12. Muscular System

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Information about 12. Muscular System

Published on February 15, 2020

Author: ruch001

Source: authorstream.com

Slide1: General Training Module Muscles of the Body RK Contents : Contents Muscle Tissue types (quick recap) Overview of functions of the muscles Skeletal Muscles: t heir structure & function Proprioception – “Sense of Self” Proprioceptors (Muscle Spindle & Golgi Tendon Organ) Posture & Balance – Muscle Tone and Spinal Reflexes Naming Muscles of the body What you should learn about muscles? Overview of muscles in different body regions Range of movements of the body (video) Muscle Types: Muscle Types Smooth Muscles – in the walls of blood vessels and internal organs such as gastrointestinal tract, respiratory tract, urinary tract etc., Cardiac muscle (Myocardium) – The heart Skeletal muscles – attached to the skeleton Functions of Muscles – An overview: Functions of Muscles – An overview Regulation of Blood supply – (Smooth Muscles in the Blood Vessels) (Involuntary activity of the voluntary Muscles) & Diaphragm Skeletal Muscles : Skeletal Muscles Muscles that are attached to the bones and the skeleton are called skeletal muscles The skeletal muscles can be contracted at your own will They provide body mobility in several ways: Moving the body in relation to the physical environment we live in: Walking, running etc., Moving a body part in relation to the rest of the body Moving a body part in relation to another part of the body They also help to modify the external environment using mainly hands and limbs in general. Skeletal Muscles : Skeletal Muscles The muscles are usually attached to the bones of the skeleton by passing over joints in the skeletal system. These muscles are arranged in groups These groups usually have antagonistic groups. That means when one group contracts the other relaxes vice versa, allowing smooth movements. This way the body posture and balance is maintained while movements are achieved. Skeletal Muscles: Skeletal Muscles All the muscles have their own nerve and blood supply The nerves bring electrical impulses to the skeletal muscles either from the brain or the spine via reflex arcs These signals either contract (or relax) muscles Blood vessels supply nutrients and oxygen required to energy production in muscles Energy is required for muscle contractions They also eliminate waste from the muscles Heat is produced when muscles are contracted Cross section of a Skeletal muscle: Cross section of a Skeletal muscle Muscle fibber - E ndomysium Fascicle - Perimysium Muscle - Epimysium Motor Endplate: Motor Endplate The Motor Endplate also known as the Neuromuscular Junction ( NMJ or Myo -neural junction) is the junction or the synapse between the motor nerve fiber ending at the muscle end and the cell membrane (Sarcolemma) of the muscle fiber that it innervates. Here the electrical signals of the motor nerve endings are passed on to the muscle fiber, chemically, using neurotransmitters upon which muscles wither contract or relax. Motor Endplate: Motor Endplate Motor Nerve Ending Synaptic vesicles with Neurotransmitters Receptors at the Post Synaptic plate Mitochondria Sarcolemma- The cell membrane of the muscle fiber Body Movements: Body Movements Skeletal muscles attached to the joints of the appendicular skeleton are the muscles responsible for voluntary movements of joints, limbs and therefore the whole body. These movements made by skeletal muscles are voluntary – that is they are carried out with conscious will of the person However maintaining the tone and posture, Reflex activities are involuntary actions of these otherwise voluntary skeletal muscles Contraction of smooth muscles on the other hand are involuntary. Muscle tone: Muscle tone Under normal circumstances few muscle fibers in a given muscle are in a state of constant contraction This results in a constant state of partial contraction of the whole muscle This state of contraction under resting conditions is called the muscle tone. The muscle tone is helpful in maintaining posture and balance of the body Proprioception: Proprioception Proprioception means the “sense of self” This is accomplished by the information received through deep somatic sensory nerves that innervate proprioceptors in muscles, tendons, bones, joints etc. as well as receptors in the ear pertaining to balance and information from the eyes via cranial nerves They give information about the position of the body and limbs in space and detect changes in position or movement of the body or its limbs.   