Muscular system Flashcards
Skeletal muscles attach to ____
Bones
Where does the flexor carpi ulnaris insert?
Onto medial carpus
What makes cardiomyocytes highly resistant to fatigue? Note - not required for LQB187 content
Cardiomyocytes have a high density of mitochondria that allows them to quickly produce ATP
What is the name of the quadriceps tendon when it continues inferior to the patella?
Patella ligament
Why are skeletal muscle cells multinucleated?
The fusion of many myocytes that forms each muscle fibre results in multinucleated cells
Name some (general) regions of the body where tendons are common
Upper and lower limbs
How many nuclei do smooth muscle cells have?
A single nucleus
What is the function of smooth muscle?
- Involuntary movement
- Moves food
- Respiration control
- Moves secretions
- Regulated blood flow in arteries by contraction
How much of body mass is made up of skeletal muscle?
40%
What does contractility allow for muscles?
Allows muscles to pull on their attachment points and shorten with force
Skeletal muscles perform voluntary movement and maintenance of ____
Posture
What is the movement faciliated by muscles in the posterior compartment of the brachium?
Extension of the elbow joint
What is the meaning of muscle tissue being ‘contractile’?
The tissue can shorten and generate a pulling force
What prevents separation of cardiomyocytes during cardiac contraction?
Intercalated discs (the specialised junctions between cardiomyocytes)
Are cardiomyocytes multinucleate?
Yes, they usually have one or two centrally located, oval shaped nuclei
Describe the histology of smooth muscle (fibres, striations, and nuclei)
- Short and spindle-shaped
- No evident striation
- Single nucleus in each fibre
What are skeletal muscle fibres comprised of?
Myofibrils bundled together by three layers of connective tissue
What are tendinous intersections?
The three transverse bands of collagenous fibres that segment the rectus abdominis muscles
Describe cardiomyocytes as they are typically found
Single cells, typically with a single centrally located nucleus
What structures of a skeletal muscle contain dense regular connective tissue?
Tendons and/or aponeuroses (tendon-like variation of deep fascia that attaches sheet-like muscles that need a wide attachment area)
The cardiac muscle pumps blood through the body and is under ____ control
Involuntary
What segments the rectus abdominis muscles?
Three transverse bands of collagenous fibres called tendinous intersections
What muscle feature is used to name the biceps brachii and the triceps brachii?
The number of muscle heads (AKA muscle bellies); ‘bi’ meaning two, ‘tri’ meaning three
What is formed by the convex surface of the thoracic diaphragm?
The elevated floor of the thoracic cavity
What muscle structures are in the posterior compartment of the brachium?
The three heads of the triceps brachii
Name the muscle that crosses the glenohumeral and elbow joints to flex both joints
Biceps brachii
What the head flexes or extends, are the neck muscles acting unilaterally or bilaterally?
Bilaterally
For what are the involuntary contractions of cardiomyocytes responsible for?
Contraction of the heart, and therefore the distribution of blood around the body
Which type of muscles attach to bones?
Skeletal muscles
Where can smooth muscle be found?
Walls of major organs and passageways
Are cardiomyocytes typically found as single cells or fused together?
Single cells
Name three structures that have passage through openings in the thoracic diaphragm
- Descending aorta
- Inferior vena cava
- Oesophagus
Cardiomyocytes form long, ____ cardiac muscle fibres that are connected through ____ discs
Branching; intercalated
What does it mean to say that muscle tissue is excitable?
Muscle tissue responds to a stimulus
What is made possible by contraction of skeletal muscle?
Locomotion, facial expressions, posture, and voluntary movements
Describe the histology of skeletal muscle (fibres, striations, and nuclei)
- Long cylindrical fibres
- Striated
- Many peripherally located nuclei
Describe the structure formed by attached cardiomyocytes
Long, branching cardiac muscle fibres
Where do the muscular domes of the thoracic diaphragm insert?
Into the central tendon
Give two examples of a muscle named according to its relative size and length compared to others in its region
- Pectoralis major (larger)
- Gluteus maximus (largest)
What are the three primary types of muscle tissue?
Skeletal, cardiac, and smooth muscle
How many heads does the pectoralis major have?
Two
What type of contraction is enabled by smooth muscle?
Involuntary
Give an example of a muscle named for its anatomical region or particular bone
Gluteus maximus (located in the gluteal region)
The muscles of mastication assist in the movement of what joint?
Temporomandibular joint
What do the inferior surfaces of the pericardial sac and pleural membranes fuse to?
