14 - Axilla and Shoulder Flashcards
acromioclavicular joint
- Synovial plane joint
- primarily supported (reinforced) by extrinsic ligaments: Coracoclavicular ligament (two strong ligaments between the coracoid process and clavicle -Conoid ligament and Trapezoid ligament)
sternoclavicular joint
- Synovial saddle-shaped joint
- Articular surfaces: manubrium, first costal cartilage and the sternal end of clavicle
- Only articulation between the upper limb and axial skeleton
- Strongly supported by ligaments and very rarely dislocated
which joints are required for movement of the scapula
sternoclavicular and acromioclavicular joints
anterior thoracoappendicular muscles (4)
Pectoralis major
Pectoralis minor
Subclavius
Serratus anterior
posterior thoracoappendicular muscles (5)
Trapezius Latissimus dorsi Levator scapulae Rhomboideus major Rhomboideus minor
scapulohumeral muscles (3)
Deltoid
Rotator cuff (Supraspinatus, Infraspinatus, Teres minor, Subscapularis)
Teres major
trapezius innervation and actions
INNERVATION- Spinal accessory n. (CN XI), C3, C4
ACTIONS -
Superior fibres - elevate scapula
Middle fibres - retract scapula
Inferior fibres - depress scapula
Sup. & Inf. fibres - rotate scapula glenoid-up
latissimus dorsi innervation and actions
INNERVATION- Thoracodorsal n.
ACTIONS- extend, adduct & medially rotate humerus at glenohumeral joint
- Forms posterior axillary fold along with teres major m.
levator scapulae innervation and actions
INNERVATION- Dorsal scapular n.
ACTIONS- elevate scapula, rotate scapula glenoid-down
rhomboideus minor innervation and actions
INNERVATION- dorsal scapular n.
ACTIONS - retract scapula, rotate scapula glenoid-down, hold scapula to thoracic wall
rhomboideus major innervation and actions
INNERVATION- dorsal scapular n.
ACTIONS - retract scapula, rotate scapula glenoid-down, hold scapula to thoracic wall
deltoid innervation and actions
INNERVATION - axillary nerve
ACTIONS -
Anterior fibers - flex & medially rotate arm
Middle fibers- abduct arm ((5)15 - 90°)
Posterior fibers - extend and laterally rotate arm
teres major
INNERVATION- lower subscapular nerve
ACTIONS - adduct and medially rotate arm
- Forms posterior axillary fold along with latissimus dorsi
Rotator cuff
There are four rotator cuff muscles. Three of them act to rotate the arm. All of the tendons of the muscles of the rotator cuff blend with and reinforce the fibrous joint capsule of the glenohumeral joint (i.e., they form a ‘cuff’ around the shoulder joint).
The rotator cuff muscles are the PRIMARY support of the glenohumeral joint. All are innervated by C5 & C6 ventral rami.
subscapularis O, I, A
O - subscapular fossa of scapula
I - lesser tubercle of humerus
ACTIONS - medial rotation & adduction of arm
infraspinatus O, I, A
O - infraspinous fossa of scapula
I - greater tubercle of humerus ACTIONS - lateral rotation of arm
Teres Minor O, I, A
O - lateral border of scapula
I - greater tubercle of humerus
ACTIONS - lateral rotation, some adduction
Supraspinatus O, I, A
O - supraspinous fossa of scapula
I - greater tubercle of humerus ACTION - initiates abduction (first 5o in isolation, but contributes up to 15o of abduction)
glenohumeral joint
- Synovial ball-and-socket joint between the head of the humerus and glenoid fossa of the scapula
- The area of contact and stability of the joint are increased by the glenoid labrum - a fibrocartilaginous ring that increases the depth of the glenoid fossa
- primary support is from Tendons of the muscles of the rotator cuff - reinforce the joint capsule posteriorly, superiorly and anteriorly. Their tonic contraction serves to hold the humeral head in the glenoid fossa.
- Weakest part is inferiorly – shoulder dislocations usually occur in the infero-anterior direction
Pectoralis major O, I, A
O: clavicle & sternum
I: Lateral lip of intertubercular groove Innervation: Lateral and medial pectoral nerves Actions: Medially rotates and adducts arm Forms anterior axillary fold
Pectoralis minor Insertion
coracoid process
Serratus anterior innervation and action
INNERVATION: Long thoracic nerve (C5,C6,C7)
Actions: Protracts and rotates scapula glenoid-up - Paralysis results in a ‘winged scapula’
Axilla
Pyramidally shaped space acting as a passageway between the neck and upper limb.
Borders of axilla
-Apex = cervicoaxillary canal (communication between
neck and axilla)
-Anterior - pectoralis major and minor
-Anterior axillary fold - formed by P. major m.
-Posterior – subscapularis (scapula), teres major,
latissimus dorsi
-Posterior axillary fold - formed by Latissimus Dorsi &
Teres major mm.