Proprioception: Proprioception In the limbs, the proprioceptors are sensors that provide information about joint angle, muscle length, and muscle tension, In the skeletal muscles the proprioceptors are the Muscle Spindle and Golgi Tendon Organs The   muscle spindle   provides information about  changes in muscle length , therefore stretch. The   Golgi tendon organ  is another type of proprioceptor that provides information about changes in muscle tension . Proprioceptors: Proprioceptors Receptors of proprioception are called proprioceptors In the muscle there are two types of receptors The Muscle Spindle The Golgi Tendon Organ Muscle Spindle: Muscle Spindle Muscle spindles are sensory receptors within the belly of a muscle that primarily detect changes in the length of this muscle. They are in parallel to other muscle fibers . They convey length information to the central nervous system via sensory neurons. This information can be processed by the brain to determine the position of body parts. The responses of muscle spindles to changes in length also play an important role in regulating the contraction of muscles, by activating motor neurons via the stretch reflex to resist muscle stretch. Golgi Tendon Organ : Golgi Tendon Organ The G olgi T endon O rgan located in muscle tendons, is a proprioceptor sense organ, that receives information from the tendon, that senses TENSION. When you lift weights, the golgi tendon organ is the sense organ that tells you how much tension the muscle is exerting. If there is too much muscle tension the golgi tendon organ will inhibit the muscle from creating any force (via a reflex arc), thus protecting the you from injuring itself . They are in series with the muscle fibres and are located in the muscle tendon. Body Posture & Balance: Body Posture & Balance The tone of striated (skeletal) muscles arranged in antagonistic groups in the muscular system of the body helps to maintain the body posture and balance in standing and sitting positions and other activities. Maintenance of tone and posture are involuntary activities of the skeletal muscles that is usually responsible for voluntary movements of the body. The brain receives sensory information for the purpose of maintaining posture and balance from the eyes, ears and deep somatic nerves from the musculoskeletal system. This is PROPRIOCEPTION and is accomplished by the cerebellum with inputs from cerebral cortex and basal nuclei of the brain. Reflex Activity: Reflex Activity The skeletal muscles sometimes also act in a reflex manner Reflexes are actions of these muscles that occur in response to certain stimuli but without the involvement of the brain or higher centers, that is without conscious will of the person. The information only go through the spinal cord and does not reach brain. Therefore they too are involuntary activities of the skeletal muscles. Spinal Reflexes - Types: Spinal Reflexes - Types Withdrawal reflexes Stretch Reflexes Golgi Tendon Reflex Crossed Extensor Reflex Monosynaptic Reflexes Polysynaptic Reflexes (Have interneurons) Stretch Reflex: Stretch Reflex When the skeletal muscles are stretched there’s a reflex initiated to contract muscles opposing the stretching that is attempted. This is a mechanism to prevent overstretching and damaging muscles during activity It also maintains the posture and balance of the body This is accomplished by a spinal reflex and is known as the stretch reflex, deep tendon reflex, Myotonic reflex or knee-jerk reflex. In fact the actual knee jerk is such a stretch reflex. Slide26: The photograph shows a Deep Tendon Reflex of the Knee Joint is being elicited in a patient. This is a spinal reflex and a Stretch Reflex and is also know as the Knee Jerk. Note the hands Crossed Extensor Reflex: Crossed Extensor Reflex The crossed extensor reflex, is a withdrawal reflex. When the reflex occurs the flexors in the withdrawing limb contract and the extensors relax, while in the other limb, the opposite occurs. An example of this is when a person steps on a nail, the leg that is stepping on the nail pulls away, while the