Muscles of the Human Body PDF

Anatomy Study Guide – Muscles of the Human Body Miss Cush Anatomy 110 Myology - the study of muscles Functions of Muscles Movement – muscles attach to and move bones Posture – occurs via tonic contraction Heat production – result of chemical energy → mechanical energy N...

Anatomy Study Guide – Muscles of the Human Body Miss Cush Anatomy 110 Myology - the study of muscles Functions of Muscles Movement – muscles attach to and move bones Posture – occurs via tonic contraction Heat production – result of chemical energy → mechanical energy Necessary body functions – digestion, breathing, speaking, pumping blood, etc. Types of Muscles Smooth muscle (Involuntary) Not under our control Widely distributed Non-striated Also called visceral muscle Skeletal muscle (Voluntary) Consciously controlled Striated Cardiac muscle (Myocardium) Heart muscle Found only in the heart Striated Involuntary Skeletal Muscle Basics Associated structures Tendons anchor muscles to bones Bursae provide protection for bones and joints Fascia is connective tissue that surrounds and secures structures Aponeuroses fibrous tissue that attaches flat, wide muscles to bones Other classifications Sphincters – circular muscles constricting an orifice Pectoral – pertaining to the front of the chest, e.g., pectoral major muscles Muscle structures The belly of a muscle is the widest/largest portion The muscle attachment to the bone that is stationary during the movement is the origin The muscle attachment to the bone that moves during a movement is the insertion Muscles may be named based on… Shape & location Divisions & attachments Direction of fibers Superficiality & depth Size Action Movement Flexion – decrease in the angle between two bones at their joint Extension – increase in the angle between two bones at their joint Abduction – movement away from the midline of the body Adduction – movement towards the midline of the body Rotation – movement around a longitudinal axis Circumduction – movement of distal portion in a circle Supination – palms of hands face anteriorly Pronation – palms of hands face posteriorly Inversion – ankle turns, sole of foot faces midline Eversion – ankle turns, sole of foot faces away from midline Constriction – vessels becomes more narrow Dilation – vessels expands or widens Elevation – movement in a superior direction Depression – movement in an inferior direction Skeletal Muscles Muscles of the face Chewing muscles Temporalis – muscle of mastication which helps to close the mandible Masseter – muscle of mastication which closes the mandible Buccinator – principle muscle of the cheek which compresses the cheeks and forms the lateral wall of the mouth Eyebrow muscles Occipitofrontalis (epicranius) – draws the scalp posteriorly and inferiorly and raises eyebrows Orbicularis oculi – closes eyelids & compresses lacrimal sacs Corrugator – a pyramid-shaped muscle of facial expression which draws the eyebrows inferiorly and medially (draws brows together) Procerus – muscle that draws the skin of the forehead inferiorly (draws brows together) Levator palpebrae superioris – muscle that raises upper eyelid “False” smiling muscles Levator labii superioris – elevates and extends upper lip Levator anguli oris – elevates the angle of the mouth Risorius – narrow superficial band of muscle that pulls the angle of the mouth laterally “Real” smiling muscles Zygomaticus major – draws superior lip posteriorly & superiorly Zygomaticus minor – draws upper lip anteriorly & superiorly Other mouth muscles Orbicularis oris – closes and puckers lips Quadratus labii superioris – large muscle from the cheekbone and lower rim of the eye socket which raises the upper lip Levator labii superior alaeque nasi – elevates the upper lip and dilates the nostril opening Depressor anguli oris – depresses the angle of the mouth Depressor labii inferioris – draws lower lip inferiorly and slightly lateral Mentalis – elevates and protrudes the inferior lip and wrinkles the skin over the chin Muscles of the Neck Platysma – thin layer of muscle covering the anterior aspect of the neck Sternocleidomastoid – muscle attached to the mastoid process of the temporal bone and by separate heads to the sternum and clavicle ; turns and nods head Omohyoid – muscle attached to the hyoid bone and the scapula functioning in depressing the hyoid bone, swallowing and breathing Digastricus – double bellied muscle which draws the hyoid bone superiorly Muscles of the Back Trapezius – triangular muscle that moves the head and shoulders Latissimus dorsi – flat, posterior muscle that extends and adducts the shoulder Teres major – adducts the humerus and assists latissimus dorsi in adducting the shoulder Muscles of the Chest Pectoralis major – superficial muscle that fans out across chest; adducts arms; rotates arms medially Pectoralis minor – superficial muscle on the chest; depresses the point of the shoulder Subscapularis – largest strongest muscle of the rotator cuff that internally rotates the humerus and assists in shoulder adduction Breathing Muscles Serratus anterior – muscle forming the lateral wall of the chest Intercostals – form chest wall and expand and contract to assist with respiration Diaphragm – muscle allowing the chest to expand & contract Muscles of the Abdomen Anterior, lateral abdominal muscles External oblique – outer, lateral abdominal muscles; flex the trunk; depress ribs Internal oblique – medial to external oblique muscles; flex and bend the trunk; depress ribs Transversus abdominis – medial abdominal muscle arising from the inguinal ligament Anterior, medial abdominal muscles Rectus abdominis – top layer of abdominal muscles; flexes the spine and functions in posture Posterior abdominal muscles Psoas major – inner hip muscle that flexes and rotates the thigh and trunk Muscles of the Upper Extremities Muscles of the proximal (upper) arm Deltoid – triangular shoulder muscle that abducts the arm Coracobrachialis – superior, anterior muscle that flexes and adducts the arm Brachialis – flexes the elbow Biceps brachii – flexes and supinates the forearm Triceps brachii – dorsal muscle that extends the forearm and adducts the arm Muscles of the distal arm (forearm) – anterior Flexor carpi radialis – flexes and abducts the hand Flexor carpi ulnaris – flexes and adducts the hand Flexor digitorum superficialis – flexes the fingers Pronator teres – pronates the forearm Flexor digitorum profundus – flexes & extends fingers Palmaris longus – flexes wrist and functions in gripping Muscles of the distal arm (forearm) – posterior Brachioradialis – flexes the forearm Supinator – supinates the forearm Muscles of the Lower Extremities Muscles of the proximal (upper) leg – anterior Sartorius – flexes and rotates the hip ; flexes knee Quadriceps femoris – flexes hip; extends knee Iliopsoas – connection between spine and lower limbs; flexes & rotates thigh ; flexes trunk at the hip Pectineus – flexes, adducts, and rotates thigh Inguinal ligament – attaches thigh muscles to the pelvis Muscles of the proximal (upper) leg – posterior Gluteus maximus – straightens the leg from the hip; extends leg from being flexed at the hip Biceps femoris – extends & rotates thigh; flexes leg Semitendinosus – extends & rotates thigh; flexes & rotates leg Semimembranosus – extends & rotates thigh; flexes and rotates leg Muscles of the proximal (upper) leg – medial Adductor longus – adducts thigh Adductor magnus – adducts thigh Popliteal Muscles Popliteus muscle – stabilizes & allows flexibility of the knee joint Oblique popliteal ligament – the supporting ligament of the knee joint Muscles of the distal (lower) leg – anterior Tibialis anterior – dorsiflexes foot Extensor hallicus longus – extends the big toe Muscles of the distal (lower) leg – posterior Gastrocnemius – plantarflexes the foot Soleus – plantarflexes the foot Calcaneal tendon (Achilles heel) – attaches muscles to the calcaneus