FOM 24: Muscle Fxn and Superficial Back Flashcards
Flexion/Extension
in a sagittal plane around a transverse axis
ABduction/ADduction
in a coronal plane around an anterioposterior axis
Rotation
in a horizontal (transverse plane) around a vertical axis
Concentric contraction
Active muscle fibers decrease in length
Typical movement of an agonist mover - fxns to produce the desired action
Eccentric Contraction
Active muscle fibers increase in length
Typical of an antagonist muscle, produces movement opposite to the agonist
*Allows for smooth, controlled movement by counteracting the force applied by the agonist muscle.
Isometric Contraction
Active muscle fibers maintain same length
Typical of a Fixator muscle - stabilizes and supports and element against the pull of an agonist.
EX: scapula fixator muscles
Synergistic contraction
Muscle contraction tends to produce motion around all possible axes
- Neutralizers are muscles whose contraction prevents undesireable action.
- Synergists are muscle whose contraction aides in producing desired motion while at the same time neutralizing undesired motion
Nerve lesions
usually a nerve injury that either partially or completely denervates a muscle resulting in muscle weakness or complete loss of function, respectively
Neutral position
point of balance in which all the motions characteristic of a joint may occur; typically involves minimal ligamentous tension, and the least muscular effort to maintain
Muscular imbalances
occurs when some muscles across a joint are weakened or paralyzed
Pectoral girdle
functional unit of the clavicle and scapula
*articulates with axial skeleton at the sternoclavicular (SC) joint (only bony articulation between pectoral girdle and the axial skeleton)
Can perform: Elevation/depression, protraction/retraction, superior/inferior rotation
Glenohumeral joint
between the glenoid fossa of the scapula and the humeral head
Intrinsic (deep) back muscles
- derived from the embryonic dorsal muscle mass
- innervated by dorsal primary rami
- Blood supply from dorsal branches of segmental arteries
- Movement of the trunk and head, and maintains posture
Extrinsic (superficial) back muscles
- Derived from the embryonic ventral muscle mass
- Innervated by ventral primary rami
- Blood supply from branches of subclavian and axillary aa.
- produce movement of the upper extremity and assist in respiration
Trapezius m. ORIGIN
Medial third of superior nuchal line, external occipital protuberance, ligamentum nuchae, T1-T12 spinous processes
Trapezius m. INSERTION
Spine of scapula, acromian, lateral third of clavicle
Trapezius m. ACTIONS
Elevates and retracts pectoral girdle, superiorly rotates and stabilizes scapula
Trapezius m. INNERVATION
Spinal accessory n. (CN XI) –> motor
C3-C4 ventral rami via cervical plexus –> sensory
Trapezius m. BLOOD SUPPLY
Transverse cervical a.
Latissimus Dorsi m. ORIGIN
T7-L5 spinal processes, thoracolumbar fascia, dorsal sacrum, iliac crest
Latissimus Dorsi m. INSERTION
Floor of intertubercular sulcus of the humerus
Latissimus Dorsi m. ACTION
Extends, adducts, and medially rotates humerus. Depresses, retracts, and inferiorly rotates scapula.
Latissimus Dorsi m. INNERVATION
Thoracodorsal n.
Latissimus Dorsi m. BLOOD SUPPLY
Thoracodorsal a.
Rhomboideus major m. ORIGIN
T2-T5 Spinous processes
Rhomboideus major m. INSERTION
medial border of the scapula
Rhomboideus major m. ACTION
Retracts and elevates the pectoral girdle, inferiorly rotates scapula, stabilizes scapula
Rhomboideus major m. INNERVATION
Dorsal scapular n. (C5)
Rhomboideus major m. BLOOD SUPPLY
Dorsal scapular a.
Rhomboideus minor m. ORIGIN
C7-T1 spinous processes
Rhomboideus minor m. INSERTION
Medial border of the scapula superior to Rhomboideus major m.
Rhomboideus minor m. ACTION
Retracts and elevates the pectoral girdle, inferiorly rotates the scapula, stabilizes scapula
Rhomboideus minor m. INNERVATION
Dorsal scapular n. (C5)
Rhomboideus minor m. BLOOD SUPPLY
Dorsal scapular a.
Levator scapulae m. ORIGIN
Slips from posterior tubercles of C1-C4 transverse processes
Levator scapulae m. INSERTION
Superior angle of the scapula
Levator scapulae m. ACTIONS
Elevates pectoral girdle, inferiorly rotates scapula, extends and laterally flexes neck
Levator scapulae m. INNERVATION
C3-C4 ventral rami via cervical plexus and dorsal scapular n. (C5)
Levator scapulae m. BLOOD SUPPLY
Dorsal scapular a.
Serratus posterior superior m. ORIGIN
C7-T3 spinous processes
Serratus posterior superior m. INSERTION
superior borders of ribs 2-5
Serratus posterior superior m. ACTIONS
Elevates ribs 2-5
Serratus posterior superior m. INNERVATION
Segmentally by ventral primary rami (intercostal nerves)
Serratus posterior superior m. BLOOD SUPPLY
Branches of the posterior intercostal aa.
Serratus posterior inferior m. ORIGIN
T11-L3 spinous processes
Serratus posterior inferior m. INSERTION
Inferior borders of ribs 9-12
Serratus posterior inferior m. INNERVATION
segmentally by ventral primary rami (intercostal nn.)
Transverse cervical a.
originates from the thyrocervical trunk off the subclavian a.
- Courses posteriorly in the neck to the levator scapulae m.
- Deep to trapezius m. giving ascending and descending branches that course with branches of the spinal accessory n. (CN XI) and C3-C4 ventral rami
Serratus posterior inferior m. BLOOD SUPPLY
Branches of posterior intercostal aa.
Dorsal scapular a.
Arises as a branch of the transverse cervical a. (50%) or a direct branch of the subclavian a. (50%)
- Courses posteriorly in the neck deep to the levator scapulae m.
- Deep to the Rhomboideus major and minor mm. with dorsal scapular n.
Thoracodorsal a.
From the subscapular a. (a branch of the axillary a.)
- Courses with the thoracodorsal n.
- Deep to the Latissimus dorsi m. (entering near humeral attachment)
Serratus posterior inferior m. ACTION
depresses ribs 9-12
