The Armpit (Human Anatomy): Picture, Function, Parts, Conditions, & More Human Anatomy Next The arrangement of the chest wall, shoulder bones and muscles, and the upper arm create a small hollow called the armpit. The armpit is the underside of the shoulder joint, and is among the warmest areas of the body. The armpit is also called the axilla. Blood and lymph vessels serving the arm travel through the armpit. There are more than 20 lymph nodes (small lumps of tissue that are part of the body's lymphatic system, which helps fight infection) in the armpit. These lymph nodes normally cannot be felt through the skin. The armpits have a high concentration of hair follicles and sweat glands. Armpit Conditions Hyperhidrosis : Excessive sweating, which often affects the armpits and hands. The cause is unknown; the perspiration is not due to anxiety or stress. Irritant contact dermatitis : Skin inflammation (redness, swelling, pain, or heat) caused by an irritating substance touching the skin. Soaps, deodorant, alcohol, and dry air may all cause irritant contact dermatitis of the armpit.

Allergic contact dermatitis : An allergic reaction to something directly touching the skin, usually causing redness and small blisters. Irritant contact dermatitis affects the armpit more often than allergic contact dermatitis. Psoriasis : The armpits are often affected by psoriasis, a condition causing red plaques with a silvery scale to appear on the skin. Psoriasis is an autoimmune condition, meaning it is caused when the immune system mistakenly attacks the body's own tissues. Acanthosis nigricans : A skin disorder causing velvety, light brown to black markings on the skin of the armpits, neck, groin, and/or under the breasts. Tinea corporis ( ringworm ): A fungal infection of the uppermost layer of the skin (epidermis). Ringworm often creates a ring-shaped rash, although no worm is involved. Tinea axillaris: A term occasionally used for ringworm affecting the armpit. Candidiasis (yeast infection): A skin infection by the yeast Candida, causing irritated skin with white plaques. Candida grows best on warm, moist skin, and may affect the armpits.

Intertrigo : A condition in which moist, warm skin becomes irritated and often mildly infected. Redness, itching, and burning of the skin in the armpits are common symptoms of intertrigo. Armpit abscess : When infected fluid (pus) collects in the armpit. The bacteria Staphylococcus is the most common cause. Hidradenitis suppurativa : A long-term (chronic) condition causing red, tender bumps in the skin of the armpits and/or groin. The bumps often turn into abscesses and can cause scarring over time. Erythrasma: A long-term (chronic) skin infection caused by the bacteria Corynebacterium. The infection causes red-brown, irritated patches of skin in the armpits or other moist areas of skin. Armpit boil (furuncle): A skin infection of a single hair follicle and surrounding skin. It causes a painful, red lump on the skin, which may grow into an abscess. Armpit folliculitis : Inflammation of the hair follicles, usually caused by bacterial infection. Most folliculitis is mild and goes away without specific treatment.

Axillary lymphadenopathy: Enlargement of the lymph nodes of one or both armpits. The swelling may be caused by infection, cancer, or other causes and may be detected during a doctor’s examination or on imaging tests. Armpit skin tags (acrochordons): Harmless, small flaps of skin that commonly occur on the neck or armpits. Skin tags are more common with older age. Continued Armpit Tests Physical examination : By observing and palpating (feeling) the armpit, a doctor may find enlarged lymph nodes or other armpit conditions. Axillary lymph node biopsy : Part or all of a lymph node is removed from the armpit and examined under a microscope, sometimes to look for cancer. Ultrasound: A device placed on the surface of the skin bounces high-frequency sound waves off the structures in the armpit. The signals are converted into images on a video screen, allowing health care providers to see structures inside the body. Computed tomography ( CT scan ): A CT scanner takes multiple X-rays, and a computer compiles the X-rays into images of the armpit and nearby structures.

Magnetic resonance imaging ( MRI scan ): An MRI scanner uses a high-powered magnet and a computer to create detailed images of the armpit and adjacent body areas. Armpit Treatments Skin moisturizers : Because skin dryness makes many skin conditions worse, moisturizing the skin can be helpful in many armpit conditions. Topical steroids : Creams or ointments that contain cortisone, which reduces skin inflammation. Topical steroids can reduce skin itching and irritation in the armpit. Axillary lymph node dissection : Removal of one or all of the armpit’s lymph nodes. This is often done as part of the surgical treatment for breast cancer. Examining the removed lymph node(s) helps identify whether and how much the breast cancer has spread. Antiperspirant: Special prescription-strength antiperspirants can help control the excessive armpit sweating of hyperhidrosis. Botulinum toxin injection (Botox): A doctor may inject Botox into the sweat glands of the armpit; this can reduce the excessive sweating of hyperhidrosis. Incision and drainage : Armpit abscesses often must be cut open and drained by a health care provider in order to allow proper healing.

Antibiotics : Skin infections in the armpit caused by bacteria can usually be treated with antibiotics. Endoscopic thoracic sympathetectomy: A surgical treatment for hyperhidrosis, in which nerves that contribute to sweating are cut. In successful cases, excessive sweating is noticeably improved. Topical antifungals : Fungal infections of the armpit (such as with Candida) can usually be treated with topical creams and ointments containing antifungal drugs. Skin tag removal : Doctors can remove skin tags using scissors or scalpel, electric cautery (burning), tying them off with string, or freezing them with liquid nitrogen. WebMD Image Collection Reviewed by Varnada Karriem-Norwood, MD on November 15, 2014 Sources Axillary Lymph Nodes Anatomy, Diagram & Function | Body Maps Your message has been sent. OK We're sorry, an error occurred. We are unable to collect your feedback at this time. However, your feedback is important to us. Please try again later. Close Axillary lymph node group The body has about 20 to 40 bean-shaped axillary lymph nodes located in the underarm area.

These lymph nodes are responsible for draining lymph – a clear or white fluid made up of white blood cells – from the breasts and surrounding areas, including the neck, the upper arms, and the underarm area. They are about 1cm in size and are arranged into five groups: subscapular axillary (posterior), apical (medial or subclavicular), pectoral axillary (anterior), brachial (lateral), and central lymph nodes. The subscapular axillary lymph nodes are located on the lower part of the armpit’s posterior (rear) wall. The apical and pectoral nodes are located respectively on the upper and lower parts of the pectoralis minor, a thin, flat muscle of the chest. The brachial nodes are located relative to the axillary vein's medial (near the middle) and posterior portions. The central axillary lymph nodes are located inside the adipose tissue near the armpit’s base. Breast cancer initially develops as a lump in the breast, but often spreads to the axillary lymph nodes, which allows it to access the lymphatic system and travel to other areas of the body.

During surgical procedures to remove breast cancer, including lumpectomies and partial, modified radical, radical, or total mastectomies, surgeons often remove some of the axillary lymph nodes to determine whether the breast cancer has spread, and also to determine cancer staging. What is the Axilla? | What is? Home » Science » What is the Axilla? What is the Axilla? What is the Axilla? The axilla is the junction between the inner part of the upper arm and the shoulder. This part is commonly known as the armpit in which many anatomical structures pass through for support of the upper extremities. The axilla is pyramidal in shape. It has an apex which is directed towards the neck area. The base of this pyramid faces downward toward the body. The apex of the axilla is bordered anteriorly by the collar bone or clavicle, posteriorly by the upper border of our shoulder blades called the scapula, and medially by the first rib. The base meanwhile is bordered by several muscles. On the anterior part, the pectoralis major borders it. On the posterior part, some muscles attached to the shoulder blade act as borders.

