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GROSS ANATOMY
UPPER LIMB
INSTRUCTOR: DR. BUENSALIDA, DR. DANGOY, DR. DELISO
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OVERVIEW
A multi jointed lever that is freely movable on the trunk at shoulder joint. ● Primary function: to maneuver the hand into positions where the hand can manipulate objects Hand is a highly evolved organ with a unique ability to grasp items in both coarse and fine ways.
- Importance of hand: centers on pincer-like opposable action of the thumb, which enables the tip of thumb to contact the tips of other digits Upper limb is organized into: ● Shoulder region ● Arm ● Cubital fossa ● Forearm ● Wrist ● Hand The arm, forearm, and hand are compartmentalized into working units.
OSTEOLOGY
Upper limb is a component of the appendicular skeleton.
- Clavicle
- Scapula
- Humerus
- Ulna
- Radius
- Carpal bones
- Metacarpal bones
- Phalanges Shoulder girdle- formed by clavicle and scapula Humerus - defines the arm Forearm- delineated by radius and ulna Wrist - formed by carpal bones Hand - constituted by metacarpals and phalanges Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan.
CLAVICLE
AKA “ collar bone ”
- Clavicul- latin for “key” Location: between the sternum and the scapula; lies horizontally across the root and neck ● Roughly S-shaped and resembles a large, old-style key
- Forms a light strut that connects the upper limb to the thorax and allows limb to move freely from trunk ● First bone to begin ossification ● Clavicle is subcutaneous and easily palpable along its entire length
- Sternal extremity - blunt, thickened, proximal (medial) end of the clavicle
- Articulates with: clavicular notch of the sternum through a compound synovial joint containing articular disc
- Acromial extremity - flattened distal (lateral) end of the clavicle
- Articulates with: acromion process of scapula
- Conoid tubercle - cono- greek for “pine cone”; a small, roughened elevation on the inferior surface, near the acromial end
- Serves as the attachment area for the conoid ligament part of coracoclavicular ligament → Clavicle fracture -sole link between the upper limb and axial skeleton
- Transmits all forces from the upper limb to the trunk ● Easily exposed to trauma ● Most commonly fractured bone in the body Important muscles and ligaments attached to clavicle: SCAPULA AKA “ shoulder bone ”; scapul- (Latin for “shoulder blade)
→ serves to broaden and deepen the joint cavity Supraglenoid tubercle - small elevation located at the apex of glenoid cavity, near the base of coracoid process Infraglenoid tubercle - a roughened area located immediately inferior to the glenoid cavity Dorsal (posterior) surface of scapula- subdivided into two unequal-sized region by the spine of scapula Supraspinous fossa - smaller, troughlike area superior to the spine Infraspinous fossa - much larger area inferior to the spine Spine - the large, triangular ridge that runs laterally from the medial border of the scapula to merge into the acromion process The lateral border of the spine blends to the neck of scapula and forms a notch-like passageway ( spinoglenoid , or greater scapular, notch ) that connects the supraspinous fossa with infraspinous fossa → this allows the suprascapular nerve and vessels to pass between the fossae Acromion - ( acromi- Greek for “point of the shoulder) is broad, flat lateral extension of the spine of scapula ● Forms the easily palpable tip of shoulder ● Partly roofs over the glenoid cavity and provides an articulation with the clavicle at the acromioclavicular joint. Costal (ventral, anterior) surface of the scapula lies against the posterior aspect of rib cage Subscapular fossa - shallow concavity formed by the large part of costal surface Coracoid process - ( coraco- Greek for “like a crow’s beak) is a thick, beaklike structure that projects anterolaterally from the junction of the neck and lateral end of the superior border of scapula ● Can be palpated via deep pressure through the anterior part of the deltoid muscle, inferior to the lateral end of the clavicle ● Main muscles and ligaments attached to the scapula: Figure 3.1 and Figure 3. DROPPED SHOULDER & WINGED SCAPULA Position of the scapula on the posterior wall of the thorax is maintained by tone and balance of muscles attached to it.