-Medial - Serratus anterior on the thoracic wall
-Lateral - intertuburcular groove (housing tendon of the
long head of biceps brachii)
-Base – skin and axillary fascia between arm and thoracic
wall
contents of axilla
Fat
Lymph
Axillary artery and vein
Axillary sheath (contains proximal parts of
axillary vessels and brachial plexus) Cords and branches of the brachial plexus
axillary lymph nodes
(20-30) drain lymphatic vessels from the lateral part of the breast, superficial lymphatic vessels from the thoracoabdominal walls above the level of the umbilicus and the vessels from the upper limb.
five groups of axillary lymph nodes
- Anterior (pectoral) - receive lymph from the lateral part of the breast and superficial vessels from the anterolateral thoracic wall above the level of the umbilicus.
- Posterior (subscapular) - receive superficial lymph vessels from the back, down as far as the iliac crests
- Lateral (humeral) - receive most of the lymph vessels from the upper limb
- Central - receive lymph from anterior, posterior and lateral nodes
- Apical - receives lymph from all other nodes, as well as lymph from the superficial arm that travels with the cephalic vein.
- -most lymph from the breast (over 75%) drains to the axillary lymph nodes
axillary vessels
- axillary artery is a short vessel that begins at the lateral border of the first rib as a distal continuation of the subclavian artery. It ends at the inferior border of the teres major muscle where it changes its name to the Brachial artery. It is surrounded by the cords and branches of the brachial plexus.
- The axillary vein lies on the medial/anterior side of axillary artery. It begins at the inferior border of teres major by the union of the brachial veins and the basilic vein and ends at the lateral border of the first rib where it becomes the subclavian vein.
- The proximal parts of the axillary vessels and the surrounding brachial plexus are enclosed in the axillary sheath (a distal continuation of the prevertebral fascia in the neck).
axillary artery parts (3)
-division is determined by presence of pectoralis minor muscle, and part number indicates number of branches
- Part 1: (lateral border of the first rib to the medial border of pectoralis minor)
i) . Superior thoracic artery - supplies muscles in the 1st and 2nd intercostal spaces
Part 2: (posterior to the pectoralis minor muscle)
i) . Thoracoacromal trunk - pierces the clavipectoral fascia has four branches:
- acromial, deltoid, pectoral, clavicular
ii) . Lateral thoracic - supplying the pectoral muscles, lymph nodes and the breast
Part 3: (lateral border of pectoralis minor to the inferior border of teres major)
i). Subscapular has two terminal branches:
Circumflex scapular (in triangular space), Thoracodorsal (to latissimus dorsi)
ii). Anterior Circumflex humeral
iii). Posterior circumflex humeral (quadrangular space)
brachial plexus
-A plexus of nerves responsible for almost all of the muscles of the upper limb
It begins in the neck and continues into the axilla (by passing through the cervicoaxillary canal)
Roots of cervical plexus
-The brachial plexus has five roots formed from the VENTRAL RAMI of C5 - T1
Trunks of cervical plexus
The five roots unite to form three trunks
- Superior trunk - union of C5 and C6
- Middle trunk - continuation of C7
- Inferior trunk - union of C8 and T1
divisions of cervical plexus
- As the trunks pass through the cervicoaxillary canal they each separate into ventral and dorsal divisions
cords and branches of cervical plexus
- The dorsal divisions unite, posterior to the axillary artery, to form the posterior cord. Branches of the posterior cord are responsible for innervating all muscles on the posterior and lateral sides of the upper limb. The terminal branches of the posterior cord are the axillary nerve and radial nerve.
- The ventral divisions recombine to form the lateral cord (C5 - C7) and medial cord (C8- T1) (named for their relationship to the 2nd part of the axillary artery). The three major ventral division nerves of the brachial plexus are the median nerve, the ulnar nerve and the musculocutaneous nerve.
cutaneous innervation of the upper limb
There is always considerable overlap between adjacent dermatomes. The regions with the least amount of overlap with adjacent dermatomes are used for testing nerves/ sensations/ spinal cord segments.
These regions are: C5 - upper/lateral arm C6 - pollex (thumb) C7 - 3rd digit (middle finger) C8 - 5th digit (pinky) T1 - medial aspect of elbow
superficial veins of upper limb
- All of the arteries are travelling with companion vv. that are responsible for draining the same structures. Some superficial veins, do not travel with arteries.
- Cephalic vein
- Basilic vein
- Median cubital
superficial fascia of the upper limb
Consists primarily of fat that contains cutaneous nerves, superficial veins and superficial lymphatics
Cutaneous innervation of the upper limb
comes from: -Supraclavicular nerves from the cervical plexus -Intercostobrachial nerve (lateral cutaneous branch of T2 that joins with the medial brachial cutaneous n.)
-branches off the brachial plexus
Cephalic vein
begins on the dorsum of the hand (dorsal venous arch/ plexus), ascends on the lateral side of the forearm and arm, runs through the deltopectoral triangle, pierces the clavipectoral fascia and drains into the axillary vein.
basilic vein
begins on the dorsum of the hand (dorsal venous arch/ plexus), ascends on the medial side of the forearm and arm, pierces the brachial fascia, merges with the companion veins of the brachial artery to form the axillary vein.
median cubital
runs diagonally across the anterior aspect of the elbow joint forming a communication between the basilic and cephalic veins. It is a common site for venipuncture.
Axillary vein
NOT a superficial v. – begins at the inferior border of the Teres Major m. as a continuation of the basilic vein