The central tendon of the diaphragm
Where can skeletal muscle be found?
Attached to bones and around entrance points to the body (e.g. mouth, anus)
What does the deltoid allow?
Abduction, flexion, extension, and medial and lateral rotation of the glenohumeral joint
What is the large triangle-shaped muscle in the posterior neck and back?
The trapezius
What is facilitated by the thoracic diaphragm changing the volume of the thoracic cavity?
Breathing
Cardiomyocytes are adapted to contract without what?
Cardiomyocytes are adapted to contract without any stimulation
The direction of a muscle’s fibres and fascicles describes the muscles in relation to what?
The midline
What movement does the head make when the neck muscles act bilaterally?
The head flexes or extends
What is the function of skeletal muscle?
- Voluntary movement
- Produces heat
- Protects organs
Is the superior surface of the thoracic diaphragm convex or concave?
Convex
Name the major abductor of the glenohumeral joint
Deltoid
What joint is flexed and adducted by the flexor carpi ulnaris?
The radiocarpal joint
The walls of hollow organs are often what kind of muscle?
Smooth muscle
How do skeletal muscle cells appear under a light microscope?
Striated with many nuclei squeezed along the membranes
The location of muscle heads is also the location of the muscle’s ____
Origins/insertions
What type of muscle forms the contractile walls of the heart?
Cardiac muscle
Name the large muscle on the posterior neck and back
Trapezius
Describe the histology of cardiac muscle (fibres, striations, and nuclei)
- Short and branched fibres
- Striated
- One or two centrally located nuclei
Where are the nuclei generally located in skeletal muscle fibres?
At the periphery of each cell
Which type of muscle is made of non-striated muscle fibres?
Smooth muscle fibres
A muscle can return to its original length when ____
Relaxed
Why do skeletal muscle cells appear striated under a light microscope?
The regular alternation of the contractile proteins actin and myosin, along with the structural proteins that couple the contractile proteins to connective tissues
What are tendons?
Cord-like attachments composed of dense regular connective tissue that attach a skeletal muscle’s fibres to relatively small areas on bone or cartilage
Where do the muscles in the anterior compartment of the antebrachium insert?
Onto different parts of the hand
What is used to describe muscles relative to the midline?
The direction of the muscle fibres and fascicles
Of skeletal, smooth, and cardiac muscle, which are excitable?
All three - their plasma membranes can change their electrical states from polarised to depolarised and send an electrical wave called an action potential along the length of the membrane
For which phase of breathing does the chest cavity expand?
Inhalation
How far do the rectus abdominis muscles extend?
Originate from the pubic symphysis and extend the length of the abdomen
What allows muscle tissue to pull on its attachment points and shorten with force?
Contractility
What shape is the thoracic diaphragm at rest?
Dome-shaped
What is the function of cardiac muscle?
Contracts to pump blood
The pectoralis major is associated with the movement of what joint?
Glenohumeral
How are the back muscles grouped?
According to the lengths and direction of the fascicles
What is produced asa by-product of skeletal muscle contraction?
Heat
Both sternocleidomastoid muscles working together are the ____ of the head
Flexors
Does the number of muscle cells vary widely over short times or remain relatively constant?
The number of muscle cells stays relatively constant throughout life
Name some of the origins of the muscular domes of the thoracic diaphragm
- The sternum (anteriorly)
- The inferior six ribs and their cartilages (laterally)
- The lumbar vertebrae and 12th ribs (posteriorly)
The appendicular muscles of the interior part of the body stabilise which structure?
The pelvic girdle
What is contraction of smooth muscle tissue responsible for?
Involuntary movements in internal organs
In what kind of locations (not specific) can smooth muscle be found?
The walls of hollow organs
Do individual skeletal muscle fibres lie parallel or perpendicular to each other?
Parallel
What enables a muscle to return to its original length when relaxed?
A quality of muscle tissue called elasticity that allows the muscle to recoil back to its original length
Where can cardiac muscle be found?
Heart
How many openings for the passage of structures between thorax and abdomen are there in the thoracic diaphragm?
Three
What are intercalated discs?
Specialised cell junctions between cardiomyocytes
Which muscle cells can respond to stimuli other than the nervous system, like hormones and local stimuli?
Cardiac and smooth muscle
Give an example of a muscle in the anterior compartment of the antebrachium
Flexor carpi ulnaris
Are the muscles in the anterior compartment of the antibrachium flexors or extensors?
Flexors
How many segmenting bands do the rectus abdominis muscles have?
Three each
Which cavities are separated by the thoracic diaphragm?
