[ANAT]LEC_004_THE_MUSCLES OF THE BACK, THORAX, ABDOMEN, AND PELVIS.pdf

(004) THE THE MUSCLES MUSCULAROFSYSTEM THE BACK, THORAX, ABDOMEN AND PELVIS DR. VILLANUEVA – DE GRANO | 09/30/2020...

(004) THE THE MUSCLES MUSCULAROFSYSTEM THE BACK, THORAX, ABDOMEN AND PELVIS DR. VILLANUEVA – DE GRANO | 09/30/2020 OUTLINE I. MUSCLES OF THE BACK II. SPINOTRANSVERSALES MUSCLES a. ERECTOR SPINAE MUSCLES b. TRANSVERSOSPINALES c. SEGMENTAL MUSCLES III. SUBOCCIPITAL MUSCLES IV. STRAINS VS SPASMS V. MUSCLES OF THORAX VI. MUSCLES OF ABDOMEN VII. POSTERIOR ABDOMINAL WALL VIII. PELVIS AND PERINEUM a. INJURY TO PELVIC FLOOR I. MUSCLES OF THE BACK b. Deep (intrinsic) group of back muscles Muscles of the back are organized into superficial, The deep or intrinsic muscles of the back extend from intermediate, and deep groups the pelvis to the skull. They include: o the extensors and rotators of the head and neck - the splenius capitis and cervicis (spinotransversales muscles), o the extensors and rotators of the vertebral column - the erector spinae and transversospinales, and o the short segmental muscles - the interspinales and intertransversarii a. SUPERFICIAL AND INTERMEDIATE GROUP c. THORACOLUMBAR FASCIA Covers the deep muscles of the back and trunk Critical to the overall organization and integrity of the region: o Superiorly: continuous with deep fascia in the neck o Thoracic region: covers the deep muscles and separates them from the muscles in the superficial and intermediate groups o Medially: attaches to the spinous processes of the thoracic vertebrae  (004) THE MUSCULAR SYSTEM DR. VILLANUEVA – DE GRANO | 09/30/2020 o Laterally: angles of the ribs c. SEGMENTAL MUSCLES Two groups innervated by posterior rami of spinal II. SPINOTRANSVERSALES MUSCLES nerves. First group: levatores costarum muscles Together, they draw the head backward, extending the Second group ( true segmental muscles of the neck. Individually, each muscle rotates the head to one back): interspinales (between adjacent spinous side-the same side as the contracting muscle. processes) and the intertransversarii (between adjacent transverse processes) Vertebral column stabilizer (allows more effective a. ERECTOR SPINAE MUSCLES Largest group of intrinsic back muscles III. SUB OCCIPITAL MUSCLES Lie posterolateral to the vertebral column between the spinous processes medially and the angles of the ribs laterally. Group of deep muscles that move the head Connect vertebra CI (the atlas) to vertebra CII (the axis) and connect both vertebrae to the base of the skull Form the boundaries of thesuboccipital triangle: o Medial: rectus capitis posteriormajor o Lateral: obliquus capitis superior o Inferior: obliquus capitis inferior b. TRANSVERSOSPINALES Found deep to the erector spinae and consist of three major subgroups - the semispinalis, multifdus, and rotatores muscles. Bilateral contraction = extension of the vertebral column Unilateral contraction= trunk turns/rotates in the opposite direction Semispinalis capitis Bilateral contraction: pulls the head posteriorly Unilateral contraction: pulls the head posteriorly and turns it, causing the chin to move superiorly and turn toward the side of the contracting muscle.  (004) THE MUSCULAR SYSTEM DR. VILLANUEVA – DE GRANO | 09/30/2020 IV. STRAINS VS SPASMS Back sprain: only ligamentous tissue is involved, without dislocation or fracture (+) excessively strong contractions related to movements of the vertebral column Back strain: common sports injury (+) overly strong muscular contraction involves some degree of stretching or microscopic tearing of muscle fibers If the weight is not properly balanced on the vertebral column, strain is exerted on the muscles Spasm: protective mechanism after an injury or in response to inflammation (+) sudden involuntary contraction of one or more muscle groups b. THORACIC WALL V. MUSCLES OF THORAX Alter the position of the ribs and sternum and so change the thoracic volume during breathing Reinforce the thoracic wall Axio-appendicular muscles extend from the thoracic cage (axial skeleton) to bones of the upper limb (appendicular skeleton) Act primarily on the upper limbs Pectoralis major and pectoralis minor and the inferior part of the serratus anterior, may also function as accessory muscles of respiration, helping elevate the ribs to expand the thoracic cavity when inspiration is deep and forceful (e.g., after a long run). Scalene muscles act primarily on the vertebral column; also serve as accessory respiratory muscles by fixing these ribs and enabling the muscles connecting the ribs below to be more effective in elevating the lower ribs during forced inspiration. a. PECTORIAL REGION  (004) THE MUSCULAR SYSTEM DR. VILLANUEVA – DE GRANO | 09/30/2020 VI. MUSCLES OF ABDOMEN Anterolateral muscles - Five muscles o Three flat muscles- external oblique, internal oblique, and transversus abdominis muscles o Two vertical muscles- rectus abdominis and pyramidalis muscles. a. DIAPHRAGM Double-domed, musculotendinous partition separating the thoracic and abdominal cavities. Chief muscle of inspiration Descends during inspiration (+) right and left domes; normally, the right dome is higher than the left dome owing to the presence of the liver. During expiration, the right dome reaches as high as the 5th rib and the left dome ascends to the 5th b. FUNCTIONS AND ACTIONS intercostal space. The muscular part of the diaphragm is situated peripherally with fibers that converge radially on the trifoliate central aponeurotic part, the central tendon o Sternal part o Costal part: forms the right and left domes o Lumbar part: forms right and left muscular crura that ascend to the central tendon. o Crura: musculotendinous bands o The right crus, larger and longer than the left crus, arises from the first three or four lumbar vertebrae. o The left crus arises from the first two or three lumbar vertebrae. Together the muscles are critical for the maintenance of many normal physiological functions. Form a firm, but flexible, wall (keeps the abdominal viscera intact and protects it from injury, and helps maintain the anatomical position of the viscera against gravity Contraction of these muscles assists in both quiet and forced expiration by pushing the viscera upward and in coughing and vomiting. Involved in any action that increases intraabdominal pressure- parturition, micturition and defecation,Move the trunk and help to maintain posture.  (004) THE MUSCULAR SYSTEM DR. VILLANUEVA – DE GRANO | 09/30/2020 VIII. PELVIS AND PERINEUM c. RECTUS SHEATH, LINEA ALBA, AND UMBILICAL RING PELVIS Rectus sheath Pelvis ( L. basin ) strong, incomplete fibrous compartment of the rectus abdominis Area of transition between the trunk and the lower and pyramidalis muscles limbs. Formed by the decussation and interweaving of the Muscles of the Pelvic Floor aponeuroses of the flat abdominal muscles Has an anterior and posterior wall for most of its length: The pelvic floor is formed by the bowl- or funnel- The anterior wall is formed by the aponeuroses of the external shaped pelvic diaphragm (coccygeus and levator ani oblique, and of half of the internal oblique. muscles + fascias) The posterior wall is formed by the aponeuroses of half the internal oblique and of the transversus abdominis. Functions ~1/3 of the distance between the umbilicus and the pubic Support the organs of the pelvic cavity symphysis- only an anterior wall exists; the rectus abdominis is Flex the sacrum and coccyx in direct contact with the transversalis fascia. Control the movement of materials through the urethra and anus The demarcation point where the posterior wall ends is called the arcuate line VII. POSTERIOR ABDOMINAL WALL  (004) THE MUSCULAR SYSTEM DR. VILLANUEVA – DE GRANO | 09/30/2020 PERINEUM DEEP PERINEAL POUCH Lies below the pelvic diaphragm “diamond” shaped structure between the external genitalia and the anus Boundaries: o Anterior – pubic symphysis o Posterior – tip of the coccyx o Roof – pelvic floor o Laterally – inferior pubic rami o Base – skin and fascia Muscles of pelvic floor form the perineal region = area divided into the anal triangle (posterior) and urogenital triangle (anterior ) o Urogenital triangle: roots of the external genitalia and, in women, the openings of the urethra and the vagina. In men, the distal part of the urethra is enclosed by erectile tissues and opens at the end of the penis o Anal triangle: anus and external anal sphincter No differences in the ♀ and ♂ deep perineal musculature  (004) THE MUSCULAR SYSTEM DR. VILLANUEVA – DE GRANO | 09/30/2020 Tearing of the puborectalis→ fecal incontinence SUPERFICIAL PERINEAL POUCH a. INJURY TO PELVIC FLOOR During childbirth, the pelvic floor supports the fetal head Perineum, levator ani, and ligaments of the pelvic fascia may be injured during childbirth Most often torn muscles: pubococcygeus and puborectalis Weakening of the levator ani and pelvic fascia may decrease support for the vagina, bladder, uterus, or rectum or alter the position of the neck of the bladder and the urethra May cause urinary stress incontinence or lead to the prolapse of one or more pelvic organs  (004) THE MUSCULAR SYSTEM DR. VILLANUEVA – DE GRANO | 09/30/2020 IX. TEST YOUR KNOWLEDGE 1. INTERCOSTAL MUSCLES ARE ATTACHED TO? a. RIBS b. RIBS AND STERNUM c. RIBS AND VERTEBRAE d. VERTEBRAE AND STERNUM Answer: A. These muscles are helpful in elevation of ribs and expansion of thoracic cavity