Anatomy of MUSCULAR SYSTEM PDF

Anatomy of MUSCULAR SYSTEM By Zerihun A. (BSc,MSc.) 1 Muscular system Myology - the study of muscles Muscle is composed of cells which can contract to cause movement  Produce movement  Allow us to move, breath,...

Anatomy of MUSCULAR SYSTEM By Zerihun A. (BSc,MSc.) 1 Muscular system Myology - the study of muscles Muscle is composed of cells which can contract to cause movement  Produce movement  Allow us to move, breath, transport materials and circulate our blood etc  Maintain posture and body position  By resisting the pull of gravity and preventing unwanted movements  They hold some articulating bones in place by maintaining tension on the tendons  Guard entrance and exits  Ring like sphincter muscles around the eyelids, pupils, and mouth control the admission of light, food, and drink into the body  Urethral and anal orifices control elimination of waste; and other sphincters control the movement of food, bile, and other materials through the body  Maintain body temperature  Skeletal muscles produce as much as 85% of our body heat, which is vital to the functioning of enzymes and therefore to all of our metabolism Muscular system … Types of muscle tissue Muscle structure There are three different types of muscle; 1. Cardiac Muscle (striated, involuntary)  Makes up the wall of the heart 2. Smooth Muscle (unstriated, involuntary)  Found in structures which we do not have control over such as blood vessels, stomach and intestine, urethra, uterus, internal muscles of the eye 3. Skeletal Muscle (striated, voluntary)  This is the muscle attached to our skeletons and allows us to move our bodies Types of muscle tissue and their structure Cardiac muscle Cardiac muscle is the muscle found in the walls of the heart It contracts to force the blood around the body Cardiac muscle contracts without stimulation  However, the strength and rate of the contraction is modified by the Cardiac muscle tissue found only in autonomic nervous system the walls of the heart Cardiac muscle does not tire. Fibres The cardiac muscle fibres are short  Contain single central nucleus with a single central nucleus; they are  Branch freely - connected via gap striated junctions The cells join directly together and are  Have very high aerobic capacity connected by connective tissue Contract according to sliding filament theory  Smooth muscle Smooth muscle is found in the walls of the internal organs, the walls of blood vessels and the intrinsic (internal) muscles of the eye Smooth muscle contracts without stimulation  However, the strength and rate of the contraction is modified by the autonomic nervous system Smooth muscle does not tire Smooth muscle cells are spindle shaped and contain a single oval, centrally located nucleus; they are unstriated They have no sheath but are connected by connective tissue Contain intermediate filaments and dense bodies – During contraction tension transmitted to intermediate filaments which pull on dense bodies Skeletal muscle Skeletal or 'voluntary' muscle is the muscle that moves our body and its limbs as well as other parts – It is under voluntary control but tires quickly Most of it is attached to bones, but there are exceptions (attached to a connective tissue via tendons) in – The tongue, upper esophagus, some facial muscles, and some sphincter It is composed of long thin cylindrical cells known as muscle fibres These muscle cells contain multiple nuclei near the surface of the cell and two types of myofilaments (actin & myosin) – The actin and myosin filaments are organized in units called sarcomeres which are joined end to end to form a myofibril The arrangement of the myofilaments inside the myofibrils are the reason that muscle cells appear striped under magnification Connective tissues of a skeletal muscle Muscle fibres are surrounded by a loose connective tissue called endomysium, this contains capillaries which supply the muscle cells with blood – The cells with their surrounding endomysium are bundled together into fasciculae The fasciculae are surrounded by a strong connective tissue called perimysium A muscle is made up of many fasciculae which are bound together by a dense connective tissue called epimysium Skeletal muscles … Are attached to bones (mostly), cartilages, ligaments, or fascia or to some combination of …  Direct = right onto bone – Epimysium of muscle fibers continuous with the periosteum a bone Example - intercostal muscles  Indirect = via tendon/aponeurosis – More common – Leave bony markings = tubercle, crest, ridge, etc. – Sometimes