Muscular System PDF

Muscular System TSDM 4112 Anatomy and Physiology 1 Ms. Wu Jie Yee Learning Objectives At the end of the session, students are able to: 1. Name the main muscles of the body regions 2. Outline the functions of the main muscles  Muscles Cells Called as muscle fibers, are...

Muscular System TSDM 4112 Anatomy and Physiology 1 Ms. Wu Jie Yee Learning Objectives At the end of the session, students are able to: 1. Name the main muscles of the body regions 2. Outline the functions of the main muscles  Muscles Cells Called as muscle fibers, are specialized contractile cells. There are three (3) types of muscle tissue: 1. Smooth Muscle Cells Not Voluntary Control 2. Cardiac Muscle Cells 3. Skeletal Muscle Cells Voluntary Control Functions of the muscles 1. Producing movement: muscles generate force to move the body 2. Maintaining posture: support the body against gravity 3. Stabilizing joints: maintaining their alignment and preventing excessive movement 4. Generating heat: heat as a byproduct of their metabolic activity  Skeletal Muscle Skeletal muscles are the muscles that are attached to bones via tendon and move the skeleton. Structure of Skeletal Muscle Epimysium Surrounds entire muscle Perimysium Surrounds bundles of muscle fibers Endomysium Surrounds individual muscle fibers Skeletal Muscle Cells (Fibers) Skeletal muscle fibers are roughly cylindrical in shape, lying parallel to one another. It have many mitochondria, essential for producing ATP from glucose to power the contractile mechanism. Present with a specialized oxygen-binding, called myoglobin, store oxygen within the muscle. Muscle of the face  Orbicularis oculi This muscle surrounds the eye, eyelid and orbital cavity. It closes the eye and when strongly contracted ‘screws up’ the eyes.  Levator palpebrae superioris This muscle extends from the posterior part of the orbital cavity to the upper eyelid. It raises the eyelid.  Masseter In chewing it draws the mandible up to the maxilla, closing the jaw, and exerts considerable pressure on the food. Temporalis It passes behind the zygomatic arch and inserts into the coronoid process of the mandible. It closes the mouth and helps with chewing. Muscle of the Neck  Sternocleidomastoid It assists in turning the head from side to side. When the muscle on one side contracts it draws the head towards the shoulder.  Trapezius This muscle covers the shoulder and the back of the neck. It pulls the head backwards, squares the shoulders and controls the movements of the scapula when the shoulder joint is in use. Muscle of the Back Muscle of the Back The arrangement of these muscles is the same on each side of the vertebral column. Muscle of the Back 1. Latissimus dorsi 2. Teres major 3. Quadratus lumborum 4. Sacrospimalis ( Erector Spinae)  Quadratus Rector Spinae lumborum Latissimus dorsi It starts from the lower spine (lower thoracic and lumbar vertebrae) and the back part of your hip bone (iliac crest). It adducts, medially rotates and extends the arm.  Teres major This originates from the inferior angle of the scapula and is connects to the humerus just below the shoulder joint. It extends, adducts and medially rotates the arm.  Quadratus lumborum It starts from the hip bone and goes up beside the spine, connecting to the 12th rib. It works with another muscle to help you breathe and bend backward. Sacrospinalis (erector spinae) These muscles lie between the spinous and transverse processes of the vertebrae. They extend the vertebrae column. Muscles of the Anterior Abdominal Wall Muscles of the anterior abdominal wall 1. Rectus abdominis 2. External oblique 3. Internal oblique 4. Transversus abdominis Rectus abdominis This is the most superficial muscle. The rectus abdominis is the so-called ‘six- pack’ muscle. It curls the trunk and support the abdominal wall when straining (in forced expiration or defecation)  External oblique When muscles contracted, it helps to twist your body, bend sideways, support abdomen  Internal oblique This muscle lies deep to the external oblique. When muscles contracted, it helps to twist your body, bend sideways, support abdomen.  Transversus abdominis The deepest muscle of the abdominal wall. Allow bending, twisting & lifting by providing a stable base for body. It also protects organs in place during activities like lifting, coughing & breathing. Functions of the Muscle of the abdominal walls The main function of these paired muscles is to form the strong muscular anterior wall of the abdominal cavity. When the muscles contract together they: 1. Compress the abdominal organs 2. Flex the vertebral column in the lumbar region 3. Contraction of the muscles on one side only bends the trunk towards that side. 4. Contraction of the oblique muscles on one side rotates the trunk. Muscle of the Thorax Muscle of the thorax These muscles are concerned with respiration, Intercostal Muscles. The intercostal muscles are deep muscles found between the ribs; the external intercostals are important in breathing because they help you to raise the rib cage when you inhale; The internal intercostals, which lie deep to the external intercostals, depress the rib cage, which helps to move air out of the lungswhen you exhale forcibly. Intercostal Muscles Muscle of the Pelvic Floor Muscles of the pelvic floor Functions The pelvic floor supports the organs of the pelvis and maintains continence, i.e. it resists raised intra-pelvic pressure during micturition and defecation. The pelvic floor is divided into two identical halves that unite along the midline. Muscles of the pelvic floor 1. Levator ani 2. Coccygeus  Muscles of the pelvic floor Levator ani Group of broad, flat muscle forms the anterior part of the pelvic floor. Coccygeus They complete the formation of the pelvic floor, which is perforated in the male by the urethra and anus, and in female by the urethra, vagina and anus. Function of the muscles of the pelvic floor Continence: The pelvic floor muscles contribute to urinary and fecal continence by providing voluntary control over the opening and closing of the urethra (for urine) and anal sphincters (for feces). Childbirth: During childbirth, the pelvic floor muscles help facilitate the passage of the baby through the birth canal. They stretch and relax to accommodate the baby's descent. Muscle of the Shoulder and Upper Limb  Deltoid It forms the fleshy and rounded contour of the shoulder. Main function is movement of the arm. The anterior part causes flexion, the middle or main part abduction and the posterior part extends and laterally rotates the shoulder joint. Muscles of the shoulder and upper limb Biceps brachii This lies on the anterior aspect of the upper arm. It helps to stabilize and flex the shoulder joint and at the elbow joint it assists with flexion and supination.  Triceps This lies on the posterior aspect of the humerus. It helps to stabilize the shoulder joint, assists in adduction of the arm and extends the elbow joint.  Brachialis This lies on the anterior aspect of the upper arm deep to the biceps. It originates from the shaft of the humerus, extends across the elbow joint and is inserted into the ulna just distal to the joint capsule. It is the main flexor of the elbow joint. Muscles of the Hip and Lower Limb Muscles of the hip and lower limb  Muscles of the hip and lower limb Quadriceps femoris This is a group of four muscles lying on the front and sides of the thigh. They are the rectus femoris and three vasti: lateralis, medialis and intermedius Only the rectus femoris flexes the hip joint.  Gluteal muscles These consist of the gluteus maximus, medius and mi nimus, which together form the fleshy part of the buttock. They cause extension, abduction and medial rotation at the hip joint.  Muscles of the hip and lower limb Hamstrings These lie on the posterior aspect of the thigh. They are the biceps femoris, semimembranosu s and semitendinosus muscles. They flex the knee joint.  Thank you