Anatomy Note

[Donahue Granados]

Therotator cuff is a group of muscles in the shoulder that allow a wide range of movement while maintaining the stability of the glenohumeral joint. The rotator cuff includes the following muscles[1][2][3]:

The glenohumeral joint is a ball and socket joint and comprises a large spherical humeral head and a small glenoid cavity. This anatomy makes the joint highly mobile, however, really unstable. Stabilization in the shoulder is provided collectively by the non-contractile tissue of the glenohumeral joint (static stabilizers) such as the capsule, the labrum, the negative intraarticular pressure, and the glenohumeral ligaments; and the contractile tissues (dynamic stabilizers) such as the rotator cuff muscles and the long head of the biceps brachii.

The primary biomechanical role of the rotator cuff is to stabilize the glenohumeral joint by compressing the humeral head against the glenoid. These four muscles arise from the scapula and insert into the humerus. The tendons of the rotator cuff muscles blend with the joint capsule and form a musculotendinous collar that surrounds the posterior, superior, and anterior aspects of the joint, leaving the inferior aspect unprotected. This arrangement is an important factor since most shoulder luxations occur because the humerus slides inferiorly through the unprotected part of the joint. During arm movements, the rotator muscles contract and prevent the sliding of the head of the humerus, allowing full range of motion and providing stability.

The suprascapular artery is a branch of the thyrocervical trunk (a major branch of the subclavian artery) and originates at the base of the neck. It enters the posterior scapular region superior to the suprascapular foramen (the nerve passes through the foramen) and supplies the supraspinatus and infraspinatus muscles.

The subscapular artery is the largest branch of the axillary artery. It originates from the third part of the axillary artery, follows the inferior margin of the subscapularis muscle, and then divides into the circumflex scapular artery and the thoracodorsal artery. It gives vascular supply to the subscapularis muscle.

The posterior circumflex humeral artery originates from the third part of the axillary artery in the axilla. It enters the posterior scapular region through the quadrangular space (accompanied by the axillary nerve) and supplies the teres minor muscle.

The subscapularis is the largest component of the posterior wall of the axilla. It prevents the anterior dislocation of the humerus during abduction and medially rotates the humerus. A large bursa separates the muscle from the neck of the scapula [4].

Rotator cuff syndrome (RCS) describes a spectrum of clinical pathology ranging from minor injuries such as acute rotator cuff tendinitis to advanced/chronic rotator cuff tendinopathy and degenerative conditions.

Rotator cuff injuries represent a common cause of shoulder pain. The rotator cuff tendons, particularly the supraspinatus tendon, are uniquely susceptible to the compressive forces of subacromial impingement. Improper athletic technique, poor posture, poor conditioning, and failure of the subacromial bursa to protect the supporting tendons results in a progressive injury from acute inflammation, to calcification, to degenerative thinning, and finally to a tendon tear.

A clinical term often used nonspecifically to describe patients experiencing pain/symptoms with overhead activities. It is best to subdivide shoulder impingement into internal and external conditions:

The primary complaint is shoulder pain localized on the lateral aspect. It worsens with overhead activities, and patients often describe a painful arc during flexion and abduction at 60 degrees to 120 degrees and report pain at night due to lying on the same side. The presentation can be acute or chronic in onset. Young patients usually have an acute presentation because of a recent traumatic event or significant overexertion (e.g., lifting a heavy box). The function is often significantly impaired. Older patients or patients with repetitive overhead activities present chronically, and the loss of strength and function occurs gradually. The range of motion is normal, with positive provocative tests like Hawkins (pain on passive forced internal rotation of the shoulder). The drop arm test is confirmatory. If weakness is present on shoulder abduction, a rotator cuff tear should be suspected (MRI is the best test for diagnosis of rotator cuff tear).

The American Academy of Orthopedic Surgeons (AAOS) suggests patients with rotator cuff problems without tears can be treated conservatively with exercise and NSAIDs. The patient must understand to limit overhead activities and to use ice packs or heating pads. Proper physical therapy effectively treats most patients without subacromial decompression. No difference in outcome has been reported for surgery over physical therapy in several trials. Subacromial injection with steroids showed a short-term benefit in some trials and may improve a patient's compliance with physical therapy. Surgical consultation merits consideration if symptoms do not improve three months after conservative management. Arthroscopic acromioplasty may be a topic to discuss with the patient.