attach to skin Skeletal muscles … General anatomy of skeletal muscles Origin insertion and belly The origin of a muscle is normally the end attached to the less movable bone The insertion of a muscle is usually the end that is attached to the most movable bone Between the origin and insertion of a muscle there is thicker middle region called the belly Muscles can have multiple origins, insertions and bellies Shape and architecture of skeletal muscles Pennate (L. pennatus, feather) – Feather-like arrangement of fascicles (fiber bundles): unipennate, bipennate, or multipennate Fusiform – Spindle shaped (round, thick belly, and tapered ends) Parallel – The fascicles lie parallel to the long axis of the muscle; flat muscles often have aponeuroses Convergent – Have a broad attachment from which the fascicles converge to a single tendon Circular – Surrounds a body opening or orifice constricting it when contracted Muscle groups in action Muscles can be classified into at least 4 categories by their actions Agonist Primary mover of a muscle, produces most of the force during a particular joint action Eg. biceps brachii is main flexor of forearm Synergists Muscles work together, adds extra force to agonistic movement – It modifies the direction or reduce undesirable movement Eg. muscles crossing 2 joints Fixators Antagonists A muscle that holds bone in place to Oppose agonistic movement or prevent provide stable base for agonist muscle overshooting agonistic motion attached to it and pull on something Eg. triceps brachii is antagonist to biceps else brachii Eg. joint stablilizers Blood and Nerve supply Blood vessels and nerves travel through connective tissues to the muscle fibres. Blood vessels Provide nutrients and oxygen for contraction – Each muscle fibre in contact with one or more capillaries Innervation Motor neurons - Convey impulses for muscular contraction Each motor axon branches to innervate a number of muscle fibers at a neuromuscular junction A motor neuron and all the muscle fibers it innervates is called a motor unit  Naming Criteria for naming the skeletal system o Named on the basis of:  Location: (eg) brachialis = arm  Shape: (eg) deltoid = triangle  Relative Size: (eg) minimus, maximus, longus  Direction of Fascicles: (eg) oblique, rectus  Location of Attachment: (eg) brachioradialis  Number of Origins: (eg) biceps, quadriceps  Action: (eg) flexor, adductor, extensor Naming of Skeletal Muscle Principal of Muscle Naming Principal of Muscle Naming Muscular system … Classification of Skeletal muscles They are classified based on the skeletal position on which they are attached – Axial muscles – Appendicular muscles Axial muscles – Muscles of the head – Muscles of the neck – Muscles of the trunk  Muscles of the vertebral column, thorax, abdomen, and pelvic and perineum Appendicular muscles – Muscles of the pectoral girdle and upper limb – Muscles of the pelvic girdle and lower limb Classification of Skeletal muscles … Axial muscles Axial muscles refer to the muscles attached to the axial skeleton – More than half of all skeletal muscles are axial muscles Axial muscles fall into several groups: Muscles of the head  Craniofacial muscles (Muscles of the Scalp and Facial expression)  Muscles that move the eyeball  Muscles of the mastication (chewing)  Muscles that move the tongue Muscles of the neck Muscles of the trunk  Lateral cervical muscles  Muscles of the vertebral column  Anterior cervical muscles /Back  Suprahyoid muscles  Muscles of the thorax /Respiration  Infrahyoid muscles  Muscles of the abdomen  Poterior cervical muscles  Muscles of the pelvic or pelvic  Included with back muscles floor and perineum Axial Muscles … Muscles of the Head Muscles of Facial Expression The muscles of facial expression are responsible for the variety and subtlety of human facial expression Arranged in groups around the orbit, nose, mouth and auricles Origin They originate on skull bones or on fascia Insersion They attach to the skin of the face so that when they move the expression of the face changes Axial Muscles … Muscles of the Head Muscles of the Scalp  Occipitofrontalis The occipitofrontalis is a helmet like strap of muscle covering the scalp It is divided into – The frontalis of the forehead and – The occipitalis at the rear of the head – They are connected to each other by a broad aponeurosis, the epicranial/galea aponeurotica The occipitofrontalis moves the scalp, forehead skin, and eyebrows Axial Muscles … Muscles of the Head Facial muscles around the eye Selected Location Action