Scapular Pectoral Regions Flashcards
Pectoral Girdle: (shoulder
clavicle and scapula
connects the UL to the axial skeleton
articulates with the sternum at the sternoclavicular joint & with the UL at the shoulder joint
Note: the sternum is NOT part of the pectoral girdle
Supported and stabilized by pectoral muscles (which are connected to the ribs & vertebrae)
Superior portion of appendicular skeleton
Humerus Radius Ulna Carpal bones (wrist) metacarpal bones of hand phalanges (fingers)
glenohumeral joint
is a synovial ball and socket articulation of the head of the humerus and the glenoid cavity of the scapula.
It is multiaxial with a wide ROM usually provided at the cost of skeletal stability.
Joint stability is provided by the rotator cuff muscles/tendons, the long head of the biceps brachii m., related bony processes, and extracapsular ligaments.
Movements include: flexion, extension, abduction, adduction, medial rotation, lateral rotation and circumduction.
Muscles of the Pectoral Girdle
Serve as Rotator cuff mm. (or assist cuff mm.) Deltoid m. = ‘shoulder pads’ Teres major m. = ‘lats’ little helper’ Supraspinatus m. = ‘S’ Infraspinatus m. = ‘I’ Teres minor m. = ‘T’ Subscapularis m. = ‘S’
Deltoid M.
O: lateral clavicle, acromion & spine of scapula
I: deltoid tuberosity of humerus
A: abducts humerus (1°), flexes, extends & rotates humerus (2°)
N: Axillary n. & Post. Circumflex Humeral vessels
Teres Major M.
O: inferior angle of scapula
I: crest of lesser tubercle of humerus
A: medially rotates & extends humerus
N: Lower (inferior) Subscapular n. & subscapular vessels
Action is at the glenohumeral joint
Teres major can also contribute to adduction of the humerus
Supraspinatus M
O: supraspinous fossa
I: greater tubercle of humerus
A: abducts humerus
(1st 15°)
N: Suprascapular n. & vessels & dorsal scapular vessels
1st 15 degrees of abduction – initiates the abduction but doesn’t drop out when the deltoid begins acting. The supraspinatus continues to play an active role reaching its maximum at approximately 110 degrees of abduction of the arm.
Infraspinatus M.
O: infraspinous fossa
I: greater tubercle of humerus
A: laterally rotates humerus
N: Suprascapular n. & vessels & subscapular vessels
Teres Minor M.
O: lateral border of scapula
I: greater tubercle of humerus
A: lateral rotation of humerus
N: Axillary n. & suprascapular & subscapular vessels
Subscapularis M.
O: subscapular fossa
I: lesser tubercle of humerus
A: medial rotation of humerus
N: upper & lower subscapular nn. & subscapular vessels
Deltoid m.
provides outer muscular support for shoulder region
Rotator cuff provides
inner muscular support for shoulder region
Subacromial (Subdeltoid) Bursa
Membranous sac containing lubricating synovial fluid
Inferior to acromion & deltoid but superior to supraspinatus m.
Does not communicate with jt. capsule
In addition to the bursae that communicate with the articular cavity through apertures in the fibrous membrane, other bursae are associated with the joint but are not connect to it. These include: subacromial (subdeltoid) bursa = between the acromion (or deltoid muscle) and supraspinatus muscle (or joint capsule)
bursa between the acromion and the skin
bursa between the coracoid process and the joint capsule, and in relationship to tendons around the joint (coracobrachialis, teres major, long head of the triceps brachii and latissimus dorsi mm.)
Note: can become continuous with joint capsule due to attrition of supraspinatus tendon
Attrition of Supraspinatus tendon
Tendon degenerates in middle age
Up to ¼ of adults rupture tendon by 65
As it wears away, underlying joint capsule thins
When capsule opens, continuous with bursa, painful shoulder with limited arm movement
Spaces of the Shoulder Region
Quadrangular space
Triangular space
Triangular interval
Neurovascular contents of the spaces of the shoulder region
Quadrangular space = Axillary N. and Posterior circumflex humeral a.
Triangular space = Circumflex scapular a.
Triangular interval = Radial N. and Profunda brachii a.
Quadrangular space
Axillary N. and Posterior circumflex humeral a.
Triangular space
Circumflex scapular a.
Triangular interval
Radial N. and Profunda brachii a.
Quadrangular space
Teres minor m. = superior
Teres major m. = inferior
Long head of triceps brachii m. = medial
Surgical neck of humerus = lateral
Contains: axillary n & posterior circumflex humeral vessels
Triangular space
Teres minor m. = superior
Teres major m. = inferior
Long head of triceps brachii m. = lateral
Contains: Circumflex scapular vessels
Triangular interval
Teres major m. = superior
Long head of triceps brachii m. = medial
Lateral head of the triceps brachii m. = lateral
Contains: Radial n. & Deep brachial a.
*Deep brachial a. = Profunda brachial a.
Neurovascular Supply of the Shoulder Region
Suprascapular N. & A.
Dorsal Scapular N. & A.
Accessory N. & Transverse Cervical A.
Upper & Lower Subscapular Nn. & Subscapular A.
