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What is the auricular surface?
Anatomical Parts The anterior surface is the auricular surface, so called from its resemblance in shape to the ear, is coated with cartilage in the fresh state, and articulates with a similar surface on the side of the sacrum.
Where is the auricular surface of ilium?
The auricular surface is located on the ilium and is the part of the pelvis that articulates with the sacrum (the lower part of the spine). Lovejoy and colleagues (1985b) identified several subtle, age-related morphological changes to the surface of the auricular surface that show regular changes with age.
Where is the dorsal surface of sacrum?
Dorsal surface This crest is palpable and is formed by the fusion of sacral spines of S1 to S4. The landmark of the sacral hiatus, which is caused by the lamina of S5 failing to meet in the median plane resulting in an exposed dorsal surface, is located just below the S4 tubercle.
What is the gluteal surface of ilium?
The gluteal lines are three curved lines outlined from three bony ridges on the exterior surface of the ilium in the gluteal region. They are the anterior gluteal line; the inferior gluteal line, and the posterior gluteal line. Right hip bone.
Is auricle and pinna the same thing?
The medical term for the outer ear is the auricle or pinna. The outer ear is made up of cartilage and skin. There are three different parts to the outer ear; the tragus, helix and the lobule.
What is dorsal and ventral surface?
The dorsal surface of an organism refers to the back, or upper side, of an organism. If talking about the skull, the dorsal side is the top. The ventral (from Latin venter, meaning 'belly') surface refers to the front, or lower side, of an organism.
What is the dorsal surface also called?
In humans, the dorsal surface can also be called the (VENTRAL) surface; however in quadruped animals, the dorsal surface is the (POSTERIOR) surface.
What attaches to the auricular surface of ilium?
The auricular surface of the ilium articulates with the sacrum to form the sacroiliac joint.
Where is the auricular surface?
There is an auricular surface on the lateral part of the sacrum that articulates with the ilium. Just posterior to the auricular surface is a rough prominence that contains three depressions intended for the attachment of strong ligaments.
What is the apex of the sacrum?
Finally, the apex of the sacrum is the inferior segment. It is the fifth sacral vertebral body and has an oval shaped facet for articulation with the coccyx. The apex projects posteriorly to increase the size of the pelvic cavity.
What is the sacroiliac joint?
Sacroiliac joint. The sacroiliac joint (SIJ) is a synovial joint occurring between the sacral and iliac articular surfaces. There is a lot of debate about the range of movement that occurs at this joint, with research suggesting it could be between 2 and 18 degrees.
What is the lumbosacral joint?
Lumbosacral joint - between the superior auricular process of sacrum and inferior articular facets of L5 . Sacrococcygeal joint - between the apex of the sacrum and the base of the coccyx. Sacroiliac joint - between lateral sacral surface and iliac articulation surface. Muscle attachments. Pelvic surface: piriformis, iliacus, coccygeus muscles.
What is the L5/S1 joint?
The lumbosacral (L5/S1) joint comprises the superior articular process of the sacrum which articulates with the inferior articular facets of L5. There is a great deal of pressure occurring at this joint, as the weight of all of the vertebrae above bears down on it, relying on it for their stability.
Why is the sacrum important?
Regarded as the keystone of the human body, the sacrum is important because it forms a link between the spine and the iliac bones, and also has an important part to play in hip stability. Sacrum is sexually dimorphic. It is shorter and wider in females than in males.
What is the triangular sacral canal?
The triangular sacral canal is formed by the sacral vertebral foramina, and descends from the opening on the basal surface to the sacral hiatus. Since the spinal cord finishes at around L2 the canal does not carry the spinal cord. It instead carries the filum terminale, long threadlike bands of connective tissue and the cauda equina, long sacral roots of spinal nerves.
What is the sacrum?
The sacrum is an irregular (sphenoid) bone that makes up the back (posterior) third of the pelvic girdle. A ridge across the front (anterior) portion of the S1 vertebra is called the sacral promontory.
What bones are connected to the sacrum?
