Muscular and Skeletal systems Flashcards
Origin
Origin or proximal attachment – less
movable, insertion or distal attachment – more movable, when a muscle contracts, its insertion is pulled towards its origin
Direct vs. indirect attachments
direct attachments – short CT fibers
indirect attachments – CT extends beyond end of muscle fibers to form a cordlike tendon (concentrates force in a limited area) or a flat aponeurosis sheet (spreads force over a wide area); indirect attachments are more common
Isometric, Concentric, and Eccentric
- isometric - no change in muscle length
- concentric - muscle length shortens
- eccentric - muscle length lengthens
1 joint vs. >1 joint
- 1 joint - palmar interosseous
- > 1 joint - sartorius
Prime mover (agonist)
muscle(s) primarily responsible for a movement, biceps brachii is an agonist in forearm flexion at EJ, as is brachialis
Antagonist
muscle(s) perform the opposite movement to the agonist, antagonists help stabilize and control movement, triceps brachii:
antagonist in forearm flexion at EJ
Synergist
compliments the action of the agonists, counteracts unwanted movements, weak but performs same movements, fixates an
intervening joint
- biceps brachii contracts, it flexes the forearm at the elbow but also supinates it
Muscle fibers
skeletal muscle fibers are composed of long, cylindrical, multinucleated cells
- sarcolemma - the plasma membrane
- sarcoplasm - the cytoplasm
Sacromere
basic unit of muscle contraction, boundaries at the two ends of the sarcomere are called Z Lines
Thin vs, thick filaments
- thin - attached to z lines, extending toward the center of the sarcomere, actin, troponin and tropomyosin
- thick - center of the sarcomere and overlapping the ends of the thin filaments, myosin, ATPase enzymes
A band, H zone, I band, M line
- A band - the enter sarcomere
- H zone - the central portion of the A band with no thin filaments
- I band - the two regions on either side of the A band that contain only thin filaments
- M line - the center of the H zone and consists of tiny rods that hold the thick filaments together
Epimysium, perimysium, and endomysium
- Epimysium – tough, dense outer layer that surrounds the entire muscle
- Perimysium – Thick CT that groups individual muscle fibers into fascicles
- Endomysium – Thin inner network of CT that surround individual
Human skeleton regions
- skull - formed by 28 bones, houses the brain and face
- axial skeleton - skeleton of the trunk: ribs, sternum, vertebrae, pelvis, and coccyx
- appendicular skeleton - the skeleton
of the limbs, including the articulations to
the axial skeleton – pelvic and shoulder
girdles, long, short, and irregular bones
Muscle and ligament attachment
points
- Tuberosity: a large, rounded projection, may be roughened.
- Trochanter: a very large, blunt, irregularly shaped process (only present on the femur).
- Tubercle: a small, rounded projection or process
Muscle and ligament attachment
points part 2
- Epicondyle: a raised area on or superior
to a condyle (a rounded articular area). - Spine: a sharp, slender, often pointed
projection. - Process: any bony prominence
Bone markings
- Foramen: a round or oval opening through a bone.
- Fissure: a narrow, slit-like opening.
- Fossa: shallow basin
- Sinus: cavity within a bone, filled with air and lined with a mucous membrane
Projections
- Condyle: a rounded articular projection, often articulates with a corresponding fossa.
- Facet: a smooth, nearly flat articular surface.
- Head: a bony expansion carried on
a narrow “neck”
Diaphysis, Epiphysis, and Periosteum
- diaphysis – tubular “shaft” of a bone
- epiphysis – ends of a bone, covered with articular cartilage
- Periosteum – innervated and vascularized CT membrane that covers the surface of each bone except the epiphyseal ends
Thoracic cage - body framework of chest
- Structure: thoracic vertebrae posterior, ribs lateral, and sternum and CC anterior
- Function: a bony cage that protects the TV, supports the shoulder girdle and upper limb, and provides attachments for many upper body muscles.
- Houses the IM that elevate and depress
the thorax during respiration
Somites
- Sclerotome (“hard piece”): cells migrate medially, gather around the notochord and neural tube: the vertebrae and ribs.
- Dermatome (“skin piece”): cells migrate to more superficial layers and become the dermis of the skin on the dorsum of body.
- Myotome (“muscle piece”): remaining cells that form the trunk and limb musculature
Sternum
manubrium – superior section, articulates with the medial ends of the clavicles, R1, R2
- body – middle portion, sides are notched at CC of ribs 2-7
- xiphoid process – inferior end of sternum, hyaline cartilage
Rib structure
- Head – articulates with the vertebral bodies by two facets.
- Tubercle – articulates with the transverse process of the thoracic vertebra of the same number.
- Shaft – the bulk of the rib.
- Costal groove – located on the inferior border, intercostal nerves and vessels
Thoracic inlet
where TC communicates, passage of trachea, esophagus, vessels, and nerves
Thoracic outlet
more spacious than thoracic inlet: passage of IVC, esophagus, and aorta
Intercostal space
intercostal vein, artery, and nerve travel in the costal groove on the inferior surface of a rib, between the internal and innermost IM
Vasculature of the Thoracic Wall
- right side - intercostal veins drain into the
azygos vein to SVC - left side - into accessory hemiazygos &
hemiazygos veins that in turn drain into the azygos vein
Thoracic Wall nerves (12)
- ventral rami of T1-T11 form intercostal nerves.
- Anterior rami of T12 nerves: subcostal nerves
- Posterior (dorsal) rami of thoracic spinal nerves supply the bones, joints, deep back muscles, and back skin
Intercostal muscles
occupy the intercostal spaces, 3 groups:
-External – Elevate rib cage
- Internal – Depress rib cage
- innermost – discontinuous – Expiratory, decrease volume of the rib cage - weak
Intercostal muscles part 2
- External layer stabilizes ribs, during forced inspiration elevates ribs.
- Internal and innermost layers stabilize ribs, during forced expiration: different parts depress and elevate ribs.
-Serratus posterior superior elevates ribs, - Serratus posterior inferior depresses ribs
Other muscles
- Upper limb muscles responsible for moving the scapula and humerus: pectoralis major, pectoralis minor, and serratus anterior
- All are innervated by branches of the brachial plexus
