Chapter 10 - The Muscular System

Question 0

What are the connective tissues and fascicles?

Answer 0

1. Endomysium - thin sheath of loose CT that surrounds each muscle cell.
2. Perimysium - CT sheath that wraps muscle cells together in bundles (fascicles) and contain larger nerves, blood vessels and stretch receptors.
3. Epimysium - fibrous sheath that surrounds the entire muscle.
4. Fascia - a sheet of CT that separates neighboring muscles.

Question 1

What is the function of muscles?

Answer 1

1. Movement - muscles enable us to move the body and body contents.
2. Stability - muscles maintain posture by preventing unwanted movements.
3. Control body openings and passages.
4. Heat production - muscles produce 85% of the body heat.
5. Glycemic control - muscles absorb, store and use a large share of the glucose and play a role in stabilizing blood glucose concentrations.

Question 2

What is the functional organization of fascicles and muscle shapes?

Answer 2

The strength of a muscle and the direction of its pull are determined partly by the orientation of its fascicles.

Question 3

What is the classification of muscles according to fascicle orientation?

Answer 3

a. Fusiform muscles - thick in the middle and tapered at each end.
b. Parallel muscles - uniform width and parallel fascicles.
c. Triangular (convergent) muscles - fan-shaped with one end broad and one end narrow.
d. Pennate muscles - feather-shaped in which the fascicles insert obliquely on a tendon that runs the length of the muscle.
e. Circular muscles (sphincters) - rings around body openings.

Question 4

What are the different types of muscle attachments?

Answer 4

1. Indirect attachment
2. Direct attachment - there is little separation between muscle and bone.
3. Origin - attachment site to the bone at the stationary end.
4. Insertion - attachment site at its mobile end.

Question 5

What is indirect attachment?

Answer 5

a. The muscle ends short of the bone and the gap is bridged by a tendon.
b. Collagen fibers of the muscle continue into the tendon and into the periosteum.
c. Aponeurosis - the tendon is a broad sheet.

Question 6

What are the functional groups of muscles?

Answer 6

1. Prime mover (agonist) - a muscle that produces most of the force during a joint action.
2. Synergist - a muscle that aids the prime mover by stabilizing a joint or modifying the direction of movement.
3. Antagonist - a muscle that opposes the prime mover and limits the speed or range of the prime mover.
4. Fixator - a muscle that prevents a bone from moving.

Question 7

What else does the antagonist do?

Answer 7

a. It prevents excessive movement and joint injury.

b. Antagonist pairs are needed because a single muscle cannot flex and extend the joint.

Question 8

What are intrinsic and extrinsic muscles?

Answer 8

1. Intrinsic muscle - muscle with origin and insertion in a particular region.
2. Extrinsic muscle - muscle with the origin in one region and the action and insertion elsewhere.

Question 9

What is muscle intervention?

Answer 9

1. Spinal nerves - from the spinal cord and innervate muscles below the neck.
2. Cranial nerves - arise from the base of the brain and innervate muscles of the head and neck.

Question 10

How are muscles named?

Answer 10

1. By the adjacent bone.
2. By the action of the muscle.
3. By the shape of the muscle.
4. By the number of heads.
5. By the location of the muscle.
6. By the size of the muscle.
7. By the origin or insertion of the muscle.

Question 11

What are the muscles of respiration?

Answer 11

a. Diaphragm
b. External intercostals
c. Internal intercostals

Question 12

What are the injection sites of muscles?

Answer 12

a. Deltoid

b. Gluteus medius

Question 13

What are the tendons of the rotator cuff?

Answer 13

a. Supraspinatus
b. Infraspinatus
c. Teres minor
d. Subscapularis

Question 14

What are the muscles of the quadriceps?

Answer 14

a. Rectus femoris
b. Vastus lateralis
c. Vastus medialis
d. Vastus intermedius

Question 15

What are the muscles of the hamstring?

Answer 15

a. Biceps femoris
b. Semitendinous
c. Semimembranous

Question 16

What are the muscles of the calf?

Answer 16

a. Gastrocnemius

b. Soleus

Question 17

What are the disorders of the muscular system?

Answer 17

1. Compartment syndrome - inelastic fascia prevents the compartment from expanding with fluid accumulation, thus obscuring blood flow by pressure on the arteries.
2. Hernias - viscera protrudes through a weak point in the muscle wall.
3. Carpal tunnel syndrome - tingling and muscle weakness in the palm and hand when swelling in carpal tunnel put pressure on the nerve.
4. Baseball finger - tear in the extension tendons of the fingers from the impact of a baseball with the extended finger.
5. Blocker’s arm - calcification in the lateral margin of the forearm from repeated impact with opposing players.
6. Charley horse - a tear, stiffness and blood clotting in a muscle.
7. Pitcher’s arm - inflammation at the origin of the flexor carpi muscles from hard wrist flexion.
8. Pulled groin - strain in the adductor muscle of the thigh.
9. Pulled hamstrings - strained muscles or a tear in their tendinous origins.
10. Rider’s bones - calcification in the tendons of the adductor muscles of the medial thigh.
11. Rotator cuff injury - a tear in the tendon of the rotator cuff muscles.
12. Shin splints - injury with pain in the crural region.
13. Tennis elbow - inflammation at the origin of the extensor carpi muscles on the lateral epicondyle of the humerus.
14. Tennis leg - a partial tear in the lateral origin of the gastrocnemius muscle.