muscles Extend fro nasal Depresses medial eyebrow; bridge to the Procuress wrinkles skin over the nose medial part of the (conveying dislike, horror ) eye brows Muscle over the Compress and dilate anterior Nasalis nose nasal opening Facial muscles around the eye Selected Location Action muscles Circular muscle Closes the Orbicularis Oculi surrounding the eyes eyes Levator Palpebrae Thin muscle within Opens the Superioris the eyelid eyes Axial Muscles … Muscles of the Head Facial muscles around the mouth Selected muscles Location Action From the cheek bone to the corner of Pulls the corners of the mouth Zygomaticus the mouth upwards and outwards Infraorbital margin(E) anterolateral Labial mm (Elevator sup. Elevates (upper) & depresses body of mandible(D) to upper(E) & & Depressor inf.) (lower) lip lower(D) lips Circular, surrounding the mouth and Orbicularis Oris Closes the mouth lips Buccinator (cheek m) From maxilla and mandible to upper Compress the cheek against the lip, angle, lower lip gum Anguli Oris At the side of the chin to the corner of Pulls the mouth corners up & Levator ,Depressor the mouth down Mentalis From mandible to skin of chin Elevates and protrudes lower lip Platysma Above & below clavicle to the base of Depresses mandible mouth Facial muscles around the mouth Muscles of Facial Expression – anterior view Muscles of Facial Expression – lateral view Axial Muscles … Muscles of the Head Muscles moving the eyeball Known as extrinsic eye muscles (six pairs) – These muscles are fast and precisely controlled Originate on skull bones and attach onto the sclera Movements include pulling toward the muscle origin, and rotation of the eyeball Muscles of the Head: Moving the Eyeball Muscles of the Head: Muscles of Mastication The muscles of mastication are strong muscles which open & close the mouth for chewing They move the jaw (mandible) forwards, backwards and from side to side at the TMJ (temporomandibular joint) Muscles of Location Action Mastication A large triangular muscle on the Temporalis Closes the jaw. side of the head. Rectangular muscle from the Masseter Closes the jaw. cheek to the outside of the jaw. Two muscles deep inside the jaw; Open and closes the jaw Medial and Lateral from the pterygoid plate to the Moves the jaw from side to side and Pterygoids mandible. forwards and backwards. Muscles of the Head: Moving the Tongue Movement of the tongue is vital during speech, mastication (chewing), deglutition (swallowing) Extrinsic tongue muscles move the tongue, while intrinsic tongue muscles change the shape of the tongue Muscles of the Head: Moving the Tongue Genioglossus Muscles of the neck Lateral cervical muscles Muscles of Location Action the Neck Both muscles together flex Long thick the neck Sternocleido muscle at the An individual muscle will mastoid side of the draw the head to that neck. shoulder. posterior scalenus lateral flexion and rotation border of the anterior of neck SCM scalenus Lateral lateral flexion of neck medius cervical region scalenus Lateral lateral flexion of neck posterior cervical region.  Anterior cervical muscles Two groups of muscles stabilize the hyoid bone, and allow movements of the tongue and larynx Suprahyoid muscles - muscles superior to the hyoid – Stylohyoid, digastric, mylohyoid, and geniohyoid Infrahyoid muscles - muscles inferior to the hyoid – The omohyoid, sternohyoid, thyrohyoid, and sternothyroid Muscles Location Action Found above Raises the hyoid Suprahyoid the hyoid bone during muscles bone swallowing Pulls the hyoid Found below Infrahyoid down after it the hyoid muscles has been raised bone in swallowing  Muscles of the Back Most body weight lies anterior to the vertebral column, especially in obese people – Consequently, many strong muscles are attached to the spinous and transverse processes necessary to support & move the vertebral column There are two major groups of muscles in the back – Extrinsic Muscles of the Back – Intrinsic Muscles of the Back The extrinsic back muscles control limb movements The intrinsic (deep) back muscles include muscles that specifically act on the vertebral column, producing its movements and maintaining posture Deep Muscles of the Back The intrinsic or deep muscles of the back are three layers 1. Superficial (Splenius) group Cranial portion - splenius capitis Cervical portion- splenius cervicis 2. Intermediate (Erector Spinae) - 3 groups Iliocostalis (lateral column) Longissimus (intermediate) Spinalis (medial column) 3. Deep (Transversospinal) group Semispinalis (capitis, thoracis, & cervicis) Multifidus (best developed in the lumbar region) Rotatores (developed in thoracic region) Muscles of the thorax/Respiration 1. External intercostals Are the most superficial Originate from inf. border of the ribs above to the sup. border of the ribs below  Obliquely from posterior to anterior 2. Internal intercostals Are b/n the external & innermost intercostals Originate from the lat. edge of costal grooves of 3. Innermost intercostal the ribs above to the sup. Deep to the internal along the medial edge of border of the ribs below the costal groove (may pass one or more spaces) (deep to the externals)  Obliquely from 4. Diaphragm parasternal regions to the A muscular dome between the abdominal and angle of ribs posteriorly thoracic cavities  EICM IICM Muscles of the thorax/Respiration … Diaphragm The diaphragm separates the thoracic and abdominal cavities – The outer muscular region surrounds a central tendon – Contraction and relaxation alter pressures in both the thoracic and abdominal cavities – Three major openings allow passage of the aorta, inferior vena cava, and esophagus Muscles of the Abdomen The anterior and lateral walls of the abdomen are reinforced by four pairs of sheet like muscles Actions of these muscles – Support and protect the viscera – Compress the abdomen in respiration, urination, defecation, vomiting, and childbirth – Flex (anteriorly & laterally) and rotate the vertebra – Stabilize the vertebral column during heavy lifting Muscles of anterolateral abdominal wall 5 muscles: 3 flat and 2 vertical Flat muscles – External oblique – Internal oblique – Transverse abdominal Vertical muscles – Rectus abdominis – Pyramidalis 41 3/14/2023 Zerihun A. 42 Muscles of the Anterior Abdominal Wall Pelvis floor muscles The floor of the pelvic cavity is formed by 3 layers of muscles & fasciae that span the pelvic outlet – They support the pelvic viscera and resist forces created by the viscera and abdominal muscles It is penetrated by the anal canal, urethra & vagina – They open into a diamond shaped region b/n the thighs called the perineum The pelvic floor is divided into 3 layers or compartments(from deep to superficial) 1. Pelvic diaphragm – deepest 2. Urogenital diaphragm – middle 3. Superficial perineal space - just deep to the skin contains 3 muscles Pelvis floor muscles … Pelvic Diaphragm The deepest compartment, called the pelvic diaphragm, is similar in both sexes It consists of two pairs of muscles - the levator ani and coccygeus Muscle Description Action Supports pelvic viscera Pubococcygeus - arises Resists intra-abdominal from the pubis Levator Ani pressure Iliococcygeus - arises Forms anal and vaginal from the obturator fascia sphincters Supports pelvic viscera Arises from ischial spine Coccygeus Resists increased intra- and inserts into the coccyx abdominal pressure Pelvis floor muscles … The other two layers lie in the perineum The perineum is a diamond shaped area inferior to the pelvic diaphragm – It has notable differences in males and females Urogenital diaphragm The middle compartment composed of 3 muscles External urethral sphincter External anal sphincter Deep transverse perineus Pelvis floor muscles … Superficial compartments The superficial perineal space lies just deep to the skin, contains 3 muscles 1. Ischiocavernosus It converge like a V from the ischial tuberosities toward the penis or clitoris and assist in erection 2. Bulbospongiosus (bulbocavernosus) In males, it forms a sheath around the base (bulb) of the penis – it expels semen during ejaculation In females, it encloses the vagina like a pair of parentheses and tightens on the penis during intercourse Voluntary contractions of this muscle in both sexes also help void the last few 3. Superfi.transverse perineus milliliters of urine It extends from the ischial tuberosities to a strong central tendon of the perineum Appendicular muscles Muscles of the upper limb  Muscles Acting on the Scapula  Muscles Acting on the Humerus  Muscles Acting on the Forearm  Muscles Acting on theWrist and Hand Muscles of the lower limb  Muscles Acting on the Hip and Femur  Muscles Acting on the Knee  Muscles Acting on the Foot Appendicular Muscles Muscles in this broad group stabilize the pectoral and pelvic girdles, and/or move the upper and lower limbs About 40% of all muscles are appendicular muscles Appendicular muscles classified into two major groups: – Muscles of the pectoral girdle and upper limb – Muscles of the pelvic girdle and lower limb In general, muscles in the pectoral girdle and upper limb have