at the junction of its medial 2/3 and its lateral 1/3
What is a main function of the clavicle?
transmit forces from upper extremity to axial skeleton
If the force on the shoulder is greater than the strength of the clavicle, what happens?
a fracture results
Where is a common location of fractures of the clavicle?
medial to attachment of coracoclavicular ligament
Who is most likely to fracture the clavicle medial to the attachment of the coracoclavicular ligament?
children and young adults
What is an incomplete (green-stick) fracture?
one cortex of the bone breaks and the opposite one bends
What is the result of an incomplete fracture?
delayed union of fracure is common owing to its poor blood supply or to interruption of its blood supply
Which muscle acts to elevate the medial fragment of the clavicle after fracture?
Which muscle is unable to hold up the lateral fragment of the clavicle because of the weight of the upper limb?
What happens since the trapezius can't hold up the lateral fragment of the clavicle?
lateral fragment of clavicle drops
How does a patient with a fractured clavicle frequently present themselves?
with upper extremity in a sling or supporting the sagging extremity with the other hand
In addition to being depressed, the lateral fragment of the clavicle is...
What pulls the lateral fragment of the clavicle medially?
adductors of arm (latissimus dorsi and pectoralis major mm.)
What does the overriding of the clavicular bone fragments cause?
shortens the clavicle
What would cause a person's serratus anterior muscle to be paralyzed?
injury of long thoracic nerve
What occurs when a person's serratus anterior muscle is paralyzed by injury of the long thoracic nerve?
medial border of scapula stands out, especially its inferior angle, giving it the appearance of a wing when the presson presses anteriorly
What is a "winged scapula"?
injury to the long thoracic nerve
With a winged scapula, what happens when the arm is raised?
the scapula is pulled away from the thoracic wall
Why is the arm unable to abduct farther than the horizontal positon with winged scapula?
serratus anterior is unable to rotate the scapula and rasise the glenoid cavity
A patient with a paralyzed serratus anterior muscle is unable to...
raise the upper extremity fully or to push with it
Why are injuries to the brachial plexus and its branches important?
they affect movements and cutaneous sensations in the upper extremity
How can the plexus be injuried?
by disease, stretching, and wounds in neck or axilla
What is the result of injuries to the brachial plexus?
loss of muscular movement (paralysis)
loss of cutaneous sensation (anesthesia, absence of feeling)
How can you assess the degree of paralysis?
test the patient's ability to perform movements
no movement can be detected
movement can be performed, but it is weak compared with that on the normal side
How can the degree of anesthesia be tested?
determining the ability of the person to feel pain (e.g., pinprick)
What are injuries to the superior (upper) parts of the plexus usually a result of?
excessive separation of the neck and shoulder
-violent stretching of an infant's neck during delivery
What happens when there is excessive separation of the neck and shoulder?
dorsal and ventral roots of the spinal nerves from C5 and C6 may be pulled out of the spinal cord
What happens if the dorsal and ventral roots of the spinal nerves from C5 and C6 are pulled out of the spinal cord?
paralysis of scapular muscles
loss of sensation over the region of the back supplied by the dorsal primary rami
paralysis of muscles and loss of sensation in the upper extremity
What happens if the lesion is confined to C5?
usually no sensory changes can be detected because this segment is not responsible for the exclusive supply of any area of skin
When both C5 and C6 are injuried, where is the detectable loss of sensation?
lateral aspect of upper extremity
What are injuries to C5 and C6 aspect of the brachial plexus called?
Erb's Palsy or Erb-Duchenne paralysis
Wounds of the neck may tear or severe what part of the brachial plexus?
superior trunk where it emerges between the scalenus anterior and scalenus medius muscles
What does an injury to the superior trunk result in?
loss of flexion, abduction, and lateral rotation of the shoulder joint
loss of flexion of elbow joint
How can one recognized an injury to the superior trunk?
characteristic position of the extremity
-hangs by side in medial rotation, a position referred to as the "waiter's tip" position
Which muscles that receive nerve fibers from C5 and C6 are most severely affected when their is an upper brachial plexus injury?
deltoid, biceps brachii, brachialis, brachioradialis, supraspinatus, infraspinatus, and teres minor
What injury could result from poor fitting crutches?
injure the posterior cord of the brachial plexus
Which nerve of the posterior cord is most often affected?
What muscles are affected when the radial nerve is injuried?
tricpes, anconeus, and extensor muscles of the wrist are paralyzed
What movements are restricted by a radial nerve injury?
unable to extend the elbow, wrist, or digits
What is wrist-drop caused by?
radial nerve injury
What is wrist-drop?
inability to extend the wrist joint and digits
What are lower brachial plexus injuries clinically known as?
Klumpke's paralysis or Klumpkei-Dejerine paralysis
Are injuries to the inferior parts of the plexus common?
