BIO237-LAB-LECTURE-11-12-13-Gross Anatomy of the Muscular System PDF

Exercise-13 Gross Anatomy of the Muscular System Gross Anatomy of the Muscular System Overview Functions of Muscles Skeletal muscles enable movement. Smiling, frowning, speaking, singing, breathing, dancing, running, and playing musical instrument are just a few ex...

Exercise-13 Gross Anatomy of the Muscular System Gross Anatomy of the Muscular System Overview Functions of Muscles Skeletal muscles enable movement. Smiling, frowning, speaking, singing, breathing, dancing, running, and playing musical instrument are just a few examples. Most often, purposeful movements require the coordinated action of several skeletal muscles. Classification of Skeletal Muscles Types of Muscles Muscles that are most responsible for producing a particular movement are called “prime movers (or agonists)”. Muscles that oppose or reverse a movement are called “antagonists”. When a prime mover is active, the fibers of the antagonist are stretched and in the relaxed state. Antagonists can be prime movers in their own right. For example, the biceps of the arm (a prime mover of flexion at the elbow) is antagonized by the triceps (a prime mover of extension at the elbow). Classification of Skeletal Muscles Types of Muscles “Synergists” aid the action of agonists either by assisting with the same movement or by reducing undesirable or unnecessary movement. “Fixators”, or “fixation muscles”, are specialized synergists. Muscles that help maintain posture are fixators; so too are muscles of the back that stabilize or “fix” the scapular during arm movements. The “fixators” immobilize the origin of a prime mover so that all the tension is exerted at the insertion. Classification of Skeletal Muscles Naming Skeletal Muscles Muscles are named on the basis of the following criteria: Direction of muscle fibers rectus (straight): rectus abdominis is the straight muscle transverse and oblique indicate that the muscle fibers run at right angles and obliquely (respectively) to the imaginary line Pattern of fascicle arrangement Muscle size maximus (largest); minimus (smallest); longus (long); and brevis (short) Muscle location Temporalis muscle overlies the temporal bone Number of origin biceps, triceps, and quadriceps are two, three, and four origins, respectively. Classification of Skeletal Muscles Naming Skeletal Muscles Muscles are named on the basis of the following criteria: Location of the attachments Sternocleidomastoid muscle has its origin on the sternum (sterno) and clavicle (cleido), and inserts on the mastoid process of the temporal bone. Muscle shape The deltoid muscle is roughly triangular (deltoid = triangle), and the trapezius muscle resembles a trapezoid. Muscle action All the adductor muscles of the anterior thigh bring about its adduction, and all the extensor muscles of the wrist extend the hand. Patterns of Fascicle Arrangement in Muscles Identification of Human Muscles Muscles of the Head and Neck The muscles of the Head serve many specific functions. The muscles of facial expression Is different from most skeletal muscles because they insert into the skin or other muscles rather than into bone. As a result, they move the facial skin, allowing a wide range of emotions to be expressed. Muscles of mastication Move the mandible during chewing The six extrinsic eye muscles located within the orbit Aim the eye The muscles of the Neck provide: The movement of the head and shoulder girdle Major Muscles of the Head-Facial Expression-1 (Occipitofrontalis) Major Muscles of the Head-Facial Expression-2 Epicranius (Occipitofrontalis): raises eyebrows Orbicularis oculi: closes eye Major Muscles of the Head- Corrugator supercilii: draws eyebrows medially and inferiorly Facial Expression Lavator labii superioris: opens lips Zygomaticus-major/minor: raises lateral corners of mouth upward Risorius: draws corner of lip laterally Depressor labii inferioris: draws lower lip inferiorly Depressor anguli oris: draw a corner of mouth downward and laterally Orbicularis oris: closes lips Mentalis: wrinkles chin Buccinator: compresses cheek Platysma: tenses skin of neck Major Muscles of the Head-Mastication Compresses cheek Major Muscles of the Head-Mastication Masseter: prime mover of jaw closure Temporalis: closes jaw Buccinator: compresses cheek Medial/lateral pterygoid: grinding movements of teeth Muscles of the Neck and Throat-Suprahyoid Muscles of the Neck and Throat-Infra-hyoid  Suprahyoid: Digastric: open mouth and depress mandible Muscles of the Neck and Throat Stylohyoid: elevates and retracts hyoid bone (Suprahyoid and Infrahyoid) Mylohyoid: elevates hyoid bone and base of tongue Infrahyoid: Sternohyoid: depresses larynx and hyoid bone Sternothyroid: