CC

Muscles (copy)

What are the different functions of muscles in the body? What systems are they found in? Functions: movement, posture, respiration, blood vessel tension, digestion, sphincter control, heat production. Found in: skeletal, cardiovascular, respiratory, digestive, urinary, and integumentary systems.

What are the three types of muscles? Describe basics of structure (mononucleate vs multinucleate, cell shape, how signals are transmitted).

  • Skeletal: multinucleate, striated, elongated; voluntary; each cell innervated individually.

  • Cardiac: mononucleate, branched, striated; involuntary; signals spread via intercalated discs.

  • Smooth: mononucleate, spindle-shaped, no striations; involuntary; cells joined in sheets.

Give an example of smooth muscle functions in each of the following systems:

  • Respiratory: controls airway diameter

  • Cardiovascular: regulates blood vessel diameter

  • Digestive: propels food via peristalsis

  • Urinary: controls bladder emptying

What is the difference between a tendon, ligament, and fascia?

  • Tendon: connects muscle to bone

  • Ligament: connects bone to bone or cartilage

  • Fascia: wraps body parts in connective tissue (e.g., silver skin)

Know the following action terms:

  • Flexion: decreases angle between parts

  • Extension: increases angle

  • Adduction: movement toward body

  • Abduction: movement away from body

  • Levator: lifts or closes

  • Depressor: lowers or opens

  • Supination: rotates palm/sole up or medially

  • Pronation: rotates palm/sole down or laterally

Know what epaxial vs hypaxial muscles are and in what species these are prominent vs reduced, or undifferentiated vs differentiated.

  • Epaxial: dorsal to vertebral column (vertebral support)

  • Hypaxial: ventral to vertebral column (body wall, respiration)

  • Fish: undifferentiated

  • Amphibians: epaxial = dorsalis trunci; hypaxial begins differentiation

  • Reptiles: epaxial differentiation (transversospinalis, longissimus, iliocostalis)

  • Mammals: highly differentiated hypaxial muscles

  • Birds: axial muscles reduced; specialized for flight

Which muscle groups form the pectoral muscular sling? Be able to contrast this to the pelvic girdle attachment.

  • Muscular sling: brachiomeric and axial muscles (e.g., trapezius, rhomboideus, serratus ventralis)

  • Pectoral girdle not attached to vertebral column by bone

  • Pelvic girdle is fused to vertebral column; fewer extrinsic muscles

What is so cool about the avian shoulder? Do know the muscles involved in raising and lowering the wing during flight.

  • Supracoracoideus lifts wing via tendon through triosseal canal (humerus, scapula, coracoid)

  • Pectoralis lowers wing

  • Allows powerful and efficient flight mechanics

What are the two main muscle groups of the hindlimb (dorsal and ventral)? Which extend vs flex the hip? Extend vs flex the stifle?

  • Dorsal: quadriceps (hip flexors, stifle extensors)

  • Ventral: hamstrings (hip extensors, stifle flexors)

What is unique about bird leg muscles compared to mammals? Bird leg muscles are consolidated proximally (near the body), allowing lightweight distal limbs for flight efficiency.

What is the common calcaneal tendon and its function? Also known as the Achilles tendon. Connects gastrocnemius to calcaneus; aids in plantar flexion.

What are the facial muscles and their functions?

  • Digastric: opens jaw

  • Masseter & Temporalis: close jaw Also includes muscles for hearing, hyoid movement, and facial expression.

What is the patagium and its associated muscles in birds? Patagium: wing membrane

  • Propatagialis muscle and tendon control wing tension and shape during flight

What defines range of motion (ROM) in joints? ROM is defined by ligaments, tendons, and muscles. Hyperextension occurs when movement exceeds normal limits.