other leg takes the weight of the whole body. The crossed extensor reflex is contralateral, meaning the reflex occurs on the opposite side of the body from the stimulus . Naming Muscles: Naming Muscles Each skeletal muscle of the body has a name There name is given based on the: Shape of the muscle ( trapezius ) Direction of muscle fibers (external oblique) The relative position of the muscle ( tibialis over tibia) The movement it produces (flexors, extensors etc) No. of attachment points (biceps, triceps) Bones to which they are attached ( … carpi radialis attached to carpal bones and the radius) What to learn about Muscles?: What to learn about Muscles? Attachments Origin Insertion Action Nerve Supply Muscles of the Head, Face & Neck: Muscles of the Head, Face & Neck Head: frontalis , occipitalis , joined by occipito-frontalis aponeurosis ,: raises the eye brows and wrinkles the forehead, stretches the scalp temporalis on either side - lifts the mandible up and closes the mouth (in chewing) Face – eye: Obicularis oculi : surrounds the eye and closes the eye Levator palpebrae superioris : extends from the posterior part of the orbital cavity to the upper eyelid- lifts the eye lid Muscles of the Head, Face & Neck: Muscles of the Head, Face & Neck Muscles of the Head, Face & Neck: Muscles of the Head, Face & Neck Face – mouth and cheeks: Obicularis oris (unpaired): surrounds the mouth and blends with the cheek muscles – closes the lips, used in whistling. Buccinator – flat muscle of the cheeks – draws the cheeks in in chewing Masseter – broad muscle extending from the zygomatic arch to the angel of the jaw/mandible – draws mandible up towards maxilla and exert pressure on food Pterygoid muscles – extends from the sphenoid bone to the mandible – closes the mouth and pulls the lower jaw forwards Muscles of the eye: Muscles of the eye Self Study question Find out: The muscles of the eye Their nerve supply Muscles of the Neck: Muscles of the Neck There are many muscles in the neck. The two largest are the Sternocleidomastoid and the Trapezius . The Sternocleidomastoid : Extends from the manubrium of the sternum and clavicle to the mastoid process of the temporal bone Turns head from side to side Both contracts together in FORCED respiration Muscles of the Neck: Muscles of the Neck The Trapezius : from the occiput above it extends to the 12 th Thoracic vertebra below Extends the neck and also controls the shoulder movements Muscles of the Chest Wall: Muscles of the Chest Wall Pectoralis Major and Minor - Intercostal Muscles Serratus Anterior Pectoralis Major & Minor: Pectoralis Major & Minor The pectoralis major muscle originates from the medial clavicle and lateral sternum and inserts on the lateral lip of the bicipital groove of the humerus (see the image below). The action of the pectoralis major is to flex, adduct, and rotate the arm medially. The pectoralis minor originates from the third to fifth ribs near the costal cartilages and inserts on the medial border and superior surface of the coracoid process of the scapula. It functions to stabilize the scapula by drawing it inferiorly and anterior against the thoracic wall. Serratus Anterior : Serratus Anterior The serratus anterior, like its name suggests, consists of multiple muscle slips that run along the anterolateral chest wall. It originates from the upper borders of the first through eighth ribs and inserts on the deep surface of the medial scapula. The long thoracic nerve innervates the serratus anterior. It acts to rotate the scapula, raising the point of the shoulder and drawing the scapula forward, or protracting it. Transection of the long thoracic nerve is carefully avoided during an axillary lymph node dissection, since its loss results in winging, as the scapula is released from the chest wall and moves upward and outward Muscles of the Back: Muscles of the Back They are described in three layers. The outer two layers are the extrinsic group and the deep innermost layer is the intrinsic group. The two outer layers (Extrinsic muscles of the back): Superficial Layer – movements of upper extreme Intermediate layer - respiration Deep layer- Intrinsic Muscles of the back Extension and rotation of the vertebral column Muscles of the Back: Muscles of the Back Clavicle is the only bony link between the vertebral column and the shoulder girdle