Musculoskeletal System: The Muscles Flashcards
What is muscle tissue?
Specialised tissue that contracts when stimulated to exert a physical force on other tissues, organs or fluids
What are the types of muscle?
Skeletal, cardiac and smooth
Where would you find cardiac muscle?
Myocardial layer of the heart
What are the features of cardiac muscle?
Striated, shorter than skeletal muscle, branched, connected by intercalated discs with a centrally located nucleus
Are smooth muscle cells innervated?
No
Give an example of smooth muscle that is innervated
Muscles in the iris
What may smooth muscle contract or relax in response to?
Chemicals, hormones, local O2 concentrations and physical factors (stretching/irritation)
What is the structure of smooth muscle?
Sheets, bundles or sheaths, cells are bound together transmitting contractile forces and has a normal background level of activity
What control is skeletal muscle under?
Somatic/ voluntary control
What is the general structure of a skeletal muscle?
Origin, belly, insertion
Where is skeletal muscle found not on the skeleton?
Voluntary sphincters of the eyelids, urethra and anus, diaphragm, tongue and some muscles of the oesophagus
What are the features of myofibres?
Cylindrical, multinucleate, striated and packed with contractile proteins
What is the skeletal muscle body covered in (and what is it called)?
Dense layer of collagen fibres - epimysium
What does the epimysium enclose?
Several muscle fasciculi
What is a fascicle?
Bundles of muscle fibre grouped together
What does the perimysium contain?
Contains blood vessels and nerves that are passing into the muscle tissue
How can muscle adapt to change in activity patterns and loading?
Muscle size, balance between protein synthesis and degradation and diseased states
How do skeletal muscles attach to bones?
Through extensions of their connective tissue components
What is an aponeurosis?
A broad flat tendon attaching a muscle to the bone
How do indirect muscular attachments work?
Muscle ends short of its bony destination and the bridge is gapped by a tendon
How do direct muscle attachments work?
Short collagen fibres gap the bridge between muscle and bone
How many attachments do biceps have?
2
How many attachments do triceps have?
3
How many attachments do quadriceps have?
4
What does a muscle do when it contracts?
Moves one bone relative to another
What is the origin of a muscle?
Bony attachment site at the stationary end
What is the insertion of a muscle?
The attachment site at the more mobile end
Where is the quadriceps femoris proximal attachment?
Femur
Where is the quadriceps femoris distal attachment?
Tibia, just below the knee
Where is the origin and insertion of the quadriceps femoris when you’re sat down and straightening your legs?
Femur is origin and tibia is insertion
Where is the origin and insertion of the quadriceps femoris when you’re standing up?
Tibia is origin and femur is insertion
What are the functional muscle groups?
Agonist, antagonist, synergistic and fixation
What is an agonist muscle?
Contraction is chiefly responsible for producing a particular movement
What is an antagonist muscle?
Action opposes that of a particular agonist - stretches but will not usually contract completely
What is a synergist muscle?
Aids agonist to stabilise joint or start movement
What is a fixator muscle?
Prevents unwanted movement and stabilises a joint
What does an increase in the number of muscle fibres do to the strength of contraction?
Increases it
How are fibres within a fascicle arranged?
Parallel
What does the orientation of fascicles determine?
Functional properties of muscle
What do fusiform muscles look like?
Thick in the middle and tapered at each end
What do parallel muscles look like?
Fairly uniform width with parallel fascicles
What do circular muscles look like?
Fibres arranged concentrically around an opening or recess
What do triangular muscles look like?
Broad at one end and narrow at the other
What are pennate muscles?
Muscles with fascicles that attach obliquely to it’s tendon
Give an example of a fusiform muscle
biceps brachii and soas major muscle
Give an example of a parallel muscle
Rectum abdominus
Give an example of a circular muscle
orbicularis oculi
How are the muscle fibres arranged in unipennate muscles?
All on the same side of the tendon
How are the muscle fibres arranged in bipennate muscles?
Approach tendon from both sides
How are the muscle fibres arranged in multipennate muscles?
Branching of the tendon within a pennate muscle
Give an example of a unipennate muscle
Palmar interosseous
Give an example of a bipennate muscle
Rectus femoris
Give an example of a multipennate muscle
Deltoid
What does the strength of any given muscle depend in part on?
Physiological cross sectional area
What are the muscles of the limbs divided into?
Discrete compartments
What are muscle compartments divided by?
A sleeve of deep fascia
In the arm what are the anterior and posterior compartments relative to?
Humerus
What two muscles both attach at the Coracoid process?
Biceps brachii and coracobrachialis
What muscles are in the anterior arm compartment?
biceps brachii, brachialis, coracobrachialis
What are the names of the compartments in the arm proper?
Anterior and posterior
What muscle is in the posterior arm compartment?
Triceps brachii
What are the compartments in the forearm?
Anterior and posterior compartments
How many muscles are there in the anterior compartment of the forearm and where are they found?
8 (4 superficial, one intermediate and three deep)
Where is the common site of origin for the superficial anterior muscles of the forearm?
Medial epicondyle humerus
What is special about the palmaris longus muscle?
It has a really long tendon
Where does the flexor digitorum profundus run to?
Distal phalanx
Where does the flexor pollicis longus run to?
Thumb
Where does the flexor digitorium profundus run to and what is its function?
Middle phalynx, flex the digits
What is the function of the anterior forearm?
Flexion of the wrist and fingers and pronation of the forearm
How many muscles are in the posterior compartment of the forearm and where are they found?
12 (7 superficial and 5 deep)
What is the common site of origin for the muscles of the posterior forearm?
lateral epicondyle humerus
What is the function of the posterior forearm?
Extension of the wrist and fingers and supination of the forearm
Where is the thigh?
Between the inguinal ligament and knee joint
What are the compartments of the thigh?
Anterior, posterior and medial
What is the function of the anterior thigh?
Extension of the knee and flexion of the hips
How many muscles are in the anterior thigh?
3
What is the function of the posterior compartment of the thigh?
Extension of the hip and flexion of the knee
What is the function of the medial thigh?
Adduct hip
How many muscles are in the posterior thigh?
3
How many muscles are in the medial thigh?
5
Which muscles join together in the thigh?
Psoas major and illiacus muscle
Which is the longest strap muscle in the body and where does it run?
Sartorius muscle - from the ASIS to the tibia
What are the compartments of the leg?
Posterior, anterior and lateral
How many muscles are found in the posterior leg?
7
Which muscles combine to form the calcaneal tendon?
Gastrocnemius and soleus
What are the posterior leg muscles involved in?
Plantarflex and inversion of the foot
What is the anterior leg involved in?
Dorsiflexion and inversion of the foot
How many muscles are in the anterior leg?
3
What is the lateral leg involved in?
Eversion of the foot
How many muscles are in the lateral leg?
2
