Muscles Flashcards
What characteristics are used to name different muscles of the body?
Shape: e.g Quadratus muscle
Sites of attachment: e.g. Sternocleidomastoid muscle
Fiber orientation: e.g. External oblique
Position of the muscle: e.g. Palmer interosseous
Function: e.g. adductor magnus
Describe parallel arrangement of muscle fascicles and give an example of a muscle with such arrangement
Muscle fascicles are arranged in the same direction as the long axis of the muscle. An example of this is the sartorius muscle.
Describe fusiform muscles and give an example
Fusiform muscles have their fascicles arranged in the same direction as the long axis of the muscle, however, the muscle has a large central belly that tapers to tendons on each end. E.g. Biceps brachii.
What type of muscle is obicularis oculi? describe this type
It is a circular muscle. It’s fascicles are arranged in concentric bundles
Describe fascicle arrangement in covergent muscles and give an example of such a muscle
Fascicles arranged in a widespread expansion over a
sizeable area that come to a single common
attachment point. This attachment point can be a tendon or aponeurosis
E.g Pectoralis major
Describe a pennate muscle
In a pennate muscle, there is a long tendon that runs through the central part of the muscle, and then the muscle fascicles stem from this tendon. These fascicles can only pull at an angle
What are the three types of pennate muscles?
Describe them and provide an example
Unipennate: muscle fascicles located to only one side of the tendon. E.g. Extensor digitorum
Bipennate: Fascicles located on both sides of the tendon. e.g. Rectus femoris
Multipennate: Fascicles that insert on multiple tendons that taper
towards a common tendon. e.g. Deltoid
What is a two-bellied muscle? give an example
A two bellied muscle has two bellies connected by a central tendon. An example of this is the gastrocnemius muscle
What is a two-headed muscle?
A muscle that has two origin points. e.g. the biceps femoris
Describe the Tapezius muscle in terms of origin, insertion, innervation and action
Origin: External occipital protuberance, ligamentum nuche, and spinous processes of C7-T12
Insrertion: Clavicle, acromion, and spine of scapula
Innervation: Accessory nerve (CN-IX)
Action: Upper fibers elevate the scapular; middle fibers retract/adduct the scapula; lower fibers depress the scapula. Collectively rotate the scapular during abduction
Describe biceps brachii in terms of origin, insertion, innervation and action
Origin: Long head - supraglenoid tubercle of the scapula
Short head - apex of the coracoid process
Insertion: tubercle of radius
Innervation: Musculocutaneous nerve
Action: Elbow flexion and forearm supination
Describe pectoralis major in terms of origin, insertion, innervation and action
Origin: Clavicle, sternum, first seven costal cartilages,
sixth rib
Insertion: Intertubercular sulcus of humerus
Innervation: Medial and lateral pectoral nerves
Action: Flexion, adduction and medial rotation of arm
Rectus abdominis
Origin:
Pubic crest, pubic tubercle and pubic symphysis
Insertion:
Xiphoid process of sternum, costal cartilages of
ribs 10-12
Innervation:
Thoracoabdominal nerves
Action:
Compress abdominal contents, flexes vertebral
column, tenses abdominal wall
External oblique
Origin:
Ribs 5 - 12
Insertion:
Iliac crest, aponeurosis that ends in linea alba
Innervation:
Thoracoabdominal nerves
Action:
Compress abdominal contents, flexes trunk, turns
anterior aspect of abdomen to the opposite side
Rectus femoris
Origin: Anterior inferior iliac spine ilium above the acetabulum Insertion: Quadriceps femoris tendon Innervation: Femoral nerve Action: Flexes the thigh at the hip joint, extends the leg at the knee joint
