Superficial Back Flashcards
To produce an action at a joint a muscle must ___
Cross the joint
How do m uncle contractions produce movement
Pulling the movable attachment (insertion) toward the fixed attachment (origin)
The force a muscle exerts is proportional to _____
It’s physiological cross-section area
The muscle’s range of contraction is proportional to ____
The resting length of its fiber
How are muscle contractions classified?
Their effect on muscle fiber length and role in producing particular actions
Concentric contraction
. Active muscle’s fibers decrease in length
. Typical of agonist
Agonist
Muscle that functions to produce a desired action
Eccentric contraction
. Active muscle’s fibers increase in length
. Typical of antagonist
.Allow smooth, controlled movement and provide a brake during rapid or forceful movements
Antagonist
Muscle that produces the movement opposite to the agonist
Isometric contraction
. Active muscle’s fibers maintain length
. Typical of a fixator
Fixator
. Muscle that stabilizes or supports an element (usually fixed attachment) against the pull of the agonist
Synergistic contraction
. Muscle contraction tends to produce motion around all possible axes
. Neutralizers contraction prevents an undesired action
. Synergists contract in coordination to produce desired motions while neutralizing undesired motions
Nerve lesion
. Injury that innervates some, but not all of the muscles that produce a particular action that action is weakened
. If lesion enervates all muscles that produce action that action is lost
Neutral position
. Point of balance from which all motions characteristic of a joint may occur
. Involves minimal ligamentous tension and requires the least muscular effort to maintain
What contractions balance forces acting around a joint to maintain it in the desired neutral position?
Isometric (tonic) contractions of antagonistic muscle groups
Muscle imbalance
Some, but not all, muscles acting across a joint are weakened or paralyzed
Unopposed contraction of normal muscles produces _______
Stereotypical limb postures associated w/ different neuromuscular syndromes
Muscle contracture
Permanent deformity that happens when Unopposed muscles shorten
Pectoral girdle
Functional unit formed by the clavicle and scapula
What does the pectoral girdle articulate with?
. Axial skeleton at sternoclavicular (SC) joint
. only bony articulation between upper extremity and the axial skeleton
Elevation of pectoral girdle
. Moving pectoral girdle superiority (shrugging shoulders)
Elevation/depression plane and axis of movement in pectoral girdle
Coronal plane around the AP axis of the SC joint
Depression in pectoral girdle
Returning to neutral position (unshrugging)
Protraction/retraction plane and axis in pectoral girdle
Transverse plane around the vertical axis of SC joint
Retraction in pectoral girdle
Drawing girdle posteriorly so medial scapular border approximates vertebral column
Protraction in pectoral girdle
Drawing girdle anteriorly as when rounding shoulders
Superior/ inferior rotation of scapula movement type and plane
Gliding movements of the acromioclavicular (AC) joint allow the scapula to rotate in a coronal plane
Superior rotation lateral rotation, abduction) of scapula
Glenoid fossa points superiority and the inf. Scapular angle rotates laterally
Inferior rotation (medial rotation, adduction) of scapula
Glenoid fossa points inferiorly and the inf. Angle rotates medially toward the vertebral column
DO pectoral glide movements occur in isolation?
NO
Glenohumoral joint
. Glenoid fossa of scapula and humeral head
. Highly mobile (add/abduction, flex/extension, and med./lateral rotation)
Scapulohumeral rhythm
Coordinated movements of pectoral girdle and glenohumoral joint required for full range of motion of the shoulder
What movements in the pectoral girdle are paired with the glenohumoral joint?
. Flexion of arm above the shoulder requires protraction and fixation of scapula
. Abduction of arm over 180 degrees requires sup. Rotation and fixation of scapula
How are back muscles divided into groups?
based on embryonic origin, innervation, and function
Intrinsic (deep) back muscles Are derived from ____
Embryonic dorsal muscle mass
What are intrinsic back muscles innervated by?