These muscles include the subscapularis and teres major. The latissimus dorsi with attachments to the ribs and trunk also form part of the posterior border for the base of the axilla. Medially, the base is bordered by the muscles in between the ribs, and laterally, the upper part of the humeral shaft along with the coracobrachialis muscle serve as borders. Located in the axilla region are lymph nodes, which are important for drainage of lymph from the upper parts of the body including the neck, shoulder, and upper arms or extremities. These lymph nodes are parts of the body’s system to provide immunity from diseases. Another important structure that passes through the axilla is the brachial plexus. This brachial plexus is like a nerve pathway which supplies sensory signals to most parts of the upper arm. If this part is damaged, then one can expect a decrease or absence of normal sensation in the upper arm region. Other structures that pass through the axilla are the axillary artery and veins with their branches, the intercostobrachial nerves, the long thoracic nerve, and the infraclavicular part of the brachial nerve.

The apocrine glands are also located in the axilla. These glands produce sweat under the arm usually at the onset of puberty. It is also at the time of puberty when hair growth is noticed in the axilla. Because of these changes, various personal hygiene activities are modified and adjusted according to the body’s needs. If you like this article or our site. Please spread the word. Share it with your friends/family. The Axilla - Human Anatomy Posterior Humeral Circumflex. Anterior Humeral Circumflex. 1. The highest thoracic artery (a. thoracalis suprema; superior thoracic artery) is a small vessel, which may arise from the thoracoacromial. Running forward and medialward along the upper border of the Pectoralis minor, it passes between it and the Pectoralis major to the side of the chest. It supplies branches to these muscles, and to the parietes of the thorax, and anastomoses with the internal mammary and intercostal arteries. 2. The thoracoacromial artery (a.

thoracoacromialis; acromiothoracic artery; thoracic axis) is a short trunk, which arises from the forepart of the axillary artery, its origin being generally overlapped by the upper edge of the Pectoralis minor Projecting forward to the upper border of this muscle, it pierces the coracoclavicular fascia and divides into four branchespectoral, acromial, clavicular, and deltoid. The pectoral branch descends between the two Pectorales, and is distributed to them and to the mamma, anastomosing with the intercostal branches of the internal mammary and with the lateral thoracic. The acromial branch runs lateralward over the coracoid process and under the Deltoideus, to which it gives branches; it then pierces that muscle and ends on the acromion in an arterial network formed by branches from the transverse scapular, thoracoacromial, and posterior humeral circumflex arteries. The clavicular branch runs upward and medialward to the sternoclavicular joint, supplying this articulation, and the Subclavius.

The deltoid (humeral) branch, often arising with the acromial, crosses over the Pectoralis minor and passes in the same groove as the cephalic vein, between the Pectoralis major and Deltoideus, and gives branches to both muscles. 3. The lateral thoracic artery (a. thoracalis lateralis; long thoracic artery; external mammary artery) follows the lower border of the Pectoralis minor to the side of the chest, supplying the Serratus anterior and the Pectoralis, and sending branches across the axilla to the axillary glands and Subscapularis; it anastomoses with the internal mammary, subscapular, and intercostal arteries, and with the pectoral branch of the thoracoacromial. In the female it supplies an external mammary branch which turns round the free edge of the Pectoralis major and supplies the mamma. 4. The subscapular artery (a.

subscapularis) the largest branch of the axillary artery, arises at the lower border of the Subscapularis, which it follows to the inferior angle of the scapula, where it anastomoses with the lateral thoracic and intercostal arteries and with the descending branch of the transverse cervical, and ends in the neighboring muscles. About 4 cm. from its origin it gives off a branch, the scapular circumflex artery. FIG. 524 The scapular and circumflex arteries. The Scapular Circumflex Artery (a. circumflexa scapulæ; dorsalis scapulæ artery) is generally larger than the continuation of the subscapular. It curves around the axillary border of the scapula, traversing the space between the Subscapularis above, the Teres major below, and the long head of the Triceps laterally (Fig. 524); it enters the infraspinatous fossa under cover of the Teres minor, and anastomoses with the transverse scapular artery and the descending branch of the transverse cervical.

In its course it gives off two branches: one (infrascapular) enters the subscapular fossa beneath the Subscapularis, which it supplies, anastomosing with the transverse scapular artery and the descending branch of the transverse cervical; the other is continued along the axillary border of the scapula, between the Teres major and minor, and at the dorsal surface of the inferior angle anastomoses with the descending branch of the transverse cervical. In addition to these, small branches are distributed to the back part of the Deltoideus and the long head of the Triceps brachii, anastomosing with an ascending branch of the a. profunda brachii. 5. The posterior humeral circumflex artery (a. circumflexa humeri posterior; posterior circumflex artery) (Fig.

524) arises from the axillary artery at the lower border of the Subscapularis, and runs backward with the axillary nerve through the quadrangular space bounded by the Subscapularis and Teres minor above, the Teres major below, the long head of the Triceps brachii medially, and the surgical neck of the humerus laterally. It winds around the neck of the humerus and is distributed to the Deltoideus and shoulder-joint, anastomosing with the anterior humeral circumflex and profunda brachii. 6. The anterior humeral circumflex artery (a. circumflexa humeri anterior; anterior circumflex artery) (Fig. 524), considerably smaller than the posterior, arises nearly opposite it, from the lateral side of the axillary artery. It runs horizontally, beneath the Coracobrachialis and short head of the Biceps brachii, in front of the neck of the humerus. On reaching the intertubercular sulcus, it gives off a branch which ascends in the sulcus to supply the head of the humerus and the shoulder-joint.

The trunk of the vessel is then continued onward beneath the long head of the Biceps brachii and the Deltoideus, and anastomoses with the posterior humeral circumflex artery. Peculiarities.The branches of the axillary artery vary considerably in different subjects. Occasionally the subscapular, humeral circumflex, and profunda arteries arise from a common trunk, and when this occurs the branches of the brachial plexus surround this trunk instead of the main vessel. Sometimes the axillary artery divides into the radial and ulnar arteries, and occasionally it gives origin to the volar interosseous artery of the forearm. Chapter 8: THE SHOULDER AND AXILLA Chapter 8: The shoulder and axilla Muscles of pectoral region The upper limb is connected to the trunk ventrally by the pectoralis major, pectoralis minor, subclavius, and serratus anterior. The pectoralis major is inserted into the humerus, the others into the shoulder girdle. They are all supplied by branches of the brachial plexus.

The origin, insertion, innervation, and action of each muscle are listed in table 8-1 . In this and subsequent tables of muscles, only the chief attachments and principal actions are given. The fascia extending between the pectoralis major and the latissimus dorsi forms the floor of the axilla. This axillary fascia is suspended from the fascia around the pectoralis minor, and traction on it produces the hollow of the armpit. It is attached above to the clavicle as the clavipectoral fascia, which is also anchored to the first rib and to the coracoid process (fig. 8-1 ). The supraclavicular nerves (lateral, intermediate, and medial) arise from the cervical plexus and cross the clavicle (where they may be rolled against the bone). They supply the skin over the shoulder and, because they arise from the same roots (C3, 4) as the phrenic nerve, diaphragmatic inflammation is one cause of pain referred to the shoulder. The pectoralis major is a large, fan-shaped muscle, the rounded, lower border of which forms the anterior axillary fold (fig. 8-2 ).

