BMS MSK Lecture 3 Fall 2023 PDF

BMS Anatomy Lecture 3 Back & Anterior Neck Muscles Presented By: Dr. K. Lumsden; [email protected] (Toronto Campus) Dr. M. Doroudi; [email protected] (Boucher Campus) Moore's Clinically Oriented Anatomy, by Arthur F. Dalley II PhD FAAA (Author), Anne M. R. Agur BSc (OT) MSc PhD FAAA (Author), 9th ed....

BMS Anatomy Lecture 3 Back & Anterior Neck Muscles Presented By: Dr. K. Lumsden; [email protected] (Toronto Campus) Dr. M. Doroudi; [email protected] (Boucher Campus) Moore's Clinically Oriented Anatomy, by Arthur F. Dalley II PhD FAAA (Author), Anne M. R. Agur BSc (OT) MSc PhD FAAA (Author), 9th ed. Back Chapter Pages 117 – 129 Neck Chapter Pages 1008, 1030 – 1032 Back Muscles There are two major groups of muscles in the back: The extrinsic back muscles include superficial and intermediate muscles that produce and control limb and respiratory movements, respectively. The intrinsic (deep) back muscles include muscles that specifically act on the vertebral column, producing its movements and maintaining posture. Extrinsic Back Muscles The superficial extrinsic back muscles include: trapezius, latissimus dorsi, levator scapulae, and rhomboids Connect the axial skeleton (vertebral column) with the superior appendicular skeleton (specifically the upper limb) Produce and control limb movements. Although located in the back region, for the most part these muscles receive their nerve supply from the anterior rami of cervical nerves and act on the upper limb. The trapezius receives its motor fibers from a cranial nerve, the spinal accessory nerve (CN XI). Extrinsic Back Muscles The superficial extrinsic back muscles will be covered later as the muscles acting on the pectoral girdle Back Muscles The intermediate extrinsic back muscles (serratus posterior) are thin, weak muscles, commonly designated as superficial respiratory muscles, but are more likely proprioceptive rather than motor in function. The serratus posterior superior lies deep to the rhomboid muscles The serratus posterior inferior lies deep to the latissimus dorsi. Both serratus muscles are innervated by intercostal nerves running within the ribcage. Back Muscles Intrinsic Back Muscles The intrinsic back muscles (muscles of the back proper, deep back muscles) are innervated by the posterior rami of spinal nerves and act to maintain posture and control movements of the vertebral column. The intrinsic back muscles are grouped into superficial, intermediate, and deep layers according to their relationship to the surface. Superficial Layer: Spinotransverse Group Splenius Capitis and Splenius Cervicis Intermediate Layer: Sacropinalis Group Erector Spinae (Spinalis, Longissimus, Iliocostalis) Deep Layer: Transversospinalis Group Semispinalis, Multifidus and Rotatores Interspinal and Intertransverse muscles Thoracolumbar Fascia The intrinsic muscles of the spine will extend from the pelvis to the cranium and are enclosed by a deep fascia known as the thoracolumbar fascia. This structure extends laterally from the spinous processes and forms a thin covering over the intrinsic back muscles in the thoracic region and a strong thick covering for muscles in the lumbar region. Thoracolumbar Fascia 7 Superficial Layer of Deep Back Muscles The splenius muscles (L. musculi splenii) are thick and flat and lie on the lateral and posterior aspects of the neck, covering the vertical muscles somewhat like a bandage, which explains their name (L. splenion, bandage). The splenius muscles cover and hold the deep neck muscles in position. In these tables Ori. & Ins. are FYI Extension Lateral flexion Rotation Intermediate Layer of Deep Back Muscles The massive erector spinae (sacrospinalis) muscles lie in a “groove” on each side of the vertebral column between the spinous processes centrally and the angles of the ribs laterally. The erector spinae are the chief extensors of the vertebral column and are divided into three columns: The iliocostalis forms the lateral column, The longissimus forms the intermediate column T The spinalis forms the medial column. Each column is divided regionally into three parts according to the superior attachments (e.g., iliocostalis lumborum, iliocostalis thoracis, and iliocostalis cervicis). The common origin of the three erector spinae columns is through a broad tendon that attaches inferiorly to the posterior part of the iliac crest, the posterior aspect of the sacrum, the sacro-iliac ligaments, and the sacral and inferior lumbar spinous processes. The erector spinae are often referred to as the “long muscles” of the back. In general, they are dynamic (motion-producing) muscles, acting bilaterally to extend (straighten) the flexed trunk. Intermediate Layer of Deep Back Muscles In these tables Ori. & Ins. are FYI Iliocostalis: Fibers run superiorly and slightly laterally attaching to angles of ribs and cervical TVP’s Longissimus: Fibers run superiorly attaching to TVP’s