Muscles of the Human Body

Over 600 in the human body Allow the skeleton to move To cause movement, both ends of each muscle must be attached to bone Origin or proximal attachment – the attachment closer to the center of the body Insertion or distal attachment – the attachment away from the center of the body

Facial Muscles

Various functions of the facial muscles Enable you to change expression and display your emotions outwardly Allow you to close your eyes and blink Essential for opening and closing the mouth for: Keeping food in the mouth Allowing you to chew Allowing you to form words Tongue Function: Allows you to move food around in your mouth and get it to a position to be swallowed Allows you to pronounce words and speak intelligently

Neck Muscles

Neck Muscles There are muscles posterior, lateral and anterior to the neck or cervical region These muscles Maintain the position in which the sits on the 1st cervical vertebra (atlas) i.e. they hold up our head Also permit a wide range of movement

Sternocleidomastoids The most important anterior pair of muscles Movements: Acting together, they flex the head toward the chest Individually, each muscle tilts the face up and toward the opposite side

Erector Spinae muscles Important posterior neck muscles Attach to sacrum inferiorly and to the skull superiorly Maintain your erect position Therefore they are also called anti-gravity muscles When someone faints, these muscles no longer function and the body falls face forward to the ground

Trapezius, Upper fibres Important lateral neck muscles Movements: Acting alone, tilt the head to the same side Together they assist in neck extension

Muscles of the pectoral Girdle

Muscles acting to hold the pectoral girdle to the chest wall: Anterior Pectoralis major Pectoralis minor Subclavius Serratus anterior Posterior Trapezius Latissimus Dorsi Levator scapulae Rhomboids Major & Minor

Pectoral Girdle - Anterior

Pectoral Girdle - Posterior

Muscles which attach from the scapula to the humerus, and act across the shoulder Joint Anterior Subscapularis Posterior Supraspinatus Infraspinatus Teres minor Teres major Lateral Deltoid

Anterior Lateral Anterior deltoid Fibers Posterior deltoid Fibers Middle Deltoid fibers

Superior and Posterior

Muscles of the Arm

Anterior Compartment Biceps Brachii Attaches Movements: Proximally to distal part of humerus (short head) Distally to proximal part of ulna (together with long head) Movements: Flexor of the elbow joint Supinator of the forearm

Anterior Compartment cont’d Brachialis Attaches Proximally to the anterior surface of the humerus Distally to the coronoid process of the Ulna Movements of the arm Powerful flexor of the elbow joint Works along with the biceps Brachii

Posterior compartment Triceps Brachii Attaches Proximally to the humerus (medial and lateral head) Distally to the olecranon process of the ulna (together with long head) Movement of the arm: Elbow extensor

Muscles of the Forearm

Forearm muscles act on the elbow, wrist and digits (fingers Flexor-pronator group Attached to the medial epicondyle of the humerus Extensor- supinator Attached to the lateral epicondyle of the humerus

Muscles of the pelvic girdle

Anterior muscles

Posterior and lateral muscles Gluteals -include 3 muscles Gluteus maximus -the largest of the three -principal extensor of the hip Gluteus medius and minimus -assist in hip extension -abduct the hip

Thigh Muscles Medial Compartment Pectinueus Gracilis Adductors: Adductor longus Adductor brevis Adductor magnus Primary action

Anterior Compartment Sartorius Quadriceps Extend at the knee Rectus femoris Vastus Lateralis Vastus Intermedius Vastus Medialis Extend at the knee Sartorius and Rectus femoris also flex at the hip

Posterior Compartment Hamstrings -biceps femoris -semitendinosus -semimembranosus Attach -proximal to the ischial tuberosity -distally, biceps femoris to the head of the fibula and the semitendinosus and semimembranosus to the tibia Flex at the knee Also extend at the hip

Leg Muscles Anterior Compartment Tibialis Anterior Extensor hallucis longus (deep) Extensor digitorium (deep) Arise from -anterolateral surface of the tibia -interosseous membrane between the tibia and fibula -anterior surface of the fibula Cross to the ankle joint Attach distally to -medial side of the foot -distal phalanges of the digits Movements: -primarily dorsi-flexors of the ankle -extensors of the toes -Tibialis anterior further inverts the foot -Peroneus tertius assist in eversion

Lateral Compartment Peroneus Longus Peroneus Brevis Proximaly attach to the lateral surface of the tibia Pass behind the lateral malleolus Distally attach to the foot Movement -plantar flexors -everters of the sole of the foot

Posterior Compartment Superficial Group Gastrocnemius -has two proximal heads -proximally attaches to the medial and lateral epicondyles of the distal femur Soleus -proximally attaches to head proximal ends of tibia and fibula Gastroc and soleus come together to form an achilles tendon Principal plantar flexors of the ankle Deep Group – primary role is flexion of the toes - assist in plantar flexion of the ankle

Obliques External oblique Internal oblique Transverse abdominus Reach from the vertebral column, ribs, and hip bone posteriorly Meet in the midline anteriorly through rectus abdominus Functions: Lateral bending of the abdomen Rotation of the abdomen Extension of the abdomen during forced inspiration Allow the development of pregnant uterus Contract to help expel fecal contents from the rectum

Muscles of the Abdomen Rectus Abdominus Paired midline muscles Powerful flexor of the anterior abdominal wall Strengthening of the abdominal muscles is a very important part of back therapy, because the abdominals support the back

Summary Human anatomy deals with the structures that make up the human body (structures determines function) The bones, joints, and muscles that make up the muscoloskeletal system allow numerous movements to occur, with varying degrees of: -motion capabilities -strength -flexibility Bones provide the structural framework necessary for support Muscles supply the power Joints supply the mechanism that allows human movement to occur

Questions Describe the anatomical position and discuss its relationship to the directional terms of the body. What are the four major planes that bisect the body? Provide an example of a movement that occurs in each plane. Define three types of movement and give an example of each. Name three types of muscle. How do slow twitch and fast twitch fibers differ? Differentiate among agonists and antagonists? Which synovial joint allow the greatest amount of movement? The least? Explain? Outline the components and roles of the axial and appendicular skeletons? What structures present at the knee provide additional support to this joint? What type of joint is the knee? What muscles are primarily responsible for maintaining an upright position? The posterior group of leg muscles are commonly called the hamstrings. What three muscles combine to form the hamstrings? What are their functions?