It functions mainly as an adductor of the arm and aids in throwing, pushing, and shoveling. When the arms are fixed in climbing, it draws the body upward. The pectoralis major covers the pectoralis minor, which, in turn, covers the second part of the axillary artery. The serratus anterior (see fig. 8-5 ) is a large, fan-shaped muscle that forms the medial wall of the axilla. Its digitations of origin (which interdigitate with those of the external oblique muscle of the abdomen) can be seen in a muscular person. The serratus rotates the scapula so that the inferior angle moves laterally; it is thereby important in abduction of the arm above the horizontal plane. It pulls the scapula anteriorward in throwing and pushing. Paralysis of the serratus anterior (e.g., from injury or inflammation of its nerve) is characterized by "winging" of the scapula, i.e., the medial border of the bone stands away from the chest wall. Superficial muscles of back (see fig.

8-4 ) The upper limb is connected to the vertebral column by the latissimus dorsi and trapezius and, deep to these, by the levator scapulae, rhomboid minor, and rhomboid major (table 8-2 ). The latissimus is inserted into the humerus, the others into the shoulder girdle. Although the muscles are located on the back, they are supplied from the ventral rami of cervical nerves. The trapezius receives its major supply from the accessory nerve (CN XI). The trapezius (fig. 8-3 ) is a large, superficial, triangular muscle that is responsible for the sloping ridge of the neck. The muscles of the two sides together form a trapezoid. The region around C7 is more aponeurotic than muscular, resulting in a slightly depressed area frequently visible. The most superior part of the trapezius, together with the levator scapulae, elevates the shoulder. The muscles of the two sides together brace the shoulders by pulling the scapulae posteriorward, and their weakness results in drooping shoulders.

The latissimus dorsi is a large, mostly superficial, triangular muscle. The posterior aspect of its most superior fibers is covered by the trapezius, and its lateral part, together with the teres major, forms the posterior axillary fold. The trapezius and latissimus dorsi intersect near the medial border of the scapula, at a small area termed the triangle of auscultation (figs. 8-3 and 8-4 ), where the thoracic wall is minimally covered by muscles. The latissimus is a powerful adductor and extensor of the arm and is important in the downstroke in swimming as well as in rowing, climbing, and hammering, and in supporting the weight of the body on the hands. Muscles of shoulder (table 8-3 ) The deltoid, supraspinatus, infraspinatus, teres minor, teres major, and subscapularis arise from the scapula and are inserted into the humerus. They are supplied by cervical nerves 5 and 6 by way of branches of the brachial plexus. The deltoid is responsible for the roundness of the shoulder (see fig. 8-2 ).

It originates from the inferolateral clavicle and spine of the scapula as well as the acromion process. It is a powerful abductor of the arm in the plane of the scapula. The anterior and posterior parts of the muscle are involved, respectively, in flexion and medial rotation and in extension and lateral rotation. The posterior and middle parts together abduct the arm in a coronal plane. The deltoid acts also as a stabilizer in horizontal movements, e.g., drawing a line across a blackboard. The supraspinatus initiates abduction and aids the deltoid in that motion, which is usually incomplete in paralysis of either of these muscles (fig. 8-5 ). The interval between the teres minor, teres major, and the surgical neck of the humerus is divided longitudinally by the long head of the triceps into a triangular space medially and a quadrangular space (containing the axillary nerve) laterally (see fig. 9-2 ).

The tendons of the supraspinatus, infraspinatus, teres minor, and subscapularis blend with the capsule of the shoulder joint and form a musculotendinous (or rotator) cuff, which is incomplete in its inferior aspect (fig. 8-6 ). The tendons of the cuff are prone to degenerative changes. Moreover, nipping of a tender structure (e.g., from a calcified deposit in the supraspinatus tendon) between the acromion and the greater tubercle of the humerus results in pain during the mid-range of abduction (painful arc syndrome). Axilla The pyramidal interval between the arm and the chest wall is termed the axilla. The pectoralis major and latissimus dorsi form prominent anterior and posterior axillary folds, respectively. A vertical line midway between the anterior and posterior axillary folds is referred to as the midaxillary line. The fascial base extends between these folds. The apex of the axilla is the interval between the posterior border of the clavicle, the superior border of the scapula, and the external border of the first rib.

Through the apex, the axillary vessels and their accompanying nerves pass from the neck to the arm. The axilla is bounded medially by the upper ribs and their intercostal muscles and by the serratus anterior; it is limited laterally by the intertubercular groove of the humerus. The chief contents of the axilla are the axillary artery and vein, a part of the brachial plexus and its branches, and the axillary lymph nodes. Nerves of the upper limb Brachial plexus (figs. 8-1 , 8-7 , 8-8 and 8-9 ) The nerves to the upper limb arise from the brachial plexus, which is situated partly in the neck and partly in the axilla. It is formed by the union of the ventral rami of the lower four cervical and first thoracic nerves (C5,6,7,8; T1). Frequently it receives a contribution from one nerve higher or one nerve lower. The brachial plexus descends in the posterior triangle of the neck. Here it lies superior to the clavicle and posterior to the sternomastoid muscle, where it can be palpated.

In surface anatomy, the brachial plexus in the neck lies inferior to a line from the posterior margin of the sternomastoid at the level of the cricoid cartilage to the midpoint of the clavicle. Here the plexus can be injected with a local anesthetic (brachial block), the pulsations of the third part of the subclavian artery (situated inferior and anterior to the plexus) being used as a guide (fig. 8-7 ). The brachial plexus descends in the concavity of the medial two thirds of the clavicle (see fig. 8-5 ) and accompanies the axillary artery under cover of the pectoralis major. The plexus is enclosed with the axillary vessels in the axillary sheath, which is a prolongation of the cervical fascia posterioinferior to the clavicle and into the axilla. The brachial plexus may be blocked in the axilla by injecting a local anesthetic into the axillary sheath. A common arrangement of the brachial plexus is shown in figures 8-8 and 8-9 .

The first two ventral rami (C5,6) unite to form the upper trunk, the next (C7) constitutes the middle trunk, and the last two (C8; T1) join to form the lower trunk. Each trunk divides into an anterior and posterior division. The anterior divisions of the upper and middle trunks unite to form the lateral cord, that of the lower trunk constitutes the medial cord, and the three posterior divisions join to form the posterior cord. The cords are named from the positions that they occupy in relation to the second part of the axillary artery. In general, the lateral and medial cords supply the ventral aspect of the limb, whereas the posterior cord supplies the dorsal aspect. At the lateral border of the pectoralis minor, the cords divide into terminal branches, each of which contains fibers derived from several spinal nerves. In summary, the brachial plexus is composed successively of ventral rami and trunks in the neck, divisions that are usually posterior to the clavicle, and cords and branches in the axilla. The nerve bundles that descend from the neck come to meet, and then to accompany, the more superficially and medially placed artery that has ascended from the thorax.

The lower trunk lies on the first rib behind the subclavian artery. When a cervical rib is present, the lower trunk may be stretched as it crosses the rib. Injuries to the brachial plexus are very important. "Upper type" injuries (to C5 or 6 or to the upper trunk) are produced when the arm is pulled downward and the head is drawn away from the shoulder. The upper limb tends to lie in medial rotation ("waiter's-tip hand"). Such injuries may occur during birth. "Lower type" injuries (to C8, Tl, or to the lower trunk) are produced when the arm is pulled upward and may occur during birth also. The short muscles of the hand are affected and "claw hand" results (see fig. 8-14 ). Involvement of the brachial plexus may also be a part of the neurovascular compression syndrome. Branches of the brachial plexus Several branches arise superior to the clavicle (fig. 8-9 ).

