L4 - GENERALITIES OF MUSCLES AND INNERVATION PDF

ITM 101 | ANATOMY LESSON # 4: GENERALITIES OF MUSCLES AND INNERVATION 1st YEAR A.Y. 2023-2024 | AUGUST 23, 2023 | DR. FAROUK JAJURIE Type of Activity CARDIAC MUSCLE - Strong, qu...

ITM 101 | ANATOMY LESSON # 4: GENERALITIES OF MUSCLES AND INNERVATION 1st YEAR A.Y. 2023-2024 | AUGUST 23, 2023 | DR. FAROUK JAJURIE Type of Activity CARDIAC MUSCLE - Strong, quick, continuous rhythmic contraction; acts to pump blood from heart Stimulation - Involuntary; intrinsically (myogenically) stimulated and propagated; rate and strength of contraction modified by autonomic nervous system. SKELETAL MUSCLE Figure 1. Cardiac Muscle Cardiac muscle is unique in its location, exclusively found in the heart. It features branching, striated cells with intercalated discs and typically one nucleus per cell. Its involuntary contractions rhythmically pump blood, influenced by the autonomic nervous system and the heart's Figure 2. Skeletal Muscle Tissue specialized conduction system. Unlike skeletal muscle's voluntary control for - are structurally different from heart muscle and movement or smooth muscle's involuntary functions smooth muscle. in organs, cardiac muscle's primary role is - unlike heart and smooth muscle, skeletal muscle maintaining the heart's pumping action through can be voluntary controlled. coordinated, steady contractions. - also called striated muscle because of its striated appearance. Location - Muscle of heart (myocardium) and adjacent Location portions of great vessels (aorta, vena cava) Composes gross, named muscles (e.g., biceps of arm) attached to the skeleton and fascia of limbs, Appearance of Cells body wall, and head/neck. - Branching and anastomosing shorter fibers with transverse striations (stripes) running parallel Appearance of Cells and connected end to end by complex junctions Large, very long, unbranched, cylindrical fibers with (intercalated discs); single, central nucleus transverse striations (stripes) arranged in parallel bundles; multiple, peripherally located nuclei. INTRODUCTION TO MEDICINE 101 | ANATOMY LESSON # 4 : GENERALITIES ON MUSCLES AND INNERVATION | AYURA 2027 1 ITM 101 | ANATOMY LESSON # 4: GENERALITIES OF MUSCLES AND INNERVATION 1st YEAR A.Y. 2023-2024 | AUGUST 23, 2023 | DR. FAROUK JAJURIE Type of Activity Location Intermittent (phasic) contraction above a baseline Walls of hollow viscera and blood vessels, iris, and tonus; acts primarily to produce movement (isotonic ciliary body of eye; attached to hair follicles of skin contraction) through shortening (concentric (arrector muscle of hair) contraction) or controlled relaxation (eccentric contraction), or to maintain a position against gravity Appearance of Cells or other resisting forces without movement (isometric Single or agglomerated small, spindle- shaped fibers contraction). without striations; single central nucleus Stimulation Type of Activity Voluntary (or reflexive) by the somatic nervous Weak, slow, rhyth- mic, or sustained tonic system. contraction; acts mainly to propel substances (peristalsis) and to restrict flow (vasoconstriction and SMOOTH MUSCLE sphincteric activity) Stimulation Involuntary by autonomic nervous system Figure 3. Smooth Muscle Tissue Table 1. Muscle Tissues Smooth muscle, predominantly situated in the Specific Instructional Objectives walls of organs and blood vessels, stands apart with its spindle-shaped cells lacking striations and having 1. Give the classification of skeletal muscles a single nucleus. It contracts involuntarily for tasks according to embryonic origin. like peristalsis, controlling blood vessel diameter, and 2. Give examples for each classification more. according to embryonic origin. Influenced by the autonomic nervous system and local factors, smooth muscle's sustained and tonic contractions support various bodily functions, differing from the voluntary control of skeletal muscle and the specialized rhythm of cardiac muscle. INTRODUCTION TO MEDICINE 101 | ANATOMY LESSON # 4 : GENERALITIES ON MUSCLES AND INNERVATION | AYURA 2027 2 ITM 101 | ANATOMY LESSON # 4: GENERALITIES OF MUSCLES AND INNERVATION 1st YEAR A.Y. 2023-2024 | AUGUST 23, 2023 | DR. FAROUK JAJURIE All of the branchiomeric muscles of the second branchial arch are innervated by the facial EMBRYONIC DEVELOPMENT OF THE MUSCLES nerve. These muscles include the muscles of facial expression, the posterior belly of the digastric, stylohyoid muscle and the stapedius muscle of the middle car There is only one muscle of third branchial arch, the stylopharyngeus. The stylopharyngeus is innervated by the glossopharyngeal nerve. Figure 4. Embryonic development of Muscles All the brachial muscles of the fourth and sixth arches are innervated by the vagus nerve. BRACHIAL ARCHES These muscles include all the muscles of the palate (exception of the tensor veli palatini which is SPECIFIC INSTRUCTIONAL OBJECTIVES: innervated by the trigeminal nerve),all the muscles of the pharynx (except stylopharyngeus which is 1. Discuss what develops/arise from innervated by the glossopharyngeal nerve, and all the branchial arches muscles of the larynx) Figure 5. Brachial Arches Figure 6. Branchiomeric Musculature Branchiomeric Musculature All of the branchiomeric muscles that come from the first branchial arch are innervated by the trigeminal nerve. These muscles include all the muscles of mastication, the anterior belly of the digastric, the mylohyoid, tensor tympani and tensor veli palatini. INTRODUCTION TO MEDICINE 101 | ANATOMY LESSON # 4 : GENERALITIES ON MUSCLES AND INNERVATION | AYURA 2027 3 ITM 101 | ANATOMY LESSON # 4: GENERALITIES OF MUSCLES AND INNERVATION 1st YEAR A.Y. 2023-2024 | AUGUST 23, 2023 | DR. FAROUK JAJURIE CRANIAL NERVES MUSCLES DEVELOPING FROM SOMITE MYOTOME CRANIAL NERVE MNEMONICS Figure 7. Epaxial Muscles 1. EPAXIAL MUSCLES - Skeletal muscles which lie DORSAL to the vertebral column. In humans, this is only a small muscle group formed by the transversospinalis, longissimus and iliocastalis muscles. Also at the ribcage level the levatores costartum muscles involved with rib elevation during respiration. Table 2. Cranial nerves Mnemonic 1. What is the longest Cranial Nerve? - VAGUS Nerve 2. What is the smallest muscle? - Some say that the STAPEDIUS muscle is the smallest located in your ear. - But the SMALLEST muscle is The Figure 8. Hypaxial Muscles ARRECTOR PILI muscle which is responsible for giving you goosebumps. 2. HYPAXIAL MUSCLES - Skeletal muscles lying VENTRAL to the vertebral column. These muscles contribute both body (trunk) and limb skeletal muscle. Hypaxial muscles INTRODUCTION TO MEDICINE 101 | ANATOMY LESSON # 4 : GENERALITIES ON MUSCLES AND INNERVATION | AYURA 2027 4 ITM 101 | ANATOMY LESSON # 4: GENERALITIES OF MUSCLES AND INNERVATION 1st YEAR A.Y. 2023-2024 | AUGUST 23, 2023 | DR. FAROUK JAJURIE include some vertebral muscle, the diaphragm, the abdominal muscles, and all 4. STABILIZES JOINTS limb muscles. 5. MAINTAINS POSTURE PARTS OF SKELETAL MUSCLES MUSCLE ROLES DURING MOVEMENT SPECIFIC INSTRUCTIONAL OBJECTIVES: 1. Discuss the different roles of muscles in movements. Prime mover Antagonist Synergist Fixator 1. Prime mover (Agonist) -Refers to the chief muscle or a member of a chief group of muscle responsible for a particular movement -ex. Triceps in extension of the forearm Figure 9. Biceps brachii Biceps brachii in flexion of the elbow 1. ORIGIN - the stable attachment. More PROXIMAL part 2. INSERTION - the mobile attachment. More DISTAL part 3. BELLY - Fleshy part of the muscle FUNCTIONS OF MUSCLES 1. MOVEMENT 2. HEAT GENERATION - Muscle contraction Figure 10. Agonist muscles requires energy and produces heat as a 2. Antagonist byproduct of metabolism. -any muscle that opposes the action of the prime mover 3. SHAPE AND CONTOUR INTRODUCTION TO MEDICINE 101 | ANATOMY LESSON # 4 : GENERALITIES ON MUSCLES AND INNERVATION | AYURA 2027 5 ITM 101 | ANATOMY LESSON # 4: GENERALITIES OF MUSCLES AND INNERVATION 1st YEAR A.Y. 2023-2024 | AUGUST 23, 2023 | DR. FAROUK JAJURIE -ex. Biceps brachii vs. Triceps brachii Quadriceps femoris vs. Biceps femoris -biceps femoris (prone to cramps during jogging) -during elbow flexion biceps are the prime mover while the triceps are the antagonists. -during elbow extension biceps then become Figure 12.Synergists muscles the antagonists while the triceps become the prime movers. 