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.