Thoracic and abdominal
What occurrence is a result of the facial expression muscles inserting in the skin rather than on bone?
When the muscle contract, the skin moves to create facial expression
What is the meaning of ‘excitable’ cells?
Their plasma membranes can change electrical states from polarised to depolarised and send an electrical wave called an action potential along the length of the membrane
Which muscle extends the radiocarpal and interphalangeal joints?
Extensor digitorum
What are the two categories of muscles?
Axial and appendicular (same as the skeletal system)
Is the inferior surface of the thoracic diaphragm convex or concave?
Concave
What is a principle characteristic of cardiomyocytes?
They contract on their own intrinsic rhythms without any external stimulation; they are capable of self-excitation
What is the major muscle that laterally flexes and rotates the head?
The sternocleidomastoid muscle
What muscles circle the anterior surface of the eye orbits?
Orbicularis oculi
What muscle changes the volume of the thoracic cavity?
Thoracic diaphragm
How are muscles named? There are six possible answers
By their shape, location, size compared to other nearby muscles, number of origins, action, or attachments to the skeleton
What is the proper term for a muscle cell?
Myocyte
When a muscle is named based on its attachments, what is named first?
The origin
What is shivering?
Involuntary contraction of skeletal muscles in response to perceived lower than normal body temperature
What is the major component of skeletal muscles?
Skeletal muscle fibres contained within the muscle belly
How many muscles are in the quadriceps femoris group?
Four
Movement of the temporomandibular joint is assisted by muscles of what action?
Mastication
What is the meaning of elasticity?
It can recoil back to its original length due to the presence of elastic fibres
What is the group of muscles in the anterior compartment of the thigh?
Quadriceps femoris group
Which type of muscles perform voluntary movement and maintain posture?
Skeletal muscles
Which type of muscle cell completely depends on signalling from the nervous system?
Skeletal muscle cells
Do cardiomyocytes fatigue?
Cardiomyocytes are highly resistant to fatigue
Give an example of a muscle named after its attachment to the skeleton
Sternocleidomastoid muscle (has origins on the sternum and clavicle, and inserts on the mastoid process of the temporal bone)
How do skeletal muscles participate in thermal homeostasis?
Skeletal muscles generate heat as a by-product of contraction
Which type of muscle tissue is made of non-striated muscle fibres that are thickest in the centre before tapering at the ends?
Smooth muscle fibres
Is skeletal muscle anucleated, nucleated, or multinucleated?
Multinucleated
What muscle is the largest of the gluteal group?
Gluteus maximum
Why is smooth muscle named ‘smooth’?
The cells do not have striations
Where is the insertion of the patellar ligament?
Tibia
Where do most muscles that insert on the femur and move it originate?
On the pelvic girdle
Name the most anterior and superficial muscle of the quadriceps femoris group
Rectus femoris
What is the anatomical term for chewing?
Mastication
When the head rotates, are the neck muscles acting unilaterally or bilaterally?
Unilaterally
What is the effect of hypertrophy of the tendinous intersections of the rectus abdominis muscles?
‘Six-pack ab’ appearance
Are the muscles in the superficial posterior compartment of the antibrachium flexors or extensors?
Extensors
What muscle originates in the sternum and clavicle and inserts into the mastoid process?
Sternocleidomastoid muscle
What is the group of muscles that are some of the largest and most powerful in the body?
Gluteal group
Give an example of a muscle in the superficial posterior compartment of the antebrachium
Extensor digitorum
Where do the tendons of the extensor digitorum insert?
Digits 2 to 5
Name a muscle of facial expression
Orbicularis oculi (a circular muscle that encloses the eye)
What joins cardiomyocytes?
Intercalcated discs (specialised cell junctions)
List some of the minor structures in skeletal muscles
Areolar connective tissue, blood vessels and their epithelial lining, nerves, nerve receptors, and nerve endings
Skeletal muscle is attached to ____
Bones
What do cardiomyocytes do that allow the cells to synchronise their actions?
The cells form long, branching cardiac muscle fibres connected through intercalated discs
What muscle flexes and adducts the radiocarpal joint?
The flexor carpi ulnaris
Are cardiac muscle cells striated under a microscope?
Yes, cardiomyocytes are striated
What structure is common to all four muscles in the anterior compartment of the thigh?
The quadriceps tendon
Give an example of a muscle named according to the direction of its muscle fibres and fascicles
The rectus (straight) abdominis muscle
Give two examples of muscles named for the movement they produce
- Flexor carpi ulnaris (flexes the radiocarpal joint)
- Extensor digitorum (extends the interphalangeal joints of the fingers)
How do cardiomyocytes attach to each another?