Dorsal primary rami
Blood supply to intrinsic back muscles
Dorsal branches of segmental arteries
Intrinsic back muscles functions
Movement of trunk and head and maintain posture
Extrinsic (superficial) back muscles derived from____
Embryonic ventral muscle mass
Extrinsic back muscle innervation and blood supply
. Blood supply branches of subclavian and axillary aa.
. Innervation from ventral primary rami
Extrinsic back muscle functions
Upper extremity movement and assist in respiration
Medial attachments of back muscles are ____, and the lateral attachment is ____
. Origins
. Insertions
Trapezius m. OIA
O: medial 3rd of sup. Nu Hal line, external occipital tuberance, ligamentum nuchae, T1-12 spinous process
I: spine of scapula, acromion, lat. 3rd of clavicle
A: elevates and retracts pectoral girdle, superiority rotates and stabilizes scapula
Trapezius m. Innervation (N) and blood supply (B)
N: motor -spinal accessory n. (CN XI)
sensory- C3-4 ventral rami via cervical plexus (pain propioception)
B: transverse cervical a.
What occurs when trapezius is denervated?
. Drooping of affected shoulder and lat. winging of scapula
. Ability to abduct the arm above shoulder level may be impaired
Latissimus Dorsi. M. OIA
O: T7-L5 spinous processes, thoracolumbar fascia, dorsal sacrum, iliac crest
I: floor of intertubular sulcus of numerous
A: extremes, adducts, and medially. Rotates humerus
Latissimus dorsi m. N and B
N: thoracodrosal n.
B: thorsacodorsal a.
How does latissimus dorsi move when an upper extremity is fixed?
It forcefully pulls the torso anteriorly and superiorily
Rhomboid major OIA:
O: T2-5 spinous processes
I: medial scapula border
A: retracts and elevated pectoral girdle, inferiorly rotates scapula, stabilizes scapula
Rhomboid major N B
N: dorsal scapular nerve
B: dorsal scapular a.
Rhomboid minor OIA:
O: C7-T1 spinous processes
I: medial border of scapula sup. To rhomboid major
A: retracts and elevates pectoral girdle, inf. Rotates and stabilizes scapula
Rhomboid minor NB
N: dorsal scapular nerve (C5)
B: dorsal scapular a.
levator scapulae m OIA
O: slips from post. Tubercles of C1-4 transverse processes
I: sup. Angle scapula
A: elevated pectoral girdle, inf. Rotates scapula, extends and laterally flexes neck
Levator scapulae NB
N: dorsal scapular n. (C5)
B: dorsal scapular a.
Intermediate back muscles
Serratus post. Sup. And post. Inf. Muscles
Serratus Superior posterior m. OIA
O: C7-T3 spinous processes
I: sup. Borders of ribs 2-5
A: elevates ribs 2-5
Serratus posterior superior m. NB
N: segmentally by ventral primary rami (intercostal nerves)
B: branches of posterior intercostal aa.
Serratus posterior inferior m. OIA
O: T11-L3 spinous process
I: inf. Borders of ribs 9-12
A: depresses ribs 9-12
Serratus posterior inferior m. NB
N: segmentally by ventral primary rami (intercostal nn.)
B: branches of posterior intercostal aa.
Transverse cervical a.
. From thyrocervical trunk off the subclavian a.
. Courses post. In neck superficial to levator scapulae
. Passes deep to trapezius giving ascending and descending branches that course with spinal accessory n. And C3-4 ventral rami
Dorsal scapular a.
. Branch of transverse cervical artery (50%) or direct branch of subclavian a. (50%)
. Courses post. In neck deep to levator scapulae
. Descends deep to rhomboid major and minor w/ dorsal scapular n.
Thoracodorsal a.
. From subscapular artery (branch of axillary a.)
. Courses with thoracodorsal n. Deep to latissimus dorsi entering near its humeral attachment