Etiologies and underlying causes are known to be multifactorial. Degeneration, impingement, and tension overload due to trauma may all lead to rotator cuff tears. Most often, the tears initially begin as partial tears of the supraspinatus tendon. Eventually, they can progress to full-thickness tears including all four of the rotator cuff muscles.

Pain and weakness are the presenting symptoms. Pain is prominent over the lateral deltoid, worsens with overhead activities, and by lying on the side at night. The absence of pain, however, does not exclude the diagnosis because a chunk of patients may also be asymptomatic. In fact, partial thickness tears cause more pain and disability than full-thickness tears. Painful arc test, drop arm test, and weakness in the external rotation is the most common observations on physical examination.

Conservative treatment with NSAIDs, and most importantly, physical therapy, should be the first attempt at therapy. Surgical treatment with arthroscopy is done in cases of both acute or chronic full-thickness tears since delay can result in significant muscle atrophy, tendon retraction, and poorer surgical results.

The mammary gland is a highly evolved and specialized organ developing on each side of the anterior chest wall. This organ's primary function is to secrete milk. Though the gland is present in both sexes, it is well-developed in females but rudimentary in males. The mammary gland is a vital accessory organ in the female reproductive system.

The mammary gland is classified as apocrine. Thus, the secretory cells' apical segment and a portion of their cytoplasm become part of the secretion. The mammary gland usually weighs between 500 and 1000 grams each. The organ is hemispherical in young adult females but becomes pendulous later in life. This article discusses the anatomy, function, and clinical importance of the mammary gland.

The mammary gland is situated in the pectoral region in the superficial fascia. However, a segment called the "axillary tail of Spence" pierces the deep fascia and lies in the axilla up to the 3rd rib level. The mammary gland extends vertically from the 2nd to the 6th rib. Horizontally, it spreads from the lateral sternal border to the mid-axillary line.

Deep to the mammary gland tissue is the retromammary space, a loose connective-tissue plane that gives free mobility to the gland. Below the retromammary space is the pectoral fascia, which covers the pectoralis muscle. The serratus anterior and external oblique are other muscles that lie deep in the mammary gland.

The skin consists of the nipple and areola. The nipple is a conical eminence situated in the 4th intercostal space (ICS). Piercing the nipple are 15 to 20 lactiferous ducts. The nipple contains richly innervated circular and longitudinal smooth muscle fibers, which make it erect upon stimulation. The nipple usually has no sweat glands, fat, or hairs.

The areola is the dark pinkish-brown area around the nipple. This area is rich in modified sebaceous glands (tubercles of Montgomery) during pregnancy and lactation. These modified glands produce oily secretions that prevent nipple and areolar cracking. Notably, the areola is devoid of fat and hair.

Glandular tissue is comprised of branching ducts and terminal secretory lobules. One lactiferous duct drains 15 to 20 lobes. These ducts enlarge to form the lactiferous sinus before they open separately into the nipple. Milk collects in the lactiferous sinuses and is released in response to the baby's suckling. The lactiferous ducts are arranged radially in the nipple. Hence, incisions in this area must be oriented radially to avoid cutting through multiple lactiferous ducts.

Fibrous stroma gives rise to septa called "suspensory ligaments of Cooper," which separate the lobes and suspend the mammary gland from the pectoral fascia. In patients with breast cancer, contraction of these ligaments causes breast rigidity and puckering of the overlying skin. In breast cancer, the Peau d'orange sign arises from lymphatic obstruction and subsequent cutaneous edema and fibrosis.

The mammary gland is best examined by dividing it into 4 quadrants, with vertical and horizontal imaginary lines passing through the nipple (see Image. Mammary Gland Quadrants). The regions are designated as the upper outer (UOQ), upper inner (UIQ), lower inner (LIQ), and lower outer (LOQ) quadrants.[1][2]

Breast development is minimal and comparable in both sexes until females reach puberty. Estrogen, progesterone, and growth hormone spurt during the pubertal phase and induce greater development in females than males. The smooth contour of female breasts is due to increased adipose tissue.

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