a greater range of motion Muscles that Move the Pectoral Girdle Several muscles stabilize the scapula during movements of the humerus Movements of the scapula increase the range of motion at the shoulder Anterior muscles – Pectoralis minor – Subclavius – Serratus anterior Posterior muscles (1) The superficial extrinsic muscles - Trapezius and (2) The deep extrinsic muscles - Levator scapulae, rhomboids major and minor Muscles that move the pectoral girdle … Posterior muscles Muscles that Move the Humerus Muscles with origins on the axial skeleton – Pectoralis major – Latissimus dorsi Muscles with origins on the scapula – Deltoid Muscle – Teres Major Muscle – Rotator cuff muscles (SITS) Supraspinatus Infraspinatus Teres Minor Muscle Subscapularis Muscles that Move the Humerus … axial skeleton origins Muscles that move the humerus … Scapular origins Deltoid Muscle Muscles that move the humerus … Scapular origins Teres Major Muscle Muscles that move the humerus … Scapular origins Rotator cuff muscles (SITS) They are 4 scapulohumeral muscles (referred to as SITS) – Supraspinatus – infraspinatus – teres minor – subscapularis They are named rotator cuff because they form a cuff around the glenohumeral joint Anterior view  Muscles that Move the Radius and Ulna Forearm flexors – Biceps brachii – Brachialis – Coracobrachialis Forearm extensors – Triceps brachi – Anconeus Muscles for Pronation and Supination Wrist movements contribute to our great flexibility in our use of our hands Pronators – Pronator teres – Pronator quadratus Supinators – Supinator  Muscles that Move the Wrist, Hand and Fingers The forearm is the location of many muscles, known as extrinsic hand muscles, that produce a wide variety of movements Most of the muscles originate on the humerus and insert on the carpals, metacarpals, or phalanges The anterior forearm muscles function as flexors The posterior forearm muscles function as extensors posterior muscle groups are arranged in two layers - superficial and deep  Muscles that Move the Wrist, Hand and Fingers  Anterior forearm muscles/Flexors The anterior forearm muscles are divided into 3 layers – Deep, intermediate and superficial layers A septum of deep fascia separates the deep layer from the superficial & intermediate layers The tendons of most flexor muscles pass across the anterior surface of the wrist These tendons are held in place by the flexor retinaculum – This retinaculum prevents bow stringing of the tendons when flexor muscles contract Muscles that Move the Wrist, Hand and Fingers Anterior forearm muscles/Flexors Name Description Action Arises from the common flexor tendon, becomes a Flexor Carpi Flexes the wrist. thin tendon at the wrist and inserts onto the base of Radialis Abducts the hand. the 2nd metacarpal. Arises from the common flexor tendon, becomes a Flexor Carpi thin tendon at the wrist and inserts onto the 5th Flexes the wrist. Ulnaris metacarpal and the carpal bones (pisiform and Adducts the wrist. hamate). Flexor Digitorum Arises from the common flexor tendon, divides into Flexes fingers 2-5. Superficialis 4 thin tendons each of which inserts onto a finger. Flexor Digitorum Arises from the ulna, divides into 4 thin tendons Flexes wrist. Profundus each of which inserts onto to a finger. Flexes fingers 2-5. Flexor Pollicis Arises from the ulna, becomes a thin tendon at the Flexes the thumb. Longus wrist and inserts onto to the thumb. Muscles that Move the Wrist, Hand and Fingers … Posterior forearm muscles/Extensors The muscles of the posterior of the forearm are divided into superficial (6) & deep (4) groups – 2 muscles in the suprf. group (brachioradialis & extensor carpi radialis longus) are attached to the lateral supraepicondylar ridge of the humerus – The other 4 in the suprf. group (extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, & extensor carpi ulnaris) are attached by a common extensor tendon to the lat. epicondyle of the humerus The long extensor tendons are held in place by a fibrous band, the extensor retinaculum  It prevents bow stringing of their tendons when the hand is hyperextended Muscles that Move the Wrist, Hand and Fingers … Posterior forearm muscles/Extensors Name Description Action Extensor Carpi Arises from comm. extensor tendon, becomes a flat tendon at Extends the wrist Ulnaris the wrist & inserts on the base of the 5th metacarpal Adducts the wrist Extensor Carpi Arises from the supracondylar ridge of the humerus, becomes a Extends the wrist Radialis Longus flat tendon at the wrist & inserts on the 2nd metacarpal Abducts