Diaphragm Anatomy

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Questions and Answers

What is the primary function of the sternocleidomastoid muscle when the head is stable?

Elevating the sternum (correct)

Elevating the ribs

Rotating the shoulders

Laterally flexing the neck

Which nerve supplies the sternocleidomastoid muscle?

Vagus nerve

Phrenic nerve

Spinal accessory nerve (11th cranial nerve) (correct)

Cervical plexus

What is the primary function of the scalene muscles?

Extending the shoulder

Elevating the ribs (correct)

Rotating the head

Flexing the neck

Which of the following actions is NOT performed by the sternocleidomastoid muscle?

Elevating the ribs Signup and view all the answers

What is the common innervation of the scalene muscles?

Cervical plexus Signup and view all the answers

What is the attachment site of the scalene muscles proximally?

Cervical vertebrae Signup and view all the answers

What is the action of the scalene muscles during inspiration?

Elevating the ribs Signup and view all the answers

What is the name given to the sternocleidomastoid muscle due to its actions?

Nosey parker's muscle Signup and view all the answers

What is the primary function of the quadratus lumborum muscle in relation to the diaphragm?

It contracts to hold the 12th rib down, preventing the diaphragm from ascending with the ribcage Signup and view all the answers

Which of the following is NOT a correct attachment of the diaphragm?

The xiphoid process Signup and view all the answers

What is the main reason for the descent of the diaphragm during inspiration?

The gravity-assisted descent of the abdominal organs Signup and view all the answers

What is the term for the process of breathing that involves the movement of the abdominal organs and diaphragm?

Abdominal breathing Signup and view all the answers

What is the effect of gravity on the diaphragm when lying down?

It hinders the descent of the diaphragm Signup and view all the answers

What is the main function of the abdominal wall during inspiration?

It undergoes reflex relaxation to allow the abdominal organs to move downwards Signup and view all the answers

Which of the following is a correct statement about the movement of the liver during inspiration?

It moves downwards towards the abdomen Signup and view all the answers

What is the innervation of the quadratus lumborum muscle?

The anterior rami of T12-L3 Signup and view all the answers

What is the primary action of the external intercostal muscle?

Largely inspiratory Signup and view all the answers

What is the role of the quadratus lumborum in respiratory movements?

Aiding the diaphragmatic movement Signup and view all the answers

What is the characteristic of an intrinsic muscle of the chest?

Having all attachments within the bony anatomy of the chest Signup and view all the answers

What is the primary function of the thoraco-abdominal pump?

Regulating the effects of posture on respiratory mechanics Signup and view all the answers

What can be said about the intercostal muscle action beyond 120 degrees?

It reverses, with the external intercostal muscle becoming expiratory Signup and view all the answers

What is the primary difference between the diaphragm and the chest wall in respiratory movements?

The diaphragm is a muscle, while the chest wall is a bony structure Signup and view all the answers

Which of the following muscles is responsible for stabilizing the 1st and 2nd ribs?

Internal intercostal muscle Signup and view all the answers

What is the primary learning outcome of this lecture on the anatomy of breathing?

To appreciate the complexities of intercostal muscle action Signup and view all the answers

What is the primary function of the transversus abdominis muscle in the process of expiration?

To compress the abdominal cavity and aid in the elevation of the diaphragm Signup and view all the answers

What is the attachment site of the rectus abdominis and external oblique abdominis muscles?

Hip bone below and rib cage above Signup and view all the answers

What is the role of the serratus posterior muscles in respiration?

They are inactive during breathing and have a proprioceptive role Signup and view all the answers

Which of the following muscles is NOT involved in the process of forceful expiration?

Serratus posterior superior Signup and view all the answers

What is the insertion site of the superior serratus posterior muscle?

Ribs 2-5 Signup and view all the answers

What is the origin of the inferior serratus posterior muscle?

Spinous processes and supraspinous ligaments of T11-L2 Signup and view all the answers

What is the role of the anterior abdominal wall muscles in respiration?

They aid in forceful expiration by pulling the ribs downwards Signup and view all the answers

What is the incorrect assumption about the serratus posterior muscles based on their attachments?

That the superior muscle is an inspiratory muscle and the inferior muscle is an expiratory muscle Signup and view all the answers

What is the primary function of the levator costarum muscles?

To elevate the ribs Signup and view all the answers

Which muscles hold the 1st two ribs stable during forced inspiration?

Scalene group of muscles Signup and view all the answers

What is the main difference between the insertion points of levator costarum brevis and levator costarum longus?

