Lab 8 - Skeletal Muscles

Muscle Fiber (Muscle Cell)

Skeletal muscles are made up of elongated muscle cells called muscle fibers. Inside of muscle fibers are the proteins responsible for contraction.

Endomusium

The endomysium is a delicate layer of connective tissue that surrounds each individual muscle fiber, providing support and facilitating the exchange of nutrients and waste between the fibers and blood vessels.

Fascicle

A bundle of muscle fibers grouped together. Each is surrounded by a layer of connective tissue called the perimysium.

Perimysium

The perimysium is a connective tissue sheath that encases a group of muscle fibers, forming a fascicle, and provides structural support and protection.

Epimysium

The epimysium is a dense layer of connective tissue that surrounds an entire muscle.

Orgin

The origin is the fixed attachment point of a muscle, usually located on a bone, from which muscle contraction generates movement.

Insertion

The insertion is the movable attachment point of a muscle, typically located on a bone, where contraction of the muscle causes movement at a joint.

Action

The action of a muscle refers to the specific movement it produces when it contracts, influencing the position or posture of body parts.

Frontalis

Occipitalis

Obicularis oris

Zygomaticus major

Buccinator

Origin, Insertion, Function

Temporalis - origin is the temporal fossa and the temporal line of the skull. Insertion is at the coronoid process of the mandible. It functions to retract the mandible.

Scalenes (3)

Digastric

Origin, Insertion, Function

Sternocleidomastoid

• origin is the manubrium of the sternum and the clavicle. Insertion is at the mastoid process of the temporal bone. It functions to flex and rotate the head.

Origin, Insertion, Function

Pectoralis major

• origin is the clavicle, sternum, and ribs. Insertion is at the greater tubercle of the humerus. It functions to flex, adduct, and medially rotate the arm.

Origin, Insertion, Function

Pectoralis minor

• origin is the third to fifth ribs. Insertion is at the coracoid process of the scapula. It functions to stabilize the scapula and assist in respiration.

Origin, Insertion, Function

Serratus anterior

• origin is the lateral surfaces of the upper eight or nine ribs. Insertion is at the medial border of the scapula. It functions to protract and stabilize the scapula.

What are the Rotator Cuff muscles?

Supraspinatus,

Infraspinatus,

Teres minor,

Subscapularis

Origin, Insertion, Function

Supraspinatus is a rotator cuff muscle that originates from the supraspinous fossa of the scapula and inserts on the greater tubercle of the humerus. It functions to abduct the arm and stabilize the shoulder joint.

Origin, Insertion, Function

Infraspinatus is a rotator cuff muscle that originates from the infraspinous fossa of the scapula and inserts on the greater tubercle of the humerus. It functions to externally rotate the arm and stabilize the shoulder joint.

Origin, Insertion, Function

Teres minor is a rotator cuff muscle that originates from the lateral border of the scapula and inserts on the greater tubercle of the humerus. It functions to externally rotate the arm and stabilize the shoulder joint.

Origin, Insertion, Function

Subscapularis is a rotator cuff muscle that originates from the subscapular fossa of the scapula and inserts on the lesser tubercle of the humerus. It functions to internally rotate the arm and stabilize the shoulder joint.

Teres major

Origin, Insertion, Function

Latissimus dorsi

origin T7-L5, scapula, iliac crest

insertion bicipetal groove

function medial rotation of shoulder joint

Origin, Insertion, Function

Deltoids

origin clavicle and scapula

insertion deltoid tuberosity on the humerus

function stabilization of shoulder abduction of shoulder

Origin, Insertion, Function

biceps brachii

origin Short head - Apex of the Coracoid process of the scapula
Long head - Supraglenoid tubercle of the scapula
Mnemonic: 'You walk Shorter to a street Corner. You ride Longer on a Superhighway'

insertion Radial tuberosity of the radius

function Flexion and supination of the forearm at the elbow joint

Origin, Insertion, Function

triceps brachii

origin scapula and humerus

insertion Olecranon of ulna and fascia of forearm

function extension of the elbow

Origin, Insertion, Function

Brachialis

origin humerus

insertion ulna

function strong flexion of forearm at the elbow joint

Origin, Insertion, Function

Brachioradialis

origin humerus

insertion radius

function Forearm flexion (when semi pronated)

Origin, Insertion, Function

Flexor digitorum superficialis

origin Medial epicondyle of humerus, coronoid process of ulna, and radial head

insertion Sides of middle phalanges of digits 2-5

function finger flexion

Origin, Insertion, Function

extensor carpi radialis longus

origin humerus

insertion Posterior aspect of base of metacarpal bone 2

function hand extension

Origin, Insertion, Function

Extensor digitorum

origin humerus

insertion digits 2-5

function finger extension

Origin, Insertion, Function

Extensor pollicus longus

origin ulna

insertion distal phalanx of thumb

function thumb extension