LM 4.2: Upper Extremity Muscles Flashcards
pectoralis major:
- innervating nerve
- nerve root
- action
- attachment
- innervating nerve
lateral pectoral
medial pectoral - nerve root
clavicular C5, C6, C7
sternocostal C8 ,T1 - action
humeral adduction
medial rotation
scapular protraction - distal attachment along the intertubercular groove of the humerus
pectoralis minor:
- innervating nerve
- nerve root
- action
- attachment
- innervating nerve
medial pectoral nerves - nerve root
C8, T1 - action
scapular stabilization, downward rotation, and depression of the shoulder
axilary breathing muscle during deep/compromised respiration
- attaches to the coracoid process of the scapula and to ribs 3-5
sternocleido-mastoid
- innervating nerve
- nerve root
- action
- attachment
- innervating nerve
spinal accessory nerve - nerve root
cranial nerve = C1, C2, C3, C4 - action
- elevated medial clavicle
- lateral flexion of the head
4. attaches to the sternum up to behind the ear
serrates anterior
- innervating nerve
- nerve root
- action
- attachment
- innervating nerve
long thoracic nerve - nerve root
C5, C6, C7 - action
protraction of scapula in a punching motion, or in reaching forward - fingerlike projections of the muscle attach proximally to the ribs and to the entire length of the medial border of the anterior scapula, including its inferior angle
subclavius muscle
- action
- attachment
- action =
- acts to depress the clavicle, or elevate the first rib
- provides structural support for the sternoclavicular joint - attachment = attaches proximally to the costal cartilage of he first rib at the manubrium and distillery to the inferior central clavicle
what happens when the long thoracic nerve is damaged or weak?
it innervates the serrates anterior so if the long thoracic nerve has problems, this causes “medial winging” of the scapula on attempted protraction
medial winging is where the medial border of the scapula protrudes from its normal place close to the posterior rib cage
levator scapulae
- innervating nerve
- nerve root
- action
- attachment
- innervated by dorsal scapular nerve
- C3, C4, C5
- elevates the scapula
- attaches to the transverse process of the atlas and axis and to the posterior tubercles of the transverse process of the 1st - 4th cervical vertebrae
rhomboid major
- innervating nerve
- nerve root
- action
- attachment
- innervated by dorsal scapular nerve
- C4, C5
- retract the medial border of the scapula superiorly and medially; used in squaring the shoulders = proper posture!!
- arises from the spines and supraspinous ligaments of the T2 to T5 thoracic vertebrae, and descends laterally to the medial border of the scapula
rhomboid minor
- innervating nerve
- nerve root
- action
- attachment
- innervated by dorsal scapular nerve
- C4, C5
- retract the medial border of the scapula superiorly and medially; used in squaring the shoulders = proper posture!!
- runs from the lower ligamentum nuchae and the spines of the C7 and T1 vertebrae
trapezius
- innervating nerve
- nerve root
- action
- attachment
- innervated by spinal accessory nerve
- cranial nerve = C1, C2, C3, C4
- upward rotation of the glenohumeral fossa
helps steady the scapula and maintaining the poise of the shoulder; acting with levator scapulae muscle, the superior fibers elevate the scapula and with it the point of the shoulder
- the lateral angles occur at the shoulder tips, the superior angle at the occipital protuberance and superior nuchal lines, and the inferior angle at the spine of the twelfth thoracic vertebra
latissimus dorsi
- innervating nerve
- nerve root
- action
- attachment
- innervated by thoracodorsal nerve
- C6, C7, C8
- humeral extension, adduction, medial rotation
used for a chin up or pulling the oar toward the chest during the power stroke of rowing
- attaches from the axial skeleton to the humerus
proximal attachment arises from the spinous processes of the inferior six thoracic vertebrae, the thoracodorsal fascia, iliac crest, and inferior 3 or 4 ribs
distal attachment is the base of the intertubercular groove of the humerus
supraspinatus
- innervating nerve
- nerve root
- action
- attachment
- innervated by suprascapular
- C5, C6
- first 15 degrees of abduction of the shoulder
- arises from the medial two-thirds of the supraspinous fossa and attaches to the greater tubercle
infraspinatus
- innervating nerve
- nerve root
- action
- attachment
- suprascapular nerve
- C5, C6
- external (lateral) rotation of the humerus
teres minor
- innervating nerve
- nerve root
- action
- attachment
- axillary nerve
- C5, C6
- external (lateral) rotation and weak adductor of the humerus
- attached to the lowest facet on the greater tubercle of the humerus
subscapularis
- innervating nerve
- nerve root
- action
- attachment
- upper subscapular, lower subscapular
- C5, C6
- adduction internal (medial) rotation of the humerus
- attaches distally on the lesser tubercle of the humerus
covers the majority of the anterior/costal surface of the scapula, aptly named the subscapular fossa
which 4 muscles make up the rotator cuff?
