Muscle System

Muscular system Includes all skeletal muscle tissue that can be controlled voluntarily

Classification of Skeletal Muscles

Types of Muscles Muscles can be classified by action Agonist (prime mover) Primary responsible for the movement Antagonist Opposes the agonists Synergist Aids the action of agonists Fixator

Origins and Insertions Muscles can be identified by origin, insertion and action Origin = stationary end Insertion = movable end

Names of skeletal muscles Names give clues to muscle characteristics Location of muscle’s origin and insertion Sternohyoid Direction of fibers Tranverse, oblique, rectus Number of origins Biceps, triceps

Names of skeletal muscles Size of the muscle Maximus, minimus Shape Deltoid, trapezius Action Adductor, flexor Location of the muscle Frontalis, orbicularis

Organization of skeletal muscle fibers Parallel muscle Convergent muscle Pennate muscle Unipennate Bipennate Multipennate Circular muscle (sphincter)

Organization of skeletal muscle fibers

Muscles of the Head and Neck

Head

Muscles of the head and neck Epicranius muscles Occipital O: occipital bone I: galea aponeurotic A: pulls the scalp posteriorly Frontal O: galea aponeurotic I: skin of the eyebrow A: raise the eyebrow Geilia apouniurotic

Muscles of the head and neck Orbicularis oculi O: frontal and maxillary bones I: eyelid A: closes eyes Corrugator supercilli O: frontal bone I: skin of eyebrow A: draws eyebrow inferiorly and medially

Muscles of the head and neck Levator labii superioris O: zigomatic and maxilla bones I: upper lip A: raises upper lips Depressor labii inferioris O: mandible I: lower lip A: pulls lower lip inferiorly

Muscles of the head and neck Depressor anguli oris O: mandible I: angle of mouth A: pulls corner of mouth down and laterally Mentalis I: skin of chin A: protudes lower lip

Muscles of the head and neck Zigomatics O: zigomatic bone I: corner the mouth A: smiling muscle Risorius O: masseter I: angle of the mouth A: pulls corner of lips laterally

Muscles of the head and neck Orbicularis oris O: maxilla and mandible I: lips A: compresses lips Buccinator I: orbicularis oris A: compresses the cheek (whistling)

Muscles of Mastication

Muscles of mastication Masseter muscles O: zigomatic and maxilla bones I: mandible A: closes the jaw Temporalis muscles O: temporal fossa

Muscles of mastication Pterygoids O: sphenoid, palatine and maxillary bones I: mandible A: elevates mandible, grinding the teeth Buccinator

Muscles of the head and neck Platysma O: fascia of chest and deltoid I: mandible, skin, corner of the mouth A: depresses mandible, pulls lip back and down Sternocleidomastoid O: manubrium and clavicle I: temporal and occipital bones A: flexion forward of the neck

Neck

Neck

Muscles of the head and neck Scalenes – anterior, middle, posterior O: cervical vertebrae I: first 2 ribs A: elevates first 2 ribs Digastric O: mandible and mastoid process I: hyoid A: elevates hyoid bone

Muscles of the head and neck Mylohyoid O: mandible I: hyoid bone A: elevates hyoid bone Sternohyoid O: manubrium and clavicle A: depresses hyoid bone

Extrinsic eye muscles Inferior and superior rectus muscles Lateral and medial rectus muscles Inferior oblique muscles Elevates the eye and turns it laterally Superior oblique muscles Depresses the eye and turns it laterally

Chapter 25 Muscles of the Trunk

Muscles of the trunk and shoulder Serratus anterior muscles O:ribs I: scapula (anterior surface) A: fixates, protracts the scapula Pectoralis minor muscles O: ribs I: scapula A: ribs fixed: moves scapula forward and inferiorly and with scapula fixed it moves up the rib cage

Muscles of the trunk and shoulder Deltoid muscles O: clavicle and scapula I: humerus A: abduction of the shoulder Pectoralis Major O: clavicle, sternum, ribs A: agonist for shoulder flexion

Muscles of the thorax (front)

Muscles of Respiration External intercostal O: rib above I: rib below A: elevates rib cage Internal intercostal O: rib below I: rib above A: depresses rib cage

Muscles of Respiration

Muscles of Respiration Diaphragm O: ribs and its cartilage, sternum, vertebrae I: central tendon of the diaphragm A: prime action in inspiration

Diaphragm

Muscles of the Trunk (back)

Muscles of the trunk (back) and shoulder Supraspinatus muscles O: scapula I: humerus A: synergist for arm abduction Infraspinatus muscles A: helps to hold the head of the humerus in the glenoid cavity, lateral rotation of humerus

Muscles of the trunk (back) and shoulder Teres major O: scapula I: humerus A: adducts humerus, medial rotation of humerus Teres minor muscles A: helps to hold the head of the humerus in glenoid cavity, lateral rotation of the humerus

Muscles of the trunk (back) and shoulder Trapezius muscles O: occipital bone, vertebrae I: scapula, clavicle A: extend head, elevate scapula Rhomboids O: vertebrae I: scapula A: adduct and stabilize scapula

Muscles of the trunk (back) and shoulder Levator scapulae O: vertebrae I: scapula A: elevates scapula Latissimus dorsi muscles O: vertebrae, ribs, ilium I: humerus A: agonist for shoulder extension

