Class 15 - Muscular System Flashcards
Functions of muscular system (6)
- Movement - Move body parts and body contents in breathing, circulation, digestion. Communication (speaking etc.)
- Stability - maintain posture; stabilize joints
- Control of body openings/passages - control food intake and elimination of waste.
- Heat production (thermogenesis) - produce 20-30% of body heat at rest, up to 85% during exercise
- Hormone secretion - exercise releases hormones which stimulate liver glucose synthesis and breakdown of visceral fat
- Glycemic control - absorb, store, and use much of body’s glucose, so help stabilize blood’s concentration
What is the study of the muscular system called?
Myology
What is the one major purpose of all muscle types?
Convert chemical energy in ATP into mechanical energy of motion
What skeletal muscles contain (4)
- Skeletal muscle tissue
- Connective tissue
- Nerves
- Blood vessels
Connective tissue components of muscle (deep to superficial) (5)
- Endomysium - thin sleeve of loose connective tissue around each fiber. Allows room for capillaries and nerve fibers, provides chemical environment
- Perimysium - Thicker layer of connective tissue wrapped around fascicles. Carries nerves, blood vessels, stretch receptors.
- Fascicles - bundles of muscle fibers wrapped together.
- Epimysium - Fibrous sheath surrounding entire muscle; blends with fascia and deeper connective tissues
- Fascia - sheet of connective tissue between muscles/muscle groups
5 muscle types + examples
- Fusiform muscles - thick in middle. Fascia converge in each tapered end.
Example: biceps brachii
- Parallel muscles - uniform width. Parallel fascicles
Example: rectus abdominis
- Triangular muscles - broad and one end with fascicles converging on the other, narrower end.
Example: pectoralis major
- Pennate muscles - feather shaped; fascicles attach obliquely on a tendon that runs length of muscle.
Example: palmar interosseous
- Circular muscles (sphincters) - fascicles form rings around body openings/passages. Prevent passage when contracted.
Example: orbicularis oculi
Muscle compartments
Groups of functionally related muscles packaged by fasciae.
Contains nerves and blood vessels that supply muscle group.
Intermuscular septa
Fasciae between muscle compartments which are extra thick
2 types of muscle attachments, 2 accessories
- Direct (fleshy) attachment to bone - Little separation between muscle and bone
- Indirect attachment to bone - Tendon connects muscle to bone. Collagen fibers of connective tissue layers continue into tendon and into periosteum/bone matrix
A. Aponeurosis - Broad, flat sheet of tendon
B. Retinaculum - connective tissue band that tendons from separate muscles pass under
Intrinsic vs extrinsic muscles
Intrinsic - entirely contained within a region
Extrinsic - act on a designated region but arise from another region.
Example: extrinsic hand muscles arising from forearm.
Action
Effect produced by a muscle to produce or prevent movement
4 categories of muscle action
- Prime mover - produces most force of a movement (brachialis flexes elbow)
- Synergist - aids prime mover (biceps brachii assist brachialis)
- Antagonist - opposes prime mover (triceps brachii extends elbow)
- Fixator - prevents bone from moving (rhomboid muscles fix scapula when biceps contract)
Spinal vs. cranial nerves
Spinal nerves - arise from spinal cord, emerge thru intervertebral foramina, branch into posterior/anterior rami, innervate muscles below neck
Cranial nerves - arise from base of brain, emerge thru skull foramina, innervate muscles of head and neck
3 facts about blood supply to muscular system
- Receives about 1.24 L blood per minute at rest, 1/4 cardiac output
- During exercise, receives more than 3/4 of cardiac output
- Capillaries branch extensively through endomysium to reach EACH muscle fiber
Hernia + 3 types
Any condition in which the viscera protrudes thru weak point in muscular wall of abdominopelvic cavity
- Inguinal - Most common (mostly men), viscera enter inguinal canal or scrotum
- Hiatal - stomach protrudes thru diaphragm into thorax. Typical of overweight people over 40.
- Umbilical - Visceral protrudes thru navel of infants
3 types of pennate muscles
- Unipennate - fascicles approach tendons from one side
- Bipennate - Fascicles approach tendon from both sides
- Multipennate - Bunches of feathers converge to single point
3 functions of tongue muscles + 2 muscle types
- Push food between molars for chewing (mastication)
- Force food into pharynx for swallowing (deglutition)
- Aid in speech
A. Intrinsic - muscles within tongue; fascicles in 3 directions
B. Extrinsic - arise from outside tongue
5 actions of chewing
- Depression - opening mouth
- Elevation - biting and grinding
- Protraction - allow incisors to cut
- Retraction - make rear teeth meet
- Lateral/medial excursion - grind food
4 attachments of muscles acting on head and neck
Arise from:
1. Vertebral column
2. Thoracic cage
3. Pectoral girdle
End on:
4. Cranial bones
6 actions of muscles acting on the head and neck
- Flexion - tipping head forward
- Extension - holding head erect/back
- Lateral flexion - tipping head to side
- Rotation - turning head
- Contralateral movement - toward opposite side
- Ipsilateral movement - toward same side
4 muscles of the orbital/nasal regions
- Orbicularis oculi
- Levator palpabrae superioris
- Corrugator supercilii
- Nasalis
8 muscles of the oral region
- Orbicularis oris
- Levator labii superioris
- Levator anguli oris
- Zygomaticus major
- Zygomaticus minor
- Risorius
- Depressor anguli oris
- Depressor labii inferioris
3 muscles of the mental/buccal regions
- Mentalis
- Buccinator
- Platysma
4 extrinsic muscles of the tongue
- Genioglossus
- Hyoglossus
- Styloglossus
- Palatoglossus