- supraspinatus
- infraspinatus
- teres minor
- subscapularis
they all have roots of C5 and C6
how does teres major play an indirect part in the rotator cuff?
does not participate in the shoulder capsule/rotator cuff, BUT it does performs upward rotation of the glenoid fossa and humeral adduction. It contributes to the posterior axial fold
medial rotator and adductor of the humerus; also helps stabilize the humeral head in the gloenoid cavity
innervated by lower subscupular nerve
what makes the muscles of the rotator cuff susceptible to wear and tear?
the coracobrachialis and short head of the biceps brachii attachments to the coracoid process
the subscapularis and supraspinatus muscles pass deep to these attachments to the coracoid process
this makes these muscles of the rotator cuff susceptible to wear and tear during shoulder flexion, abduction, and rotation
teres major
- innervating nerve
- nerve root
- action
- attachment
- innervated by lower sub scapular nerve
- C5, C6, C7
- internal rotation; forms posterior fold of axilla and upward rotation
4.
coracobrachialis
- innervating nerve
- nerve root
- action
- attachment
the deepest of the brachial anterior compartment muscles
- innervated by musculocutaneous nerve
- C5, C6
- flexion; resists shoulder dislocation
- proximal insertion is the tip of the coracoid process, deep to the short head of the biceps brachii, and posterior to the long head of biceps brachii
distal insertion is the medial, middle third of the humerus. It assists in humeral flexion and adduction
deltoid
- innervating nerve
- nerve root
- action
- attachment
the most superficial of the brachial anterior compartment muscles; it overlies the point of the shoulder, and gives it a rounded appearance
- innervated axillary nerve
- C5, C6
- abduction, flexion, extension at the glenohumeral joint
- anterior segment proximal attachment to the lateral third of the clavicle
middle segment proximal attachment to the acromion process of the scapula
posterior segment proximal attachment to the spine of the scapula
distal attachment of the deltoid is the deltoid tuberosity of the humerus
what are the 3 segments of the deltoid?
the deltoid has 3 functional segments
when working independently, each segment act on the humerus individually
the anterior segment flexes the humerus after initiation of the motion by the supraspinatus muscle for the first 15°
the posterior segment extends the humerus
what are bursae?
synovial membranes filled with fluid that prevent tissue damage from sliding/friction
what are the two important bursa in the body?
- subscapularis bursa
communicates normally with the joint space of the glenohumeral joint
- subacromial bursa
does not normally communicate with the joint space
biceps brachii
- innervating nerve
- nerve root
- action
- attachment
- innervated by musculocutaneous nerve
- C5, C6
- flexion/supination of the forearm
- the long head occupies the inter tubercular groove of the humerus and travels through the glenohumeral joint space to attach to the supraglenoid tubercle
the short head is anterior to the long head and its proximal attachment is on the coracoid process
the distal attachment is to the biceps aponeurosis and radial tuberosity