- If one of these muscles is paralyzed, the balance is upset, as in a dropped shoulder, which occurs with paralysis of trapezius , or winged scapula caused by paralysis of the serratus anterior.
HUMERUS ( humer- latin for “shoulder”)
- Location: in the arm (brachium) and is the longest bone of the upper limb. ● Proximally, the humerus articulates with the glenoid cavity of the scapula, at the glenohumeral ( shoulder ) joint. ● Distally, it articulates with the head of the radius and the trochlear notch of the ulna, at the elbow joint Humerus can be divided into three main regions:
- Proximal extremity
- Body or shaft
- Distal extremity Major muscles and ligaments attached to the humerus: Figure 3.1 and Figure 3.
PROXIMAL EXTREMITY
Head - round, smooth, proximal end of the humerus ● Forms about 1/3 of a sphere and is oriented medially, superiorly, and slightly posteriorly ● Articulates with: glenoid cavity of the scapula to form the glenohumeral joint in the shoulder joint complex Greater tubercle - large, roughened elevation on the lateral proximal ends of humerus, lateral to the head Lesser tubercle - small, roughened elevation on the anterior proximal ends of humerus, inferior to the head and medial to the tubercle Anatomical neck - slightly constricted region surrounding the articular surface of the head
● Easily palpable ● Forms an important surface landmark in the arm ● The ulnar nerve crosses the posterior surface of this epicondyle in the shallow ulnar sulcus and is susceptible to injury here (e.g., via blunt trauma or bony fracture) ● Nerve can be palpated and rolled against the epicondyle ● Stimulation of the nerve by contact against the epicondyle elicits the characteristic “funny bone” response of tingling sensations in the medial border of the hand and fifth digit (So why is this a “funny bone”? Because it borders on the “humerus”) Capitulum - ( capit- Latin for “head”-- in this grammatical case, “little head”) is the rounded, half-spherical, articular process at the distal, lateral end of the humerus. ● Lies immediately lateral to trochlea ● Articulates with the head of the radius ● Shapes of these structures allow both flexion/extension and rotation at the humeroradial joint Trochlea - ( trochle- Greek for “pulley”) is the pulley-shaped articular process at the distal, medial end of humerus ● Lies immediately medial to the capitulum ● Articulates with trochlear notch of ulna ● Shapes of the articulated trochlea and trochlear notch (plus the presence of the humeroradial joint) limit lateral movements of the ulna, resulting in a hinge action at the humeroulnar joint. Coronoid fossa - depression on the distal, anterior end of the humerus, immediately proximal to the trochlea ● Receives the coronoid process of the ulna when the elbow is fully flexed Radial fossa - shallow depression on the distal, anterior end of the humerus, immediately proximal to the capitulum ● Receives the margin of the head of the radius when the elbow is fully flexed. Olecranon fossa - deep depression on the distal, posterior end of the humerus, immediately proximal to the trochlea ● Holds the apex of the olecranon process of the ulna when the elbow is extended PROXIMAL END OF HUMERUS FRACTURE
RADIUS Radius ( radi- Latin for “spoke” or “ray”)
- Location: the bone on the lateral side of the forearm (antebrachium) ● Proximally, it articulates with both the capitulum of the humerus and the radial notch of the ulna, in the elbow joint ● Distally, articulates with the head of the ulna and the scaphoid and lunate bones, in the wrist ● During pronation and supination, the radius rotates about its long axis at its proximal end and circumducts the ulna at its distal end Major muscles and ligaments attached to the radius: Figure 3. Head- expanded, round, proximal end of the radius ● Proximal surface is shallow concavity for articulation with the capitulum of the radius ● Periphery articulates with the radial notch of the ulna ● Held in place against the ulna by encircling the annular ligament. ● Note: the head of the radius is at its proximal end, whereas the head of the ulna is at its distal end Neck- constricted area immediately distal to the head Radial tuberosity - raised, mostly roughened area on the anteromedial, proximal aspect of the radius, just distal to the neck ● Insertion site of the biceps brachii muscle Body (shaft) - elongated midportion of the radius ● Widens along its proximal to distal extent ● Medial border of the shaft forms a sharp crest ( interosseous border ) for the attachment of the interosseous membrane that binds together the radius and ulna Ulnar notch - shallow depression on the distal, medial aspect of the radius ● This is the articular surface for the head of ulna
