Exam 3 Review:  Chapter 10:  Fiber Orientation in Naming Muscles  

parallel - A muscle fiber orientation in which the component skeletal muscle cell is an equal distance apart for the entire length of the fibers everywhere; this fiber orientation provides more range of motion but less power for contraction.

oblique - Structures situated in a slanting position; not transverse or longitudinal: oblique skeletal muscles or ligaments; the orientation of skeletal muscle fibers in pennate and convergent skeletal muscles; this fiber orientation provides less range of motion but more power for contraction.

deltoid - Triangular; shaped like the Greek letter delta; a thick triangular multi-pennate skeletal muscle covering the shoulder joint, used to raise (abduct) the arm from the side of the trunk.

pennate - The name given to a specific arrangement of fascicles in a skeletal muscle, reminiscent of a feather; in this pattern, the muscle fascicles are short and they attach at an oblique angle to a central tendon which runs the length of the skeletal muscle; such an arrangement of skeletal muscle cells in fascicles provides increased power for contraction but may compromise the range of motion of the muscle; if the muscle fibers extend from only one side of the tendon, the muscle is termed unipennate; if the muscle fibers extend from both sides of a tendon, the muscle is termed bipennate; if several bipennate units are combined by attaching to a common tendon, e.g., as seen in the deltoid, the muscle is termed multi-pennate.

convergent - Tending to one point of focus; tending to approach each other; a skeletal muscle fiber arrangement in which the fibers are in an somewhat parallel orientation, spread across a wide bone surface at the origin and coming together at a tendon attachment at the insertion; this fiber orientation provides a good compromise in providing for both  range of motion and power for contraction.

rhomboid - A parallelogram with unequal adjacent sides; a configuration of skeletal muscle fibers producing the shape of a rhombus as seen in a unipennate skeletal muscle.

trapezoid -

1. A quadrilateral having two parallel sides; e.g., the trapezoid ligament which connects the coracoid process and the clavicle; e.g., the trapezius muscle -- either of two large flat triangular skeletal muscles running from the base of the occiput to the middle of the back that support and make it possible to raise the head and shoulders, and so named because of the shape of the skeletal muscles paired.
2. A small carpal bone in the wrist, situated near the base of the index finger.

sphincter - A ringlike muscle that normally maintains constriction of a body passage, tubular organ, or orifice and that relaxes as required by normal physiological functioning; most sphincters are composed of smooth muscle, e.g., sphincters of the digestive and urinary tracts; a few sphincters are composed of skeletal muscle, at least in part, e.g., the anal sphincter.

List:

2. Six criteria used in naming individual skeletal muscles.

Sketch and label:

2. The various shapes of skeletal muscles with reference to their fiber/fascicle orientation.