University:
Kentucky State University
Course:
BIO 301 | Human Anatomy
Academic year:

2019
Views:

241

Pages:

70
Author:

hekeldigzjbz

The Muscular System Skeletal muscles are formed of several bundles (fascicles) of skeletal muscle cells. They are attached by tendons to bones  When the skeletal muscle contracts, the tendon will be pulled and this will pull the bone resulting in Movement   The belly of the muscle is the fleshy (wide) part between the tendons Muscles have more than one bony attachment:  the attachment of a tendon to the stationary bone is called the origin.  the attachment of the muscle’s other tendon to the movable bone is called the insertion.  the action/s of a muscle are the main movements that occur during contraction (e.g., flexion or extension). Coordination among muscles: It is common to attribute a specific action at a joint to a single muscle, but remember that muscles do not work in isolation.  Movements usually result from several skeletal muscles acting as a group. 1) Most skeletal muscles are arranged in opposing pairs at joints (antagonistic) (e.g., flexors vs. extensors):  Prime mover or agonist and is responsible for the action  Antagonist stretches (relaxed) and yields to the effects of the agonist.  Muscles Of Facial Expression  Muscles of facial expression     Lie within the subcutaneous layer Usually originate in the fascia or skull bones & insert into the skin. Main function: serve as sphincters or dilators of face orifices Because of their insertions, the muscles of facial expression move the skin rather than a joint when they contract. Because of this, these muscle produce the wide variety of emotional expressions that humans have Muscle Nerve Supply Main Action Occipitofrontalis (Surprise!!) SCALP muscle Raises eyebrow Produce wrinkles in forehead Orbicularis oculi (Blinking) Closes eyelids gently and forcibly Elevators of upper lip* Elevates the upper lip Depressors of lower lip Platysma (pouting) Facial (VII) nerve Depresses the lower lip Depresses out angle of lower lip Risorius (Grimacing) Pulls angles of mouth laterally Orbicularis oris (Kissing) Brings lips together – closes mouth Buccinator (Whistling) Presses cheek on teeth as in blowing, sucking and chewing *Zygomaticus major Smiling muscle Draws angle of mouth superior & lateral Bell’s palsy, also known as facial paralysis, is a unilateral paralysis of the muscles of facial expression.     Extrinsic Eye Muscles Six extrinsic eye muscles control movements of each eyeball. They are called extrinsic because they originate on the outside of the eyeballs in the bony orbit and insert on the outer surface of the sclera (the white of the eye). Move the cornea Strabismus III & IV & VI cranial nerves Oculomotor III Abducent V1 LR6 Trochlear IV SO4 Oculomotor III Oculomotor III Oculomotor III Extrinsic Eye Muscles Muscle 1. Lateral rectus 2. Medial rectus 3. Superior rectus 4. Inferior rectus 5. Superior oblique 6. Inferior oblique Action 1. Called extrinsic because they originate on the outside of the eyeballs in the bony orbit and insert on the outer surface of the sclera (the white of the eye). 2. Control movements of each eyeball 3. Move the cornea (abduction, adduction, elevation, depression) Nerve Supply III & IV & VI cranial nerves Levator palpebrae Raises the upper eyelids, opens the superioris eyes Intrinsic eye Smooth muscles control pubil Autonomic muscles diameter nervous system Levator palpebrae superioris: Raises the upper eyelids, opens the eyes L R Muscles of Mastication (Chewing)       Four pairs of muscles move the mandible, and are known as ‘muscles of mastication’. They are all supplied by the mandibular branch of the trigeminal nerve (cranial nerve V) The masseter, temporalis, and medial pterygoid close the mouth and account for the strength of the bite. The medial and lateral pterygoid muscles help to chew by moving the mandible from side to side. The medial and lateral pterygoid protract (protrude) the mandible. The lateral pterygoid also depresses the mandible as in opening the mouth. Note that Gravity is the main depressor of mandible Retraction of mandible? Temporalis muscle Muscles of Mastication (Chewing) Muscle Action Nerve Supply The masseter Move the mandible (TMJ) Mandibu 1. Open mouth lar Temporalis 2. Close mouth branch of 3. Help to chew by moving the the mandible from side to side trigemina Medial pterygoid 4. Protract (protrude) the