The sides of the sacrum connect to the right and left hip ( iliac) bones . The apex is connected to the tailbone ( coccyx ). The base is connected to the largest and lowest of the lumbar vertebrae, L5.
What is the condition where the sacrum does not fuse?
The curvature of the sacrum varies widely between individuals. In some cases, the first and second sacral vertebrae do not fuse and instead remain separately articulated. 5 . Failure of the vertebral canal to completely close during formation is a condition known as spina bifida, which may arise from the sacral canal.
Why do humans need larger sacrums than other mammals?
Humans need larger sacrums than other mammals because we walk upright and need extra stability for balance and mobility. The size and orientation of the sacrum also affect the human birthing process. Humans are born with four to six sacral vertebrae rather than a single bone.
How many sacral vertebrae are there?
While the most common is five, anomalies documented in humans have included having four or six sacral vertebrae. 4
What is the disc in the lower back?
The disc that is between these two lumbar vertebrae is a common source of lower back pain. On either side of the lumbosacral joint are winglike structures (sacral ala) which connect to the iliac bones and form the top of the sacroiliac (SI) joint. Attached to either side of the sacrum are the iliac bones.
What is the human sacrum?
Anatomy. The human sacrum is a robust bone that can endure a lot of pressure and motion. It serves as an anchor point that holds the spinal column together with the pelvis. The sacrum and coccyx provide a stable platform for humans to sit upright.
What is the anterior surface of the ear?
The anterior surface is the auricular surface, so called from its resemblance in shape to the ear, is coated with cartilage in the fresh state, and articulates with a similar surface on the side of the sacrum. The posterior portion, known as the iliac tuberosity, is elevated and rough, for the attachment of the posterior sacroiliac ligaments ...
What is the posterior portion of the iliac tuberosity?
The posterior portion, known as the iliac tuberosity, is elevated and rough, for the attachment of the posterior sacroiliac ligaments and for the origins of the Sacrospinalis and Multifidus.
What is the lateral surface of the sacrum?
Lateral surface. The lateral surface of the sacrum is broad above, but narrows into a thin edge below. The upper half presents in front an ear-shaped surface, the auricular surface, covered with cartilage in the immature state, for articulation with the ilium.
Which surface of the sacrum is concave?
Pelvic surface. Dorsal surface. The pelvic surface of the sacrum is concave from the top, and curved slightly from side to side. Its middle part is crossed by four transverse ridges, which correspond to the original planes of separation between the five sacral vertebrae.
What is the name of the projection on the lumbar plexus?
On either side of the base is a large projection known as an ala of sacrum and these alae (wings) articulate with the sacroiliac joints. The alae support the psoas major muscles and the lumbosacral trunk which connects the lumbar plexus with the sacral plexus.
What are the two projections of the sacrum called?
The two projections at the sides of the sacrum are called the alae (wings), and articulate with the ilium at the L-shaped sacroiliac joints. The upper part of the sacrum connects with the last lumbar vertebra (L5), and its lower part with the coccyx (tailbone) via the sacral and coccygeal cornua.
How many vertebrae are in the sacrum?
In dogs the sacrum is formed by three fused vertebrae. The sacrum in the horse is made up of five fused vertebrae. In birds the sacral vertebrae are fused with the lumbar and some caudal and thoracic vertebrae to form a single structure called the synsacrum. In the frog the ilium is elongated and forms a mobile joint with the sacrum that acts as an additional limb to give more power to its leaps.
What is the sacrum in anatomy?
FMA. 16202. Anatomical terms of bone. The sacrum (plural: sacra or sacrums ), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1–S5) between ages 18 and 30. The sacrum situates at the upper, back part of the pelvic cavity, between the two wings of the pelvis.
What does the Greek word "os sacrum" mean?
As the Greek adjective ἱερός may also mean "strong", it has also been suggested that os sacrum is a mistranslation of a term intended to mean "the strong bone". This is supported by the alternative Greek name μέγας σπόνδυλος by the Greeks, translating to "large vertebra", translated into Latin as vertebra magna.