4. Fixators (not to be confused w/ LTO fixers) -This is a muscle that contracts isometrically (increases muscle tone but produces no movement) to stabilize the origin of the prime mover so that it can act efficiently. -ex. Deltoid muscle during arm movement Figure 11. Antagonist muscles 3. Synergist Figure 13. Fixator muscle -the muscles that complements the actions of the prime movers MUSCLE TONE -These muscles help make movements more accurate and fluid. (proceed to further research) -is the amount of tension (or resistance to ex. during elbow flexion the brachioradialis movement) in muscles. Our muscle tone helps us to synergizes with the biceps brachii hold our bodies upright when we are sitting and INTRODUCTION TO MEDICINE 101 | ANATOMY LESSON # 4 : GENERALITIES ON MUSCLES AND INNERVATION | AYURA 2027 6 ITM 101 | ANATOMY LESSON # 4: GENERALITIES OF MUSCLES AND INNERVATION 1st YEAR A.Y. 2023-2024 | AUGUST 23, 2023 | DR. FAROUK JAJURIE standing. Changes in muscle tone are what enable Figure 14. Motor Units us to move. -Afferent neurons, also called sensory -During physical exams physicians examine the neurons, are the nerve fibers responsible for muscle tone of patients. bringing sensory information from the outside -Partial state of contraction of muscles while resting. world into the brain. -Facial toning usually done in cosmetic medicine is a -Efferent neurons, also called motor means of increasing muscle tone and facial volume neurons, are the nerve fibers responsible for by promoting muscular hypertrophy, and preventing carrying signals from the brain to the muscle loss due to aging or facial paralysis. peripheral nervous system in order to initiate an action. MOTOR UNIT The basic system present throughout spinal cord *proceed to further research anatomy is that *correlate with physiology and biochemistry 1. Dorsal roots carry afferent fibers 2. Ventral roots carry efferent fibers. SPECIFIC INSTRUCTIONAL OBJECTIVES: 3. Similarly, the ventral horn contains efferent cell bodies, and the dorsal root ganglion 1. Describe pyramidal and extrapyramidal contains afferent cell bodies. tract of motor system (Remember that the white matter contains myelin and is therefore where you can find axons. The cell -Consists of a motor neuron in the anterior bodies will be located in the gray matter.) gray horn or column of the spinal cord and all the muscle fibers it supplies MNEMONIC - SAD DAVE Sensory = Afferent = Dorsal -The combination of an individual motor Dorsal = Afferent | Efferent = Ventral neuron and all of the muscle fibers that it innervates is called a motor unit. The number of fibers innervated by a motor unit is called its innervation ratio. Figure 15. Afferent nerve mnemonic INTRODUCTION TO MEDICINE 101 | ANATOMY LESSON # 4 : GENERALITIES ON MUSCLES AND INNERVATION | AYURA 2027 7 ITM 101 | ANATOMY LESSON # 4: GENERALITIES OF MUSCLES AND INNERVATION 1st YEAR A.Y. 2023-2024 | AUGUST 23, 2023 | DR. FAROUK JAJURIE -Every skeletal muscle is supplied by one or more Importance of nerve supply to muscles nerves. The nerve trunk is a mixed nerve (60 % Read on Muscle Action Potential motor and 40 % sensory) which also contains ○ Depolarization sympathetic fibers ○ Overshoot ○ Repolarization ○ Hypopolarization ○ Hyperpolarization *NOTES* Revisit and Memorize Anatomical terms and DISUSE ATROPHY movements Memorize the Brachial Plexus SPECIFIC INSTRUCTIONAL OBJECTIVES: Memorize the specific muscles and their innervation, insertion, origin, action, function, 1. Discuss the importance of nerve supply to and blood supply. a muscle Give more emphasis on the muscles of the 2. Discuss disuse atrophy upper and lower extremities, the