mandible l nerve 5. Rotaract mandible (cranial nerve V) Lateral pterygoid Muscles Of The Tongue Muscle Action Nerve Supply Genioglossus Extrinsic Muscle (originate outside the tongue, insert into tongue) Hyoglossus Styloglossus Tongue movements (protraction – retraction…..) Palatoglossus Intrinsic Muscles (originate and insert within tongue) Change shape of tongue Most of them innervated by Hypoglossal (XII) nerve Muscles Of The Neck       The Sternocleidomastoid (SCM) muscle is an important anatomical landmark in the neck. The SCM muscle arises from the sternum and clavicle and is inserted into the mastoid process and the occipital bone. It divides the neck into an anterior and a posterior triangle. Its motor supply is by the accessory cranial nerve (XI). Two muscles acting together (bilaterally) extend head and flex neck One muscle contracts (unilaterally) rotates head to opposite side  1. 2. 3.  1. 2. 3. Anterior Triangle: Anterior border: midline Posterior border: SCM muscle Superior border: Mandible Posterior Triangle: Anterior border: SCM muscle Posterior border: Trapezius muscle Inferior border: Clavicle Muscles of the anterior part of neck:  There are two main muscle groups in the anterior neck:     Suprahyoid muscles, are superior to the hyoid Infrahyoid muscles, are inferior to the hyoid. Both groups of muscles stabilize the hyoid bone, allowing it to serve as a firm base on which the tongue can move. Assist in Deglutition (swallowing) and speech Lateral Vertebral Muscles – The Scaleni:  These are attached to the cervical part of the vertebral column and pass laterally – attached to 1st and 2nd ribs  Scalenus anterior is an important landmark in the neck with several important relations • V ---- Subclavian vein • A ---- Subclavian artery • N ---- Trunks of the brachial plexus nerves Muscle Scalenus Anterior (1st rib) Scalenus Medius (1st rib) Scalenus Posterior (2nd rib) Action 1. Lateral flexion and rotation of cervical part of vertebral column 2. Assist in respiration N ----nerves A ---- artery =========== V ---- vein Respiratory Muscles Of The Thorax  Respiratory muscles alter the size of the thoracic cavity which affects the pressure in the lungs, and that determines whether we inhale or exhale. Intercostal muscles arranged in three layers: the 1. External intercostal muscle 2. Internal intercostal muscle 3. Innermost intercostal muscle. Accessory muscles useful in forced breathing: 4. SCM (Sternocleidomastoid muscle) 5. Scaleni muscles The Diaphragm The diaphragm is the most important muscle of respiration Muscle Origin Insertion Nerve Action 1) Sternal part: Xiphoid process 2) Costal part: Lower 6 costal Diaphrag cartilages and m adjacent ribs 3) Vertebral part: Upper 3 lumbar vertebrae and their discs All Contraction of muscle the diaphragm fibers increases converge vertical to be Phrenic diameter of inserted nerve thoracic cage into a causing centrally inhalation. Its located relaxation leads tendon to exhalation. Three major openings • Caval opening (inferior vena cava) T8 • Esophageal hiatus T10 • Aortic hiatus T12 Anterior Abdominal Wall Muscles The anterolateral abdominal wall includes: 1. External oblique muscle 2. Internal oblique muscle 3. Transversus abdominis muscle 4. Rectus abdominis muscle  The aponeuroses of #1+2+3 form the rectus sheaths.  Rectus sheath encloses #4 right and left Rectus abdomins  Linea alba: a median connective tissue band of the rectus sheath extending from the xiphoid process to the pubic symphysis.  Inguinal ligament: Thick ligament formed of the aponeurosis of the external oblique extend from Anterior superior iliac spine Pubic tubercle  Six-Pack Abs Superficial inguinal ring, the outer opening of the inguinal canal an inguinal hernia Actions: 1. 2. 3. 4. They retain the organs within the abdominal cavity. The oblique muscles laterally flex and rotate the trunk. The rectus abdominis flexes the lumbar vertebrae. By contracting simultaneously with the diaphragm, they increase intra-abdominal pressure and help in micturition, defecation, vomiting, and labor. 5. They may contract at the end of expiration, pushing the relaxed diaphragm further upwards into the thorax (forced exhalation). Posterior Abdominal Wall Muscles 1. Quadratus lumborum: depresses 12th rib, lateral flexion of lumber region spine Muscles of the Gluteal Region That Move the Femur 1. Iliacus 2. psoas major Insert in femur Flex thigh on trunk. If thigh is fixed, flexes trunk on thigh (Waking up muscle supine) Muscles Of The Upper Limb Muscles that move the Pectoral Girdle 1) Serratus anterior (Punching muscle): connects first 8 or 9 ribs to the scapula Known as “boxer’s muscle” because it is important in horizontal arm movements such as punching and pushing. 