What could cause an injury to the infeior part of the plexus?
when upper limb is suddenly pulled superiorly
-forceful pull of an infant's shoulder during birth
-when person grasps something to break a fall
What happens when the upper limb is suddenly pulled superiorly?
injury to inferior trunk of brachial plexus (C8-T1)
What often occurs with injury to inferior trunk of brachial plexus?
pulls dorsal and ventral roots of spinal nerves out of the spinal cord
What results whens C8 and T1 dorsal and ventral roots of the spinal nerves are pulled out of the spinal cord?
paralysis and anesthesia usually affting muscles and skin supplied by ulnar nerve
What are the chief disabilities caused by ulnar nerve injury?
wrist and digital movements
-impairment of wrist flexion
-movements of intrinsic muscles of hand
-reduced sensation along medial side of arm, forearm, and hand
What is thoracic outlet syndrome?
a chronic injury caused by compression of nerves and blood vessels in the thoracic outlet, in the region of the apex of the axilla
What are the possible causes of thoracic outlet syndrome?
1. cervical rib exerts pressure on inferior trunk of brachial plexus
2. poor posture -drooping of the shoulders; holding head forward
3. trauma can cause internal changes that compress the nerves in the thoracic outlet
4. repetitive activity
5. pressure on joints
6. pregnancy (results in lossened joints)
The breasts are usually equal in size, if one is larger and more inferior it is usually which breast?
the right one
What is contained in the superolateral quadrant of the breast?
a large amount of glandular tissue
Where do most breast cancers develop?
the superolateral quadrant of the breast
Where does the glandular tissue of the breast extend?
supeior to the clavicle and/or inferiorly into the epigastrium
When does the vasulariy of the breasts begin to increase?
early in pregnancy
What does increased vaularity of the breast during pregnancy do to the breast's appearance?
often makes blood vessels visible
What happens during contraction of the pectoralis major muscle when carcinoma of the breast invades the retromammary space and attaches to or invades the deep fascia covering the muscle?
contraction causes the breast to move superiorly
If contraction of the pectoralis major muscle causes the breast to move supeiorly, what is this a sign of?
advanced malignant disease of the breast
Cancer cells are carried from the breast by...
lymph vessels to the lymph nodes (in the axilla)
Which lymph nodes are the most common site of metstases from carcinoma of the breast?
axillary lymph nodes
surgical excision of a breast
only the tumor and surrounding tissues are removed from breast
radiographic examination of the breast
-used to detect breast masses
How does a CT scan detect breast cancer cells?
patient is given an iodide-contrast material intravenously
-breast cancer cells have an affinity for iodide and so become recognizable
If the radial nerve is severed superior to the origin of the branches to the triceps muscle...
extension of the elbow joint is impossible
What spinal nerves supply the long thoracic nerve?
What does the long thoracic nerve supply?
serratus anterior muscle
What could cause injury to the long thoracic nerve?
stab wound, during weight lifting, thoracic surgery or remval of cancerous axillary lymph nodes
What does crushing, severe stretching or cutting the long thoracic nerve result in?
paralysis of serratus anterior muscle and winging of scapula
What movements are difficult to do with injuried long thoracic nerve?
flexing or abducting arm above 45-degree angle from side of body
Which spinal nerves supply the axillary nerve?
C5 and C6
Where is the axillary nerve found?
wraps around the neck of the humerus
What could cause injury to the axillary nerve?
fracture of the humerus
dislocation of the shoulder joint
What occurs with an axillary nerve injury?
deltoid muscle is paralyzed and udergoes atrophy
loss of sensation (anesthesia) over lateral side of proximal part of arm
actions of deltoid and teres minor muscles affected
Which spinal nerves supply the thoracodorsal nerve?
C6, C7, and C8
What could cause injury to the thoracodorsal nerve?
surgical operations in the axilla
What does injury to the thoracodorsal nerve result in?
paralysis of the latissimus muscle
Where can the axillary artery be palpated?
in the lateral wall of the inferior part of the axilla
How can you compress the axillary artery during an injury?
pressing axillary artery against humerus
Are there many arterial anastomoses around the scapula?
What is the clinical importance of the collateral circulation owing to anastomoses?
becomes apparent during ligation of injured axillary or subclavian artery
Where can the axillary artery be ligated?
between the thyrocervical trunk and the subscapular artery
What occurs when the axillary artery is ligated between the thyrocervical trunk and the subscapular artery?
the direction of blood flow in the subscapular artery is reversed and blood reaches the distal portion of the axillary artery first
Which arteries does the subscapular artery receive blood through anastomoses?
transverse cervical a.
What happens if the axillary artery is ligated distal to the subscapular artery?
cuts off the blood supply to the arm, forearm, and hand
An aneurysm of the axillary artery that compresses the nerves of the brachial plexus causes:
pain and subsequently anesthesia in the areas of the upper limb supplied by the nerves concerned
Which groupof axillary lymph nodes is the first one to be involved in lymphangitis?
What is lymphangitis?
inflammation of lymphatic vessels
What characterizes lymphangitis?
development of red, warm, tender streaks in the skin
axillary nodes often become enlarged and tender
Which muscles make up the triangle of auscultation?