the wrist Extensor Carpi Arises from the comm. extensor tendon, becomes a flat tendon Extends the wrist Radialis Brevis at the wrist and inserts onto the 3rd metacarpal Adducts the wrist Extensor Arises from the common extensor tendon, divides into 4 thin Extends the wrist. Digitorum tendons each of which inserts onto a finger Extends fingers 2-5 Extensor Digiti Arises from the common extensor tendon, becomes a thin Extends the little Minimi tendon at the wrist and inserts onto the little finger finger Extensor PollicisArises from the ulna it becomes a thin tendon at the wrist and Extends the thumb Longus inserts onto the first finger Extensor PollicisArises from the radius it becomes a thin tendon at the wrist and Extends the thumb Brevis inserts onto the base of the thumb. Arises from the ulna becomes a thin tendon at the wrist and Extends the index Extensor Indicis inserts onto the index finger finger Intrinsic Muscles of the hand Intrinsic hand muscles both originate and insert within the hand are innervated by branches of the ulnar and median nerves They can be divided into 4 groups: A. Thenar muscles in the thenar compartment B. Hypothenar muscles in the hypothenar compartment C. Lumbrical muscles in the central compartment D. Interosseous muscles b/n the metacarpal bones The flexibility of the hand is due to the large number of bones and joints, as well as to the many muscles controlling them Intrinsic Muscles of the Hand Muscles of the hand … Thenar muscles They produce the thenar eminence They are chiefly responsible for the movement known as the opposition of the thumb – Opposition - most important movement of the thumb  The tip of the thumb is brought in contact with the palmar surface of the 5th digit & opposed to other digits Muscles of the hand … Thenar muscles Name Description Action A triangular muscle with 2 heads; it arises from the 3rd Adductor Pollicis Adducts thumb. metacarpal and inserts onto the thumb. Abductor Pollicis A long thin muscle; it arises from the ulna and radius and Abducts thumb. Brevis inserts onto the thumb. The fleshy part of the thumb; it arises from the flexor Opponens Pollicis Opposes thumb. retinaculum and trapezium and inserts onto the thumb. A thin muscle, it arises from the flexor retinaculum and Flexor Pollicis carpal bones (trapezium, trapezoid and capitate) and Flexes thumb. Brevis inserts onto the thumb. Hypothenar muscles These muscles deal with the movement of the 5th digit They lie in the hypothenar compartment of the palm with the 5th metacarpal bone The hypothenar muscles produce the hypothenar eminence, or ball of the 5th digit They are all supplied by the deep branch of the ulnar nerve Muscles of the hand … Hypothenar muscles cont.. Hypothenar (little Muscles of the little finger. Little finger movements. finger) Group A small muscle arising from the flexor Abductor Digiti retinaculum and pisiform and inserting Abducts little finger. Minimi onto the little finger. A small thin muscle arising from the flexor Flexor Digiti retinaculum and hamate and inserting Flexes little finger Minimi Brevis onto the little finger. A small muscle arising from the flexor Opponens Digiti Opposes little finger to retinaculum and hamate and inserting Minimi thumb. onto the little finger.  Lumbrical muscles There are 4 slender lumbrical (L. lumbricus, earthworm) muscles- one for each digit Action – Flex & extend digits at the metacarpophalangeal & interphalangeal joints respectively Muscles of the hand … Lumbricals and Interosseous (Dorsal & Palmar) Mid palmar Muscles of the palm. Metacarpal and finger movements. Group Flex metacarpophalangeal joints of Four muscles which originate in the palm Lumbricals (1-4) fingers 2-5. from the tendons of flexor digitorum Extends interphalangeal joints of profundus and insert onto the 2nd-5th fingers fingers 2-5. Four muscles which arise from the adjacent Abducts fingers 2-4. Dorsal sides of the 1st and 2nd, 2nd and 3rd, 3rd and 4th Flex metacarpophalangeal joints of Interosseous (1-4) and 4th and 5th metacarpal bones. They insert fingers 2-4. onto the 2nd-4th fingers respectively Extends interphalangeal joint. Three muscles which originate from the 2nd, Adducts fingers 2, 4 and 5. Palmar 4th and 5th metacarpal bones and insert onto Flex metacarpophalangeal joints. interosseous (1-3) the 2nd, 4th and 5th fingers respectively Extends interphalangeal joint.  