Maximus Gage
The external oblique muscle is one of the outermost abdominal muscles, extending from the lower half of the ribs around and down to the pelvis. It is the largest and most superficial of the flat abdominal wall muscles. The external oblique muscle is one of the muscles that form the anterior abdominal wall. It is broad, thin, and irregularly quadrilateral, with its muscular portion occupying the side and its aponeurosis occupying the anterior wall of the abdomen. The external oblique muscle contributes to various trunk movements, and injuries to the muscle can be debilitating.
| Characteristics | Values |
|---|---|
| Definition | The external oblique muscle is one of the outermost abdominal muscles. |
| Location | The lateral and anterior parts of the abdomen. |
| Shape | Broad, thin, and irregularly quadrilateral. |
| Size | The largest of the flat abdominal muscles. |
| Function | Holds organs in place, supports the body during movement, and helps protect the spine. |
| Attachments | Originates from ribs 5–12 and inserts into the iliac crest and pubic tubercle. |
| Innervation | Thoracoabdominal nerves (T7–T11) and subcostal nerve (T12). |
| Blood supply | Lower posterior intercostal arteries, subcostal artery, and deep circumflex iliac artery. |
| Common injuries | Abdominal strains and hernias. |
Explore related products
$10.15 $15.95
What You'll Learn
- The external oblique muscle is the largest and outermost of the abdominal muscles
- It originates from the ribs, typically ribs 5-12
- It inserts into the iliac crest and pubic tubercle
- It contributes to the inguinal canal and ligament
- It is one of five abdominal muscles, along with pyramidalis, rectus abdominis, internal obliques and transversus abdominis
The external oblique muscle is the largest and outermost of the abdominal muscles
The external oblique muscle is one of the abdominal muscles that form the anterior abdominal wall. It is the largest and outermost of the three flat abdominal muscles of the lateral anterior abdomen. The external oblique is situated on the lateral and anterior parts of the abdomen. It is broad, thin, and irregularly quadrilateral, with its muscular portion occupying the side and its aponeurosis occupying the anterior wall of the abdomen. The external oblique muscle typically originates from the ribs, with the number of ribs ranging from seven to nine, although there are documented variants that show the number of ribs ranging from four to twelve. The most superior origin of the muscle is most commonly the fifth rib, followed by the sixth rib, and then the fourth rib. The most inferior origin of the muscle is the twelfth rib.
The external oblique muscle has several attachments. Its superior attachments on the ribs are close to the respective ribs' costal cartilage, while the middle attachments are affixed to the ribs with a relatively large space between the attachments and costal cartilages. The lowest attachments are at the cartilaginous apexes of the twelfth ribs. The muscle fibres attach to the eleventh and twelfth ribs and extend vertically downwards, inserting into the anterior portion of the iliac crest, including the anterior superior iliac spine, pubic tubercle, and pubic crest. The external oblique's aponeurotic fibres insert into the whole length of the linea alba, with extensions onto the pubic crest and pectineal line.
The external oblique muscle has various functions. It contributes to the flexion and rotation of the torso, allowing the trunk to twist from side to side. The muscle also pulls the chest downwards, compressing the abdominal cavity and increasing intra-abdominal pressure. This is important for maintaining consistent internal pressure in the abdomen and supporting the spine and trunk during movements such as walking, sitting, and standing. Additionally, the external oblique muscle assists in expiration by depressing the ribs and helps regulate pressure during essential bodily functions such as breathing, coughing, and vomiting.
The external oblique muscle is susceptible to strain or injury due to its contribution to various trunk movements. Oblique strain is a common injury in sports such as baseball, particularly in pitchers and batters. It can affect the leading side external oblique or the trailing internal oblique.
Explore the Intrinsic Muscles Within Your Body
You may want to see also
Explore related products
It originates from the ribs, typically ribs 5-12
The external oblique muscle is one of the outermost abdominal muscles, extending from the lower half of the ribs around and down to the pelvis. The external oblique is situated on the lateral and anterior parts of the abdomen. It is broad, thin, and irregularly quadrilateral, with its muscular portion occupying the side and its aponeurosis occupying the anterior wall of the abdomen.
The external oblique muscle typically originates from the ribs, with the number of ribs from which it originates varying from seven to nine. The most superior origin is usually the fifth rib, although in some cases it can be the fourth or sixth rib. The most inferior rib of origin is typically the 12th rib, although in some individuals, it may only extend to the 11th rib.
The external oblique muscle arises from the outer surface of the middle of the shaft of the lower eight ribs as fleshy fibres. At its origin, the upper four slips and lower four slips interdigitate with the serratus anterior and latissimus dorsi muscles, respectively. The muscle gradually becomes aponeurotic, inserting into the whole length of the linea alba and extending to the pubic crest and pectineal line.
The upper two-thirds of the external oblique muscle are supplied by the lower intercostal nerves T7-T11 and the subcostal nerve T12. The lower third is supplied by the iliohypogastric L1 from the lumbar plexus. The upper part of the muscle receives blood supply from the lower intercostal arteries, while the lower part is supplied by branches of the deep circumflex iliac artery.
Heal Your Neck: Simple Muscle Relaxation Techniques
You may want to see also
Explore related products
It inserts into the iliac crest and pubic tubercle
The external oblique muscle is one of the outermost abdominal muscles, extending from the lower half of the ribs down to the pelvis. It is broad, thin, and irregularly quadrilateral, with its muscular portion occupying the side and its aponeurosis occupying the anterior wall of the abdomen.
