Anatomy 161 Human Muscular System 2024 PDF

Torso = trunk = thorax, abdomen and pelvis and Introduction to ANA 161...

Torso = trunk = thorax, abdomen and pelvis and Introduction to ANA 161 perineum Body Major contents Anatomy region module Head Skull, brain, eyes, nose ,oral cavity Neck Skeletal muscles, salivary glands, blood vessels, major ANA 162 nerves Thorax Heart, lungs, great blood vessels and major nerves, oesophagus, trachea, ribs Abdomen Stomach, liver, intestines, spleen, kidneys ANA 161 Pelvis Reproductive organs, urinary bladder, rectum Upper Skeletal muscles, blood vessels and nerves, bones limbs ANA 152 Lower Skeletal muscles, blood vessels and nerves, bones limbs G. Venter (2024) (www.commons.wikimedia.org) Unit 1: Muscular system ANA 161 - 2024 G. Venter (2024) Unit 1: Muscular system Sub-units: 1. Overview of muscular system 2. Fascia 3. Muscles of respiration 4. Abdominal wall muscles 5. Back muscles 6. Pelvic floor muscles 7. Perineum muscles G. Venter (2024) Overview of the muscular system G. Venter (2024) Overview of the muscular system What is the muscular system? All the muscles in the human body Properties of muscular tissue: Electrical excitability Contractility Extensibility Elasticity G. Venter (2024) (https://synergystix.com/wait-muscles-are-organs/) Overview of the muscular system Functions of the muscular system: Movement Glycemic control Stability Muscular system Control of Heat production body openings G. Venter (2024) Overview of the muscular system What is muscular tissue? Specialised muscle cells Able to contract when stimulated 3 types of muscle tissue Smooth muscle Cardiac muscle Skeletal muscle Each one of these types has a different: Development Function Location Nerve supply G. Venter (2024) (www.commons.wikimedia.org)  Skeletal muscle Smooth muscle Cardiac muscle Long threadlike cells (muscle Fusiform shape and relative short Striated appearance fibres) (myocytes) Cells are shortened Most muscles are attached to bones Only 1 nucleus (cardiomyocytes) Each cell has multiple nuclei Involuntary Only 1 nucleus Striated appearance Layers in walls of digestive, Muscles are connected by Voluntary respiratory and urinary tracts intercalated discs Involuntary Major groups of muscles Named examples: Found in the heart only Thoracic wall muscles Trachealis muscle (trachea) (myocardium) Abdominal wall muscles Detrusor muscle (bladder) Back muscles Internal anal sphincter Pelvic floor muscles Internal urethral sphincter External urethral sphincter Erector pili muscle (skin) Perineum muscles Myometrium (uterus) Other examples: Walls of digestive tract Walls of bronchi (respiratory tract) Walls of urinary tract (ureters and urethra) Walls of blood vessels (arteries and veins) Walls of uterine tubes (females) or G. Venter (2024) walls of vas deferens (males) * Oesophagus, rectum and urethra contain both skeletal muscle AND smooth muscle it its walls (depending on the location)  Skeletal muscle Smooth muscle Cardiac muscle G. Venter (2024) (www.commons.wikimedia.org) Fascia G. Venter (2024) Fascia What is fascia? Sheet of connective tissue Separates groups of muscles from each other Divides groups of muscles into compartments “glue” of the human body 2 main types: Superficial fascia Deep fascia G. Venter (2024) (https://my.clevelandclinic.org/health/body/23251-fascia) Fascia Superficial fascia Deep fascia Loose connective tissue Dense connective tissue Contains fat Contains no fat Forms part of subcutaneous Examples of deep fascia tissue in hypodermis Thoracolumbar fascia Clavipectoral fascia G. Venter (2024) Groups of skeletal muscles G. Venter (2024) Groups of skeletal muscles 1. Muscles of respiration (thoracic wall) 2. Abdominal wall muscles 3. Back muscles 4. Pelvic floor muscles 5. Perineum muscles G. Venter (2024) (https://www.istockphoto.com/photos/human-muscle-anatomy) Skeletal muscles - Muscles of thoracic wall G. Venter (2024) Muscles of respiration (of thoracic wall) 2 types of muscles: Principal (main) muscles Accessory muscles Principal muscles: Diaphragm Intercostal muscles Accessory muscles: Erector spinae (back muscles) Pectoralis muscles (pectoralis major and pectoralis minor) Serratus muscles Sternocleidomastoid Scalene muscles G. Venter (2024)  Nerve supply is important (and self- Muscles of thoracic wall study) Types of muscles: Axio-appendicular muscles True wall muscles Axio-appendicular muscles True wall muscles Pectoralis major Serratus posterior (superior and inferior) Pectoralis minor Levatores costarum Serratus anterior Intercostal