2) Pectoralis minor: connects ribs 2 to 5 and Coracoid process of scapula. Moves scapula and helps in inhalation 3) Levator scapulae, Rhomboid major and rhomboid minor: Originate from the vertebrae and insert into the scapula. They elevate and adduct the scapula. 4) Trapezius: The trapezius is a large, flat, triangular sheet of muscle extending from the skull and vertebral column medially to the pectoral girdle laterally (clavicle, acromion, scapulae spine). It is the most superficial back muscle and covers the posterior neck region and superior portion of the trunk. The two trapezius muscles form a trapezoid (diamond-shaped quadrangle) Both Trapezius and Serratus anterior muscles will rotate the scapula so that its glenoid cavity is raised. This allows the arm to be raised above the head (abduction of arm > 90°).  These muscles also stabilize (fixators) the girdle so that the free limb can have a firm base to move on ly n o Read Muscles of shoulder and thorax that move the humerus (cross shoulder joint) Muscle Origin Insertion Main Actions Deltoid Injection Clavicle and scapula Deltoid tuberosity Abduction of arm (15-90°) Teres major Scapula Pectoralis major Clavicle, sternum and costal cartilages Latissimus dorsi “swimmer’s muscle” Vertebrae (T-L-S) humerus Extensor of the arm Intertubercular sulcus (Bicipital groove) Main flexor of arm humerus Extensor of the arm Medial rotates arm Subscapularis Supraspinatous Scapula Humerus Infraspinatous helps initiate abduction of the arm 0-15° Lateral rotate arm Teres minor Rotator Cuff Muscles The Rotator Cuff Muscles tendons all blend with the capsule of the shoulder joint, thus help in stabilizing it. Muscles of the arm (that move the forearm) Anterior compartment Nerve supply: Musculocutaneous nerve Muscle Biceps brachii Brachialis Origin Two heads (Long / Short) scapula Humerus Insertion Radial tuberosity (radius) Ulna Action Flexion and Supination of forearm Most powerful Flexor of the forearm The biceps long head pass through the humerus intertubercular sulcus and inserts into the radial tuberosity. Biceps at elbow forms an aponeurosis that inserts medially which can produce supination of the forearm. Posterior compartment Nerve supply: Radial nerve Triceps brachii Three heads Long (scapula)/ Lateral / Medial (humerus) Olecranon process (ulna) Most powerful Extensor of the forearm Movement of Forearm Flexion (elbow) Extension (elbow) Muscles that produce them Biceps Brachialis Triceps Supination Biceps Twist a corkscrew Supinator (forearm muscle) (radioulnar) Pronation Pronator teres (forearm muscle) Twist a corkscrew Pronator quadratus (forearm muscle) (radioulnar) Muscles of the Forearm (20)      Muscles in this group that act on the wrist, hand and digits are known as extrinsic muscles of the hand because they originate outside the hand and insert within it. Based on location and function, these muscles are divided into: Anterior compartment (flexors – medial epicondyle) posterior compartment (extensors – lateral epicondyle) The tendons of these muscles that continue into the hand are held close to the bones at wrist by strong fascial bands called flexor and extensor retinaculum.  Some muscles in the forearm act on the forearm, like the Supinator – Pronator Quadratus - Pronator teres Compartment Muscles Flexor carpi radialis (Pulse) Anterior (Flexor) compartment Palmaris longus Flexor carpi ulnaris Flexor digitorum superficialis Flexor pollicis longus Flexor digitorum profundus ….. Extensor carpi radialis longus (brevis) Extensor digitorum Posterior (Extensor) Extensor carpi ulnaris. compartment Abductor pollicis longus (brevis) Tennis elbow Extensor pollicis longus Extensor indicis. ……. Anterior (Flexor) compartment Posterior (Extensor) compartment Intrinsic Muscles of the Hand (19)  Produce weak but precise movements. Writing - Typing - Playing a piano – Pincer-like action.  Split into 3 groups:. 1. The intermediate group (12) includes A. The lumbricals (4): B. The palmer interossei (4): adduct the fingers towards the middle finger. C. The dorsal interossei (4): abduct the fingers away from the middle finger. 