The depressor labii inferioris muscle is a four-sided facial muscle located in the jaw area that draws the lower lip down and to the side. The muscles of the face give it general form and contour, help you outwardly express your feelings, and enable you to chew your food. The quadriceps femoris is a group of muscles located in the front of the thigh. The Latin translation of 'quadriceps' is 'four headed,' as the group….
The palmaris brevis muscle lies just underneath the skin. It is a short muscle on the flat of the hand. The muscle begins at the flexor retinaculum in…. The movement of the upper arm and shoulder is controlled by a group of four muscles that make up the rotator cuff. The ischium is divided into the body, superior ramus of the ischium, and inferior ramus of the ischium. The ischial tuberosity, which supports weight when sitting, is located on the ischium.
Key Terms ischium : The most inferior of the three bones that make up each side of the pelvis. Pubis The pubis is the lowest and most anterior portion of the hip bones of the pelvis. Learning Objectives Describe the pubic bone. Key Takeaways Key Points The most anterior portion of the pubis, the pubic symphysis, is where the two hip bones of the pelvis are fused together. The pubis has a body, a superior ramus, and an inferior ramus.
The body of the pubis contributes to the lunate surface and acetabular fossa in the acetabulum. Key Terms pubic symphysis : A cartilaginous joint between the two bones of the pubis. False and True Pelves The false greater pelvis is larger and superior to the true lesser pelvis where the pelvic inlet is located. Learning Objectives Describe the differences between false and true pelves. Key Takeaways Key Points Some believe that the false pelvis is actually part of the abdominal cavity and therefore that the true pelvis is the only true portion of the pelvis.
The true pelvis contains the pelvic inlet and is a short, curved canal, deeper on its posterior than on its anterior wall. The false pelvis supports the intestines specifically, the ileum and sigmoid colon and transmits part of their weight to the anterior wall of the abdomen. Key Terms true pelvis : Bounded in front and below by the pubic symphysis and the superior rami of the pubis; above and behind, by the sacrum and coccyx; and laterally, by a broad, smooth, quadrangular area of bone, corresponding to the inner surfaces of the body and superior ramus of the ischium, and the part of the ilium below the arcuate line.
Comparison of Female and Male Pelves The female pelvis has evolved to its maximum width for childbirth and the male pelvis has been optimized for bipedal locomotion. Learning Objectives Apply the diagnostic criteria to determine whether a pelvis is male or female. Key Takeaways Key Points The pelvis is one of the most useful skeletal elements for differentiating between males and females. Female pelves are larger and wider than male pelves and have a rounder pelvic inlet.
Male iliac crests are higher than females, causing their false pelves to look taller and narrower. The male sacrum is longer, narrower, straighter, and has a pronounced sacral promontory relative to the female sacrum. The angle between the inferior pubic rami is acute 70 degrees in men, but obtuse 90— degrees in women. Accordingly, the angle is called the subpubic angle in men and the pubic arch in women.
Key Terms pelvis : The large compound bone structure at the base of the spine that supports the legs. Pelvic Structure and Childbearing The human pelvis has evolved to be narrow enough for efficient upright locomotion, while still being wide enough to facilitate childbirth.
Learning Objectives Describe the evolution of the human pelvis. Key Takeaways Key Points The human pelvis is narrower and smaller than that of our closest living relatives, the apes. This narrower pelvis enables efficient bipedal locomotion. The human head and brain is also larger in proportion to the rest of the body in comparison to apes. The female pelvis has evolved to be as wide as possible, to make childbirth easier, without becoming so wide as to make bipedal locomotion too inefficient.
The male pelvis is narrower, since they do not have to give birth. Men therefore have greater locomotive efficiency. Key Terms bipedal locomotion : Walking upright; a form of terrestrial locomotion where an organism moves by means of its two rear limbs, or legs.
The surface of the ilium is covered in a thin fibrous membrane known as the periosteum. The periosteum is made of dense irregular connective tissue and plays an important role in the connection of muscles to the surface of the ilium. Deep to the periosteum is a layer of compact bone that contains bone cells embedded in a hard mineral and protein matrix.
Compact bone provides most of the strength and structural integrity to the ilium. The inner portion of the ilium is filled with many columns of spongy bone.
Spongy bone supports the surrounding compact bone like the girders of a bridge, while leaving hollow spaces inside the bone to reduce its weight. These spaces are also filled with red bone marrow, which is responsible for the production of blood cells. The anterior gluteal line is a flat ridge situated almost in the middle of the wing of the ilium on its external surface between the sites of origin of the gluteus medius and gluteus minimus muscles.
The posterior gluteal line is a bony ridge on the outer surface of the wing of the ilium between the fields of origin of gluteus medius and gluteus maximus muscles. The inferior gluteal line is a ridge located above the acetabulum between the sites of origin of the gluteus minimus and rectus femoris muscles.
Ilium Article Media. Parts Each iliac bone has two parts, which are: body of the ilium, and wing of the ilium. Landmarks The ilium also presents several important landmarks, such as: arcuate line, iliac crest, featuring anterior superior iliac spine, anterior inferior iliac spine, iliac fossa, sacropelvic surface, presenting auricular surface, iliac tuberosity, gluteal surface, featuring anterior gluteal line, posterior gluteal line, inferior gluteal line.
0コメント