in thoracic and cervical regions and the mastoid process of the occiput Spinalis: Fibers run superiorly within the laminar groove attaching to SP’s in thoracic and cervical regions Deep Layer of Deep Back Muscles Deep to the erector spinae is an obliquely disposed group of much shorter muscles, the transversospinalis muscle group, consisting of the semispinalis, multifidus, and rotatores. These muscles mainly originate from transverse processes of vertebrae and pass to spinous processes of more superior vertebrae. They occupy the “gutter” between the transverse and the spinous processes and are attached to these processes, the laminae between them, and the ligaments linking them together.. Deep Layer of Deep Back Muscles The semispinalis is the superficial member of the group. As its name indicates, it arises from approximately half of the vertebral column. It is divided into three parts according to the superior attachments; semispinalis capitis, semispinalis thoracis, and semispinalis cervicis Primary Actions: Extension of head, cervical spine and thoracic spine Contralateral rotation. Deep Layer of Deep Back Muscles The multifidus is the middle layer of the group and consists of short, triangular muscular bundles that are thickest in the lumbar region. Primary Actions: stabilization of vertebral column The rotatores, or rotator muscles, are the deepest of the three layers of transversospinalis muscles and are best developed in the thoracic region. Primary Actions: stabilization of vertebral column; proprioception of vertebral column, may assist in small rotatory movements in thoracic spine The interspinales, intertransversarii, and levatores costarum are minor deep back muscles that are relatively sparse in the thoracic region. They are also called the segmental muscle of the back. The interspinales and intertransversarii muscles connect spinous and transverse processes, respectively. The interspinales = extension and rotation Intertransversarii, = Stabilization and lateral flexion Levatores costarum= assit with respiration in elevation of ribs; lateral flexion of column. In these tables Ori. & Ins. are FYI Suboccipital and Deep Neck Muscles The suboccipital region is a muscle “compartment” deep to the superior part of the posterior cervical region, and deep to the trapezius, sternocleidomastoid, splenius, and semispinalis muscles. It is a pyramidal space inferior to the external occipital prominence of the head that includes the posterior aspects of vertebrae C1 and C2. The four small muscles of the suboccipital region lie deep (anterior) to the semispinalis capitis muscles and consist of two rectus capitis posterior (major and minor) and two obliquus muscles. All four muscles are innervated by the posterior ramus of C1, the suboccipital nerve. Primary Actions: Extension of atlanto-occipital joint Rotation of atlanto-axial joint Anterior Neck Muscles The anterior neck muscles can be divided into two major groups; superficial and deep. The superficial group contains the platysma and sternocleidomastoid. All muscles in the group are innervated by the ventral rami of the cervical spinal nerves at the corresponding Platysma Ori: Fascia over deltoid & pectoralis major muscles Ins: Mandible and skin of the lower face Fun: (2) 1. Depresses and draws lower lip inferiorly 2. Depresses mandible @ TMJ N: - C.N. VII (Facial N.) Sternocleidomastoid (SCM). Ori: - medial 1/3 of clavicle - Manubrium of sternum. Ins: - the mastoid process of temporal bone - lateral ½ of superior nuchal line of occipital bone q Sternocleidomastoid (SCM). Fun: (5) Total (unilateral contraction Vs, bilateral contraction) Unilateral contraction: 1. Lateral flexion of head & neck 2. Contralateral rotation of head & neck Bilateral contraction: 1. Ext. of head & upper neck 2. Flex. of the lower neck 3. Elevation of sternum and clavicle (during forced inhalation) N: C.N. XI (Spinal accessory nerve). Anterior Neck Muscles The deep group includes the following muscles: 1. Longus capitis 2. Longus coli 3. Rectus capitis anterior 4. Rectus capitis lateralis 5. Anterior Scalene 6. Middle Scalene 7. Posterior Scalene All muscles in the group are innervated by the ventral rami of the cervical spinal nerves at the corresponding levels Anterior Neck Muscles The deep group includes the following muscles: 1. Longus capitis 2. Longus coli Anterior Neck Muscles The deep group includes the following muscles: 1. Longus capitis 2. Longus coli 3. Rectus capitis anterior 4. Rectus capitis lateralis Anterior Deep Neck Muscles Anterior * Middle * Raise first rib during inspiration Posterior scalene 2nd rib during inspiration In this table Ori. & Ins. are FYI Anterior Deep Neck Muscles PRINCIPAL MUSCLES PRODUCING MOVEMENTS OF INTERVERTEBRAL JOINTS Principal muscles producing movements of thoracic and lumbar intervertebral joints. For trunk movements, we focus on the back muscles NOW until we learn about the abdominal muscles!