Mod 4 Musculoskeletal system Anatomy of the head, neck and trunk

Question 1

What is myosin?

Answer 1

Myosin (thick) close to the M line

Question 2

What is actin?

Answer 2

actin (thin) close to the Z line

Question 3

How does the muscle contract with actin and myosin?

Answer 3

1) the myosin pulls the actin along the cross-bridges of the myosin filaments
2) the myosin filaments attach to the actin filaments and exert force for them to move (a sliding mechanism)

Question 4

Muscle contraction with actin and myosin ext.

Answer 4

• The myosin head extends and attaches to the binding site on actin (forming the cross-bridge) also where ATP binds and converts it to ADP.
• the Powerstroke is triggered when the myosin pulls the actin towards the M line (shortening the muscle)

Question 5

Ca+2 and muscle contractions?

Answer 5

• muscles contractions are associated with the Ca2+ levels
• tropomyosin: relaxes the muscle as it blocks the cross-bridge on actin
• Ca+ binds to troponin –> it allows the binding site
• Ca+ ions are stored in the SR and are released from the NS
• neurotrans. are released and bind to receptors depolarises the membrane of the muscle fiber.
• the impulse travels down the T-tubules and opens the Ca+ stores, calcium ions flow to the myofibrils where a muscle contraction is triggered

Question 6

Actin and myosin summary?

Answer 6

The actin and myosin slide along with each other, the sarcomere shortens as the Z lin draws closer to the M line (shortening and then contracting the muscle).

Question 7

What is the sarcoplasmic reticulum?

Answer 7

It is smooth endoplasmic reticulum in muscle fibres

Question 8

What are myofibrils surrounded by?

Answer 8

Myofibrils are surrounded by sarcoplasmic reticulum and T-tubules

Question 9

What does the sarcoplasmic reticulum store?

Answer 9

The sarcoplasmic reticulum store Ca 2+ released during a muscle contraction

Question 10

What are T-tubules?

Answer 10

T-tubules are a part of a sarcolemma that runs between the SR –> and AP propagating down T-Tubules cause the release of Ca+ from the SR: which allows the actin and myosin to bind

Question 11

What are thin filaments made of?

Answer 11

Thin filaments are made of actin, tropomyosin, troponin

Question 12

What is tropomyosin?

Answer 12

Tropomyosin blocks myosin binding site in the relaxed muscle (with a protein blocking the binding site on myosin-binding sites on actin)

Question 13

Troponin?

Answer 13

Has the binding site for Ca+, the Ca+ binds to the troponin, making the tropomyosin move away from the active sites on actin, the actin then binds to myosin to form cross-bridges (ATP)

Question 14

What are thick filaments?

Answer 14

Thick filaments are myosin which has binding sites for ATP

Question 15

Muscle contraction summary

Answer 15

1) AP travels down a motor neuron
2) Acetylcholine is released at the neuromuscular junction (synapse between neuron and muscle)
3) AP runs down the sarcolemma of the muscle
4) AP travels down the T-tubules
5) Ca 2+ is released from the Sarcoplasmic reticulum
6) Ca+ causes actin and myosin to bind
7) sarcomeres shorten
8) muscle contracts

Question 16

What are axial muscles?

Answer 16

Muscles of the head and neck are in includes in the axial muscles. The muscles of facial expression, mastication, pharynx, and larynx. Muscles of the vertebral column and the thorax, abdomen and pelvis

Question 17

What are muscles of facial expression?

Answer 17

mostly originate on the skull and attach to the fascia and the skin, the contractions move the skin and controls the orifices (openings like eyes and mouth), and basis for facial expression.

Question 18

LABEL the parts of facial expression!

Answer 18

Occipitofrontalis (forehead), orbiclaris oculi (eyes), orbicularis oris (Oral) and buccinator (mouth)

Question 19

What are facial expressions innervated by?

Answer 19

Facial expressions are innervated by the facial nerve - damage like lesions cause drooping like Bell’s palsy

Question 20

LABEL the muscles of mastication

Answer 20

1) temporalis, masseter, medial pterygoid, and lateral pterygoid.

Question 21

What is the temporomandibular joint? (TMJ)

Answer 21

Both TMJs form a single bilateral articulation

Question 22

What is the classification of the temporomandibular?

Answer 22

Synovial, modified (gliding and hinge)- functional: uniaxial diarthrosis

Question 23

Why is the temporomandibular modified?

Answer 23

Modified because the fibrocartilaginous articular disc separates the mandibular fossa and the condyle of the mandible

Question 24

LABEL the extrinsic muscles of the eye

Answer 24

• superior rectus, lateral rectus, inferior oblique, superior oblique, medial rectus and inferior rectus

Question 25

What do the extrinsic muscles of the eye do?

Answer 25

they control the position of the eye

Question 26

What do muscles of the tongue do?

Answer 26

it positions and shapes the tongue for speech, mastication and swallowing.

Question 27

What do the pharynx and larynx do?

Answer 27

Swallowing, speech (voice box)

Question 28

LABEL the muscles of the anterior neck?

Answer 28

pp

Question 29

What do the muscles of the anterior neck do?

Answer 29

move the head and neck (the sternocleidomastoid) (SCM), support the floor of the mouth and are the extrinsic muscles of the larynx 1) Elevators (suprahyoid) and 2) depressors (infrahyoid)

Question 30

What actions do the sternocleidomastoid do?

Answer 30

unilateral action, lateral flexion and contralateral rotation
- bilateral action (upper cervical extent) and lower cervical flexion (waking up and lifting your head off the pillow)

Question 31

What actions do the suboccipital muscles do?

Answer 31

Bilaterally: head extension
Unilaterally: ipsilateral rotation and lateral flexion

Question 32

LABEL the muscles of the vert. column (erector spinae)

Answer 32

1) Illocostalis
2) Longissimus
3) Spinalis

Question 33

What action do the bilateral and unilateral muscles of the vert. column?

Answer 33

Bilateral action: extension

unilateral action: lateral flexion

Question 34

What are the transversospinales group and what do they do?

Answer 34

Rotatores, multifidus, and semispinalis - they attach to the transverse and spinous processes BILATERAL ACTION: extension

Question 35

what are the segmental muscles?

Answer 35

interspinales and intertransversales (proprioceptive)- position in space

Question 36

Label the muscles of the vertebral column

Answer 36

pp

Question 37

Label the muscles in the thorax?

Answer 37

To complete the thoracic wall
3 layers of
intercostals (between ribs)
1. External intercostals
inspiration
2. Internal intercostals
expiration
3. Innermost intercostals

Question 38

Label the muscles in the abdominal wall and their actions

Answer 38

pp - posterior, lateral and anterior

Question 39

Label the muscles in the pelvic wall and their actions

Answer 39

–

Question 40

What are tropomyosin and troponin?

Answer 40

Tropomyosin blocks myosin binding sites on actin molecules, preventing cross-bridge formation, which prevents contraction in a muscle without nervous input. The protein complex troponin binds to tropomyosin, helping to position it on the actin molecule.