trunk and the neck -Disuse (physiologic) atrophy is caused by not What happens to specific muscles during using your muscles enough. If you stop using denervation your muscles, your body won't waste the ○ Loss of motor innervation induces energy it needs to take care of them. Instead, rapid skeletal muscle fiber your body will start to break your muscles degeneration with the activation of down, which causes them to decrease in size atrophy-related signaling and and strength. subsequent disassembly of the sarcomeres. This results in a loss of muscle function. Some of these changes can be observed within just a few hours after denervation. INTRODUCTION TO MEDICINE 101 | ANATOMY LESSON # 4 : GENERALITIES ON MUSCLES AND INNERVATION | AYURA 2027 8 ITM 101 | ANATOMY LESSON # 4: GENERALITIES OF MUSCLES AND INNERVATION 1st YEAR A.Y. 2023-2024 | AUGUST 23, 2023 | DR. FAROUK JAJURIE - Depth can also influence the naming of the muscle - Ex. Superficial = Superficialis ➔ Flexor Digitorum Superficialis Deep = Profundus ➔ Flexor Digitorum Profundus 4. Position - The location or position of muscle to a particular bone often determines its name. Figure 16. Normal vs Atrophied muscle - Ex. Chest = Pectoralis ➔ Pectoralis major & minor BASES OF NOMENCLATURE OF MUSCLES The arm = Brachii ➔ Biceps brachii 1. Action Back = Dorsi - The muscle is named for the movement ➔ Latissimus dorsi they produce Thigh = Femoris ➔ Rectus femoris - Ex. Dilator Nares 5. Number of heads or bellies Pronator Teres - Some muscle names indicate the number Flexor carpi radialis of muscles in a group. Levator scapulae - Ex. Supinator Biceps = two origin Extensor indicis Triceps = three origin Quadriceps = four origin 2. Attachements/Structure - It is named based on the muscle where it 6. Size is attached to. - Size can also influence the name of the - Ex. muscle Sternocleidomastoid Muscle (SCM) - Ex. - from sternum (sterno) and clavicle Major & Minor (cleido) to mastoid process In the buttocks Coracobrachialis - from coracoid ➔ gluteus maximus (largest) process to arms ➔ gluteus medius (medium) ➔ gluteus minimus (smallest) 3. Depth INTRODUCTION TO MEDICINE 101 | ANATOMY LESSON # 4 : GENERALITIES ON MUSCLES AND INNERVATION | AYURA 2027 9 ITM 101 | ANATOMY LESSON # 4: GENERALITIES OF MUSCLES AND INNERVATION 1st YEAR A.Y. 2023-2024 | AUGUST 23, 2023 | DR. FAROUK JAJURIE 7. Shape - Names of some muscles can be reflected sub under SUBmarines move by their shape. underwater. - Ex. Triangular = Deltoid ductor something that A conDUCTOR makes a Square = Quadratus moves train move. Diamond = Rhomboid major & minor anti against If you are antisocial, you are against engaging in 8. Direction of fibers social activities. - The direction of the muscle fibers are used to describe muscles. - Ex. epi on top of n/a Straight = rectus At an angle = obliques apo to the side of n/a Horizontal = transverse 9. Combination longissim longest “Longissimus” is longer us than the word “long.” - The combination of two or more muscles can influence their name. - Ex. longus long long Long flexors of digits = Flexor digitorum longus brevis short brief Broadest muscle of the back = Latissimus dorsi Pectorialis Major maximus large max medius medium “Medius” and “medium” Mnemonic Device for Latin Roots both begin with “med.” minimus tiny; little mini Example Latin or Greek Mnemonic Device Translation rectus straight To RECTify a situation is to straighten it out. ad to; toward ADvance toward your goal multi many If something is MULTIcolored, it has ab away from n/a many colors. INTRODUCTION TO MEDICINE 101 | ANATOMY LESSON # 4 : GENERALITIES ON MUSCLES AND INNERVATION | AYURA 2027 10 ITM 101 | ANATOMY LESSON # 4: GENERALITIES OF MUSCLES AND INNERVATION 1st YEAR A.Y. 2023-2024 | AUGUST 23, 2023 | DR. FAROUK JAJURIE uni one A UNIcorn has one horn. Extrinsic Muscles of the Eye Levator palpebrae superioris Superior oblique muscle bi/di two If a ring is DIcast, it is Superior rectus muscle made of two metals. Medial rectus muscle Lateral rectus