muscles of the anterior (flexor) compartment of the arm axillary - innervates the deltoid & teres minor. radial - muscles of the posterior (extensor) compartments of the arm & forearm ulnar - muscles of the anterior (flexor) compartment of the forearm & hand median - muscles of the anterior (flexor) compartment of the forearm & hand

Which Non-Terminal Branches of The Brachial Plexus Come from the Trunks?

n. to subclavius - innervates the subclavius. suprascapular n. - innervates the supraspinatus & infraspinatus.

What is the Innervation of the subclavius Muscle?

nerve to subclavius

Where Does the posterior circumflex humeral a. Travel?

passes through the quad- rangular space in company with the axillary n. and anastomoses with the ant. circumflex humeral a. forming an arterial circle around the surgical neck of the humerus

Where Does the Axillary Nerve Travel?

passes to post. aspect of arm through quadrangular space in company with post. circumflex humeral a. and then winds around surgical neck of humerus

What are the Muscles in the Anterior Group of the Extrinsic Muscles of the Shoulder?

pec. major, pec. minor, subclavius, and serratus anterior.

What is the Action of the Serratus Anterior Muscle?

protracts scapula, raises ribs when scapula is fixed; stabilizes scapula

Where Does the Axillary Lymph Nodes Receive Lymph From?

receive lymph from the upper limb, but also 75% of the lymph drainage from the breast - which makes the axillary lymph nodes important in the diagnosis of breast cancer.

What are the Attachments of the Serratus Anterior Muscle?

ribs 1-9, scapula (medial border)

What are the Attachments of the Pectoralis Minor Muscle?

ribs 3 - 5, scapula (coracoid process)

Movements at the Shoulder Joint

rotation: - lateral (external) - medial (internal - adduction - abduction

What are the Attachments of the infraspinatus Muscle?

scapula (infraspinous fossa), humerus (greater tubercle

What are the Attachments of the Teres Major Muscle?

scapula (lateral border near inferior angle), humerus (bicipital groove)

What are the Attachments of the teres minor Muscle?

scapula (lateral border), humerus (greater tubercle)

What are the Attachments of the subscapularis Muscle?

scapula (subscapular fossa), humerus (lesser tubercle)

What are the Attachments of the supraspinatus Muscle?

scapula (supraspinous fossa), humerus (greater tubercle

What muscles are responsible for protraction?

serratus anterior (& pec. minor)

What Kind of Nerve Fibers are in the Brachial Plexus and What do they do??

somatic nerve plexus formed by ventral rami nerves of C5-T1 spinal cord segments controls the sensory and motor innervation of the upper limb (including the pectoral region, shoulder region, arm, forearm, and hand).

What Kind of Fibers are in the Cervical Plexus?

somatic nerve plexus with cutaneous (sensory) and motor branches. It is formed by C1-4 ventral rami nerves.

What is the Action of the Pectoralis Minor Muscle?

stabilizes & protracts scapula

What are the Attachments of the Pectoralis Major Muscle?

sternum, costal cartilages 1-6, clavicle, humerus (bicipital groove)

What Arteries That Form the Scapular Anastomosis?

subclavian a. --> thyrocervical trunk --> transverse cervical a. and suprascapular a. The rest of the arteries are: - axillary a. ( 3rd part ) - posterior circumflex humeral a. - subscapular a. - circumflex scapular a. - intercostal as. - dorsal scapular a.

The Sternoclavicular (SC) Joint Innervation

supraclavicular nerves and nerve to subclavius m

What are the 2 Major Parts of the Brachial Plexus?

supraclavicular part - posterior triangle of the neck. infraclavicular part - occupies the axilla.

The Acromioclavicular (AC) Joint Innervation

supraclavicular, lateral pectoral, and axillary nerves.

What is the Innervation of the infraspinatus Muscle?

suprascapular n.

What is the Innervation of the supraspinatus Muscle?

suprascapular n.

Innervation of The Glenohumeral Joint

suprascapular, lateral pectoral, and axillary ns.

Where does the Axillary Nerve Originate?

terminal br. of post. cord of brachial plexus

What is in the Roof/investing fascia of the posterior triangle?

the cutaneous branches of the cervical plexus: the lesser occipital, great auricular, transverse cervical, and supraclavicular nerve These are all sensory nerves.

What is the Rotator Cuff Critical Zone?

the portion of the rotator cuff that is a a potential site of tears and calcium deposit buildup. an area of vascular anastomoses within the rotator cuff. This anastomosis is alternately ischemic or hyperemic depending on whether there is tension on the cuff

What is scapulohumeral rhythm?

the scapula and humerus must move in a smoothly coordinated and integrated fashion in order to position the hand

What is the Quadrangular Space?

transmits the axillary n. and posterior circumflex humeral a. - note how these 2 structures wrap around the surgical neck of the humerus

What muscles are responsible for depression?

trapezius (inferior fibers)

What muscles are responsible for retraction?

trapezius (middle fibers) rhomboids

What muscles are responsible for superior rotation?

trapezius (superior & inferior fibers), serratus anterior

What muscles are responsible for elevation?

trapezius (superior fibers) levator scapulae

What is the Innervation of the subscapularis Muscle?

upper & lower subscapular ns.

Which Non-Terminal Branches of The Brachial Plexus Come from the Posterior Cord?

upper subscapular n. - innervates the subscapularis. thoracodorsal n. - innervates the latissimus dorsi. lower subscapular n. - innervates the subscapularis & teres major