The ventral rami give rise to (1) the dorsal scapular nerve (chiefly C5) to the rhomboids and (2) the long thoracic nerve (C5-7) to the serratus anterior. The upper trunk gives off (1) the nerve to the subclavius (chiefly C5), which frequently contributes to the phrenic nerve, and (2) the suprascapular nerve (C5,6) to the supraspinatus and infraspinatus. The terminal branches of the cords arise inferior to the clavicle. Several of them send articular twigs (e.g., to the shoulder joint), although these are not listed separately here. The lateral cord gives origin to (1) lateral pectoral nerves (C5-7) to the pectoralis major and minor, (2) the musculocutaneous nerve, (3) the lateral head of the median, and (4) possibly a contribution to the ulnar (fig. 8-9 ). The medial cord (fig.

8-9 ) provides (1) medial pectoral nerves (C8; T1) to the pectoralis major and minor, (2) the medial brachial cutaneous nerve (T1) to the medial side of the arm, (3) the medial antebrachial cutaneous nerve (C8; T1) to the medial side of the forearm, (4) the ulnar, and (5) the medial head of the median. The posterior cord gives off (1) the upper subscapular nerve(s) (C5) to the subscapularis, (2) the thoracodorsal nerve (C7,8) to the latissimus dorsi, (3) the lower subscapular nerve(s) (C5,6) to the subscapularis and teres major, (4) the axillary, and (5) the radial. A simple scheme (fig. 8-10 ) shows the basic arrangement of the segmental innervation (dermatomes) of the skin of the upper limb, which is supplied successively down the preaxial border and then up the postaxial border.

Table 8-4 shows the segmental innervation of the muscles of the upper limb. The five most important branches of the brachial plexus are the musculocutaneous, median, ulnar, axillary, and radial nerves. The musculocutaneous nerve (C5-7) (fig. 8-11 ) The musculocutaneous nerve, very variable, arises from the lateral cord and usually pierces the coracobrachialis. It may carry a part or all of the lateral head of the median nerve and send these fibers to the medial head in the arm. The musculocutaneous nerve supplies the flexor muscles on the anterior aspect of the arm and the skin on the lateral side of the forearm. The median nerve (C[5,] 6-8; T1) (fig. 8-11 ) The median nerve arises by lateral and medial heads from the lateral and medial cords, respectively. The median nerve supplies most of the flexor muscles on the front of the forearm, most of the short muscles of the thumb, and the skin on the lateral part of the front of the hand. In injury to the median nerve (see fig.

8-14 ), anesthesia and proprioceptive loss in the digits impose a severe handicap on the proper use of the hand. In section superior to the elbow, pronation is lost, flexion and abduction of the hand are impaired, interphalangeal flexion is lost in the lateral two fingers, and thumb movements, especially opposition, are severely impaired. In section at the wrist, a serious condition, anesthesia and impaired thumb movements result. Median nerve lesions are commonly followed by painful disorders (e.g., causalgia). The ulnar nerve (C7, 8; T1) (fig. 8-12 ) The ulnar nerve arises from the medial cord, occasionally with a small contribution from the lateral cord. The ulnar nerve supplies some of the flexor muscles of the anterior forearm, many of the short muscles of the hand, and the skin on the medial part of the palmar and dorsal aspect of the hand. In injury to the ulnar nerve, anesthesia and proprioceptive loss occur in the ulnar portion of the hand, including the little and ring fingers.

In section superior to the elbow, adduction of the hand is impaired, the fingers cannot be adducted or abducted, the proximal phalanges cannot be flexed, and the middle and distal phalanges cannot be extended. The result is a "claw hand" (main en griffe) (see fig. 8-14 ), which is the opposite of the Z-position (see fig. 11-8 ). In section at the wrist, clawing is more marked. Recovery after ulnar nerve lesions is seldom complete. The axillary nerve (C5, 6) (fig. 8-13 ) The axillary nerve is a branch of the posterior cord. The site of the axillary nerve may be represented by a horizontal line through the middle of the deltoid. At the lower border of the subscapularis, it turns posteriorward through the quadrangular space (with the posterior circumflex humeral artery), between the long and lateral heads of the triceps (see fig. 9-2A ). It divides into anterior and posterior branches. The former winds around the surgical neck of the humerus and supplies the deltoid and gives some cutaneous twigs.

The posterior branch supplies the teres minor and deltoid and becomes the upper lateral brachial cutaneous nerve. Section of the axillary nerve results in paralysis of the deltoid (and incomplete abduction of the arm by the supraspinatus) and loss of sensation in a small patch of skin over the deltoid. The radial nerve (C[5,] 6-8; [T1]) (fig. 8-13 ) The radial nerve may be regarded as the continuation of the posterior cord. It spirals around the posterior aspect of the humerus under cover of the lateral head of the triceps (see figs. 6-12 and 9-2 ) and thereby reaches the lateral aspect of the limb (hence the name radial). The radial nerve supplies the extensor muscles of the posterior arm and forearm and the skin on the posterior arm, forearm, and hand. The radial nerve may be injured in the axilla by pressure of a crutch or by hanging the arm over the back of a chair (" Saturday night palsy"). Section of the radial nerve in the axilla causes extensive muscular paralysis, including loss of extension of the forearm, wrist, and proximal phalanges (fig. 8-14 ).

In a lesion at the elbow, extension of the forearm and wrist are preserved; supination mayor may not be weakened. Thumb movements are impaired. Anesthesia is slight, owing to overlapping of adjacent nerves. Radial nerve fibers regenerate well. Blood vessels Subclavian and axillary artery The main artery carrying blood to the upper limb provides branches to the cervical, scapular and pectoral regions on its course. It also gives rise to the vertebral artey, that is critical for the supply of vital centers in the medulla oblongata. The vessel is named successively subclavian, axillary, and brachial (see figs. 7-3 and 8-7 ). The subclavian artery ascends into the neck to form an arch, which lies on the first rib and extends superior to the clavicle. In severe arterial bleeding from the upper limb, the main vessel can be compressed against the first rib in the angle between the clavicle and the posterior margin of the sternomastoid. At the apex of the axilla, where the subclavian artery reaches the lateral border of the first rib (see fig. 8-7 ), its name is changed to axillary.

The pectoralis minor crosses the axillary artery, and it is customary to consider the vessel in three parts: (1) medial, (2) posterior, and (3) lateral to that muscle. The first part is enclosed in fascia (axillary sheath) in common with the axillary vein and the brachial plexus (see fig. 8-1 ). The second part, being covered by the pectoralis minor, is inferior and medial to the coracoid process. The cords of the plexus are named from the positions that they occupy in relation to the second part of the artery. The third part is fairly superficial and is the one used for compression and ligation. Branches of the axillary artery (see fig. 7-3 ) The axillary artery provides half a dozen named but quite variable branches. The branches vary in their level of origin, but it is frequently stated that the first part gives one branch, the second part two, and the third part three. The significant point is the existence of an extensive arterial anastomosis around the scapula and on its costal and dorsal surfaces.

