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Flashcards in Myology Deck (39)
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Differentiate skeletal muscle tissue from skeletal muscles (which are organs) by listing the tissues present in any skeletal muscle.

-skeletal muscle tissue
- smooth muscle tissue
- c.t. proper
- epithelium
- nervous tissue (innervate)
- blood


List the various functions that skeletal muscles perform in the body.

- Locomotion
- Posturing
- Respiration: increase in size of the thoracic cavity caused by contraction of the diaphragm and other thoracic muscles produce a partial vacuum
- Prehension: getting food and drink into the oral cavity
- Mastication: chewing it
- Deglutition: swallowing
- orifice closure: closing lips
- abdominal press: involves contraction of the diaphragm and the muscles forming the abdominal wall to increase the pressure within the abdominal and thoracic cavities (vomiting, defecation, urination, coughing, etc.)
- vocalization
- eye movements
- venous return: contraction of muscles assists movement of blood through the appendicular veins
- heat production: most skeletal muscles produce heat when they contract (shivering)


Define the following as they relate to skeletal muscle structure: belly, tendon, aponeurosis, origin, insertion, epimysium, perimysium, endomysium, and fascicle.

belly: contractile part

tendon: fibrous connective tissue attachments

aponeurosis: broad sheet-like tendons (how some bellies attach)

origin: the attachment of muscle belly to the fixed part of the skeleton

insertion: attachment at the moveable end of a muscle belly

epimysium: skeletal muscles bellies are ensheathed in this fibrous connective tissue

endomysium: surrounds each muscle cell

perimysium: extend inward from the epimysium and segment muscle cells into groups

fascicle: cell groups


what is a fleshy attachment?

tendons that are so short that the muscle belly appears to be directly anchored to bone.


(Explain how each of the following relate to or interact with skeletal muscles.)

*know the diff. kinds of c.t. proper

Fasciae (know 2 kinds)

irregular collagenous connective tissue

bonds the skin to the underlying muscularture, binds muscles into groups, and serves as an avenue of penetration for vessels and nerves

1. superficial fascia (hypodermis, subcutaneous tissue) - directly under the skin; loose fibers
2. deep fascia - surrounds groups of muscles; denser irregular fibers


(Explain how each of the following relate to or interact with skeletal muscles.)

*know the diff. kinds of c.t. proper


dense regular collagenous connective tissue

binds tendons into groups and hold them in certain locations


(Explain how each of the following relate to or interact with skeletal muscles.)

*know the diff. kinds of c.t. proper


synovial fluid sacs that are structurally similar to joint capsules (hv. fibrous outer layer and a synovial membrane lining)

they cushion (protect) the tendons and reduce sliding friction


(Explain how each of the following relate to or interact with skeletal muscles.)

*know the diff. kinds of c.t. proper

Tendon Sheaths

bursae that completely surround tendons and from closed, fluid - filled encapsulations


(Explain how each of the following relate to or interact with skeletal muscles.)

*know the diff. kinds of c.t. proper

Sesamoid Bones

accessory structures of skeletal muscles since they serve as bearing surfaces and protect tendons from frictional degeneration

ex) patella lifts the tendons up so you're not rubbing on bone


Name 3 muscles whose tendons usually contain sesamoid bones.

patella - largest sesamoid bones embedded in the tendons of the quadriceps femoris muscles

pair of sesamoid bones at the base of each thumb - embedded in the tendons of the flexor pollicis brevis muscles

pair as the base of each big toe - in the tendons of the flexor hallucis brevis muscles


Differentiate myofiber, myofribil, myofilament, and myomere.

- myocytes (muscle cells) are also called myofibers

- myofibrils: specialized organelles; elongated cylinder

- myofilaments: rod-like contractile structures located in myofibrils

. myofilaments consist of thinner proteinaceous filaments composed of actin, troponin, myosin, and tropomyosin

- myomere: basic unit of skeletal muscle microstructure from Z line to Z line


Schematically represent the arrangement of the thick and thin myofilaments in a myofibril and indicate what causes the A band, I band, H band, M line, and Z line.