muscles Subclavius muscle External intercostal Internal intercostal Innermost intercostal Subcostal muscles Transversus thoracis muscle G. Venter (2024)  Nerve supply is important (and self- Muscles of thoracic wall study) Axio-appendicular muscles Pectoralis major Pectoralis minor Serratus anterior (inferior part) Subclavius muscle Serratus anterior G. Venter (2024)  Axio-appendicular muscles Pectoralis minor Pectoralis major Serratus anterior G. Venter (2024) Muscles of thoracic wall True wall muscles: Serratus posterior (superior and inferior) Levatores costarum Intercostal muscles External intercostal Internal intercostal Innermost intercostal Subcostal muscles Transversus thoracis muscle Direction of muscles fibres: External intercostal muscles: downward and medially (2024) G. Venter Internal intercostal muscles: downward and laterally Innermost intercostal muscles: downward and laterally Muscles of thoracic wall Intercostal space Space between adjacent ribs Filled by 3 intercostal muscles: External intercostal muscle Internal intercostal muscle Innermost intercostal muscle Contains intercostal neurovascular bundle between innermost and internal intercostal muscles Contains the intercostal neurovascular bundle Intercostal vein Intercostal artery Order of neurovascular bundle Intercostal nerve from superior to inferior: VAN (vein, artery, nerve) G. Venter (2024) G. Venter (2024) Muscles of thoracic wall Clavipectoral fascia Layer of deep fascia Located between the 2 pectoral muscles Protects underlying axillary vessels and nerves Encloses 2 muscles: Subclavius muscle Pectoralis minor muscle G. Venter (2024) Skeletal muscles – Abdominal wall muscles G. Venter (2024) Abdominal wall muscles 2 groups of abdominal wall muscles Anterior wall muscles Posterior wall muscles Anterior wall muscles Posterior wall muscles External oblique Diaphragm Internal oblique Psoas major Transverse abdominis Psoas minor Rectus abdominis Quadratus lumborum Pyramidalis Iliacus Cremaster G. Venter (2024) Abdominal wall muscles Strong muscles to support organs Assist in expiration by pushing viscera upward Assist in increasing intra-abdominal pressure 2 muscles attach via a common tendon: “conjoint tendon” Internal oblique muscle Transverse abdominis muscle Rectus abdominis muscle has a special sheath Also contains inguinal region (groin) Region contains opening: inguinal canal Region contains anatomical triangle: inguinal triangle G. Venter (2024) Abdominal wall muscles Rectus sheath Special thick sheath Covers rectus abdominis muscle Formed by the aponeurosis of the following muscles: External oblique muscle Internal oblique muscle Transverse abdominis muscle Arcuate line is line used to indicate a change in the rectus sheath pattern Below arcuate line: rectus sheath only anterior to rectus abdominis muscle Above arcuate line: rectus sheath encloses the rectus abdominis muscle completely G. Venter (2024)  Anterior abdominal wall muscles G. Venter (2024) (Gray’s anatomy for students, 5th edition) Abdominal wall muscles Inguinal canal Oblique passage through lower part of anterior abdominal wall 4 cm long in adults Lies above inguinal ligament Female contents: round ligament of uterus AND ilio-inguinal nerve Male contents: spermatic cord Spermatic cord details will be discussed later in reproductive systems G. Venter (2024)  Inguinal canal contents - males Inguinal canal contents - females G. Venter (2024) Abdominal wall muscles Inguinal triangle Medial: lateral border of rectus sheath Lateral: inferior epigastric artery Inferior: inguinal ligament Site for direct inguinal hernia Inguinal ligament Connects anterior superior iliac spine with pubic tubercle Formed by lower border external oblique aponeurosis (folded back on itself) Lower border attached to deep fascia of thigh (fascia lata) G. Venter (2024)  (https://quizlet.com/ca/507139527/abdominal-wall-flash-cards/) Abdominal wall muscles Anterior abdominal wall fascia 2 layers of superficial fascia Fatty layer: Camper’s fascia Membranous layer: Scarpa’s fascia Between skin and anterior abdominal wall muscles G. Venter (2024) Abdominal wall muscles Posterior abdominal wall muscles All these muscles are deep to the abdominal organs Covered by fascia Closely related to the posterior surfaces of the kidneys 2 muscles unite when they exit the pelvis (enter lower limb) Iliacus + psoas major = iliopsoas muscle G. Venter (2024) Abdominal wall muscles Diaphragm Muscle that separates thoracic- and abdominal cavities Main muscle of respiration Consist of 2 parts: Peripheral