Trunk Part 2: Chest Wall Anatomy

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Questions and Answers

What is the function of the internal oblique muscle?

Flexion and extension of the lower limbs

Support and stabilization of the pelvic floor

Lateral flexion, rotation, and maintenance of abdominal tone (correct)

Elevation and descent of the ribs

How does the orientation of the transversus abdominis muscle's fibers differ from those of the internal and external oblique muscles?

The fibers are circular

The fibers are vertical

The fibers are horizontal (correct)

The fibers are diagonal

Which of the following muscles originates from the internal oblique and transversus abdominis in males?

Piriformis

Cremaster (correct)

Quadratus lumborum

Pyramidalis

Which muscle is primarily responsible for the extension of the trunk when contracted together?

Quadratus lumborum Signup and view all the answers

What is the primary function of the levator ani muscles?

Support of the pelvic viscera Signup and view all the answers

What is the primary function of the cartilaginous portion of the ribs in relation to the sternum?

To allow greater mobility and elasticity during breathing Signup and view all the answers

Which anatomical feature serves as the landmark for the articulation between the manubrium and the body of the sternum?

Sternal angle Signup and view all the answers

Which part of the rib is described as being more irregular in structure?

Head Signup and view all the answers

What distinguishes true ribs from false ribs in the context of their connection to the sternum?

True ribs are directly articulated to the sternum Signup and view all the answers

What type of joint is formed by the articulation of the 1st rib with the manubrium?

Synchondrosis Signup and view all the answers

How do the sizes of the ribs change from 1 to 12?

They become shorter and more irregular Signup and view all the answers

Which portion of the sternum is the smallest compared to the manubrium and body?

Xiphoid process Signup and view all the answers

In terms of their connection to the sternum, which ribs are classified as floating ribs?

Ribs 11-12 Signup and view all the answers

What is the primary landmark for the pelvic inlet?

Sacral promontory Signup and view all the answers

Which statement best describes the shape of the pelvic inlet in females?

Round/oval and larger Signup and view all the answers

How does the angle of the pubic arch differ between males and females?

Larger in females Signup and view all the answers

What is the function of the linea alba in the rectus abdominis?

Divides the muscle into two parts Signup and view all the answers

What does the external oblique muscle primarily assist with in terms of trunk movement?

Lateral flexion and rotation Signup and view all the answers

Which of the following is NOT a characteristic of the male pelvis compared to the female pelvis?

Wider and shallow shape Signup and view all the answers

What is the anatomical relationship of the inguinal ligament?

Connects anterior superior iliac crest to pubic tubercle Signup and view all the answers

Which muscle lies directly beneath the skin in the anterior portion of the abdomen?

Rectus abdominis Signup and view all the answers

Which of the following defines the boundary between the greater and lesser pelvis?

Pelvic brim Signup and view all the answers

What is a significant difference in the sacrum between males and females?

Longer and more curved in males Signup and view all the answers

What is the primary action of the serratus posterior superior muscle?

Elevates the ribs Signup and view all the answers

Which muscle is responsible for the downward movement of the ribs?

Serratus posterior inferior Signup and view all the answers

What unique feature does the diaphragm have that differs between its right and left sides?

Asymmetrical dome height Signup and view all the answers

Which portion of the diaphragm is the largest?

Costal portion Signup and view all the answers

Which muscles are considered as part of the respiratory system along with the diaphragm?

Serratus posterior superior and inferior Signup and view all the answers

What structures pass through the hiatuses formed by the diaphragm?

Nerves, lymphatic vessels, and blood vessels Signup and view all the answers

What is the function of the iliac crest on the hip bone?

Attachment point for muscles Signup and view all the answers

Which structure is composed of fused ileum, ischium, and pubis bones?

Hip bone Signup and view all the answers

What is the role of the quadratus lumborum muscle in the body?

Aids in lateral flexion and rotation of the vertebral column Signup and view all the answers

Which of these is NOT a function of the diaphragm?

Supporting the abdominal muscles Signup and view all the answers

What is unique about the first rib in terms of its articulation with vertebrae?

It only articulates with the last cervical vertebra. Signup and view all the answers

Which intercostal muscles are primarily responsible for rib elevation during inspiration?

External intercostal muscles Signup and view all the answers

How are the interchondral joints characterized?

They form connections between rib cartilages. Signup and view all the answers

What role do the costocorporeal joints play?

They connect rib heads to vertebra bodies. Signup and view all the answers

What is the function of the inferior costal facet?

To articulate with the rib below. Signup and view all the answers

Which of the following best describes the movement of the rib cage during respiration?

It changes the thoracic cavity volume. Signup and view all the answers

Which structural characteristic is consistent for gliding synovial joints in the ribs?

They possess flat articular surfaces. Signup and view all the answers

Which statement about the internal intercostal muscles is true?

They run vertically adjacent to the ribs. Signup and view all the answers

What is the primary function of the subcostales muscles?

To move the ribs downward. Signup and view all the answers

Why do gliding joints in the rib cage have a reduced potential for movement?

They have multiple attachment points to vertebrae. Signup and view all the answers

Study Notes

Chest Wall Anatomy

The sternum consists of three parts:
- Manubrium: Upper segment, larger in frontal view.
- Body: Intermediate section where rib cartilages articulate.
- Xiphoid Process: Smaller caudal portion.
Sternal angle serves as a landmark for chest prominence.
Ribs:
- Twelve pairs, classified as flat bones.
- True Ribs (1-7): Directly articulate with the sternum.
- False Ribs (8-10): Connect to the sternum via cartilage from the 7th rib.
- Floating Ribs (11-12): Do not articulate with the sternum.