A (anisotropic) band: dark cross bands produced by the thick myofilaments polarize visible light

(A dArk)

I (isotropic) band: don't polarize visible light; extend from the edge of one stack of thick filaments (myosin) to the edge of the next stack of mysoin

(I light)

H band: the lighter central region of each A band consists of thick filaments (no overlap)

M line: dark transverse line (center of H band)

- protein overlap that connects myosin together

Z line: center of each I band crossed by a dark band = z line

- overlap that connects actin together

- formed by cross linking proteins that bind thin myofilaments together


Which ultrastructural features get shorter during contraction?

I band, H band, and the distances between adjacent Z lines and M lines get narrower (everything but A band really)


What is the action of a muscle cell?

the potential movement that contraction of the muscle evokes


What three things happen when a muscle contracts?

1. no movement
2. the movement described by its stated action (you get what you want)
3. the opposite movement from its stated action (opposite action of what you want)


what causes action?

1. contraction
2. elastic recoil
3. gravity


Define and properly use the terms agonist, synergist, antagonist, and fixator.

1. Synergist - muscles which have the same action
2. Antagonist - muscles with opposing actions
3. Agonist - any muscle that is contracting; particular point of reference
4. Fixator - muscles which can contract to reduce or prevent one or more actions of a given muscle (while allowing other actions of the muscle to occur)

- antagonists to one or more actions of multi-actioned cells


Explain why single - actioned muscles can be fixators but cannot have fixators.

A single actioned muscle can be a fixator by having its action be the antagonist to another action in the muscle. It can't have a fixator because it has only one action so there are no other actions that need to be prevented.


Explain why some muscles can have only one stated actions whereas others can have two or even more actions.

they only cross one joint so therefore they only have one action

they cross multiple joints


Define motor unit and explain why muscles over which we have precise control are composed of small motor units.

Motor unit - single motor neuron and the groups of myofibers that it controls collectively

small motor units are used in muscles capable of precise movements because they are very quick and finite


List the 7 major groups of skeletal muscles.

- muscles of the head
- neck
- back
- thorax
- abdomen
- superior limb
- inferior limb


Divide the muscles of the head into 6 groups.

1. Muscles of the Face
- m. orbicularis oculi
- m. orbicularis oris
- m. zygomaticus major
- m. zygomaticus minor
- m. levator labii superioris (cut)
- m. depressor labii inferioris (cut)
- m. mentalis

2. Muscles of the Ear

3. Muscles of the Eye

4. Muscles of Mastication
- m. temporalis
- m. masseter
(strongest muscles of mastication)
- lateral pterygoid m.
- medial pterygoid m.


What muscles are on the most superior part of the head? (occipital)

- Galea aponeurotica
- Frontal Belly of occipitofrontalis m.


Divide the muscles of the neck into six groups.

Suprahyoid m.

Infrahyoid m.

Suboccipital m.

Pharyngeal m.

Laryngeal m.

other muscles of neck:

platysma (depress lower lip)
m. sternocleidomastoideus (turn head opposite side)


What is the largest muscle of the thorax and what does it cover?

Largest: major pectoral muscle

- most powerful flexor of shoulder joint

Covers: minor pectoral muscle


What muscle of the thorax joins the scapula to the ribs?

serratus anterior muscle


What do intercostal muscles of the thorax do and give the name of the one that slants down and back from one rib to the next.

- they draw the ribs closer together

- internal intercostal muscle


Schematically represent a transverse section through the anterior abdominal wall and label the bellies and aponeuroses of the muscles involved.

on pg. 249


Differentiate the pelvic and urogenital diaphragms.

(muscles of the abdomen)




Pelvic Diaphragm: surround anus
(between pubis, ischium, and rectum)

- levator ani (4 parts)
- coccygeus
- external anal sphincter muscles

Urogenital Diaphragm: surrounds vagina
(between pubis and rectum in perineal region)

- ischiocavernosus
- bulbospongious
- transversus perinei superficiales muscles
(superficial group)

- urethral sphincter
- urethral compressor
- urethrovaginal m.
- transversus perinei profundus m.
(deep group)


Define hypaxial and epaxial muscles.

(muscles of the back)

Hypaxial muscles: those anterior to the transverse processes of the vertebrae (include those m. of the thorax and abdomen)

Epaxial muscles: muscles of the posterior trunk which are positioned behind the transverse processes of the vertebrae