Muscular System Axial and Appendicular Divisions PDF

The Muscular System Axial and Appendicular Divisions Ch 10 & 11 Intro The muscular system, like the underlying skeletal system, is devided into Axial and Appendicular components: The Axial Musculature Originates on the Axial Skeleton It positions the head and vertebral column and helps in breathing...

The Muscular System Axial and Appendicular Divisions Ch 10 & 11 Intro The muscular system, like the underlying skeletal system, is devided into Axial and Appendicular components: The Axial Musculature Originates on the Axial Skeleton It positions the head and vertebral column and helps in breathing The Appendicular Musculature insert onto and stabilize or move the appendicular skeleton Axial Musculature There are 4 groups of Axial Musculature: 1. 2. 3. 4. Muscles of the head and neck Muscles of the vertebral column Muscles that form the walls of Abdominal and Pelvic Cavities Muscles of the perineal and Pelvic Diaphragm Muscles of the Head and Neck Further subdivided into several groups: Muscles involved in facial expressions Extraocular Muscles Muscles of mastication Muscles of the tongue Muscles of the pharynx Muscles of the Vertebral Column The muscles of the back are arranged into three layers: Layers 1 & 2 are the extrinsic back muscles: Assist in moving the pectoral girdle and ribs during respiration Layer 3 are the intrinsic back muscles: They interconnect, move and stabilize the vertebral column Oblique and Rectus Muscles The oblique muscles are responsible for rotating the vertebral column The rectus muscles are important flexors of the vertebral column and antagonists of the intrinsic back muscles Muscles of the Perineal Region The muscles of the Perineal region and pelvic diaphragm extend from the sacrum and coccyx to the ischium and pubis. These muscles support the organs of the pelvic cavity, flex the joints of the sacrum & coccyx and control the opening of the urethra and anus The Appendicular Musculature There are 2 major groups of Appendicular Muscles: 1. The muscles of the pectoral girdle and upper limb The upper limb has a large range of motion due to the muscular connections between the pectoral girdle and the axial skeleton 2. The muscles of the pelvic girdle and lower limb In the lower limb the focus is on strength not mobility The pelvic girdle transfers the weight from the axial skeleton to the lower limbs There is limited range of motion The Pectoral Girdle The muscles of the pectoral girdle and upper limb are divided into 4 groups: 1. 2. 3. 4. Muscles that position the pectoral girdle Muscles that position the arm Muscles that move the forearm and hand Muscles that move the hand and fingers Muscles that Position the Pectoral Girdle Muscles of the upper limb, or extrinsic muscles of the shoulder, originate from the axial skeleton and insert onto bones of either the pectoral girdle or arm. Moving these muscles maximizes the range of motion of the shoulder joint Muscles of the Forearm and Hand Almost all of the muscles that move the forearm and wrist originate on the humerus and insert on the radius/ulna or carpal bones The exceptions are the long heads of the Biceps and Triceps Brachii Muscles that Move the Hand and Fingers The position of the wrist affects the functioning of the hand Many muscles of the forearm, therefore, affect the actions of the wrist because: All the muscles that flex or extend the wrist originate on the humerus, radius or ulna Many of the muscles that flex the fingers originate on the radius or ulna The Pelvic Girdle The muscles of the pelvic girdle, lower limbs, and feet contract in a coordinated manner This allows the body to move from place to place The attachment of the pelvic girdle to the axial skeleton allows for motion. There are 3 groups of pelvic muscles: 1. Muscles that move the thigh 2. Muscles that move the leg 3. Muscles that move the feet and toes Muscles that Move the Thigh Many of the muscles that move the thigh originate on the ilium and insert onto the femur Remember that insertion is what moves! Muscles that Move the Leg The relationship of action lines and the axis of the knee joint help predict the movement of the muscles of the leg. However, the anterior/posterior orientation of the muscles that move the leg is reversed due to rotation during embryological development Muscles that Move the Feet and Toes Muscles of the posterior compartment of the leg planter-flex the foot and toes. The anterior compartment muscles dorsiflex the foot and toes