Interosseous muscles There are 7 interossei muscles located b/n the metacarpal bones They are arranged in 2 layers: 3 palmar and 4 dorsal muscles Action – The dorsal interossei abduct the digits (DAB: Dorsal ABduct) Interosseous muscles… Palmar interossei 1 to 3 Action – The palmar interossei adduct the digits (PAD: Palmar ADduct) – They also assist the actions of the lumbrical muscles. – These are important movements in typing, writing, and playing the piano Appendicular Muscles … Muscles of the lower limb Muscles Acting on the Hip and Femur Muscles Acting on the Knee Muscles Acting on the Foot Lower limb muscles are larger and stronger - with posture and stability being more important than range of motion are specialized for locomotion and balance. They include the muscles that move the thigh and leg and those that control movement of the foot Many of these muscles cross two joints and act on both Muscles Acting on the Hip and Femur Muscles crossing the hip and knee can be grouped into – Hip flexors (4) – Anterior compartment (4 knee extensors) – Gluteal muscles (3) – Lateral rotators (5) – Medial compartment (6 adductors) – Posterior compartment (3 knee flexors) Thigh muscles - Anterior compartment Hip flexors  Psoas Muscles Long, thick, powerful muscle passes from the abdomen to the thigh deep to the inguinal ligament Arise from the sides of lumbar vertebrae to the lesser trochanter of femur  Iliacus  Other hip flexors  Sartorius Large triangular or fan-  Rectus femori shaped muscle lies along the lateral side of the psoas major in the pelvis Arise from the iliac fossa Action of Iliopsoas to the lesser trochanter Strongest flexor of the thigh at the hip joint Anterior Thigh muscles … Hip flexors  Sartorius It is the longest muscle in the body, lies superficially in the anterior compartment it arises from the anterior superior iliac spine, travels obliquely in front of the thigh & attaches to the tibia It descends inferiorly as far as the side of the knee and acts across two joints It flexes the hip and participates in flexion of the knee joint It also weakly abducts the thigh and laterally rotates it  The actions of both sartorius muscles bring the lower limbs into the cross- legged sitting position Thigh muscles … Anterior compartment  Quadriceps Femoris It is the great extensor muscle of the leg, It covers almost all of the anterior surface and sides of the femur It is divided into 4 parts: – Rectus femoris – Vastus lateralis – Vastus medialis – Vastus intermedius Thigh muscles... Anterior compartment Quadriceps Femoris The rectus femoris has deep fibres that run straight down the thigh The vastus intermedius is located between vastus lateralis and medialis – They arise from the femur and attach via a conjoined tendon to the patella The tendons of all of this large muscle unite to form the quadriceps tendon This broad tendon attaches to and surrounds the patella and then continues as the patellar ligament (ligamentum patellae), which is attached to the tuberosity of the tibia Thigh muscles … Anterior compartment Quadriceps Muscle All parts of the quadriceps, acting through the patella ligament, extend the leg at the knee joint – Through the actions of the rectus femoris, they flex the hip joint All four parts of this muscle is used during climbing, running, jumping, and rising from a chair Thigh muscles … Gluteal muscles This is the group of muscles that form the buttocks They include gluteal muscles consist of three glutei mm. – Gluteus maximus – G. Medius – G. Minimus Gluteal muscles … G. maximus G. medius G. minimus Thigh Muscles … Medial compartment/Adductors These muscles form the inside (medial side) of the thigh They include – Adductor magnus – Adductor longus – Adductor brevis – Pectineus – Gracilis – Obturator externus Medial compartment/Adductors Thigh Muscles … Posterior thigh muscles - Hamstring muscles Large bulk of 3 muscles on the back of the thigh They arise from the ischial tuberosity Insert into the tibia or fibula – Biceps Femoris (2 heads; long & short) – Semitendinosus (has a long thin tendon). – Semimembranosus (it is membranous at its origin) Extend hip and flex knee joint The semimembranosus and semitendinosus also rotate the leg medially, being attached to the medial head of the tibia Muscles of the leg – Anterior Compartment Just like the forearm muscles move the wrist and fingers, most of the leg muscles are concerned with moving the ankle and toes The anterior compartment, or dorsiflexor (extensor), is located anterior to the interosseous membrane – between the lateral surface of the tibial shaft and the medial surface of the fibular shaft As they approach the ankle they become tendinous before passing into the foot