Suprascapular N. & A.
Nerve: ventral rami of C5-C6
Runs under supr. trans. scap. lig. thru suprascap. notch
Artery: thyrocervical trunk
Runs over supr. trans. scap. lig. above suprascap. notch
Both: pass thru spinoglenoid notch to infraspinatus fossa & supply supraspinatus & infraspinatus mm.
Suprascapular N runs under the superior transverse scapular ligament while the artery passes over the superior transverse scapular ligament.
Dorsal Scapular N. & Deep Transverse Cervical A.
Nerve: ventral ramus of C5
Artery: Deep trans. cervical a.
Both: run parallel to vertebral border of scapula & supply levator scapulae & rhomboid mm.
Accessory N. & Transverse Cervical A.
Nerve: brainstem (CN XI)
descends thru neck & joins artery
Artery: superficial transverse cervical a.
Branch of the thyrocervical trunk
runs deep to trapezius m.
Both: supply trapezius m.
Accessory nerve on deep surface of the trapezius m
Note: C3-C4 ventral rami (cut) at the medial edge that contribute to the plexus
Transverse cervical a. & v. = runs deep to the trapezius m., posterolaterally from the thyrocervical trunk
Accessory N. & Transverse Cervical A
Nerve: brainstem (CN XI)
descends thru neck & joins artery
Artery: superficial transverse cervical a.
Branch of the thyrocervical trunk
runs deep to trapezius m.
Both: supply trapezius
Accessory nerve on deep surface of the trapezius m
Note: C3-C4 ventral rami (cut) at the medial edge that contribute to the plexus
Transverse cervical a. & v. = runs deep to the trapezius m., posterolaterally from the thyrocervical trunk
Upper & Lower Subscapular Nn and Subscapular A.
Nerve: posterior cord of brachial plexus
ventral rami of C5-C6
Artery: Axillary A.
Subscapular a.
splits to thoracodorsal a. & circumflex scapular a.
All: supply subscapularis m.
Note: lower subscap. n. & subscap. a. – supply teres major m.
Subscapular A.
off Axillary A.
gives rise to circumflex scapular a
anastomoses with suprascapular (via infraspinatus a) and dorsal scapular aa.
Collateral Circulation of the Scapular Region
Extensive collateral circulation
Ensures adequate blood supply to UL
in event of insufficient flow thru axillary a. / temporary ligation
collateral circ. by thyrocervical trunk & subscapular a.
Collateral Circulation of the Scapular Region: ligated axillary a
ligate between thyrocervical trunk & subscapular a.
blood flow in subscapular a. reverses
allows blood to flow to UL
ligate anywhere distal to subscapular a & blood cannot flow to UL
Pectoral Region
Region of m. attachment between upper limb & anterior chest
Composed of pec. major m. & pec. minor m.
Pec. major divided into clavicular & sternocostal heads
Pec. minor enveloped in clavipectoral fascia
Pectoralis Major M.
O: clavicle, sternum & ribs 2-6
I: crest of greater tubercle of humerus
A: adducts& medially rotates humerus
N: med. & lat. pectoral nn. & thoracoacrominal vessels
Pectoralis Minor M.
O: ribs 3-5
I: coracoid process of scapula
A: protracts scapular
N: Medial Pectoral n. & Thoracoacromial vessels
Pectoral Region Arterial Supply
Lateral Thoracic (Mammary) A.
Internal Thoracic (Mammary) A.
Thoracoacromial A.
Lateral Thoracic (Mammary) A.
Branch of axillary a. (deep to pec. minor m.)
Runs with long thoracic n.
Supplies lateral thorax, lateral pec region & lateral breast
Internal Thoracic (Mammary) A.
Branch of Subclavian a. (inside thorax)
Descends across intercostal spaces lateral to sternum
Supplies ant. thorax, med. pec region & med. Breast
Thoracoacromial A.
Branch of Axillary A. (under pec minor)
sends off 4 subsequent branches
Pectoral a. – supplies upper pec. region
Clavicular a. – supplies clavicle region
Acromial a. – supplies upper shoulder region
Deltoid a. supplies lower shoulder region
Pectoral Region Innervation
Cutaneous Nerves
Medial Pectoral Nerve
Lateral Pectoral Nerve
Long Thoracic Nerve
Cutaneous Nerves
General sensory
T1-T6
lateral & anterior cutaneous branches of intercostal nn.
Medial Pectoral Nerve
Medial cord of brachial plexus
Derived from ventral rami (C8-T1)
Pierces pectoralis minor m. to enter pectoralis major m.
Supplies pectoralis minor m. & part of pectoralis major m.
Lateral Pectoral Nerve
Lateral cord of brachial plexus
Derived from ventral rami (C5-C7)
Runs above pectoralis minor m. to enter pectoralis major m.
Supplies remainder of pec. major m.
Long Thoracic Nerve
Derived from ventral rami (C5-C7)
Supplies serratus anterior m. superficially
Damage to long thoracic n. can occur during mastectomy
Results in “winged scapula”
Long thoracic nerve ‘holds UL to thoracic wall’
Lies on the superficial surface of serratus anterior
