BIO L 105-lab 9 Muscle Gross Ana Muscular System Skeletal muscles work together or in opposition to each other Muscles can only pull, never push As a muscle shortens, the insertion (attachment on movable bone) moves toward the origin (attachment on bone that does not move) Whatever one muscle or muscle group does, another muscle or muscle group can “undo” BIO L 105-lab 9 Muscle Gross Ana

BIO L 105-lab 9 Muscle Gross Ana Skeletal Muscles: Functional Groups Prime movers-Agonist Provide major force for producing specific movement Antagonists Oppose or reverse specific movement May stretch or remain relaxed when prime mover contracts Typically help regulate action of prime mover by contracting slightly to help control movement Located on opposite sides of joint (from the prime mover) on which it acts BIO L 105-lab 9 Muscle Gross Ana

BIO L 105-lab 9 Muscle Gross Ana Synergists Add force to a movement Reduce undesirable or unnecessary movement Fixators Synergists that immobilize a bone or muscle’s origin to add a stable base upon which to act Muscles which help maintain upright position BIO L 105-lab 9 Muscle Gross Ana

BIO L 105-lab 9 Muscle Gross Ana Naming Skeletal Muscles Location—bone or body region associated with the muscle Shape—e.g., deltoid muscle (deltoid = triangle) Relative size—e.g., maximus (largest), minimus (smallest), longus (long) Direction fibers or fascicles run in relation to an imaginary line or longitudinal body axis Rectus- fibers run straight, Transversus-fibers run at right angles Oblique -fibers run at an oblique angle BIO L 105-lab 9 Muscle Gross Ana

BIO L 105-lab 9 Muscle Gross Ana Number of origins—e.g., biceps (2 origins) and triceps (3 origins) Location of attachments—named according to point of origin or insertion Sternocleidomastoid muscle—origin = sternum and clavicle, insertion on mastoid process of temporal bone Action—e.g., flexor or extensor BIO L 105-lab 9 Muscle Gross Ana

BIO L 105-lab 9 Muscle Gross Ana Major Skeletal Muscles of the Body Grouped by function and location Information for each muscle Name and description—note information in name Origin and insertion—is usually a joint between origin and insertion Action—insertion moves toward origin; best learned by acting out muscle movement on your own body BIO L 105-lab 9 Muscle Gross Ana

BIO L 105-lab 9 Muscle Gross Ana Muscles of the Head Two groups Muscles of facial expression Muscles of mastication and tongue movement Muscles of Facial Expression Insert into skin Important in nonverbal communication Epicranius (occipitofrontalis) 2 part muscle consisting of the Frontalis – raises eyebrows Occipitalis – pulls scalp backward Galea aponeurotica —cranial aponeurosis (fibrous connective tissue sheet connecting these muscles and part(s) they move) BIO L 105-lab 9 Muscle Gross Ana

BIO L 105-lab 9 Muscle Gross Ana Muscles of the Torso Muscles of respiration External intercostals —more superficial muscles that elevate ribs for inspiration Internal intercostals —deeper muscles that aid forced expiration Diaphragm Partition between thoracic and abdominal cavities Most important muscle in inspiration BIO L 105-lab 9 Muscle Gross Ana

BIO L 105-lab 9 Muscle Gross Ana Muscles of the Abdominal Wall Fascicles of muscles run at angles to one another, providing added strength Four paired muscles; their fasciae and aponeuroses form lateral and anterior abdominal wall Internal obliques External obliques Transversus abdominis Rectus abdominis BIO L 105-lab 9 Muscle Gross Ana

BIO L 105-lab 9 Muscle Gross Ana Extrinsic shoulder muscles Act in combination to fix shoulder girdle (mostly the scapula) and move it to increase range of arm movements Actions include elevation, depression, rotation, lateral and medial movements, protraction, and retraction Anterior extrinsic shoulder muscles Serratus anterior Pectoralis minor Subclavius (Pectoralis major considered later with muscles that act on the humerus) BIO L 105-lab 9 Muscle Gross Ana

BIO L 105-lab 9 Muscle Gross Ana Muscles Crossing the Shoulder Joint Insert on and move the humerus Three are prime movers of the arm Pectoralis major Latissimus dorsi Deltoid Actions include flexion, extension, adduction, abduction, and rotation of humerus BIO L 105-lab 9 Muscle Gross Ana

BIO L 105-lab 9 Muscle Gross Ana Selected Muscles of the Upper Arm Anterior flexor muscles Brachialis and biceps brachii —chief forearm flexors Brachioradialis—synergist and stabilizer Posterior extensor muscles Triceps brachii —prime mover of forearm extension Anconeus—weak synergist BIO L 105-lab 9 Muscle Gross Ana

Muscles of the Forearm: Anterior Compartment Flexors Flexor carpi radialis Palmaris longus Flexor carpi ulnaris Flexor digitorum muscles (superficialis and profundus) Flexor pollicis longus

Muscles of the Forearm: Posterior Compartment Extensors Extensor carpi radialis longus and brevis Extensor digitorum Extensor carpi ulnaris Extensor pollicis brevis and longus Extensor indicis Abductor pollicis longus

Muscles Crossing Hip and Knee Joints Most anterior muscles flex femur at hip and extend lower leg at knee Most posterior muscles extend thigh and flex lower leg Medial muscles all adduct thigh

Hamstring muscles (prime movers of extension) Thigh extensors Hamstring muscles (prime movers of extension) Biceps femoris Semitendinosus Semimembranosus Gluteus maximus (prime mover during forceful extension)

Movements of the Thigh Anterior Leg Muscles Abductors Gluteus maximus (also laterally rotates thigh) Gluteus medius (also medially rotates thigh) Gluteus minimus (also medially rotates thigh) Anterior Leg Muscles Primary toe extensors and ankle dorsiflexors Tibialis anterior

Flexors of foot and toes Gastrocnemius Soleus

Six extrinsic eye muscles attach to scleral layer and move eyeball Originate from bony orbit; insert on eyeball Enable eye to follow moving objects; maintain shape of eyeball; hold in orbit Four rectus muscles originate from common tendinous ring; names indicate movements Superior, inferior, lateral, medial rectus muscles Two oblique muscles move eye in vertical plane and rotate eyeball Superior and inferior oblique muscles

BIO L 105-lab 9 Muscle Gross Ana LABWORK Identify, describe, and state the actions of the selected muscles in the handout provided. BIO L 105-lab 9 Muscle Gross Ana