two band-like thickenings of the fascia form retinacula (sup & inf) that bind their tendons before and after they cross the ankle joint – prevent them from bowstringing anteriorly during dorsiflexion of the joint Muscles of the leg – Anterior Compartment Muscles of the anterior compartment are – Tibialis anterior (inversion) – Extensor digitorum longus – Extensor hallucis longus – Peroneus tertius (eversion) These muscles pass and insert anterior to the transversely oriented axis of the ankle (talocrural) joint – Therefore, are dorsiflexors of the ankle joint, elevating the forefoot and depressing the heel Leg Muscles – Lateral/peroneal compartment The lateral compartment or Longus - from upper lateral evertor compartment, is the surface of the fibula to the base of the 5th toe smallest (narrowest) of the leg compartments Brevis – from lower lateral surface of This group is plantar flexor and fibula to the base of evertor of the foot, fibular 1st metatarsal abduction and maintain transverse arch – Peroneus longus – Peroneus brevis The compartment ends inferiorly at the superior fibular retinaculum, which spans between the distal tip of the fibula and the calcaneus Leg Muscles Muscles that –Move Posterior compartment the Foot and Toes Muscles of the posterior compartment are primarily plantar flexors and flex the toes Superficial – Gastrocnemius – Soleus – Plantaris Deep – Tibialis posterior – Flexor digitorum longus – Flexor hallucis longus – Popliteus Copyright 2010, John Wiley & Sons, Inc. Leg Muscles – Posterior compartment The dorsum of the foot There are two closely connected muscles on the dorsum of the foot Extensor digitorum brevis Extensor hallucis brevis ( medial slip of the extensor digitorum brevis ) These broad thin muscles form a fleshy mass on the lateral part of the dorsum of the foot, anterior to the lateral malleolus, which can be seen in most feet and felt in all of them Actions: the extensor digitorum brevis extends the second to fourth digits at the metatarsophalangeal joints, and the extensor hallucis brevis extends the first digit or great toe at the metatarsophalangeal joint. These muscles help the long extensor muscles extend the toes  The sole of the foot Plantar aponeurosis- thickened deep fascia, tout when toes are dorsiflexed (arch of foot increases) – Attachments- posterior- tubercle of calcaneus; anteriorly divide in to five slips and again each divide in to two and become continuous with flexor sheaths of the digits – Function – protection, keep the longitudinal arch There are four muscular layers in the sole of the foot 1. First layer – three muscles 2. Second layer – two muscles and two tendons 3. Third layer - Three muscles 4. Fourth layer - Two muscles and two tendons These muscles serve major roles in support of the body and locomotion Flexion of the toes and a role in the longitudinal arch of the foot are specific roles of these muscles First layer Two abductors and one flexor in b/n the abductors Origin – calcaneus 1. Abductor hallucis inserts in to the proximal phalanx of hallux. 2. Abductor digiti minimi inserts in the proximal phalanx of toe 5 3. Flexor digitorum brevis inserts in to the middle phalanges of 2- 5 by splitting in to 2 bands These muscles act as a functional group that acts as an elastic spring for supporting the arches of the foot and maintaining the concavity of the foot.  Second layer Muscles of the second layer flex, adduct, and abduct the toes Muscles include – Flexor digitorum accessorius (quadratus plantae); has to heads (medial and lateral); – Four lumbricales- origin form medial side of the long tendons of flexor muscles arranged from 1st to 4th from medial to lateral. The lateral 3 are innervated by deep division of lateral plantar and the 1st by medial p.  Tendons – flexor hallucis longus and flexor digotrum longus Third layer This layer has 3 short muscles of the great and small digits, which lie in the anterior half of the sole of the foot. Two act on the great digit and one on the small digit. Includes: – flexor hallucis brevis, – adductor hallucis and – flexor digiti minimi. A sesamoid bone adheres to each of the tendons of the two heads of flexor hallucis brevis. Fourth layer Tendons of tibialis posterior and peroneus L Muscles 1. Plantar interossei – three Action - adduct 3rd, 4th, and 5th toes toward 2nd toe 2. Dorsal interossei- 4 , each arise from adjacent metatarsal (bipennate arrangement) Action- adduction of 2nd , 3rd &4th digits away from line of 2nd toe, flex metacarpophalangeal J. and extend interphalangeal J 98