● Lateral border of the shaft forms a sharp crest (the interosseous border ) for the attachment of interosseous membrane Head - small, rounded distal end of the ulna ● Has an articular surface on its lateral side for contact with the ulnar notch of the radius ● The distal end of the head is separated and excluded from the wrist joint by an articular disc Styloid process - small projection from the posterolateral, distal end of the ulna CARPAL BONES Carpal ( carp- Greek for wrist) bones
- Eight small bones comprising the wrist
- Arranged in two rows (proximal and distal), with four bones in each row ● Arrangement of the bones forms a deep concave groove on the ventral aspect of the wrist ● Groove is roofed over by a strong ligamentous band (the flexor retinaculum), forming the osseofascial carpal tunnel → the carpal tunnel conveys several flexor tendons and the median nerve into the hand Carpal Tunnel Syndrome - compression of the tunnel space and/or trauma to its contents ● Bones of the hand are cartilaginous AT BIRTH ● The capitate begins to ossify during the 1st year, and the others begin to ossify at intervals thereafter until the 12th year, when all the bones are ossified
[Mnemonic: “ S ome L overs T ry P ositions T hey C annot H andle]- first letter of each word represents the first letter of each carpal bone, arranged by row (proximal row first), from lateral to medial.
PROXIMAL ROW
From lateral to medial: S caphoid, L unate, T riquetrum, and P isiform
- The scaphoid and lunate bones articulate with the carpal articular surface of the radius Scaphoid - ( scaph- Greek for something hollowed out, such as “bowl”, “boat”, or “trough”) is the largest, most lateral carpal bones of the proximal row ● Location: floor of the anatomical snuffbox ● Fractured frequently by impact on the base of the hand when the wrist is hyperextended and abducted, as when trying to break a fall with the outstretched hand Lunate - ( lun- Latin for “moon”) is the roughly semilunar-shaped carpal bone ● Location: between the scaphoid and triquetrum
Triquetrum - ( triquetr- Latin for “triangular”) is the roughly pyramidal-shaped, most medial bone in the proximal carpal row ● Pisiform lies anterior to the triquetrum Pisiform - ( pis- Greek for “pea”) is the small, pea-shaped, sesamoid bone formed in the tendon of the flexor carpi ulnaris muscle
DISTAL ROW
From lateral to medial: T rapezium, T rapezoid, C apitate, H amate
- Articulates distally with the metacarpal bones of the hand Trapezium - ( trapez- Greek for “table”) is the most lateral carpal bone of the distal row ● Forms a saddle joint with the first metacarpal bone, allowing great mobility of the thumb ● Remember: “The thumb swings on the trapezium” Trapezoid - bone located between the trapezium and the capitate ● Named for its trapezoid shape Capitate - ( capit means “head”) is the central and largest carpal bone, located between the trapezoid and the hamate ● Named for its rounded head, which sits in the concavity formed by the scaphoid and lunate bones ● Forces generated in the hand (during a punching blow with the fist) are transmitted through the third metacarpal bone to the capitate ● Then proximally through the lunate to the radius Hamate - ( hamat- Latin for “hooked”) is the most medial bone in the distal carpal row ● Distinguishing feature : the hamulus (hook), which is one of the attachment points of the flexor retinaculum METACARPAL BONES Five bones located between the carpal bones and the phalanges of the hand
- Comprises the body of the hand, whereas the phalanges make up the fingers