Specialised cell junctions called intercalated discs
How does the temporalis muscle assist with eating?
It retracts the mandible
Describe the nucleus of a smooth muscle myocyte
Centrally located, cigar-shaped nucleus
In what region is the pectoralis major located?
Thorax
Where are the muscular domes of the thoracic diaphragm?
To the sides of the central tendon
In which compartment are the muscles that flex the hip and extend the knee, anterior or posterior compartment of the thigh?
Anterior compartment of the thigh
For which phase of breathing does the chest cavity volume decrease?
Exhalation
What surrounds each skeletal muscle?
Dense irregular connective tissue, known as the deep fascia
What is prevented by intercalated discs during cardiac contraction?
Separation
Can the origin of a muscle move?
No
Skeletal muscle tissue is arranged in ____ surrounded by connective tissue
Bundles
What is allowed by the precise attachent of skeletal muscle fibres to bones/cartilage via tendons?
Production of fine motor movements
What movement is allowed by the attachment of the patellar ligament to the tibia?
Extension of the knee joint
What movement does the head make when the neck muscles act unilaterally?
The head rotates
What is the patellar ligament?
The inferior continuation of the quadriceps tendon past the patella
Where do the rectus abdominis muscles originate?
Pubic symphysis
What are the fibres of the muscle insertions of the facial expression muscles intertwined with?
Connective tissue and the dermis of the skin
In which compartment is the rectus femoris?
Anterior compartment of the thigh
What does ‘extensibility’ mean in regards to muscles?
The muscles can stretch or extend
Give some examples of involuntary contraction enabled by smooth muscles (there are two possible answers)
- Vasoconstriction (restricts blood flow)
- Peristalsis (aids digestion and elimination of waste from the body
What is formed by the concave surface of the thoracic diaphragm?
The curved roof of the abdominal cavity
What feature of cardiac muscle allows the tissue of the heart to produce synchronised contractions?
The cardiomyocytes being branched and tightly joined by intercalated discs that prevent separation during contraction
____ muscle cells completely depend on signalling from the nervous system
Skeletal
Where do the muscles in the anterior compartment of the antebrachium originate?
On the humerus
What kind of tissue forms the deep fascia?
Dense irregular connective tissue
Name a muscle in the anterior compartment of the brachium
Biceps brachii
Which muscles lie anteriorly in the abdominal wall?
The rectus abdominis, a pair of long, linear muscles
Describe the two heads of the pectoralis major
Larger sternal head and a smaller, more superior clavicular head
Name a vessel located in the thorax but associated with movement of the glenohumeral joint
Pectoralis major
What structures fuse onto the central tendon of the thoracic diaphragm?
The inferior surfaces of the pericardial sac and pleural membranes
Of smooth, skeletal, and cardiac muscle cells, which one/s appear striated?
Skeletal and cardiac muscle cells
Which types of muscle cells can be influenced by the nervous system to some degree?
Cardiac and smooth muscle cells
What is the proper term for cardiac muscle cells?
Cardiomyocytes
What are cardiomyocytes?
Cardiac muscle cells
Which muscle covers much of the superior portion of the anterior thorax?
Pectoralis major
What are the structures to the sides of the central tendon of the thoracic diaphragm?
The muscular domes (the skeletal muscle portions of the thoracic diaphragm
Where is the insertion of the quadriceps tendon?
In the patella
Skeletal muscles perform ____ movement and maintence of posture
Voluntary
Which muscle is the major abductor of the glenohumeral joint, and facilitates flexion, medial rotation, extension, and lateral rotation?
Deltoid
Where are the origins of the muscles of facial expression?
On the surface of the skull
What shape are smooth muscle cells?
Spindle-shaped
In which compartment are the three heads of the triceps brachii?
Posterior compartment of the brachium
List some organs that have smooth muscle in the walls
Hollow organs:
- Urinary bladder
- Uterus
- Stomach
- Intestines
- Passageways (arteries and veins)
- Tracts of the respiratory, urinary, reproductive systems
Give two examples of terms that describe a muscle’s shape
- Deltoid (triangle)
- Orbicularis (circular)
What muscle is superficial to the temporal bone?
Temporalis
Muscle tissue is characterised by properties that allow ____
Movement
Involuntary movements in internal organs are the result of contraction of what kind of muscle?
Smooth muscle
What joints are extended by the extensor digitorum?
Radiocarpal and interphalangeal joints
