Anatomy Course Module 1 Sample

Module One Course Index

Lesson 1:

Approaches to studying anatomy

Quiz

Lesson 2:

Muscular systems

Quiz

Lesson 3:

Skeletal system and joints

Quiz

Lesson 4:

Regions of the lower limb, bones of pelvis and thigh

Quiz

Lesson 5:

Bones of the leg

Quiz

Lesson 6:

Posterior leg

Lesson 7:

Lateral leg

Lesson 8:

Anterior leg

Quiz

Special terms of comparison Special terms of comparison are used for specific regions.

SEARCH TIP Type “Palmer surface of hand” for example, into search bar. Click on “structures” below to view and explore. Do the same for any special term of comparison. See Image 24

IMAGE 24

Image 24. The palm of the hand is called the palmer surface

G. Terms of laterality App: Click or copy this link to view a 3 min. video on “terms of laterality.” https://3d4medic.al/eMIaAad6 • Paired structures on both left and right sides of the body are regarded as bilateral.

• Unpaired structures may be midline, or, if they are only on one side unilateral.

• Ipsilateral refers to structures on the same side of the body while contralateral refers to those on the opposite side. Image 25.

IMAGE 25

Image 25. When rotating to the right the left external oblique muscle is a contralateral rotator, and the internal oblique muscle is an ipsilateral rotator.

During active axial rotation in one direction, the external oblique muscle on one side functions synergistically with the internal oblique on the other side. This functional synergy produces a diagonal line of force that crosses the midline through the muscles’ mutual attachment into the linea alba. Contraction of the two muscles therefore reduces the distance between one shoulder and the contralateral iliac crest.

Module One Lesson Two Muscular system and muscles Contents A. • M uscular system • M uscle structure and attachments • C onnective tissue in muscles • B ony markings from muscle attachments • M uscle types- bellies, origins & insertions B. • Tendons • A poneurosis • R aphe • Fascia • S ynovial sheaths C. • M ovement and skeletal muscle, levers • M uscle form • M uscle shapes • M uscle actions and contractions • Terminology related to the actions of muscles • M uscular force couples • M otor units and functional units

A. Muscular system The muscular system is made up of the skeletal muscles together with associated structures. These are condensations of fibrous tissue including tendons and fibrous connective sheaths, as well as synovial tendon sheaths.

• The other types of muscles are smooth muscle, and cardiac muscle. Smooth muscle is found throughout the visceral and vascular systems and cardiac muscle is found in the walls of the heart.

• Muscles are arranged in groups that tend to share a common fascial compartment and produce a common action. In a coming section, we will look common fascial compartments in more detail.

Muscle structure and attachments • Muscle is the active producer of movement.

• Skeletal muscle typically moves bones and is capable of voluntary movement.

• It is composed of large striated muscles fibers which are dependent on a somatic motor nerve supply to generate a contraction.

• The strength of a muscle contraction is proportional to the number of muscle fibers recruited.

• The physiologic cross-sectional area of a muscle is the area of muscle (in mm2 or cm2) measured from a perpendicular cut through the long axis of all the muscle fibers. Because this measurement reflects the amount of contractile proteins, a greater cross-sectional area predicts a greater force potential from the muscle. See Image 1.

IMAGE 1

The pelvic girdle The pelvic girdle (bony pelvis) is a bony ring composed of the sacrum and right and left hip bones joined anteriorly at the public symphysis. Image 3 and 4.

IMAGE 3

Image 3. Pelvic girdle IMAGE 4

Image 4. Sacroiliac articulation

The Deep Compartment App: Click or copy this link to view a 4 minute video on the compartment below https://3d4medic.al/63MftEFF

Table 2. Deep muscles of posterior compartment of leg Muscle

Proximal Attachment

Distal Attachment

Innervation

Main Action

Popliteus

Lateral surface of lateral condyle of femur and lateral meniscus

Posterior surface of tibia, superior to soleal line

Tibial nerve (L4, L5, S1)

Weakly flexes knee and unlocks it by rotating femur 5° on fixed tibia; medially rotates tibia of unplanted limb

Flexor hallucis longus (4)

Inferior two thirds of posterior surface of fibular; inferior part of interosseous membrane

Base of distal phalanx of great toe (hallux)

Tibial nerve (S2, S3)

Flexes great toe at all joints; weakly plantarflexes ankle; supports medial longitudinal arch of foot

Flexor digitorum longus (5)

Medial part of posterior surface of tibia inferior to soleal line; by a broad tendon to fibula

Bases of distal phalanges of lateral four digits

Tibialis posterior (6)

Interosseous membrane; posterior surface of tibia inferior to soleal line; posterior surface of fibula

Tuberosity of navicular, cuneiform, cuboid, and sustentaculum tali of calcaneus; bases of 2nd, 3rd and 4th metatarsals

Flexes lateral four digits; plantarflexes ankle; supports longitudinal arches of foot

Tibial nerve (L4, L%)

Plantarflexes ankle; inverts foot

IMAGE 7

Image 7. Transverse planes are horizontal planes passing through the body at right angles to the medial and frontal planes, dividing the body into superior (upper) and inferior (lower) parts.