- Bones are identified by number (1-5), starting with the most lateral unit (i.e., metacarpal 1 aligns with the thumb) → each bone has a base, a body, and a head Base - the expanded proximal end of the bone ● Articulates with the distal row of carpal bones Body (shaft) - the elongate, slender, midportion of the bone ● The shaft of each metacarpal bone is slightly concave anteriorly and is triangular in transverse section
Elbow - the area connecting the arm with the forearm Cubital fossa - a depression across the front of the elbow Forearm (lower arm, antebrachium) - the segment of the upper limb from the elbow to the wrist Wrist (carpus) - a complex of small bones connecting the forearm and hand Hand (manus) - a very important organ, located at the distal end of the upper limb PECTORAL REGION Anterior aspect of the shoulder
- May be considered part of the anterior thoracic wall, several structures here (e.g., pectoral muscles) connect with and function as part of the upper limb, thus uniting these areas ● Pectoral region also houses the breasts ● General topography of the pectoral region: Figures 3.11 through 3.13:
BREASTS
Not anatomically part of the upper limb However, they are situated in the pectoral region ● Their blood supply and lymphatic drainage are largely related to the arm pit
LOCATION AND DESCRIPTION
Specialized accessory glands of the skin that secrete milk ● Present in both sexes ● Share similar structure in males and immature females Areola - colored area of the skin that surrounds the nipples (nipples are small) Breast tissue consists of a system of ducts embedded in connective tissue that doesn’t extend beyond the margin of the areola
PUBERTY
In females: breasts gradually enlarge and assume their hemispherical shape under the influence of ovarian hormones
- The ducts elongate, but the increased size of the glands is mainly from the deposition of the fat
- The base of the breast extends from the second to sixth rib and from the lateral margin of the sternum to the midaxillary line ● The greater part of the gland lies in the superficial fascia Axillary tail - an extension of the gland continues upward and laterally, pierces the deep fascia at the lower border of the pectoralis major muscle, and enters the axilla Each breast consists of 15 to 20 lobes , which radiate out from the nipple ● Main duct from each lobe opens separately on the summit of the nipple and possesses a dilated ampulla just before its termination ● Base of the nipple is surrounded by: AREOLA The underlying areolar glands produce tiny tubercles on the areola Lobes of the gland are separated by fibrous septa that serve as suspensory ligaments A space filled by loose connective tissue called the retromammary space lies deep to the breast and superficial to the underlying pectoral muscles
YOUNG WOMEN
Breasts tend to protrude forward from a circular base
BLOOD SUPPLY
● Arterial supply to the breast: perforating branches of the internal thoracic artery and the intercostal arteries. ● Axillary artery also supplies the gland via its lateral thoracic and thoracoacromial branches ● Veins correspond to the arteries.
LYMPH DRAINAGE
The lymph drainage of the mammary gland is important because of the frequent development of cancer in the gland, and the malignant cells along the lymph vessels to the lymph nodes. ● Lateral quadrants of the breast : drain into the anterior axillary or pectoral group of nodes (situated just posterior to the lower border of the pectoralis major muscle). ● Medial quadrants : drain by means of vessels that pierce the intercostal spaces and enter the internal thoracic group of nodes (situated within the thoracic cavity along the course of the internal thoracic artery) ● Few lymph vessels : follow the posterior intercostal arteries and drain posteriorly into the posterior intercostal nodes (situated along the course of the posterior intercostal arteries) Some vessels communicate with lymph vessels of the opposite breast and with those of the anterior abdominal wall. WITCH’S MILK IN NEWBORNS While the fetus is in the uterus, maternal and placental hormones cross the placental barrier and cause proliferation of the duct epithelium and the surrounding connective tissue.