2. The thenar muscles plus the adductor pollicis form the thenar eminence. These produce the various movements of the thumb (Pollex). 3. Hypothenar muscles act on the little finger and form the hypothenar eminence. Muscles Of The Lower Limb     Larger and powerful than upper limb Lower limb muscles function in stability, locomotion, and maintenance of posture. In contrast, upper limb muscles are characterized by versatility of movement. Muscles of the lower limbs often cross two joints and can act equally on both. Most muscles that move the femur originate on the pelvic girdle and insert on the femur. Muscles of the Gluteal region (Buttocks) Muscle Action Notes Gluteus maximus Powerful Extensor With fat forms the buttocks Gluteus Medius (IM) Powerful Abductor Tilts pelvis when walking to permit opposite leg to clear ground initiating walking Gluteus minimus Abduct thigh Tensor fasciae latae Assists gluteus maximus in extending knee Piriformis Gemellus superior Obturator internus Gemellus inferior Quadratus femoris Lateral rotators of the thigh Insert into Iliotibial tract Between these two muscles is a small space through which pass the Sciatic nerve Powerful Abductor of thigh Chief extensor of the femur Main muscles of the Thigh Three fascial septa pass from the inner aspect of the deep fascial sheath of the thigh to the linea aspera of the femur divide them into: 1. Anterior Compartment:  Sartorius (flex thigh & flex knee)  Quadriceps femoris (4 muscles): main extensor of knee also part of it flex thigh  Nerve supply: Femoral nerve 2. Medial Compartment: (adductors of thigh)  Gracilis, adductor longus, adductor brevis, adductor magnus  Nerve supply: Obturator nerve 3. Posterior Compartment: (extend thigh & flex knee)  Hamstring muscles: (1- Biceps femoris 2- Semitendinosus 3Semimembranosus)  Nerve supply: Sciatic nerve Anterior compartment of the thigh is divided into 2 triangles by the Sartorius muscle The Sartorius (cross-leg, tailor’s) is the longest muscle in the body. It originates from the anterior superior iliac spine and is inserted into the medial surface of the upper part of tibia. It flexes, abduct and laterally rotates the thigh, it also flexes the leg  Above the Sartorius: Iliacus and Psoas major (iliopsoas muscle) main flexor of thigh (waking up muscle). Below the Sartorius: Quadriceps femoris is formed of: 1) Rectus femoris 2) Vastus medialis 3) Vastus intermedius 4) Vastus lateralis. All extend knee (main extensor) and Rectus femoris flex thigh • The tendon of the quadriceps inserts into the patella. • The patellar ligament arises from the apex of the patella and inserts into the tibial tuberosity.  Anterior Compartment Medial Compartment Popliteal fossa Posterior Compartment Muscles of the Leg  Leg muscles, like those of the thigh, are divided by deep fascia into three compartments: anterior, lateral, and posterior.  Anterior compartment muscles: Dorsiflex the foot (e.g., tibialis anterior).  Lateral compartment muscles plantarflex & Eversion the foot. (Peroneus longus and brevis)  Posterior compartment muscles are split into two groups: 1. Superficial group: (Calf muscles) 1) Gastrocnemius 2) Soleus 3) Plantaris. All share a common tendon of insertion, the calcaneal tendon (or Achilles tendon). They Plantar flex the foot and the gastrocnemius also flexes the leg at knee. 2. Deep group: Plantar flex the foot (e.g., tibialis posterior): Inversion of foot by Tibialis anterior and Tibialis posterior supports medial longitudinal arch of foot Intrinsic Muscles of the Foot These muscles are termed intrinsic because they originate & insert within the foot.  These muscles are limited in action. They’re designed for support and locomotion, and are split into: A. Dorsal muscles (2) Extensor digitorum brevis and Extensor Hallucis brevis which extend toes and big toe (hallux). B. Plantar muscles are arranged in four layers (various actions):  1st layer (most superficial) (3 muscles)  2nd layer (lumbricals and 1 muscle)  3rd layer (3 muscles).  4th layer (deepest) contain 4 dorsal and 3 plantar interossei  (a) 10, (b) 1, (c) 9, (d) 8, (e) 12, (f) 17, (g) 2, (h) 6, (i) 8 (j) 14, (k) 5, (l) 4, (m) 2, (n) 15, (o) 1, (p) 11, (q) 13, (r) 12, (s) 7, (t) 16, (u) 11, (v) 17, (w) 16, (x) 15, (y) 3, (z) 10

The Muscular System

Related Documents

Recommended Documents

Description

Related Documents

Free up your schedule!

Take 5 seconds to unlock