Lecture 8: Skeletal Muscles Flashcards by Anupama Adikaram

What are the three types of muscle tissue? Briefly explain similarities and differences

Skeletal Muscle: movement of bones, striated, voluntary\
Cardiac Muscle: located in the heart only, striated (branching), involuntary
Smooth Muscle: outside walls of viscera, no striations, involuntary

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Elaborate the process on how we move:

Skeletal muscle attaches to bones via tendons and pulls bone along the joint to produce movement.

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In the appendicular skeleton what are the attachment points called:

Origin: Attached to the stationary bone

Insertion: Attached to the moveable bone

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In the axial skeleton what are the attachment locations called.

Superior attachment: moveable bone

Inferior attachment: less mobile bone

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What are the functions of skeletal muscles:

→ Movement

→ Maintain posture

→ Protection

→ Regulation of waste products

→ Heat Production

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What is the classification tree for a typical skeletal muscle:

Myofilaments: actin and myosin
myofibers: Muscle cells
Fascicles: Bundles of myofibers
Skeletal muscle: Group of fascicles.

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Identify the connective tissue which surround the myofibers, fascicles, and fascicle bundles respectively.

Endomysium: CT around myofiber

Perimysium: CT around fascicle

Epimysium: CT around fascicle bundles

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What are the 2 types of contraction: Name a scenario when this can occur:

Isometric Contraction: Tension = no change in muscle length (holding a baby)

Isotonic Contraction: Tension = change in muscle length (moving a baby up)

→ Concentric- muscle length decreases

→ Eccentric- muscle length increases

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What are the three components of the lever system:

Fulcrum: fixed point which lever moves

Load: the force imbalance provided by either some weight or bone to oppose movement

Effort: Force provided by muscle which causes movement

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What are the types of levers? Give examples.

First-Class Lever: L-F-E , either advantageous or disadvantageous (head movement)

Second-Class Lever : E-L-F, always advantageous (plantarflexion movement)

Third Class Lever F-E-L, Always disadvantageous (Lifting something with hand)

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What are the classification of skeletal muscles?

Parallel
Fusiform
Circular
- Triangular

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What are the groupings for muscle coordination: Name one example

Agonist: Prime mover (contraction = movement) triceps brachii

Antagonist: Contraction opposes that of the agonist and allows for smoother movement : biceps brachii

Synergist: assist by contributing tension and stabilizing point of origin

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Describe the pennate and classify:

Short fascicles which branch of the main tendon of the skeletal muscle:

Unipennate: Arranged in only one side of the tendon

Bipennate: Arranged on 2 sides of the tendon

Multipennate: Attached to tendon from many different directions

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What is the innervation and function of the facial muscles.

Innvervated by the FACIAL NERVE

Function: Moves the skin (not bone) to produce facial expression

COMMON: Orbicularis Oris (mouth),,, Orbicularis oculi (eye),,, Nasalis

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What is the innervation and function of the muscles of mastification

Innervated by the TRIGEMINAL NERVE
- Function: Allow to chew (mastificate)

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Identify the muscles and what they are used for

(superior → inferior)

Temporalis

Masseter

Used for mastification

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Identify the muscles and what they are used for

(superior → Inferior)

Temporalis

Lateral pterygoid

Medial pterygoid

USED FOR MASTIFICATION

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What is the innervation for the muscles of the abdomen and what are their function:

Innervated by thoracic spinal nerve

Function: Flexion of the trunk and support of viscera

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Identify the important muscles and what they are used for:

RHS: top to bottom

Rectus Abdominis

Transverse abdominis

Internal Oblique

External Oblique

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What is the innervation for the muscles of respiration and what is their function

Main Muscle is the Diaphragm which is innervated by the phrenic nerve.

Function: respiration by the flattening of its surface to increase thoracic cavity for respiration

Identify the important muscles and what they are used for:

External Intercostals and Internal Intercostals:

Used in the muscles of respiration

What is the innervation of the muscles of the back, and what are their function?

