Back Lecture 1 : Muscles Flashcards
What does the back provide?
The Back provides musculoskeletal axis of
support for the trunk
What do the bony elements of the back consist of?
The Bony elements consist mainly of vertebrae
What does the back contain?
The Back contains the spinal cord and proximal
parts of the spinal nerves
List the functions of the back.
The back :
o supports the body’s weight
o transmits forces through the pelvis
to the lower limbs
o carries and positions the head
o braces and helps maneuver upper
limbs
The vertebral column consists of :
33 vertebrae
The 33 vertebrae consist of :
▪ 7 cervical ▪ 12 thoracic ▪ 5 lumbar ▪ 5 sacral ▪ 3-4 coccygeal vertebrae
What does the sacral vertebrae fuse into?
The Sacral vertebrae fuse into a single bony
element, the sacrum
What do the coccygeal vertebrae vary in? What do they often fuse into?
Coccygeal vertebrae vary in number
from three to four, and often fuse into
a single coccyx
What groups do the muscles of the back consist of?
Muscles of the back consist of extrinsic and intrinsic groups
What does each group of muscles do?
- Extrinsic muscles - move the upper limbs and ribs
* Intrinsic muscles - maintain posture and move vertebral column
The movements of the muscles include :
Movements include flexion (anterior bending), extension, lateral flexion, and rotation
What are the extrinsic muscles involved in? What are they innervated by?
EXTRINSIC MUSCLES: involved in
movement of the Upper Limb (UL)
and thoracic wall and are innervated
by the anterior rami of spinal nerves or cranial nerve XI(trapezius).
What is the superficial group(of the extrinsic muscles) related to and involved in?
The Superficial group is related to and involved in the movement of the upper limb
What is the intermediate group(of the extrinsic muscles) related to and what does it serve as?
Intermediate group - is related to the
thoracic wall and serve as a
respiratory function.
Describe the position of the intrinsic muscles.
INTRINSIC MUSCLES: are deep in
position
What are intrinsic muscles innervated by?
The intrinsic muscles are innervated by the posterior rami
Name the superficial muscles of the back.
- Latissimus dorsi
- Levator scapulae
- Rhomboid major
- Rhomboid minor
- Trapezius
What are the superficial muscles of the back generally involved in?
These muscles are generally involved in movements of the shoulder
Describe each trapezius.
Each trapezius is flat and triangular with the base
situated along the vertebral column and the
apex pointing towards the tip of the shoulder
Origin of the trapezius :
- Superior nuchal line
- External occipital protuberance
- Ligamentum nuchae
- Spinous processes of C7 to T12
- Corresponding supraspinous ligaments
Insertion of the trapezius :
Insertion: Lateral 1/3 of clavicle;
acromion and spine of scapula
The action performed by the trapezius :
Assist in rotating scapula during abduction of humerus ❑upper fibers elevate scapula ❑middle fibers adduct scapula ❑lower fibers depress scapula
Which nerve is responsible for the innervation of the trapezius?
Accessory nerve (motor) [CNXI]
Describe the Latissimus Dorsi.
The Latissimus Dorsi is large, flat and triangular at lower
portion of back and ends in tendon that
attaches to the humerus.
Origin of the Latissimus Dorsi :
- Spinous processes of T7 to T12
- Posterior layer of lumbar fascia
- Outer lip of iliac crest
- Ribs (lower 4 – rib 8-12)
- Inferior angle of the scapula
Insertion of the Latissimus Dorsi :
Floor of the intertubercular sulcus
of the humerus
The action performed by the Latissimus Dorsi :
Extends, adducts, medially
rotates humerus
Which nerve is responsible for the innervation of the Latissimus Dorsi?
Thoracodorsal nerve (motor)
Describe the Levator scapulae.
The Levator scapulae is a slender muscle
Origin of the Levator scapulae :
Origin:
• Transverse processes of C1 &C2
• Posterior tubercles of the transverse
processes of C3 & C4
Insertion of the Levator scapulae :
Superior angle and upper part of
medial border of the scapula
The action performed by the Levator scapulae :
Elevates scapula
Which structures are responsible for the innervation of the Levator scapulae?
Innervation: dorsal scapular nerve (C5) and
C3-C4 anterior rami (motor)
Describe the Rhomboid Minor and state what it arises.
Rhomboid minor - small,
cylindrical and arises from
ligamentum nuchae, spinous
processes of C7-T1
Origin of the Rhomboid Major :
T2 to T5 spinous
processes and supraspinous ligaments
Insertion of the Rhomboid Minor :
•Rhomboid minor - Medial scapula
border
Insertion of the Rhomboid Major :
•Rhomboid major - Medial scapula
border below rhomboid minor
The action performed by the Rhomboid major and minor :
Work together to retract the
scapula to the vertebral column
Which nerve is responsible for the innervation of the Rhomboid major and minor?
Dorsal scapular nerve
Name the intermediate muscles.
- Serratus Posterior Superior
* Serratus Posterior Inferior
What is the Serratus Posterior Superior?
❑ Two flat muscular sheets that lie in the superior and inferior aspects of the back
Where do the fibres from the Serratus posterior superior and inferior?
❑The fibres from Serratus posterior superior and inferior pass outwards from the
vertebral column to attach to the ribs. Referred to as the respiratory group
Origin of the Serratus posterior superior :
• Deep to the rhomboid muscles
• Nuchal ligament & spinous process of
C7 to T3
• Fibres descend from vertebral column
Insertion of the Serratus posterior superior :
Upper borders of the 2-5 ribs
Action performed by the Serratus posterior superior :
Elevates ribs 2-5 and aids deep
Inspiration