Muscle and Skin, 2025 PDF

Muscular System Skin & fascia Dr. Anfal M. Elawady Hello!  Intended Learning Outcomess: (ILOs) Differentiate between skeletal, smooth and cardiac muscles according to site, structure , contraction and innervation. Classify the skeletal muscles according to: - Direction of fibers - S...

Muscular System Skin & fascia Dr. Anfal M. Elawady Hello!  Intended Learning Outcomess: (ILOs) Differentiate between skeletal, smooth and cardiac muscles according to site, structure , contraction and innervation. Classify the skeletal muscles according to: - Direction of fibers - Shapes - Action of muscles. Describe the layers of the skin. Identify the appendages of the skin. Identify the sites of the skin having no hair, no sweat glands Describe the three types of fascia superficial, deep and subserous. Origin of the word muscle Diminutive of Greek word MUS → means mouse - Body & head of mouse → Belly - Tail → tendon  Muscles are classified into 3 types: Smooth, Cardiac, and Skeletal. Smooth Cardiac Skeletal Site Wall of internal viscera In myocardium Attached to the skeleton, and blood vessels hence its name Contraction Involuntary Involuntary Voluntary Striation Absent Present Present Nerve supply Autonomic Autonomic Somatic Muscle cell Spindle-shaped with Branch and fuse together; Multinucleated single nucleus with single nucleus (one syncytium) Fatigability Not easy Not fatigability Easily Muscles are classified into 3 types: Smooth, Cardiac, and Skeletal.  Ways of Muscle Attachments 1. To bone directly → intercostal muscles 2. To bone indirectly Through tendon that merges into Bone → biceps brachii to scapula 3. To collagen fibers (dermis) → muscles for facial expression 4. To a broad sheetlike tendon (APONEUROSIS) → certain abdominal muscles Function of the skeletal muscle 1. Movement 2. Maintain posture & stabilize joints 3. Produce energy 4. Keeps the blood and lymph moving inside blood vessels 5. Protects internal organs  Connective tissue covering muscle 1. Epi-mys-ium → surrounds entire muscle 2. Peri-mys-ium → surrounds bundles of muscle fibers 3. Endo-mys-ium → surrounds individual muscle fibers  Anatomy of Skeletal Muscles Origin →stationary end of a muscle when contracts Flesh (Belly) → thicker, middle region of muscle Insertion → mobile end of muscle Classification of skeletal muscles The skeletal muscles are classified according to: A- Fiber’s direction B- Action of muscles C- Number of fleshy head D- Number of joints they act upon Muscle types based on Fiber’s direction 1. Muscles with fibers arranged parallel with the line of pull Q: - Quadrilateral → thyrohyoid. - Strap-like → sartorius. - Strap-like with tendinous intersections → rectus abdominis. - Fusiform → lumbrical, biceps brachii, brachioradialis 2- Muscles with pennate fibers (pennate = feather like) arranged obliquely to the line of pull: Q: a. Uni-pennate muscles: - The tendon lies along one side of a muscle - The fibers pass obliquely - (like half a feather). Flexor pollicis longus. Palmar interossei muscle b. Bi-pennate muscle: - The tendon lies at the center of the muscle - The fibers pass to it form two sides. - (Like a feather) c. Multipennate muscles: - Formed of a group of bipennate muscles lying alongside one another - Converge on the tendon of the muscle  d. Circumpennate: - The tendon lies centrally in the axis of the muscle - The fibers pass to it from all sides  Muscles with fibers arranged obliquely to the line of pull but not pennate: ▪ Triangular (convergent) → temporalis, pectoralis major. ▪ Spiral (wrapping) → supinator, latissmus dorsi ▪ Cruciate (X-shaped) →masseter. ▪ Circular → Orbicularis oculi, orbicularis oris Which of the following muscles is bipennate? A- Deltoid C- Sartorius B- Palmar interossei D- Rectus femoris Which of the following muscles is convergent? A- Temporalis C- Latissmus dorsi B- Pectoralis minor D- Rectus abdominus Deltoid muscle fibers are classified to be which of the following muscles? A- Unipennate C- Multipennate B- Bipennate D- Circumpennate  Muscle types based on Action of muscles 1- Prime mover (Agonist): 2- Antagonist: - Muscles responsible for initiation of - Muscles, which opposes the action a particular movement. of prime movers - In flexing the elbow, - Preventing excessive movement the agonist: and injury. Biceps brachii, - In flexing the elbow, Triceps brachii Brachialis. antagonize the action of brachialis. 