This anastomosis usually enables a collateral circulation to become established after ligature of the third part of the subclavian or the first part of the axillary artery. The highest, or superior thoracic, artery supplies adjacent muscles. The thoracoacromial artery divides into branches that ramify on the thoracic wall (supplying the pectoral muscles) and the acromion (hence the name). The lateral thoracic artery descends along the lateral border of the pectoralis minor and gives off mammary branches. The subscapular artery descends along the lateral border of the subscapularis, gives off the circumflex scapular artery (which passes posteriorward through the triangular space), and then accompanies the thoracodorsal nerve as the thoracodorsal artery. The anterior circumflex humeral artery is inconstant. The posterior circumflex humeral artery passes posteriorward through the quadrangular space with the axillary nerve. Axillary vein (see fig. 8-7 ) The basilic and brachial veins unite to form the axillary, which accompanies the artery on its medial side.

It receives the cephalic vein and commonly the thoraco-epigastric veins (which provide a collateral route in obstruction of the inferior vena cava). At the lateral border of the first rib, the axillary becomes the subclavian vein, which does not rise superior to the clavicle. It unites with the internal jugular to form the brachiocephalic vein. Joints of shoulder Shoulder joint (see figs. 6-3 , 6-4 , and 8-6 ) The shoulder, or glenohumeral, joint is a large, freely movable, ball-and-socket articulation between the glenoid cavity of the scapula and the head of the humerus. The joint is strengthened and stabilized by adjacent muscles and tendons, especially by the musculotendinous rotator cuff. The coracoid process, the coraco-acromial ligament, and the acromion form a protective arch above the supraspinatus tendon and the head of the humerus. The arch and the cuff are separated by a large, common subacromial and subdeltoid bursa.

The shallow glenoid cavity is slightly deepened by a fibrous or fibrocartilaginous lip, the glenoid labrum, attached to its margin. The joint capsule, which is fused to the tendons of the cuff, is attached to the margin of the glenoid cavity and to the anatomical neck of the humerus, except medially, where it extends inferiorly onto the shaft, thereby allowing abduction although permitting downward dislocation. The upper epiphysial line of the humerus is extracapsular, except medially. The capsule is thickened by various ligaments between the two bones. The joint is supplied by adjacent nerves, e.g., from the posterior cord. The synovial membrane that lines the capsule provides a sheath for the biceps tendon as the latter traverses the joint and descends in the intertubercular groove of the humerus. The joint cavity usually communicates with the subcoracoid bursa and the subscapular bursa (beneath the subscapularis tendon).

Several other bursae (e.g., the subacromial bursa and its continuation, the subdeltoid bursa) occur around the shoulder but usually do not communicate with the joint. Sternoclavicular joint The sternum and first costal cartilage articulate with the medial end of the clavicle to form, on the basis of the movements that occur, a ball-and-socket joint. The capsule is strengthened by ligaments such as the costoclavicular. The articular surfaces are largely fibrocartilaginous and are separated by a fibrous or fibrocartilaginous articular disc. Acromioclavicular joint The medial border of the acromion forms a plane joint with the lateral end of the clavicle (see fig. 6-3 ). The articular surfaces are largely fibrocartilaginous, and the joint may be divided. The coracoclavicular ligament (which consists of conoid and trapezoid parts) extends from the coracoid process to the conoid tubercle and trapezoid line on the inferior surface of the clavicle. This ligament reinforces the acromioclavicular joint.

Scapular ligaments The coraco-acromial ligament has already been mentioned. The (superior) transverse scapular ligament, which may be ossified, bridges the scapular notch. The suprascapular artery and nerve pass over and under the ligament, respectively. ("Army over and navy under the bridge.") Movements of shoulder Movements at shoulder joint (figs. 6-4 and 8-15 ). The movements at a ball-and-socket joint are abduction and adduction, flexion and extension, and rotation and circumduction. The shoulder has the greatest freedom and range of movement of any joint, owing in large part to the addition of scapular movement. The glenoid cavity and the head of the humerus do not fit snugly, but the ever-present tendency for dislocation during movement is resisted by the muscles of the musculotendinous cuff, which hold the head of the humerus in place. The movements described here are those related to the plane of the body of the scapula. Hence abduction is movement lateral and slightly anterior, away from the trunk; adduction is the converse.

Similarly, in flexion the arm is carried anterior and medial across the front of the chest, and in extension it moves posterior and lateral away from the chest. Lateral movement in a strictly coronal plane includes extension and lateral rotation as well as abduction. If the arm is fixed, as in climbing, movements of the scapula on the humerus occur. Abduction is performed by the deltoid and supraspinatus, and, at least in many patients, this movement is impaired if either muscle is paralyzed. The chief adductors against resistance are the pectoralis major, latissimus dorsi, and teres major. The main flexors are the pectoralis major, anterior part of the deltoid, and biceps. The extensors are the latissimus dorsi and posterior part of deltoid. The subscapularis rotates the humerus medially, and the infraspinatus and teres minor rotate it laterally. Abduction and lateral rotation are mainly under the control of the C5 segment of the spinal cord, and adduction and medial rotation are controlled by C6-8 segments. Movements of shoulder girdle.

Little if any motion occurs at the shoulder joint without accompanying movement or displacement of the rest of the shoulder girdle. Displacements of the scapula include (1) elevation and depression, (2) rotation, (3) lateral or anterior movement (protraction), and (4) medial or posterior movement (retraction). During movement, the acromion is kept away from the chest wall by the clavicle, which acts as a strut. The lateral end of the clavicle travels in an arc around the sternoclavicular joint, which acts as a pivot. The medial border of the scapula is held against the chest and travels in the arc of the chest wall. Movement at the acromioclavicular joint is continuous, and the clavicle must be free to rotate around its longitudinal axis. Elevation of the scapula, as in shrugging the shoulders, is produced by the upper part of the trapezius and the levator scapulae. Depression is usually left to gravity. Anteriorward movement (protraction) of the scapula along the chest wall, as in pushing, is produced by the serratus anterior.

Posteriorward movement (retraction), as in bracing the shoulders, is caused by the trapezius muscles and the rhomboids. The serratus anterior rotates the scapula so that its inferior angle moves laterally, and this movement generally accompanies elevation of the arm. The opposite rotation can be carried out against resistance by the levator scapulae and rhomboids. A movement such as elevation of the arm is highly complicated and requires precise integration. The deltoid and supraspinatus begin abduction, then the scapula commences to rotate. The inferior angle of the scapula travels laterally (serratus anterior), and the lateral angle proceeds superiorly and medially (trapezius). The clavicle moves also. The humerus can be elevated on the scapula to about 120 degrees, and the scapula on the chest about 60 degrees, so that the combined movements allow elevation of the arm to a fully vertical position. Injury to the accessory nerve (CN XI) interferes with shrugging of the shoulder.

Damage to the long thoracic nerve (which innervates the serratus anterior) results in "winging" (posterior displacement of the medial border) of the scapula during movements of the shoulder girdle. Questions 8-1 Name important muscles involved in (a) throwing and pushing, (b) climbing and hammering, (c) drawing a line across a blackboard. 8-1 The pectoralis major is involved in throwing and pushing, the latissimus dorsi in climbing and hammering, and the deltoid muscle in drawing a line across a blackboard. 8-2 What is "winging of the scapula" and how is it produced? 8-2 Normally, the serratus anterior keeps the scapula close to the thoracic wall in pushing. When the muscle is paralyzed, e.g., by injury to the relatively exposed long thoracic nerve, the medial border and inferior angle of the scapula move laterally and dorsally (winging). 8-3 What is the chief effect of paralysis of the trapezius? 8-3 Paralysis of the trapezius results in inability to shrug the shoulder and to raise the arm above the horizontal.

