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Muscle of neck n vertebral column: intro
The deep muscles of the neck and vertebral column function in producing head movements and trunk extension.
They are complex w multiple origins and insertions,
Different groups will move the head, thorax, or pelvic girdle
Muscles of the Neck and Vertebral Column that Move the Head
Movement of the head is by muscles originating from the axial skeleton.
Anterior / flex group, posterios/ antagonist group
Both groups work to rotate the head when working singly.
Scalenes (anterior, middle, posterior)
Longus capitis & coli
Flex & rotate head
Splenius capitis & cervicis
Longissimus capitis & cervicis*
Extend, rotate and laterally bend head
general function of anterior n posterior muscles
In general, muscles on the anterior or ventral surface of the body function to flex the head,
and the antagonistic muscles located on the dorsal surface function to extend or hyperextend the head.
The longissimus capitis and cervicis are part of a much larger mass of deep back muscles called the erector spinae.
Previously, we saw that the sternocleidomastoid is a useful superficial anatomical landmark because it divides the structures in the neck into anterior and posterior triangles.
The sternocleidomastoid is a two-headed muscle
with its origins on the sternum and clavicle and
insertion on the mastoid process of the temporal bone.
This muscle is the prime mover of head flexion when both sides contract at the same time.
It also moves the head from side to side when only one side contracts—it tilts the head to the side that's contracting.
Deep to the sternocleidomastoid are the scalenes
which are muscles of the posterior triangle,
and have their origins on the transverse processes of the cervical vertebrae.
Muscles That Move The Vertebral Column & Head: scalene: O, I, list
The scalene group of muscles have their origins on the transverse processes of the cervical vertebrae
and their insertion of the first and second ribs.
The anterior scalene muscles are superficial to the middle and posterior scalenes when the body is viewed from the anterior.
The middle scalene muscles are the longest of the three,
and the posterior scalenes are the smallest.
Working together these muscles flex, laterally flex and rotate the head.
They also can function in forced or deep breathing.
By pulling the ribs toward the head, the volume of the thoracic cavity is increased thus assisting with forced inspiration.
Forced breathing occurs when exercising or under pathological conditions involving diseases of the lungs.
Muscles That Move The Vertebral Column & Head:
longus capitis and longus colli.
They are deep muscles of the anterior triangle.
The origin of the longus capitis is from the transverse processes of the cervical vertebrae,
and its insertion is on the occipital bone at the base of the skull.
Working together, the longus capitis muscles act to flex the head.
The longus colli muscles have their origin from the bodies of cervical and superior thoracic vertebrae.
These muscles also act to flex the head.
Muscles of the Neck that Move the Head: Posterior
the splenius muscles: splenius capitis , splenius cervicis
They have their origins on the midline of vertebral column
(ligamentum nuchae and spinous processes of C7 and T1-6).
The splenius capitis (capitis = head) has its origin on the ligamentum nuchae
which is a strong, elastic ligament extending from the occipital bone along the spinous processes of the cervical vertebrae
binding them together and inhibiting excessive head and neck flexion
which prevents damage to the spinal cord.
It inserts on the occipital bone and mastoid process of the temporal bone.
Its action is to extend, laterally flex, and rotate the head.
The splenius cervicis extends from the thoracic vertebrae to the skull and inserts on the transverse processes of C2-C4.
Acting together on both sides, extend head, acting unilaterally they laterally flex and rotate head to same side as the contracting muscle
Head extension is accomplished by the splenius muscles which lie deep to the trapezius.
longissimus capitis: O, I, def
The longissimus capitis is the superior part of a huge muscle mass called the erector spinae
that parallels the longitudinal axis of the body on either side of the vertebral column.
The origin of the longissimus capitis is from the transverse processes of T1-T4 and
the insertion is on the mastoid process of the temporal bone.
longissimus capitis: fn
When both sides contract together, the longissimus capitis extends the head;
when one side contracts, the head is rotated so that the face is facing the same side of the contracting muscle.
Extension of the trunk is controlled in part by
Extension of the trunk is controlled in part by the deep or intrinsic muscles of the back.
Intrinsic muscles are those that have their origins and
insertions within the vertebral column
extrinsic muscles of trunk/ back
extrinsic muscles which may have their origins on the vertebrae,
but their insertions on the shoulder girdle and upper limbs.
For example, extrinsic muscles would include the superficial muscles of the back, such as the trapezius.
The largest of the deep, intrinsic back muscles is the erector spinae. (sacrospinalis)
Largest muscle mass of the back
Forms the bulge on either side of vertebral column.
Chief extensor of the vertebral column
It is a thick column of muscle that extends from the sacrum to the skull,
and is comprised of many muscles of varying length.
Each individual muscle works like a thin rope
that when pulled causes one or several vertebrae to extend
or to rotate on the vertebrae below.
Because the origins and insertions of the muscle groups overlap,
entire regions of the vertebral column can be moved simultaneously and smoothly.
erector spinae consists of three groups of overlapping muscles:
1. Iliocostalis group
(iliocostalis cervicis, thoracis and lumborum).
2. Longissimus group
(longissimus capitis, cervicis and thoracis).
3. Spinalis group
(spinalis capitis, cervicis and thoracis)
erector spinae fn
When all the erector spinae muscles contract together, they extend or hyperextend the vertebral column.
When only one side contracts,
the trunk, neck or head move laterally toward the contracting side.
The movement is accomplished because the articular facets of the vertebrae glide on each other.
Controls flexion, lateral flexion and rotation.
Maintains the lumbar curve
transversospinalis. : def
Deep to the erector spinae muscle groups is another mass called the transversospinalis. .