3- Synergists (accessory): 4- Fixator (stabilizers): - Aids the prime mover (work together) - Prevents uncontrolled movements. - May stabilize the nearby joint. - Fix proximal joints during move of distal - Or modify the direction of movement. joints - In flexing the elbow, Brachioradialis - In flexing the elbow, rhomboids hold works with brachialis, biceps brachii. the scapula in place, Deltoid and Trapezius hold shoulder in place..  Muscle types based on Number of fleshy head ▪ Biceps muscle: with 2 heads ▪ Triceps muscle: with 3 heads. ▪ Quadriceps muscle: with 4 heads. ▪ Digastric and Omohyoid: have 2 bellies attached together by an intermediate tendon Muscle types based on Number of joints they act upon Uni-articular: - Act on only one joint e.g., brachialis muscle. Bi-articular: - Act on two joints e.g., sartorius. Multi-articular: - Act on more than two joints e.g., flexors and extensors of the digits.  Skeletal Muscle Innervation ❑ Cranial nerves - Arising from brain - Exit through → skull foramina - Numbered I to XII ❑ Spinal nerves - Arising from spinal cord - Ex it the vertebral column through → intervertebral foramina Skin & fascia  THE SKIN - The largest organ in the body - The skin consists of a) Outer epithelial layer called epidermis. (Has melanocytes melanin → skin color) b) Inner connective tissue layer called dermis. (Give skin → strength, support, flexibility) c) Inner most layer called hypodermis.  Skin appendages Q: ❑ The nails: Are keratinized plates on the dorsal surface of the tips of fingers and toes. Root: → the proximal edge of the nail. Nail folds: →the folds of the skin which surround & overlap the nail except at its lower edge. Nail bed: →the surface of the skin covered by the nail. ❑ Hairs ❑ Sebaceous glands - Shaft → Secrete oily materials. - Follicle → Open into hair follicle - Erector pilli muscle  Skin appendages Q: ❑ Sweat glands: 2 types ❑ Eccrine glands - More numerous - Found all over the body - Ducts open at the surface - Secretion → clear (water & salt) ❑ Apocrine glands - Fewer - At arm pit & genital areas - Ducts open into hair follicle - Secretion → (contain fatty acids & proteins) Sites Of Skin Having No Hairs: 1. Lips 7. Sides of the toes 2. Palms of the hands 8. Glans penis 3. Sides of the hands 9. Clitoris 4. Sides of fingers 10. Labia minora Q: 5. Soles of the feet 11. Internal surface of the labia 6. Sides of the feet majora Sites Of Skin Having No Sweat Glands: 1. Red margin of the lips 3. Glans penis 2. Nail beds 4. Clitoris  The Fascia - Fascia is the tissue that lies immediately deep to the skin. - There are two types of fasciae: 1. Superficial fascia. 2. Deep fascia. 3. Subserous Last 2 are called extraperitoneal fascia. Deep fascia: ❑ Tough & made of dense fibrous connective tissue Includes: - Thickness in palm & sole → palmar & plantar aponeurosis - Localized thickness around wrist & ankle → retinacula - Tough membrane separates group of muscles → intermuscular septum Sites of superficial fascia having numerous bundles of collagen fibers (dense C.T.): 1. Scalp 3. Palms of the hands 2. Back of the neck 4. Soles of the feet Q: Sites of superficial fascia devoid of adipose tissue: 1. Eyelids 4. Scrotum 2. Auricle of the ear 5. Clitoris 3. Penis 6. Nipple and areola of the breast Thank you