What enlarges the triangle of auscultation?
when scapula is drawn anteriorly by folding the arms across the chest and trunk is flexed
How can you test strength of deltoid clinically?
patients's arm is abducted, and then patient is asked to hold it in position against resistance
Inability to hold arm in abducted position against resistance indicates injury to which nerve?
What separates the tendon of the supraspinatus from the coracoacromial ligament, the acromion, and the deltoid muscle?
What happens when the subacromial bursa is inflamed?
abduction of the arm is painful
What is the most commonly torn part of the rotator cuff?
What is the function of the rotator cuff?
holds the head of the humerus in the glenoid cavity of the scapula
What could damage the rotator cuff?
injury or disease
What happens when the rotator cuff is injuried?
instability of the shoulder joint
Who is most likely to get degenerative tendonitis of the musculotendinous rotator cuff?
Tendonitis and inflammation of the subacromial bursa result in...
shoulder pain that is intensified by attemps to abduct the arm
The supraspinatus tendon does not rupture very often in young people because their tendons are usually so strong tat they will...
tear away the tip of the greater tubercle of the humerus rather than rupture the tendon
What provides the main stability of the shoulder joint?
the musculotendinous rotator cuff
What forms the musculotendinous rotator cuff?
the fusion of tendons of the rotator cuff muscles with the fibrous capsule of the joint
Fractures of the surgical neck of the humerus are common in who?
What do fractures of the surgical neck of the humerus usually result from?
falls on the elbow when the arm is abducted
Which nerves may be injured in fractures of the humerus?
axillary, radial, and ulnar nn.
When does the proximal epiphysis of the humerus fuse with the body of the humerus?
at about 18 years of age in females and 20 years of age in males
Why does fracture-separation of the proximal humeral epiphysis occur in children?
the articular capsule of the shoulder joint is stronger than the ephiphyseal cartilaginous plate
The brachial artery is doubled in what percentages of people?
In people who have duplicated brachial arteries, where do the arteries lie?
one superficial and one deep to the median nerve
What is the brachial artery lying superficial to the median nerve called?
the superficial brachial artery
Where can the brachial artery be clamped or ligated without producing tissue damage?
distal to the inferior ulnar collateral artery
Which artery is compressed by the sphygmomanometer during blood pressure readings?
The first audible spurt of blood in a blood pressure reading indicates what?
the systolic blood pressure
Volkmann's ischemic contracture:
Flexion deformity caused by occlusion or laceration of the brachial artery in an emergency; necrotic muscle is replaced by fibrous scar tissue that causes the involved muscles to become permanently shortened
What is the result of injury to the median nerve proximal to the elbow?
loss of sensation on the lateral portion of the palm, palmar surface of thumb, and lateral two and one-half digits
-med. n. supplies no muscles in the arm
-pronation of forearm, flexion of wrist and digits, and important movement of thumb are lost or severely affected
What does injury to the ulnar nerve in the arm result in?
impaired flexion and adduction (medial deviation) of the wrist and impaired movement of the thumb, ring, and little fingeres, resulting in a poor grasp
What is the characterisitic clinical sign of ulnar nerve damage?
inability to adduct of abduct the medial four digits owing to loss of power of the interosseou muscles
loss of sensation on lateral surface of the forearm supplied by lateral antebrachial cutaneous nerve
What results in injury to the musculocutaneous nerve in the axilla?
paralysis of the coracobrachialis, biceps, and brachialis muscles
What movements are impaired with injury to the musculocutaneous nerve in the the axilla?
flexion of the elbow joint and supination of the forearm are greatly weakened
What is the result of injury to the radial nerve proximal to the origin of the triceps?
paralysis of the triceps, brachioradialis, supinator, and extensors of the wrist and digits
loss of sensation in the arease of skin supplied by this nerve
What is the characteristic clinical sign of radial nerve injury?
wrist-drop (inability to extend the wrist and digits)
What is the result of a fall on the outstretched hand?
a fracture of the distal end of the radius
sometimes fracture of styloid process of ulna
distal fragment of the radius is displaced posteriorly
-results in radial and ulnar styloid processes being at approximately the same horizontal level (abnormal condition)
What happens if the median nerve is severed in the elbow region?
loss of flexion of proximal interphalangeal joints of all the digits
loss of flexion of distal interphalangeal joints of second and third digits
Where is the median nerve commonly injured?
just proximal tot he flexor retinaculum
nerve entrapment syndrome caused by compression of median nerve near elbow
Where might the median nerve be compressed in pronator syndrome?
between the two heads of the pronator teres
When the caused the median n. to be compressed between the heads of the pronator teres?
trauma, muscular hypertrophy, or fibrous bands
Where does ulnar nerve injury commonly occur?
where nerve passes posterior to medial epicondyle of humerus
How does damage to the ulnar nerve often occur?
when elbow hits a hard surface and the epicondyle is fractured
What is the result of ulnar nerve injury?
extensive motor and sensory loss to the hand
when flexion of wrist is attempted, hand s drawn to radial side by flexor carpi radialis
difficult to make fist -can't flex 4t and 5th digits at DIP joints
caused by ulnar nerve injury
can't make a fist because can't flex 4th and 5th digits at DIP joint