Innervated by cervical, thoracic, spinal nerves,

Function: Erects the spine

Identify the 3 main muscles and what they function to do.

Erector Spinae (left to right as seen posteriorly)

→Iliocostalis group

→longissimus group

→spinalis group

Identify the main muscles of the pectoral girdle + thorax

LHS:

Deltoid

Pectoralis Major

Bicep brachii long head

bicep brachii short head

RHS:

Pectoralis Minor (deep)

Identify the main muscles of the pectoral girdle + thorax

RHS: Trapezius Latissimus Dorsii LHS: Rhomboid Minor Rhomboid Major

What is the innervation and function of the upper limb (anterior compartment)

innervated by the **musculocutaneous nerve** Function: Flexion of the arm

Identify the important muscles and what they are used for

bicep brachii (long head) bicep brachii (short head) tricep brachii

Identify the main muscles of the rotator cuff muscles:

Anterior view: Supraspinatus… subscapularis Posterior View: Infraspinatus… Teres Minor

What is the innervation of the Upper limb (posterior of arm) and function.

Innervated by the **Radial Nerve**. Function: Extension of the arm

Identify the important muscles and their function:

Top to Bottom: **Triceps Brachii →** Long Head → Medial Head → Lateral Head

What is the innervation and function of the upper limb (anterior compartment of forearm)

Innervated by the **Median + Ulna Nerve** Function: Flexion of the wrist and fingers.

Identify the Important muscles and their function:

**Top to Bottom** Pronator Terres Flexor Carpi Radialis Palmaris Longus Flexor Carpi Ulnaris

Identify the main muscle in charge of the flexion of the fingers

Flexor Digitorium Superficialis

What is the innervation of the posterior compartment of the forearm and what is its function

Innervated by the Radial Nerve Function: Extension of the wrist and fingers

What is the antagonist muscle which controls the extension of the fingers

Extensor digitiorum

What is the innervation of the hand and its function?

Innervated by the median + Ulnar nerve Function: Fine movements of the finger

What are the main muscles and what are their function?

RHS: **Hypothenar Eminence** **→** Flexor Digitorum minima brevis → Abuctor Digitorum minima LHS: **Thenar Eminence** **→** Flexor pollicis brevis → Abductor pollicis brevis

What is the function of the gluteal region, name all important muscles.

Function: extension of hip, thigh and external rotation ## Footnote TOP TO BOTTOM Gluteus Medius Gluteus Maximus

What is the innervation of the lower limb (anterior compartment of thigh) and its function:

Innervated by the **Femoral Nerve** Function: extensions of the knee

Identify the main muscles and label the function.

Left → Right Vastus Lateralis Rectus Femoris Vastus Medialus POSTERIOR: Vastus intermedius

What is the innervation of the medial compartment of the thigh? Identify the function of these muscles.

Innervated by the **obturator nerve**: Function: Adduction of the hip

Identify the main muscles and label its function:

TOP TO BOTTOM Adductor longus Adductor magnus **Adduction of the hip**

What is the innervation of the lower limb (posterior compartment of the thigh)

Innervated by the Sciatic Nerve Function: Extend the Hip and flexion of the knee

Identify the main muscles and their function

Hamstring group: LEFT → RIGHT * semimembranous * semitendinous * bicep femoris long head * bicep femoris short head

What is the innervation of the lower limb (anterior compartment of the leg). Identify the function:

Innervated by the deep fibular nerve Function: Allows dorsiflexion

Identify all the main muscles, and label its function.

Left → Right Extensor digitorum longus Extensor hallucis longus Tibialis anterior

What is the innervation of the lower limb (lateral compartment of the leg), identify the function.

innervated by the superficial fibular nerve function: Eversion of the foot

Identify the main muscles and label its function:

Left → Right * Fibularis Longus * Fibularis Brevis

what is the innervation of the lower limb (posterior compartment of the leg)

Innervated by the tibial nerve Function: Plantarflexion