8-4 What gives roundness to the shoulder? 8-4 The deltoid gives roundness to the shoulder. When the muscle is atrophied, the shoulder appears "squared." 8-5 Which structures form the musculotendinous cuff and what is its clinical importance? 8-5 The tendons of the supraspinatus, infraspinatus, teres minor, and subscapularis form the musculotendinous cuff. Degeneration or calcified deposits may cause pain on abduction (painful arc syndrome). 8-6 On what does the lower trunk of the brachial plexus lie? 8-6 The lower trunk of the brachial plexus lies on the first rib, posterior to the subclavian artery (see figs. 8-7 and 20-5 ). In rare instances, a variable cervical rib (i.e., a rib associated with C7 vertebra) is found either unilaterally or bilaterally. Angulation of the subclavian artery, brachial plexus, or both over a cervical rib is one example of the "neurovascular compression syndrome" of the upper limb.

Features may include pain on movement of the arm and numbness of the fingers. It is of interest to note that a mesenchymal or cartilaginous cervical rib is normally present bilaterally in the fetus. 8-7 Why is the upper limb in medial rotation ("waiter's-tip hand") after an "upper type" (Erb-Duchenne) injury to the brachial plexus? 8-7 In "upper type" injuries to the brachial plexus, the upper limb is in medial rotation because the subscapularis (medial rotator) is unopposed by the paralyzed lateral rotators (infraspinatus and teres minor, supplied by C5,6). 8-8 Why may "claw hand" follow a "lower type" (Klumpke-Dejerine) injury to the brachial plexus? 8-8 "Claw hand" may result from a "lower type" injury to the brachial plexus because the flexors and extensor are unopposed by the paralyzed interossei and lumbricals (supplied by the ulnar nerve). See figure 11-8 .

8-9 What are the results of deltoid paralysis? 8-9 In deltoid paralysis, abduction of the arm by the supraspinatus alone is usually incomplete, although aefective abduction at the shoulder joint may be masked by lateral rotation of the scapula caused by the trapezius. Complete division of the axillary nerve also results in some loss of sensation over the deltoid muscle. See figure 8-13 . 8-10 Which bursae usually communicate with the cavity of the shoulder joint? 8-10 The subcoracoid and subscapular bursae usually communicate with the cavity of the shoulder joint. 8-11 What normally resists the tendency of the shoulder joint to become dislocated? 8-11 The muscles of the musculotendinous cuff, which hold the head of the humerus in place, resist any tendency of the shoulder to become dislocated. When dislocation occurs, the head of the humerus escapes through the inferior and anterior part of the capsule, where it is thinnest and weakest. The dislocation is primarily subglenoid and then usually becomes subcoracoid.

Figure legends Figure 8-1 Diagram of the clavipectoral fascia and its relation to the axillary sheath. Sagittal section. Figure 8-2 Surface landmarks of the upper limb. (From Royce, J., Surface Anatomy, Davis, Philadelphia, 1965.) Figure 8-3 Surface landmarks of the back and upper limbs. (From Royce, J., Surface Anatomy, Davis, Philadelphia, 1965.) Figure 8-4 The superficial muscles of the back. Note how the latissimus dorsi covers the inferior angle of the scapula. The left trapezius is removed to show the rhomboids and levator scapulae. (Based on Mollier.) Figure 8-5 The shoulder from above. Note the relation of the neurovascular bundle (subclavian vessels and brachial plexus) to the clavicle. Note also that the insertion of the trapezius in the concavity formed by the spine, acromion, and clavicle is embraced by the origin of the deltoid muscle from the corresponding convexity.

Figure 8-6 The musculotendinous (or rotator) cuff and the capsule of the shoulder joint, shown after cutting the cuff and removing the humerus. The tendons of the supraspinatus, infraspinatus, teres minor, and subscapularis blend with the capsule and form the cuff, which is incomplete below. The subscapular bursa communicates with the joint cavity (between the superior and middle glenohumeral ligaments). Figure 8-7 The relationships of the brachial plexus and the axillary vessels. Note that the subclavian artery and vein are separated by the scalenus anterior. Figure 8-8 Diagram of the anterior aspect of the brachial plexus. A, anterior divisions of trunks; P, posterior divisions of trunks. The muscles to which the rami are ultimately distributed are listed in Table 8-1 . Figure 8-9 Simplified scheme of cervical and brachial plexuses, showing the distribution of nerve fibers in the roots of origin. T.D., thoracodorsal.

(Brachial plexus based partly on Seddon.) Figure 8-10 A, The basic arrangement of the segmental innervation (dermatomes) of the skin of the upper limb, which is supplied successively down the pre-axial border and then up the postaxial border. B, An embryo of 7 weeks (measuring 17 mm between small arrows), showing the longitudinal axes (A) of the upper and lower limbs. The parts of the limbs rostral to the axes are called pre-axial, those caudal to the axes are termed postaxial. The sequence of dermatomes from pre-axial to postaxial is shown on each limb. Cf. fig. 15-11 . Figure 8-11 Diagram of the muscular and cutaneous branches of the musculocutaneous and median nerves. The smaller drawing shows the approximate areas of cutaneous innervation. Figure 8-12 Diagram of the muscular and cutaneous branches of the ulnar nerve. The smaller drawing shows the approximate areas of cutaneous innervation. Two common varieties of distribution are presented for the back of the hand.

Figure 8-13 Diagram of the muscular and cutaneous branches of the axillary and radial nerves. The adjacent drawing shows the approximate areas of cutaneous innervation. Two common varieties of distribution are presented for the back of the hand. Figure 8-14 Drawings showing the main motor defects after section or other damage to the ulnar, radial, and median nerves. Figure 8-15 Movements at the shoulder. Jump to: Anatomy Tables - Pectoral Region & Breast an imaginary vertical line passing through the middle of the axilla used as a surface landmark for descriptive purposes midclavicular line an imaginary vertical line passing through the midshaft of the clavicle used as a surface landmark for descriptive purposes deltopectoral triangle ( TG2-12 ) a triangle in the upper chest region that is bounded medially by the clavicle, superiorly by the deltoid m., and inferiorly by the pectoralis major m.

the deltopectoral triangle is pierced by the cephalic vein on its course from the upper limb to join the axillary vein in the axilla nipple ( N182 , TG2-10 ) located superficial to the 4th intercostal space in the male and prepuberal female; areola is dark ring surrounding nipple location of the left nipple may be used to help locate the apex of heart, which is approximately 8 cm from the midline in the left 5th intercostal space; a surface landmark used to place the stethoscope for auscultation of the bicuspid valve suprasternal notch ( N185 , TG4-04 ) the notch located at the superior border of the manubrium of the sternum, between the sternal ends of the clavicles also known as: jugular notch Osteology of the Pectoral Region Bone an "S" shaped bone located between the sternum and the scapula it articulates medially with the manubrium of the sternum and laterally with the acromion process of the scapula; it forms a strut that supports the upper limb; it is frequently fractured; it is the first bone to begin

 ossification during development (Latin, clavicula = little key, this term was used to refer to the catch that fastens a window as well as to keys.