part (muscular) Left dome Right dome Central part (tendon) Central tendon supports the heart G. Venter (2024) (Gray’s anatomy for students, 5th edition) Abdominal wall muscles Diaphragm contains 2 arches: 2 crura: Right crus Left crus 3 Arcuate ligaments: Median arcuate ligament Medial arcuate ligament Lateral arcuate ligament G. Venter (2024)  Abdominal wall muscles The diaphragm contains 3 main openings: Aortic opening Esophageal opening Caval opening T12 vertebral level T10 vertebral level T8 vertebral level Transmits Transmits Transmits Descending aorta Esophagus Inferior vena cava Thoracic duct Anterior vagal trunk (was left vagus Terminal branches of right Azygos vein nerve) phrenic nerve Hemi-azygos vein Posterior vagal trunk (was right vagus Lymphatic vessels nerve) Esophageal branches of left gastric G. Venter (2024) vessels Lymphatic vessels from lower ⅓ of esophagus Skeletal muscles – Back muscles G. Venter (2024) Back muscles Strong muscles to support body and maintain posture 3 groups of muscles: Superficial Intermediate Deep Superficial muscles Intermediate muscles Deep muscles Trapezius Serratus posterior superior Spinotransversales muscles Latissimus dorsi Serratus posterior inferior Erector spinae muscles Levator scapulae Transversospinales muscles Rhomboid major Segmental muscles Rhomboid minor G. Venter (2024) Back muscles Superficial back muscles Superficial muscles are involved in movements of the upper limb Muscles: Trapezius Latissimus dorsi Levator scapulae Rhomboid minor Rhomboid major Nerve supply (innervation) of these muscles are important! G. Venter (2024) Back muscles Intermediate back muscles Involved in respiratory function Very thin muscles Muscles: Serratus posterior superior Serratus posterior inferior G. Venter (2024)  Actions of these muscles are important! Back muscles Deep back muscles Very well developed in humans Occupies hollow on each side of spinous processes Extend from sacrum to skull Act to maintain posture and control movements of vertebral column Muscles: Erector spinae (spinales, longissimus, iliocostalis) Spinotransversales Transversospinales Segmental muscles G. Venter (2024)  (https://insyncphysio.com/how-to-remedy-thoracolumbar-fascia-back-spine-pain/) Back muscles Thoracolumbar fascia Visible layer of deep fascia Covers deep muscles of the back Consists of 3 layers in lumbar region: Posterior layer - Covers erector spinae muscles Middle layer Anterior layer - Covers quadratus lumborum G. Venter (2024) Skeletal muscles – Pelvic floor muscles G. Venter (2024) Pelvic floor muscles Strong muscles and fascia that support the pelvic organs Muscle group is also called the pelvic diaphragm Levator ani (x2) – 1 on each side Coccygeus (x2) – 1 on each side Each levator ani muscle consists of 3 smaller muscle-components Pubococcygeus Puborectalis Iliococcygeus There are 2 other muscles also found/seen here, but not part of this group: Obturator internus G. Venter (2024) Piriformis  Pelvic floor muscles (https://www.surreyphysio.co.uk/article/pelvic-floor-rehab-guide/) G. Venter (2024) Skeletal muscles – Perineum muscles G. Venter (2024) Perineum muscles Support the anus and external genitalia Perineum-region is a diamond-shaped area Muscles form part of borders Can be divided into 2 triangles: Urogenital triangle Anal triangle 3 groups of muscles in the perineum Superficial perineal muscles Deep perineal muscles Anal triangle muscles G. Venter (2024)  Pudendal nerve supplies ALL these muscles Perineum muscles Superficial perineal muscles Located in superficial perineal pouch of urogenital triangle Same muscles in males and females 3 muscles in this group Ischiocavernosus Bulbospongiosus Superficial transverse perineal muscle Ischiocavernosus and bulbospongiosus cover external genitalia Males: parts of the penis Females: vestibular bulbs and clitoris G. Venter (2024)  Pudendal nerve supplies these muscles. Perineum muscles Deep perineal muscles Located in deep perineal pouch of urogenital triangle Same muscles in males and females 2 muscles in this group: External urethral sphincter Deep transverse perineal muscle G. Venter (2024) (https://healyourposture.com/blog/2016/9/20/sisters-of-the-pelvis)  Pudendal nerve supplies this muscle. Perineum muscles Anal triangle muscles Contains only 1 muscle External anal sphincter Circular muscle surrounds anal opening Skeletal muscle – voluntary control Consists of 3 smaller parts There is also an internal anal sphincter Smooth muscle – involuntary control Not part of this group of muscles G. Venter (2024)