Muscles of Abdominal Wall

Muscles of Abdominal Wall Rectus abdominis O: pubis I: xiphoid process, ribs A: flexes vertebral column,increase abdominal pressure External oblique, O: ribs I: linea alba, pubis, ilium A: see above, helps trunk rotation and lateral flexion

Muscles of Abdominal Wall Internal oblique O: lumbar fascia, ilium, inguinal ligament I: linea alba, pubis, ribs A: same as external oblique Transversus abdominis O: ribs, inguinal ligament, ilium, lumbar fascia I: linea alba, pubis A: compresses abdominal content

Chapter 25 Muscles of the Arm

Muscles of the arm Biceps brachii muscle O: scapula, shoulder joint I: radius A: agonist for flexion of the elbow

Muscles of the arm

Muscles of the arm Brachialis O: humerus I: ulna A: flex the elbow Brachioradialis I: radius A: synergist for flexion of the elbow

Muscles of the arm

Muscles of the arm Triceps brachii muscle O: scapula, humerus I: ulna A: agonist for extension of the elbow

Muscles of the arm

Muscles of the arm

Rotator Cuff Muscles Supraspinatus, infraspinatus, teres minor, and subscapularis Function mainly to reinforce the capsule of the shoulder

Rotator Cuff Muscles

Muscles of the forearm Flexion of the wrist (O: humerus) Flexor carpi ulnaris I: metacarpus and carpus Flexor carpi radialis I: metacarpus Palmaris longus I: palm of the hand A: also extends the palm of the hand

Muscles of the arm and forearm

Muscles that affect the wrist Extension of the wrist (O: humerus) Extensor carpi radialis I: metacarpus Extensor carpi ulnaris Pronation of the forearm (I: radius) Pronator teres muscle O: humerus

Muscles of the forearm

Muscles of the forearm

Muscles of the forearm Extensors of the digitus Extensor digitorum O: humerus I: phalanges

Chapter 25 Muscles of the Leg

Muscles of the pelvis and lower limbs Gluteus maximus O: ilium, sacrum, coccyx I: femur A: extension of thigh (climbing stairs) Gluteus medius and minimus O:ilium A: abducts thigh, steadies pelvis

Muscles of the leg Tensor fascia latae O: ilium I: fascia latae A: flexes, abducts the thigh; tenses the fascia latae

Muscles of the leg

Iliopsoas muscle Formed from the merging of the psoas major and the iliacus muscles O: ilium, vertebrae I: femur Flexes trunk on thigh, flexes thigh

Muscles of the Leg

Muscles of the leg Sartorios O: ilium I: tibia A: flexes the thigh and helps in crossing the leg Adductors of the leg O: pubis I: femur

Muscles of the pelvis and lower limbs Gracilis O: pubis I: tibia A: adducts, flexes and medially rotates the thigh

Muscles of the leg Quadriceps (I: tibia; A: extends the knee) Rectus femoris O: ilium Vastus medialis, intermedius, lateralis O: femur

Leg

Leg

Muscles of the leg The hamstrings (O: ischium; I: tibia; A: extend thigh, flexes knee) Biceps femoris muscles Semimembranosus muscles Semitendinosis muscles

Muscles of the lower leg Plantar flexion (I: calcaneal tendon) Gastrocnemius muscle O: femur Soleus muscle O: fibula and tibia Eversion and plantar flexion Fibularis muscle O: fibula I: metatarsal bones (lateral side)

Muscles of the lower leg

Muscles of the lower leg Popliteus O: femur I: tibia A: unlocks the knee joint

Muscles of the leg

Muscles of the lower leg Tibialis anterior O: tibia I: metatarsus and cuneiforme A: dorsiflexion of the foot Tibialis posterior I: tarsal and metatarsal bones A: foot inversion

Muscles of the lower leg Extensor digitorum O: Tibia and fibula I: Digitus A: Extends the digits

Chapter 25 Cat Dissection

Skinning the Cat Leave the skin of the back attached. Do not skin paws, tail, genital area, or head. Remove fat if possible. When you are done, use the skin to wrap the cat in. Use the pencil and tape to label the bag.

Skinning the Cat Cut the bag from the top to allow you to store the cat in it. Keep as much embalming fluid as possible in the cat for it’s preservation. Use several rubber bands; if one breaks, the bag will remain closed. Clean and dry tray, tools and lab bench before leaving.

Cat Dissection – Neck Muscles Mylohyoid Digastric Sternohyoid Sternothyroid Thyrohyoid

Cat Dissection – Thoracic Muscles Anterior muscles Pectoralis Major and Minor Serratus anterior Intercostals Internal External

Cat Dissection – Thoracic Muscles Posterior muscles Trapezius Latissimus dorsi Rhomboids Supraspinatus Infraspinatus

Cat Dissection – Abdominal Muscles External oblique Internal oblique Rectus abdominis Transversus abdominis

Cat Dissection – Arm Muscles Brachial muscles Biceps brachii Triceps brachii Long head Lateral head

Cat Dissection – Arm Muscles Antebrachial muscles Pronator teres Flexor carpi radialis Palmaris longus Flexor carpi ulnaris Extensor carpi ulnaris Extensor digitorum Extensor carpi radialis

Cat Dissection – Leg Muscles Upper leg Sartorius Gracilis Rectus femoris Vastus lateralis Vastus medialis Adductors

Cat Dissection – Leg Muscles Semimembranosus Semitendinosus Biceps femoris Lower leg Gastrocnemius Soleus Tibialis anterior Extensor digitorum Fibularis