Curved window fasteners resemble the shape of this bone) rib ( N185 , TG4-04 ) the bone forming the lateral thoracic wall 12 pairs; several types are described: typical or "true" ribs, "false" ribs, "floating" ribs; all three types of ribs have many features in common: head, neck, tubercle, angle, body, costal groove sternum the broad flat bone forming the anterior thoracic wall it is formed by three parts: manubrium, body, xiphoid process (Latin, sternum = breastbone, sternere = spread out) manubrium the superior part of the sternum (Latin, manubrium = handle) jugular (suprasternal) notch a notch on the superior border of the manubrium it is located between the clavicular notches which articulate with the sternal ends of the clavicles (Latin, jugulum = throat) clavicular notch a notch on the superolateral border of the manubrium it articulates with the sternal end of the clavicle sternal angle the junction of the manubrium and body of the sternum it is an anterior projection located at the level of the

 costal cartilage of rib 2; an important landmark for internal thoracic anatomy body the middle part of the sternum it articulates with the manubrium superiorly and the xiphoid process inferiorly; laterally it articulates with the costal cartilages of ribs 2-7 xiphoid process the inferior part of the sternum it is variable in size, shape & ossification; it articulates with the body of the sternum superiorly (Greek, xiphos = sword + eidos = appearance) scapula the bone of the shoulder the scapula floats in a sea of muscles, so it is difficult to fracture; it articulates with the axial skeleton through only one bone - the clavicle at the coracoclavicular and acromioclavicular joints coracoid process ( TG2-03 ) a beak-like process that projects anteriorly from the lateral end of the superior border of the scapula it is the attachment site for the short head of the biceps brachii m., the coracobrachialis m., the pectoralis minor m.

and the coracoacromial and coracoclavicular ligaments (Greek, korax = crow + eidos = appearance. The coracoid process of the scapula is shaped like a crow's beak) humerus the bone of the arm (brachium) the humerus articulates proximally with the scapula at the glenoid fossa; it articulates distally with the radius and ulna at the elbow joint greater tubercle the large projection located lateral to the head of the humerus it is the attachment site of the supraspinatus, infraspinatus & teres minor mm.

intertubercular groove the groove on the anterior surface of the humerus that is located between the crest of the greater tubercle and the crest of the lesser tubercle it is occupied by the tendon of the long head of the biceps brachii m.; the transverse humeral ligament spans the intertubercular groove and holds the biceps tendon in place; it is the attachment site for the tendon of the pectoralis major (lateral lip), teres major (medial lip), and latissimus dorsi (floor) (Latin, tuber = knobby process, nodule) crest of the greater tubercle the ridge of bone on the anterior surface of the humerus extending inferiorly from the greater tubercle it forms the lateral lip of the intertubercular groove; it is the attachment site for the transverse humeral ligament and the pectoralis major m. crest of the lesser tubercle the ridge of bone on the anterior surface of the humerus extending inferiorly from the lesser tubercle it forms the medial lip of the intertubercular groove; it is the attachment site for the transverse humeral ligament and the teres major m.

Muscles of the Pectoral Region Muscle cubital nodes; lymphatic vessels from the upper limb, thoracic wall and subscapular region efferents vessels form the subclavian trunk, some drainage to inferior deep cervical nodes upper limb, most of the mammary gland, some of the anterolateral chest wall, posterior thoracic wall and scapular region axillary nodes number from 20 to 30 and are organized in five groups based on their position within the axilla: 1) pectoral nodes, along the lateral border of the pectoralis major m.; 2) lateral nodes, located along the distal axillary v.; 3) central nodes, centrally located along axillary v.; 4) subscapular nodes, located along the subscapular v.

and its tributaries; 5) apical nodes, located at the apex of axilla parasternal nodes lateral border of sternum, along the course of the internal thoracic vessels anterior phrenic nodes, lymphatic vessels from the anterior thoracic wall larger lymphatic vessels in the root of the neck medial side of the mammary gland; medial part of the anterior chest wall and muscles parasternal nodes constitute an important drainage pattern in cases of cancer of the mammary gland; one or two parasternal nodes may be found in the anterior end of intercostal spaces 1-6; also known as: sternal nodes pectoral nodes along the lateral border of the pectoralis major m. along the course of the lateral thoracic vessels lymphatic vessels from the mammary gland and anterolateral thoracic wall central axillary nodes anterolateral thoracic wall and muscles; most of the mammary gland an important group of nodes to examine during a breast physical exam; also known as: anterior axillary nodes Nerves ventral primary rami of spinal nerves T1-T11 lateral & anterior cutaneous brs.

intercostal muscles; abdominal wall muscles (via T7-T11); muscles of the forearm and hand (via T1) skin of the chest and abdomen anterolaterally; skin of the medial side of the upper limb (via T1-T2) intercostal n. travels below the posterior intercostal a. in the costal groove (Latin, costa = rib) long thoracic n. brachial plexus (ventral primary rami of spinal nerves C5-C7) no named branches serratus anterior m. no cutaneous branches located on the superficial surface of the serratus anterior m.; lesion of this nerve causes scapular winging, hence the saying "C5, 6, & 7 keep the wings from heaven" pectoral, lateral lateral cord of the brachial plexus no named branches pectoralis major m. no cutaneous branches lateral pectoral n. communicates with the medial pectoral n. anterior to the axillary a.; it pierces the clavipectoral fascia pectoral, medial medial cord of the brachial plexus no named branches pectoralis minor m., pectoralis major m.

no cutaneous branches medial pectoral n. communicates with the lateral pectoral n. anterior to the axillary a.; it pierces the pectoralis minor m. Viscera/Fascia ( N188 , N428 , TG2-12 , TG4-07 ) deep fascia attaching to clavicle, surrounding subclavius m., thickened below as costocoracoid ligament, extending inferiorly to pectoralis minor as costocoracoid membrane (pierced by cephalic v., lateral pectoral n., thoracoacromial a.), encloses pectoralis minor, extends inferolaterally to attach to axillary fascia as suspensory ligament of axilla mammary gland ( N182 , TG2-10 ) located anterior to pectoralis major m.

from rib 2/3 to rib 6/7 the breast, a modified sweat gland, comprises glandular tissue arranged in up to 20 lobules, surrounded by subcutaneous connective tissue and supported by suspensory ligaments lactiferous ducts drain the lobules of the mammary gland at the nipple beneath the nipple, the ducts dilate to form lactiferous sinuses areola darkly pigmented skin surrounding the nipple Clinical Terms deviation or departure from the normal or common order, form, or rule gynecomastia excessive development of the male mammary glands, sometimes secreting milk. This can be idiopathic, or as a result of an underlying disease process. (Greek, gyn = female + mastos = breast) axillary tail (of Spence) part of the mammary gland may extend along the inferolateral edge of the pectoralis major toward the axilla (armpit), forming an axillary tail (of Spence).

This portion of breast tissue is in the upper-outer quadrant of the breast which is important because 50% of breast cancer is located in this quadrant and in the axillary tail supernumerary nipples (polythelia) more than the normal number of nipples, may be on the breast or other parts of the body-found along the "milk line" from axilla to groin. These accessory nipples resemble raised nevi (commonly called "moles").

supernumerary breasts (polymastia) a condition in which more than two breasts are present carcinoma any of the various types of malignant (invasive) neoplasm derived from epithelial tissue in several sites, occuring more frequently in skin, bronchi, stomach, and prostate gland in men, and in the breast, cervix, and skin in women (Greek, carcino- = cancer + -oma = tumor) mastectomy/lumpectomy amputation of the breast or of an affected portion (Greek, mastos = breast + -ectomy = excision) mastitis inflammation of the mammary gland (Greek, mastos = breast + -itis = inflammation) scintigraphy record indicating the intensity, location, and distribution of radioactivity in tissue following the use of radioactive tracer substances mammogram special imaging examination of the breast to detect breast cancer. The American Cancer Society currently recommends that screening should begin annually at the age of 40 (and earlier in those patients with a family history of breast cancer). The material presented in these tables is contained in the book: MedCharts Anatomy by Thomas R.