and upper limb. This allows free movement of the upper limb/extremity from the trunk/axial skeleton. The superficial layer of the muscles of the back facilitates these movements. The intermediate layer is associated with respiration The deep layer is concerned with the extension and rotation of the vertebral column (trunk and neck) Muscles of the Back - Superficial Layer:: Muscles of the Back - Superficial Layer: Originates from the vertebrae in the axial skeleton and insert into the shoulder girdle and the arm - clavicle, scapula and the humerus . Trapezius Latissimus Dorsi Levator scapulae Rhomboids: major and minor Muscles of the Back - Intermediate Layer:: Muscles of the Back - Intermediate Layer: Originates from the vertebrae in the axial skeleton and insert into the ribs. Serratus Posterior Superior (1) Serratus Posterior Inferior (2) Levatores Costorum (3) They are associated with respiration 3 Muscles of the Back – Deep Layer:: Muscles of the Back – Deep Layer: There are three sub groups each with several more sub groups: Splenius: capitis and cervicis Erector Spinae (has three parallel sub groups): Spinalis – most medial Longissimus - intermediate Iliocostalis -most lateral: Transverso-spinalis : semispinalis , multifidus and rotators These muscle groups when act bilaterally extend the trunk and neck. When act unilaterally they rotate the trunk These may have sub groups named capitis , cervicis , thoracis and lumborum Muscles of the Back - Splenius: Muscles of the Back - Splenius Fibers run supero -laterally Erector Spinae: Erector Spinae Fibers run parallel to vertebral column Muscles of the Back – Transversospinalis: Muscles of the Back – Transversospinalis Fibers run superomedially Muscles of the Abdominal Wall: Muscles of the Abdominal Wall Anterior Abdominal wall Rectus abdominis External oblique Internal Oblique Transversus abdominis Posterior Abdominal wall Quadratus lumborum Psoas major+/- minor Illiacus Diaphragm Bilateral action: These muscles compress the abdominal organs, flex the lumbar vertebral column, Unilateral action: bend the trunk to one side, rotation of the trunk Quadratus -Extension and lateral flexion of the vertebral column. Iliopsoas – flexion of the thigh/hip Psoas -lateral flexion of the vertebral column. Psoas minor – flexion of the vertebral column Anterior Abdominal Wall: Anterior Abdominal Wall The anterior wall is divided longitudinally in the midline by a tendinous cord that runs form the xiphoid of the sternum above to pubic symphysis below known as Linea Alba The two rectus abdominis muscles are the most superficial vertical muscles on either side of the midline, linea alba. Then there are three muscles laterally in the wall External Oblique Internal oblique Transversalis abdominis Rectus Abdominis: Rectus Abdominis “Six packs” Rectus Sheath – cross section : Rectus Sheath – cross section The rectus sheath is formed by the  aponeuroses  (flattened tendons) of the three flat muscles laterally, and encloses the rectus abdominus muscle. Lateral wall Muscles: Lateral wall Muscles External oblique – extends downwards and forwards from the lower ribs ( infero-medialy ) Internal oblique – extends upwards and towards midline ( Supero-medialy ) Fibers of these two muscles are perpendicular to each other Transverse abdominis – deepest. Fibers run transeversly right angles to the rectus abdominis External & Internal Oblique: External & Internal Oblique Posterior Abdominal wall: Posterior Abdominal wall Quadratus lumborum Psoas major Psoas minor (60%) Illiacus Diaphragm Psoas and iliacus muscles unite to form ilio-psoas that inserts into the femur Muscles of the Pelvis: Muscles of the Pelvis Muscles of the Pelvic Floor: Muscles of the Pelvic Floor Levator ani : Is made up of three parts: Pubo-rectalis muscle Pubo-coccygeus muscle Illio-coccygeus muscle Coccygeus There are opening for the rectum, urethra and vagina (in females) to pass through in the pelvic floor Muscles of the Pelvic Floor: Muscles of the Pelvic Floor Muscles of the Pelvic FLoor: Muscles of the Pelvic FLoor Muscles of the Upper Limbs: Muscles of the Upper Limbs Muscles of the Lower Limbs: Muscles of the Lower Limbs Range of Body Movements: Range of Body Movements Video in the skeletal system ppt End of Unit 9 – Part B: End of Unit 9 – Part B

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