depresses larynx and hyoid bone Omohyoid: depresses larynx and hyoid bone Thyrohyoid: depresses hyoid bone; elevates larynx if hyoid is fixed Identification of Human Muscles Muscles of the Trunk The trunk musculature included muscles that move the vertebral column Anterior thorax muscles that act to move ribs, head, and arms Muscles of the abdominal wall Which play a role in the movement of the vertebral column but more importantly form the “natural girdle”, or the major portion of the abdominal body wall. Muscles of the Neck and Vertebral Column: Head Movements Muscles of the Neck and Vertebral Sternocleidomastoid: flexion of neck, rotate head toward shoulder Column: Head Movements on opposite side Scalenes (anterior, middle, posterior): elevates ribs 1-2 Splenius (capitis/cervicis): As a group, extend or hyperextend head Muscles of the Neck and Vertebral Column: Trunk Extension Muscles of the Neck and Vertebral Column: Trunk Extension Erector spinae: extend and bend the vertebral column laterally Semispinalis: acting together, extend head and vertebral column; cause rotation toward the opposite side Quadratus lumborum: each flexes vertebral column laterally Muscles of the Thorax and Shoulder Muscles of the Thorax and Shoulder Acting on the Scapula and Arm (Anterior View) Thorax-Shoulder (Superficial): Pectoralis major: prime mover of arm flexion; adducts, medially rotates arm Serratus anterior: prime mover to protract and hold scapula against chest wall, rotates scapula Deltoid: acting as a whole, prime mover of arm abduction Pectoralis minor: with ribs fixed, draws scapula forward and inferiorly Muscles of the Thorax: Muscles of Respiration Deep Muscles of the Thorax: Muscles of Respiration External interocostals: pull ribs toward one another to elevate rib cage Internal interocostals: draw ribs together to depress rib cage Diaphragm: prime mover of inspiration flattens on contraction Muscles of the Abdominal Wall Anterior View of the Muscles Forming the Abdominal Wall Rectus abdominis: flexes and rotates vertebral column External oblique: compresses abdominal wall; trunk rotation and lateral flexion Internal oblique: as for external oblique Transverse abdominis: compresses abdominal contents Muscles of the Shoulder and Thorax Muscles of the Shoulder and Thorax Trapezius: raises, rotates, and retracts (adducts) scapula and stabilizes it Latissimus dorsi: prime mover of arm extension; adducts and medially rotates arm Infraspinatus: lateral rotation of arm Teres minor: same as for infraspinatus Teres major: extends, medially rotates, and adducts arm Muscles of the Shoulder and Thorax Supraspinatus: initiates abuduct of arm Levator scapulae: elevates and adducts scapula Rhomboids-major/minor: stabilize scapulae Identification of Human Muscles Muscles of the Upper Limb The muscles of the upper limb fall into three groups: Those moving the arm The muscles that cross the shoulder joint to insert on the humerus and move the arm (subscapularis, supraspinatus and infraspinatus, deltoid, and so on) are primary trunk muscles that originate on the axial skeleton or shoulder girdle. These muscles are included with the trunk muscles. Those causing movement of the forearm These muscles cross the elbow joint and move the forearm, consisting of muscles forming the musculature of the humerus. These muscles arise mainly from the humerus and insert in forearm bones. They are responsible for flexion, extension, pronation, and supination. Those moving the hand and fingers These muscles form the musculature of the forearm. For the most part, these muscles cross the wrist to insert on the digits and produce movements of the hand and fingers. Muscles of the Humerus (Arm) That Move the Forearm  Muscles of the Humerus (Arm) That Move the Forearm Triceps brachii: powerful forearm extensor Anconeus: abducts ulna during forearm pronation Biceps brachii: flexion and supination of forearm Brachioradialis: synergist in forearm flexion Brachialis: flexor of forearm Anterior view Posterior view Muscles of the Forearm That Move the Hand and Fingers (Anterior-Superficial) Muscles of the Forearm That Move the Hand and Fingers (Anterior-Deep)  Muscles of the Forearm That Move the Hand and Fingers Anterior-Superficial: (Anterior superficial and deep) Pronator teres: pronate forarm Flexor carpi radialis: powerful flexor and abductor Palmaris longus: tenses skin and facia of palm Flexor capris ulnaris: flexes and adducts hand Flexor digitorum superficialis: flexes hand and middle phalanges of fingers II-V Anterior-Deep: Flexor pollicis longus: flexes thumb Flexor digitorum profundus: flexes distal phalanges Pronator quadratus: pronates forearm Muscles of the Forearm That Move the Hand and Fingers (Posterior-Superficial) Muscles