Gest & Jaye Schlesinger Published by ILOC, Inc., New York Copyright © 1995, unauthorized use prohibited. The excellent editorial assistance of Anatomy and physiology of the breast - Canadian Cancer Society A- | A | A+ Anatomy and physiology of the breast Women and men both have breasts, but women have more breast tissue than men. Each breast lies over a muscle of the chest called the pectoral muscle. The female breast covers a fairly large area. It extends from just below the collarbone (clavicle), to the armpit (axilla) and across to the breastbone (sternum). Structure The breast is a mass of glandular, fatty and connective tissue. The breast is made up of: lobules – glands that produce milk ducts – tubes that carry milk from the lobules to the nipple fatty and connective tissue – surrounds and protects the ducts and lobules and gives shape to the breast areola – the pink or brown, circular area around the nipple that contains small sweat glands, which release (secrete) moisture as a lubricant during breast-feeding nipple – the area at the centre of the areola where the milk comes out Ligaments support the breast.

They run from the skin through the breast and attach to muscles on the chest. There are several major nerves in the breast area, including nerves in the chest and arm. There are also sensory nerves in the skin of the chest and axilla. The lymphatic system of the breast The breast has many blood vessels and lymph vessels. Lymph vessels are thin tubes similar to blood vessels. They collect and move lymph lymphA clear, yellowish fluid that contains nutrients, lymphocytes (a type of white blood cell that fights germs, foreign substances or cancer cells) and antibodies. Lymph fluid circulates throughout the body in lymph vessels and bathes body tissues. fluid away from the breast into small bean-shaped masses of lymphatic tissue, called lymph nodes lymph nodesA small, bean-shaped mass of lymphatic tissue along lymph vessels (tubes through which lymph fluid travels in the body). Lymph nodes store lymphocytes (a type of white blood cell that fights germs, foreign substances or cancer cells) and filters bacteria and foreign substances (including cancer cell, in the area around the breast.

The lymph vessels and lymph nodes are part of the lymphatic system lymphatic systemThe group of tissues and organs that produce and store cells that fight infection and diseases., which helps fight infections. The breast lymph nodes include: supraclavicular nodes – above the collarbone infraclavicular (or subclavicular) nodes – below the collarbone axillary nodes – in the armpit (axilla) internal mammary nodes – inside the chest around the breastbone (sternum) Axillary lymph nodes There are about 30–50 lymph nodes in the axilla. The number varies from woman to woman.

The axillary lymph nodes are divided into 3 levels according to how close they are to the pectoral muscle on the chest: level I (low axilla) – located in the lower or bottom part of the armpit, along the outside border of the pectoral muscle level II (mid axilla) – located in the middle part of the armpit, beneath the pectoral muscle level III (high axilla) – located below and near the centre of the collarbone, above the breast area and along the inside border of the pectoral muscle When breast cancer spreads, it usually goes to level I lymph nodes first, to level II next and then to level III. Breast development Breast tissue changes at different times during a woman’s life. It changes during puberty, during the menstrual cycle, during pregnancy and after menopause. Female breasts do not begin growing until puberty (around 10–12 years of age). At this time, the breasts respond to hormonal changes (mostly increased estrogen and progesterone) in the body and begin to develop. During puberty, the breast ducts and milk glands grow. The breast skin stretches as the breasts grow, creating a rounded appearance.

Young women tend to have denser breasts (more glandular tissue) than older women. In older women, much of the glandular and ductal tissue is replaced with fatty tissue and breasts become less dense. Ligaments also lose their elasticity when women age, causing the breasts to sag. The size and shape of women’s breasts vary considerably. Some women have a large amount of breast tissue and have larger breasts. Others have a smaller amount of tissue with little breast fat. A woman’s breasts are rarely the same size. Often one breast is slightly larger or smaller, higher or lower or shaped differently than the other. Hormones and the breast Estrogen is the main female hormone. It influences female sexual characteristics, such as breast development, and it is necessary for reproduction. Most of the estrogen in a woman’s body is made by the ovaries, though a small amount is made by the adrenal glands. Progesterone is the other female sex hormone made in the ovaries. Its role is to prepare the uterus (womb) for pregnancy and the breasts for producing milk for breast-feeding (lactation). The breast tissues are exposed to monthly cycles of estrogen and progesterone throughout a woman’s childbearing years.

In the first part of the menstrual cycle, estrogen stimulates the growth of the milk ducts. Progesterone takes over in the second part of a woman’s menstrual cycle, stimulating the lobules. After menopause, the monthly cycle of estrogen and progesterone end. However, the adrenal glands continue to produce estrogen so that a woman keeps her sexual characteristics. Function The breast’s main function is to produce, store and release milk to feed a baby. Milk is produced in lobules throughout the breast when they are stimulated by hormones in a woman’s body after giving birth. The ducts carry the milk to the nipple. Milk passes from the nipple to the baby during breast-feeding. Axilla - definition of axilla by The Free Dictionary Axilla - definition of axilla by The Free Dictionary n. pl. ax·il·lae (-sĭl′ē) 1. The armpit. 2. A body part analogous to the armpit, such as the hollow under a bird's wing. [Latin.] 1. (Anatomy) the technical name for the armpit 2.

(Zoology) the area on the undersurface of a bird's wing corresponding to the armpit [C17: from Latin: armpit] n., pl. ax•il•lae (ækˈsɪl i) 1. the armpit. 2. the corresponding region under the wing of a bird. [1610–20; < Latin] Noun 1. axilla - the hollow under the arm where it is joined to the shoulder; "they were up to their armpits in water" armpit , axillary cavity , axillary fossa bodily cavity , cavum , cavity - (anatomy) a natural hollow or sinus within the body arteria axillaris , axillary artery - the part of the main artery of the arm that lies in the armpit and is continuous with the subclavian artery above and the brachial artery below shoulder - the part of the body between the neck and the upper arm Translations axilla n (pl -lae) axila Want to thank TFD for its existence? Tell a friend about us , add a link to this page, or visit the webmaster's page for free fun content .

Link to this page: subaxillary References in periodicals archive ? XSTAT is a first-in-kind hemostatic device for the treatment of severe bleeding in the axilla or groin area (known as junctional wounds). Unusual presentation of metastatic ovarian carcinoma as an enlarged intramammary lymph node Of course we know that deodorants don't have any reinforcements to keep you from sweating--once you apply deodorant to your axilla and go for your daily gym session, you're going to perspire. Bacterial pathogens associated with Hidradenitis Suppurativa, France According to the group, a more recent study found higher levels of one paraben, n-propylparaben, in the axilla quadrant of the breast where the highest proportion of breast tumors is found. Dear EarthTalk: A friend of mine recently stopped using skin and beauty products with parabens in them. What are parabens and should we all be avoiding them? We recently attempted 16 radial blocks at or below the elbow in patients in whom a primary attempt for radial nerve block in the axilla had failed.

Question: Which part of the human body has the anatomical name axilla?
Answer: THE ARMPIT