Rib Structure

Ribs have a flat anterior end and an irregular posterior end featuring a head, neck, and tubercle.
Articular facets are located on the head for vertebral connections.
Ribs allow flexibility and mobility for lung volume changes during respiration.

Joints of the Chest Wall

Sternocostal Joints:
- 1st rib attaches to the manubrium via a synchondrosis (fixed joint).
- 2nd rib has a double synovial gliding joint.
- Ribs 3-7 feature single synovial gliding joints.
- Ribs 8-10 connect via cartilaginous joints with the above ribs.
Interchondral Joints: Formed between cartilages of ribs VI to XI, supported by interchondral ligaments.
Costocorporeal and Costotransverse Joints:
- Connect the rib’s head and tubercle to the vertebral body and transverse process, respectively.

Musculature of the Chest Wall

Intercostal Muscles:
- External intercostals elevate ribs for inspiration.
- Internal and innermost intercostals depress ribs for expiration.
Subcostales: Located inferiorly, connected over multiple ribs.
Transversus Thoracis: Links sternum to rib cartilages, assisting in rib depression.
Serratus Posterior Superior/Inferior:
- Superior elevates ribs, inferior depresses ribs.
Levatores Costarum: Elevate ribs and assist vertebral movements.

Diaphragm

Major respiratory muscle with dome-shaped structure.
Connects to the sternum, ribs, and lumbar vertebrae.
Has distinct portions: sternal, costal, and lumbar, each with specific attachments.
Features three hiatuses for major vessels and nerves.

Pelvic Anatomy

Comprised of two hip bones and the sacrum.
Each hip bone consists of three fused parts: ilium, ischium, and pubis.
The acetabulum is the socket where the hip bone articulates with the femur.
Important landmarks on the ilium include the iliac crest and spines, critical for muscle attachment.

Pelvic Cavity

Defined by the pelvic inlet and outlet:
- Inlet: Heart-shaped in males, round/oval in females.
- Outlet: Size differences due to pelvic bone morphology.
Notable sexual dimorphism exists in pelvic shape affecting childbirth.

Anterolateral Abdominal Wall

Layers include skin, adipose tissue (Camper fascia), and connective tissue (Scarpa fascia).
Rectus Abdominis: Central muscle aiding trunk flexion; features tendinous intersections for increased strength.
External Oblique:
- Most superficial lateral muscle, involved in trunk rotation and lateral flexion.
- Forms the inguinal ligament from its inferior margin.

Key Muscles and Functions

Abdominal wall muscles regulate pressure, posture, and movement.
Diaphragm's position varies with respiration, influencing lung expansion.### Inguinal Canal
Originates at the superficial inguinal ring in the aponeurosis of the external oblique muscle.
Passes through the internal oblique and transverse muscles, leading to the deep inguinal ring at the fascia transversalis level.

Internal Oblique Muscle

Positioned beneath the external oblique muscle with opposite fiber orientation.
Attaches to the iliac crest, pubic crest, linea alba, ribs, and xiphoid process.
Facilitates lateral flexion, rotation, and maintenance of abdominal tone.

Transversus Abdominis

The deepest muscle in the anterolateral abdominal wall with horizontal fiber orientation.
Attached posteriorly to the vertebral column and anteriorly to the linea alba, iliac crest, xiphoid, and last ribs.
Muscle contraction occurs towards the linea alba, its origin.

Cremaster Muscle

Small muscle with fibers along the spermatic cord in males and the round ligament in females.
Originates from the internal oblique and transversus abdominis.
Functions to raise and lower the testes for scrotal temperature regulation.

Pyramidalis Muscle

Very small muscle linked to the pubis and linea alba.
Maintains tension in the lower linea alba.

Posterior Abdominal Wall

Houses muscles such as quadratus lumborum and iliopsoas, crucial for lower limb movement.

Quadratus Lumborum

Fibers exhibit various orientations attached to the iliac crest, lumbar transverse processes, and last ribs.
Functions as an extender of the trunk and assists with lateral movement.

Thoracolumbar Fascia

Organizes and separates muscle compartments in the posterior abdominal region.
Comprises three layers: anterior, middle, and posterior.
- Anterior layer covers quadratus lumborum and attaches to vertebrae and transversus muscle connective tissue.
- Middle layer is situated posteriorly to quadratus lumborum.
- Posterior layer encapsulates back muscles.

Pelvic Muscles

Includes piriformis and obturator internus.
Piriformis originates from the sacrum and iliac portion, attaching to the greater trochanter.
Obturator internus is situated in the pelvis, closing the obturator foramen of the hip bone.

Pelvic Floor Muscles

Consists of levator ani group:
- Puborectalis: attaches to the pubis and encircles the rectum.
- Pubococcygeus: lies between pubis and coccyx.
- Iliococcygeus: more lateral attachment from ischial spine to coccyx.
- Ischiococcygeus: spans between ischial spine and coccyx.

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Description

This quiz focuses on the anatomy of the chest wall, specifically the sternum and its three portions: the manubrium, body, and xiphoid process. Familiarize yourself with the anatomical features and articulations related to the sternum and its positioning in the trunk. Perfect for students studying human anatomy.