Radiologists refer to transverse planes and transaxial which is commonly shortened to axial planes.

D. Special Terms of Movement IMAGE 11

• Special terms are used for certain movements.

• Moving the head to one side for example, is called lateral flexion.

• Pronation and supination refer to movement of the proximal and distal radioulnar joints between the two joints in the forearm.

• Pronation is to “face down” and • Supination is to face back up.

See Image 12

Image 11. Lateral flexion IMAGE 12

Image 12.

The right forearm is supinated.

The long prontator teres muscles can be seen with its proximal insertion on the medial supracondylar ridge of the humerus.

SEARCH TIP Type “pronation” into the search bar on your “models” page and select from “videos” or “motions” to see pronation and supination and the muscles involved. You can also rotate the arm to see the muscles from various angles.

• The opposite surface is called the dorsum of the hand.

• The sole of the foot is called the planter surface and its opposite is the dorsum of the foot.

• Cranial (skull) is closer to the head while caudal(tail) is closer to the tail.

• Within the head, rostral (beak) is closer to the front, while occipital is closer to the back of the head.

• Combined terms describe intermediate positional arrangements: inferomedial means nearer to the feet and median plane – for example, the anterior parts of the ribs run inferomedially; superolateral means nearer to the head and farther from the median plane.

Other terms of relationship and comparisons are independent of the anatomical position or the anatomical planes, relating primarily to the body’s surface or its central core: • Superficial, intermediate, and deep describe the position of structures relative to the surface of the body or the relationship of one structure to another underlying or overlying structure.

• External means outside of or farther from the center of an organ or cavity, while internal means inside or closer to the center, independent of direction.

• Proximal and distal as described above, are used when contrasting positions nearer to or farther from the attachment of a limb or the central aspect of a linear structure, respectively.

Approaches to this module

There are various ways to explore this module.

One is to read through the text, and to follow the ‘search tips’ where it is suggested that you interrupt your reading to view brief but relevant videos.

If you prefer to watch videos than to read, use the following approach:

1. Go to your hub/home screen below and select “courses”

Connective tissue in skeletal muscles • A skeletal muscle is composed of bundles of large striated muscle fibers (the contractile elements) surrounded by collagen and elastic fibers (the connective tissue elements.)

• A thin tubular sheath of connective tissue termed endomysium (within muscle) surrounds each skeletal muscle fiber.

• Bundles of skeletal muscle are surrounded by connective tissue termed perimysium (around muscle).

• The whole skeletal muscle is wrapped in a layer of connective tissue termed the epimysium (upon muscle). See Image 1 and 2.

Structure of a Skeletal Muscle

IMAGE 2

Bony markings from muscle attachments • Skeletal muscle attachments to bone may be fleshy (directly from the muscle belly) or tendinousos (via a tendon or aponeurosis.)

• In each case their collagen fibers blend with the bone via the periosteum.

• The periosteum is a dense layer of vascular connective tissue enveloping the bones except at the surfaces of the joints.

• Tendinous attachments to bone, in contrast to those of fleshy muscles, produce bony markings.

• The attachment of a tendon occupies much less area on a bone.

• The force generated by the muscle pulls on the periosteum with correspondingly greater pressure, leading to prominent markings (and bone mass maintenance).

• These may be in the form of a roughening, a line, a crest, or a tubercle. See Image 3.

IMAGE 5

Image 5.

The deltoid muscle of the shoulder with the middle fibers highlighted.

Muscle belly • Skeletal muscles have a variety of shapes determined by the arrangement of their components.

• A muscle belly lies between the attachments of a skeletal muscle. In many cases there is also a tendon connecting the belly to the site of attachment.

• The site where the muscle becomes continuous with a tendon is called the musculotendinous junction. (See Image 6) • Skeletal muscles are subject to considerable anatomical variation, as are bones. The gastrocnemius usually has a larger medial than lateral head for example, but they can be roughly equal in size. It can have longer fibers and shorter tendons, or vice versa.

• Variations will affect movement and strength abilities.