- May cause swelling of the mammary glands in both sexes during the 1st week of life ● Witch’s milk - milky fluid that is expressed from nipples The condition is resolved spontaneously as the maternal hormone levels in the child fall. MAMMOGRAPHY ● Radiographic examination of the breast
Extensively used for screening the breasts for benign and malignant tumors and cysts SCAPULAR REGION ● Posterior aspect of the shoulder ● Maybe considered part of the back and/or posterior thoracic wall
MUSCULOSKELETAL AND
NEUROVASCULAR STRUCTURES
General topography of the scapular region: Figures 3.19 and Figures 3.
QUADRANGULAR SPACE
Intermuscular space, located immediately below the glenohumeral (shoulder) joint ● Bounded above: by the subscapularis and teres minor muscles and the capsule of the shoulder joint and below by the teres major muscle. ● Bounded medially : by the long head of the triceps and laterally by the surgical neck of the humerus The significance of quadrangular space: the axillary nerve and the posterior circumflex humeral vessels emerge through this space to reach their terminal destinations in the shoulder. AXILLA ● “Armpit”, is a pyramid-shaped space
- Location: between the upper part of the arm and the side of the chest Forms an important passage for nerves, blood vessels, and lymph channels as they travel between the root of the neck to the upper limb ● Upper end of the axilla, or “apex” - directed into the root of the neck and is bounded:
- in front by the clavicle,
- behind the upper border of the scapula,
- medially by the outer border of the first rib ● Lower end, or “base”- bounded:
- in front by the anterior axillary fold (formed by the lower border of the pectoralis major muscle),
- behind by the posterior axillary fold (formed by the tendons of latissimus dorsi and teres major muscles)
- medially by the chest wall
AXILLARY WALLS
Four walls of the axilla are constructed as follows:
● Crosses the axilla and divides the are into three subregions:
- Proximal
- Deep
- Distal to the muscle
CLAVIPECTORAL FASCIA
A strong sheet of connective tissue lying immediately deep to the pectoralis major muscle (3.12, 3.22) ● Superiorly: attaches to the clavicle ● Inferiorly: splits to enclose the subclavius and pectoralis minor muscles, and continues downward as the suspensory ligament of the axilla , and joins the fascial floor of the armpit Lateral pectoral nerve, cephalic vein, branches of thoracoacromial artery, lymphatic channels from the infraclavicular nodes pierce the clavipectoral fascia in order to make superficial-deep connections. ARM ● (Upper arm; Brachium) ● Proximal segment of the upper limb from shoulder to elbow
OSSEOFASCIAL COMPARTMENTS
The arm is enclosed in a sheath of deep fascia (3.24) ● Two fascia intermuscular septa:
- On the medial side
- One the lateral side → extends inward from this sheath and are attached to the medial and lateral supracondylar ridges of the humerus In this way: the upper arm is divided into an anterior and posterior osteofascial compartment
CONTENTS OF ARM OSSEOFASCIAL
COMPARTMENTS
MUSCLES:
● ANTERIOR COMPARTMENT:
- Biceps brachii
- Coracobrachialis
- Brachialis ● POSTERIOR COMPARTMENT:
- Triceps brachii MOTOR NERVE SUPPLY ● ANTERIOR COMPARTMENT:
- Musculocutaneous nerve
● POSTERIOR COMPARTMENT:
- Radial nerve BLOOD SUPPLY ● ANTERIOR COMPARTMENT:
- Brachial artery ● POSTERIOR COMPARTMENT:
- Profunda brachii artery
- Ulnar collateral arteries STRUCTURES PASSING: ANTERIOR OSSEOFASCIAL COMPARTMENT
- Musculocutaneous nerve
- Median nerve
- Ulnar nerve
- Brachial artery
- Basilic vein ● Radial nerves is present in the lower part of the compartment STRUCTURES PASSING: POSTERIOR OSSEOFASCIAL COMPARTMENT
- Radial nerve
- Ulnar nerve
- Profunda brachii vessels