Levator costarum brevis inserts onto the rib immediately below the vertebra of origin, while levator costarum longus inserts onto the rib two levels below the vertebra of origin Signup and view all the answers

What is the role of the diaphragm during quiet expiration?

It elevates Signup and view all the answers

Which muscles are responsible for preventing the bellowing of the intercostal spaces during quiet expiration?

Intercostal muscles Signup and view all the answers

What is the role of the abdominal muscles during forced expiration?

They contract to depress the ribcage Signup and view all the answers

What is the primary function of the accessory muscles of inspiration?

To play a role in forced inspiration Signup and view all the answers

Which muscles elevate the ribs during forced inspiration?

External intercostal and interchondral part of the internal intercostal muscles Signup and view all the answers

Study Notes

The Diaphragm

The diaphragm attaches to the boundaries of the thoracic outlet and rises up to the 4th rib on the right and 5th intercostal space on the left.
During inspiration, the diaphragm descends, and in forced breathing, the ribs ascend.
The 12th rib is held down to prevent the diaphragm from ascending with the ribcage, achieved by contraction of the quadratus lumborum muscle.

Quadratus Lumborum

The quadratus lumborum muscle is attached to the iliac crest of the hip bones below and the 12th rib above.
It is also attached to the transverse processes of the lower lumbar vertebrae and iliolumbar ligament.
The key attachment is to the iliac crest.
It is innervated by the anterior rami of T12-L3.

Posture and Breathing

In “quiet” breathing, the rib cage does not need to move much, and expansion of the thoracic cavity is achieved through descent of the diaphragm.
In the upright position, gravity assists the diaphragm by causing descent of the abdominal organs.
The abdominal wall undergoes reflex relaxation to assist this process, allowing the abdominal organs to be displaced.
To expire, the opposite occurs – the abdominal wall undergoes reflex contraction to force the abdominal organs and diaphragm upwards.

Breathing in the Supine Position

When lying down, the effects of gravity have a negative effect on breathing, since the liver moves upwards towards the chest.
This is due to the presence of a curve in the vertebral column.

Muscles Attached to the Inlet

The sternocleidomastoid muscle attaches to the sternum, clavicle, and mastoid process of the skull.
It can turn the head to the side, or acting with its partner on the opposite side, pull the head forward and tilt it backwards.
It elevates the sternum when the head is stable.
It is supplied by the spinal accessory nerve (11th cranial nerve).

Scalene Muscles

The scalene muscles attach to the cervical vertebrae proximally and 1st and 2nd ribs distally.
They elevate the ribs when the neck is stable.
They are innervated by nerves of the cervical plexus.

Intercostal Muscles

The external intercostal muscles are inspiratory and internal ones expiratory, but this reverses beyond 120 degrees as the muscles approach the sternum.
The external intercostal muscle is largely inspiratory, and the interchondral portion of the internal intercostal muscle is also inspiratory.

Accessory Muscles of Respiration

The extrinsic muscles of the chest aid movement of the ribcage.
The anterior abdominal wall muscles stabilize the 1st and 2nd ribs.
The rectus abdominis and external oblique abdominis muscles pull the ribs downwards.
The transversus abdominis muscle causes compression of the abdominal cavity, which assists the elevation of the relaxed diaphragm towards the thoracic cavity.

Serratus Posterior Muscles

The superior serratus posterior muscle arises from the spinous processes and supraspinous ligaments of C7-T2 and inserts onto ribs 2-5.
The inferior serratus posterior muscle arises from the spinous processes and supraspinous ligaments of T11-L2 and inserts onto ribs 9-12.
These muscles are thought to be involved in measuring stresses at the top and bottom of the thoracic spine, having a proprioceptive role for the vertebral column.

Levator Costarum Muscles

The levator costarum muscles arise from the transverse processes of C7 to T11.
They elevate the ribs, but are small and weak, and do not contribute any significant action during respiration.

Muscles of Inspiration and Expiration

Forced inspiration involves the action of the scalene group of muscles, sternocleidomastoid muscle, external intercostal and interchondral part of the internal intercostal muscles, and the diaphragm.
Quiet expiration requires relaxation of the inspiratory muscles, and the ribcage is lowered, and the diaphragm elevates.
In forced breathing, the intercostal part of the internal intercostal muscle possibly depresses the ribs, and the abdominal muscles contract to depress the ribcage and compress the abdominal cavity.

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Description

Review the attachments and movements of the diaphragm, including its boundaries, domes, and interactions with the ribcage during inspiration and forced breathing.