muscle tri three TRIple the amount of Inferior oblique muscle money is three times as Inferior rectus muscle much. (4 recti muscles, 2 oblique muscles + 1 levator palpebrae superioris) quad four QUADruplets are four children born at one Extrinsic muscles of the eye are situated outside birth. the eyeball (Extraocular muscles), voluntary. externus outside EXternal internus inside INternal Table 3. Mnemonic Device EXTRINSIC AND INTRINSIC MUSCLE Specific Instructional Objectives 1. Memorize and Differentiate all the extrinsic and intrinsic muscles Figure 18. Intrinsic Muscles of the Eyes 2. Understand the actions involved in extrinsic and intrinsic muscles Intrinsic Muscles of the Eye Ciliary muscle Sphincter pupillae (Iris) Dilator pupillae (Iris) Intrinsic muscles of the eye are situated inside the eyeball (Intraocular muscles), involuntary. - We should understand and know what the extrinsic and intrinsic muscles are, are they only present in the eyes ? - “No” Figure 17. Extrinsic Muscles of the Eyes INTRODUCTION TO MEDICINE 101 | ANATOMY LESSON # 4 : GENERALITIES ON MUSCLES AND INNERVATION | AYURA 2027 11 ITM 101 | ANATOMY LESSON # 4: GENERALITIES OF MUSCLES AND INNERVATION 1st YEAR A.Y. 2023-2024 | AUGUST 23, 2023 | DR. FAROUK JAJURIE There are regions of the human body where intrinsic muscles are present such as on your feet (e.g., when you trail or hike and use your feet for balance, this can be very painful) and your hands, they are attached on the phalanges such as the metacarpophalangeal joints. Figure 19. Metacarpophalangeal joints Figure 20. Intrinsic Hand Muscles As Intrinsic muscles are found entirely within the body part upon which it acts, Extrinsic muscles originate outside of the part where it is found or upon which it acts, attached to different body segments, with at least one (1) point of attachment inside the body or part upon which it acts and at least one (1) attachment outside. INTRODUCTION TO MEDICINE 101 | ANATOMY LESSON # 4 : GENERALITIES ON MUSCLES AND INNERVATION | AYURA 2027 12 ITM 101 | ANATOMY LESSON # 4: GENERALITIES OF MUSCLES AND INNERVATION 1st YEAR A.Y. 2023-2024 | AUGUST 23, 2023 | DR. FAROUK JAJURIE Abnormalities and Disease mentioned: 1. Chorea -is a movement disorder that causes sudden, unintended, and uncontrollable jerky movements of the arms, legs, and facial muscles. Chorea is seen in many diseases and conditions and is caused by an overactivity of the chemical dopamine in the areas of the brain that control movement. “Para kang nagbre-break dance” (Jajurie, 2023). 2. Hemiballismus -is a hyperkinetic involuntary movement disorder characterized by intermittent, sudden, violent, involuntary, flinging, or ballistic high amplitude movements involving the ipsilateral arm and leg caused by dysfunction in the central nervous system of the contralateral side. 3. Myelitis (Transverse) - Myelitis refers to inflammation of the spinal cord. It can damage the insulating material, called myelin, that covers nerve cell fibers. Transverse refers to the pattern of changes in sensation—there is often a band-like sensation across the trunk of the body, with sensory changes below that area. 4. Paraplegia -the inability to voluntarily move the lower parts of the body -hospital cases mostly due to motor and vehicular accidents (damage to the spinal cord). INTRODUCTION TO MEDICINE 101 | ANATOMY LESSON # 4 : GENERALITIES ON MUSCLES AND INNERVATION | AYURA 2027 13 ITM 101 | ANATOMY LESSON # 4: GENERALITIES OF MUSCLES AND INNERVATION 1st YEAR A.Y. 2023-2024 | AUGUST 23, 2023 | DR. FAROUK JAJURIE Suggested Reference: Snell’s Clinical Anatomy (Favourite book ni Doc Jajz) *Random Advices From Doc Jajurie* -Don’t forget to exercise (very very important, pampatanggal ng stress) -Don’t let studying be the reason for your body to shut down -”Don’t waste your time basa lang ng basa” (Jajurie, 2023) -Study the normal before moving on to the abnormal INTRODUCTION TO MEDICINE 101 | ANATOMY LESSON # 4 : GENERALITIES ON MUSCLES AND INNERVATION | AYURA 2027 14