The external oblique muscle arises from the outer surface of the lower eight ribs as fleshy fibres. At its origin, the upper four slips and lower four slips interdigitate with the serratus anterior and the latissimus dorsi muscles, respectively. The muscle gradually becomes aponeurotic, inserting into the whole length of the linea alba and extending to the pubic crest and the pectineal line. The lower fleshy fibres attach to the outer lip of the anterior two-thirds of the iliac crest.
The iliac crest is the upper curved part of the ilium, the broad upper bone of the pelvis. The iliac crest is palpable along the flank and serves as the origin or attachment of numerous muscles, including the external oblique muscle. The external oblique muscle fibres that attach to the 11th and 12th ribs extend almost completely vertically and insert into the iliac crest's anterior portion, including the anterior superior iliac spine, pubic tubercle, and pubic crest.
The pubic tubercle is a small, rough projection located on the superior and medial aspect of the pubic bone. It serves as a site of muscle attachment, with the external oblique muscle inserting into the pubic tubercle, along with other muscles such as the rectus abdominis and adductor longus. The pubic tubercle is an important landmark in pelvic anatomy and can be used to identify the location of other pelvic structures.
The external oblique muscle plays a crucial role in trunk movements and contributes to various functions, including pulling the chest downwards, compressing the abdominal cavity, and increasing intra-abdominal pressure. It also allows for side-bending and contralateral rotation of the torso, enabling the trunk to twist and turn.
Loosening Your Piriformis Muscle: Techniques for Relief
You may want to see also
Explore related products
It contributes to the inguinal canal and ligament
The abdominal external oblique muscle is the largest and outermost of the three flat abdominal muscles of the lateral anterior abdomen. It is situated on the lateral and anterior parts of the abdomen, extending from the lower half of the ribs around and down to the pelvis.
The external oblique muscle contributes to the inguinal canal and ligament. The inguinal canal is a short passage that extends inferiorly and medially through the inferior part of the abdominal wall. It acts as a pathway for structures to pass from the abdominal wall to the external genitalia. The inguinal canal is made up of a floor, anterior wall, posterior wall, and a roof. The floor of the canal is made of the inguinal ligament, which is a thickened inferior portion of the external oblique aponeurosis. The anterior wall is made of the external oblique aponeurosis, reinforced laterally by the internal oblique muscle. The posterior wall is formed by the transversalis fascia, conjoint tendon, and deep inguinal ring. The roof is formed by the medial crus of the aponeurosis of the external oblique, the musculoaponeurotic arches of the internal oblique and transverse abdominal muscles, and the transversalis fascia.
The external oblique muscle also contributes to the inguinal ligament, which is a thickened, inferior portion of the external oblique aponeurosis. The inguinal ligament is the floor of the inguinal canal, and it helps to prevent the ring from widening. The inguinal canal and ligament are of clinical importance as they can be a site of herniation.
The Science Behind a Dog's Tail: Muscles and More
You may want to see also
Explore related products
It is one of five abdominal muscles, along with pyramidalis, rectus abdominis, internal obliques and transversus abdominis
The external oblique muscle is one of the outermost abdominal muscles, extending from the lower half of the ribs around and down to the pelvis. It is the largest and most superficial of the flat abdominal wall muscles. The external oblique is situated on the lateral and anterior parts of the abdomen. It is broad, thin, and irregularly quadrilateral, its muscular portion occupying the side, its aponeurosis the anterior wall of the abdomen.
The external oblique is one of five abdominal muscles, along with pyramidalis, rectus abdominis, internal obliques, and transversus abdominis. The internal oblique muscle sits underneath the external oblique on each side of the trunk and functions similarly, except it rotates ipsilaterally. The internal oblique is also much thinner and smaller than the external oblique.
The abdominal muscles have many important functions, from holding organs in place to supporting the body during movement. Together with the back muscles, they make up the body's core muscles, helping to protect the spine and keep the body stable and balanced. They also help to stabilise the trunk and maintain consistent internal pressure in the abdomen.
The external oblique muscle typically originates from the ribs, with the number of ribs it originates from varying between individuals. It arises from seven to nine ribs total, with the 4th rib being the most superior and the 12th rib being the most inferior. However, there are many variants documented in the literature, with the most superior origin of the muscle found to be the 4th, 5th, or 6th rib in different studies.
The external oblique's superior attachments on the ribs are relatively close to the respective ribs' costal cartilage, while the middle attachments are spaced further apart from the costal cartilages. The lowest attachments are to the cartilaginous apexes of the 12th ribs.
Muscle Tearing Splits: What You Need to Know
You may want to see also
Frequently asked questions
The external oblique muscle is one of the outermost abdominal muscles, extending from the lower half of the ribs around and down to the pelvis.
The external oblique muscle helps to pull the chest downwards, compressing the abdominal cavity and increasing intra-abdominal pressure. It also allows the torso to rotate and twist.
The external oblique muscle is situated on the lateral and anterior parts of the abdomen. It is the largest and most superficial of the flat abdominal wall muscles.
The external oblique muscle supports the trunk, helps with movement and holds organs in place.
There are two external oblique muscles, one on each side of the rectus abdominis.