of the Forearm That Move the Hand and Fingers (Posterior-Deep) Muscles of the Forearm and Wrist That Move the Hand and Fingers (Posterior superficial and deep) Posterior-Superficial: Extensor carpi radialis longus: extends and abducts hand Extensor carpi radialis brevis: extends and abducts hand Extensor digitorum: prime mover of finger extension Extensor carpi ulnaris: extends and adducts hand Posterior-Deep: Extensor pollicis longus: extend thumb Extensor pollicis brevis: extend thumb Abductor pollicis longus: abducts and extends thumb Supinator: synergist of biceps brachii to supinate forearm Identification of Human Muscles Muscles of the Lower Limb Muscles that act on the lower limb cause movement: At the hip, knee, and ankle joints. Since the human pelvic girdle is composed of heavy, fused bones that allow very little movement, no special group of muscles is necessary to stabilize it. Muscles acting on the thigh (femur) cause various movements at the multiaxial hip joint. These include the iliopsoas, the adductor group, and others. Identification of Human Muscles Muscles of the Lower Limb Muscles acting on the leg (between knee and ankle) form the major musculature of the thigh. The thigh muscles cross the knee to allow flexion and extension of the leg. They include the hamstrings and the quadriceps. The muscles originating on the leg cross the ankle joint and act on the foot and toes. Muscles That Move the Thigh and Leg, Anterior and Medial Aspects Anterior and Medial Muscles Promoting Movements of the Thigh and Leg Origin on the Pelvis: Iliopsoas (iliacus/psoas major): flex trunk at hip joint, flex thigh; lateral flexion of vertebral column (psoas) Sartorius: flexes, abducts, and laterally rotates thigh; flexes leg Anterior view of the deep muscles of the pelvis and superficial muscles of the right thigh Muscles That Move the Thigh and Leg, Anterior and Medial Aspects Anterior and Medial Muscles Promoting Adductor muscles of the medial Movements of the Thigh (Femur) and Leg compartment of the thigh Medial compartment: Adductors (magnus/longus/brevis): adduct and medially rotate and flex thigh Pectineus: adducts, flexes, and medially rotates thigh Gracilis: adducts thigh; flexes and medially rotates leg Muscles That Move the Thigh and Leg, Anterior and Medial Aspects Muscles That Move the Thigh and Leg Anterior Compartment: Quadriceps femoris Rectus femoris: extends leg and flexes thigh Vastus lateralis: extends leg and stabilizes knee Vastus medialis: extends leg; stabilizes patella Vastus intermedius: extends leg Tensor fascia lata: steadies trunk The vastus muscles of the quadriceps group Anterior view of the deep muscles Muscles That Move the Human Thigh and Leg, Posterior Aspect Muscles of the Right Hip and Thigh (Posterior Aspect) Origin on the Pelvis-Posterior Aspect: Gluteus maximus: powerful thigh extensor Gluteus medius: abducts and medially rotates thigh Gluteus minimus: abducts and medially rotates thigh Muscles That Move the Human Thigh and Leg, Posterior Aspect Muscles of the Thigh and Leg (Posterior Compartment) Hamstrings-Posterior Compartment: Biceps femoris: extends thigh; flexes leg; laterally rotates leg Semitendinous: extends thigh; flexes leg Semimembranous: extends thigh; flexes leg; medially rotates leg Hamstring: Is any one of the three posterior thigh muscles in between the hip and the knee (from medial to lateral: biceps femoris, semitendinosus, and semimembranosus). Muscles That Move the Foot and Ankle Muscles That Move the Foot and Ankle (Muscles of the Anterolateral Aspect of the Right Leg) Lateral compartment: Fibularis (peroneus) longus: plantar flexes and everts foot Fibularis (peroneus) brevis: plantar flexes and everts foot Anterior compartment: Tibialis anterior: prime mover of dorsiflexion Extensor digitorum longus: prime mover of toe extension Fibularis (peroneus) tertius: dorsiflexes and everts foot Extensor hallucis longus: extends great toe Muscles That Move the Foot and Ankle Muscles That Move the Foot and Ankle (Posterior Aspect of the Right Leg) Posterior compartment-Superficial: Triceps surae: plantar flex foot Gastrocnemius (medial/lateral heads): plantar flexes foot Soleus: plantar flexion Triceps surae (Calf muscle): Is a pair of muscles located at the calf (the two- headed gastrocnemius [medial/lateral] and the soleus) Muscles That Move the Foot and Ankle Muscles That Move the Foot and Ankle (Posterior Aspect of the Right Leg) Posterior compartment-Deep: Popliteus: flexes and rotates leg medially to “unlock” knee when leg flexion begins Tibialis posterior: prime mover of foot inversion Flexor digitorum longus: flexes toes; plantar flexes and inverts foot Flexor hallucis longus: flexes great toe; plantar flexes and inverts foot