The transversospinalis group is deepest layer of muscle
consisting of short muscles that are
located in the groove between the spinous and transverse processes of the vertebrae.
As the name indicates, the fibers of the transversopinalis group run from the transverse processes to the spinous processes of the vertebrae.
transversospinalis. : list
Semispinalis capitis (transverse processes to occipital bone);
Semispinalis cervicis inserts on spinous processes of C1-C5);
Semispinalis thoracis runs from the transverse processes of T6-10 to spinous processes of C5-7, T1-4.
transversospinalis. : fn
They function to extend, rotate and stabilize the vertebral column.
When both sides of these muscles act together they extend the head and/or vertebral column;
acting singly they rotate head or vertebral column to the opposite side of the contracting muscle.
Intrinsic Back Muscles: Segmental muscle group:
This slide shows the relationship of the multifidus and rotatores of the transversospinalis, and two other intersegmental groups;
and the intertransversarii which connect the transverse processes of adjacent vertebrae.
Segmental muscle group: fn
The primary function of these segmental muscles is to stabilize the vertebral column during movement preventing the vertebrae from slipping off their articular facets when the larger muscles of trunk contract.
Unite the spinous and transverse processes of consecutive vertebrae.
Muscles of the Thorax that Function in Breathing
1. external intercostal
2. internal intercostal
The deep muscles of the thorax function in breathing.
The external intercostal muscles are the most superficial and
function along with the diaphragm in inspiration;
they function to lift the rib cage making it larger in the anterior to posterior and side-to-side dimensions.
The internal intercostals form the deeper layer and aid in forced expiration by depressing the rib cage (make it smaller).
Muscles of the Thorax that Function in Breathing: diaphragm: O, I, def
Recall that the diaphragm is the muscular partition that divides the superior thoracic cavity from the inferior abdominopelvic cavity.
The origin of the diaphragm is on the inferior border of rib cage and sternum, costal cartilages of last 6 ribs and lumbar vertebrae.
It inserts on the central tendon of the diaphragm with is continuous with the fibrous pericardium in the thorax.
When the diaphragm is relaxed (between inhalations),
it forms a parachute or umbrella-like dome
that covers the inferior surface of the rib cage and sternum, costal cartilages of the last six ribs and lumbar vertebrae.
When stimulated to contract by the phrenic nerve, the dome flattens thereby increasing the volume of the thoracic cavity.
The resulting negative pressure is enough to "suck" air into the lungs.
diaphragm: looking up at the diaphragm from the abdominopelvic cavity.
In this view, we are looking up at the diaphragm from the abdominopelvic cavity.
Notice the opening in the diaphragm for the passage of the aorta, esophagus and inferior vena cava.
Fibers converge on central tendon of diaphragm causing it to flatten when the muscle contracts
Mammals are the only vertebrates with a diaphragm.
It is innervated by the phrenic nerve (cervical nerves C3-C5).
Severe upper neck injuries, can result in death by asphyxiation.
abdominal cav protection
The anterior and lateral abdominal wall has no bony protection.
Only skin, fascia, four pairs of muscles and their enveloping fascia and aponeuroses protect the abdominopelvic viscera.
Muscles of the Abdominal Wall: Trunk Movements & Compression: list
The muscle include the rectus abdominis which is the most medial of the muscles,
external oblique and internal obliques and
the deep transversus abdominis.
external, internal oblique
wrap around laterally and join the rectus sheath,
The muscle fibers of the external and internal oblique muscles and the transversus abdominis run cross-directionally to one another which provides strength.
The rectus abdominis runs entire length of the abdomen from pubic symphysis (origin) to xiphoid process (insertion) of sternum.
Three-five tendinous inscriptions cross the rectus muscles forming segments.
Because the inscriptions are made of collagen fibers, they do not increase in size with exercise,
however the muscle fibers hypertrophy with repetitive use forming the "six pack" when the abs are well developed.
There are individual variations in the placement and number of inscriptions.
The rectus sheath prevents the muscles from protruding anteriorly when the muscles contract.
The External Oblique is the largest and most superficial of the three lateral muscles..
Its fibers run downward and medially and their aponeurosis turns under inferiorly forming the inguinal ligament.
The origin of the external oblique is on the inferior borders of ribs 5-12,
and it inserts on the linea alba, pubic tubercle and iliac crest.
external oblique: fn
The action of the internal oblique is to compress the abdomen,
flex the vertebral column,
and aid the back muscles in trunk rotation.
The Internal Oblique is the intermediate muscle located between the external oblique and the transversus abdominis.
Its origin is from the lumbar fascia, iliac crest and inguinal ligament.
It inserts on the linea alba, pubic crest, costal cartilages.
It has the same action as the external oblique.
The Transversus Abdominus is the deepest of the three.
Its fibers run horizontally from their origin on the inguinal ligament, iliac crest, lumbar fascia and costal cartilages to
its insertion on the linea alba and pubic crest.
The transversus abdominis is probably the main compressor of the abdomen.
Oblique and Rectus Muscles: work together
Working together, the muscles of the anterior and lateral abdominal wall function to support and protect the abdominal viscera,
as well as promoting lateral flexion and anterior flexion of the vertebral column.
The external and internal oblique muscles flex the vertebral column,
and function with the muscles of the back in trunk rotation and lateral flexion.
The obliques and the transversus abdominis all play a roll in compression of the abdominal wall.
This increases abdominal pressure the finer things in life such as urination, defecation, child birth, vomiting, coughing, screaming, sneezing, burping, and nose blowing.
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